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MCA-166 User Manual v2.2

1. Batt connector of the MCA By the electronics in the battery pack charge exchange current between the batteries is limited to 1A and reverse current if an empty battery pack is connected to the MCA is inhibited The current from the battery pack can be seen in the diagnostics menu as charger current The amount of current from the battery pack depends on voltage differences between the batteries and the impedance off the MCA battery about 1 Ohm If there is no current from the battery pack or only something like 2 mA then the voltage of the battery pack is lower than voltage of the MCA battery It should also be noted that in the diagnostic menu only the amount and not the sign of a charging current is registered So a power consumer e g a resistor placed willfully at the Batt connector may be not distinguished from a power source The battery pack can be connected to a charger via the Batt connector For even longer measurement times infinite numbers of battery packs can be connected in chain 100 9 80 D o 60 D g 5 40 e g 20 ss a 0 6 7 8 Battery Voltage V Fig 3 Charge state of the MCA battery in dependence of the battery voltage The charge state off the additional battery pack alone can be evaluated by measuring its voltage at the Batt connector This is practically best done by plugging in the cable to the charger with the connecting block on the charger side rem
2. neg 1o24 CdZnTe CZT500 Ritec Leem x x pos 1024 128 Scintiblock gines o oa p Nal 25825 Scionix pn x x Nal 72016 Robotron 800 512 1 72000 E CCNEEBCOUCENNEI IO a UA CANNE S NNNM ec eneen BB ll Gen 15 190 3000 pos age 24 IS GR 2018 3000 neg sos 241 2 GL 0310 Canbera 2000 x x x neg fso 23 2 m ue ll planar EGC 30 190R 3000 jpos uge 52 IS EGPC 25 185 Eus 52000 neg 4098 8s 12 3 12 Some of the most important photon energies Isotope Half Energy keV Branching ratio Am241 35 Con ma mm S of Ra226 137 640 30 3007y Lr 66 ei 1 Eu152 S E 3 y 121 E EAT 28 778 91 28 E 59 12 98 14 46 1 SEH 11 1112 07 1408 0 3 57 20 85 Hg203 46 61d 27 19 81 84 312 2d 834 82 9998 Pb214 26 8min daughter 241 a RIE 09 351 86 7 eessen 17 37 06 of Ra 226 Ra226 1600y 186 11 328 e 28 Sn113 175 080 515 sss 64 84d sao 0 laa U235 7 04E8y 143 a WA 63 37 185 73 10 STEREO 7 53 15 4 7 205 33 me 898 04 45 X Z amp ELEKTRONIK Pb fluorescence 74 96 72 79 84 99 46 lt E amp ELEKTRONIK 4 Technical Data 4 1 Mini MCA MCA 166 Hardware Specifications 4 1 1 Amplifier 1 Type Gaussian programmable shaping amplifier with pile up rejector and gated base line restorer 2 Gain e From 1 1000 Mini
3. Use the spacebar to toggle between amplifier input pulses with negative or positive input polarity Remember Wrong polarity is a common reason for measuring strange spectra or getting no signal at all PUR Use the spacebar to turn the pile up rejector PUR on or off The pile up rejector should cancel pulses which are very close together in time in order to avoid registering them as one pulse with the energy summed The corresponding dead time is accounted for by the dead time correction scheme Do visual PZC adjustment Press Enter to access the graphical screen which visualizes the pole zero adjustment For adjusting PZC a count rate of 1000 10000 should be optimum 300 30000 may still work and the majority of these pulses should fill the measurement range at least to the half The bar indicates the difference between the voltage at the ADC 11 us after the pulse peak 22 us for 2 us shaping time and 100 us after the pulse peak This voltage should be adjusted to zero A wrong PZC setting may lead to a degraded resolution in particular at high countrates It is also possible to observe the amplifier signal at the amplifier test output with a scope using a high impedance low capacitance probe and to adjust PZC 3 2 3 3 Stabilization setup This function is mostly useful for scintillation detectors as Nal The pulse amplitude of these detectors depends not only on photon energy but is also sensitive to photomultiplier voltage and
4. 4 1 8 Mechanical specification Size 155 mm x 95 mm x 45 mm footprint of palmtop HP 200LX Weight Box incl battery ca 700 g Line voltage sensing Charger ca 320 g 4 1 9 Environmental ratings Range of storage temperature 20 60 degrees C Range of operational temperatures 0 50 degrees C 49 mbH o ELEKTRONIK e Range of humidity e up to 90 non condensing EMC Electro Magnetic Compatibility according to European standard EN 55022 50 GBS ELEKTRONIK isjowayey o Gn MU ees S9uoLiM Bojeuy t 3 a J teba dO NO LING OZd d Addas e i L7 TER LA su o9z Ha e Lpsag4tt aper E 191uno2 10 m z am A o 199189pxe34 e WeOg HIB L E Wels 007 vmgpeiegn o o JEN Cas We gay sueun Q 3 0A ddng OH G ZEZSH o m M E iat stl ope z z418 ug stl p lt 5 AOL 7 5 H ee 5 g I d at AWOL E 1 Deg 00011 sii zii o N S379 Wvu Iesung indul ueg Ju jod a St 51 Figure 11 Block Diagram of the MCA 166 X Z amp ELEKTRONIK 9 gt 45V Proc int e rr Se int int A P Charger LL dis input 54 8 es 12V 60mA batter cto i 12V 60mA Preamplifier Ga 24V 30mA Powersupply o 24V 30mA o 50V 3kV Detectorbias Pg Figure 12 Block Diagram of the MCA 166 Power Supply Table 2 Wiring Diagram of the PC Serial Interface RS2
5. MCS program always 512 Threshold Allows to set a threshold value between 2 and 60 of the current MCA scale Default is 2 This analogue threshold cuts the pulses before they reach the ADC Setting the threshold high discriminates unwanted low energy pulses Do visual threshold adjustment Allows to adjust the threshold using visual control of the spectrum LLD ULD LLD allows to set the lower level discriminator of the ADC The value for LLD must be lt ULD Default is 0 ULD allows to set the upper level discriminator ULD of the ADC The value for ULD must be gt LLD Default is highest possible channel In LLD ULD mode only these counts are used for the MCS spectrum which are between the LLD and the ULD limit LLD and ULD do not affect the measured amplitude spectrum Do visual LLD ULD adjustment Starts acquiring a full spectrum by pressing F5 and by not accepting the current values you can enter new values by moving the cursor to LLD and ULD channel 3 4 2 6 Setup Summary This feature provides an overview on the MCA setup parameters It does not allow any editing The MCS setup parameters can only be seen in the mcS setup menu 3 4 3 Data acquisition menu The acquire menu provides a start function to start data collection The data gathering is controlled from the graphic screen It further provides an energy calibration menu 3 4 3 1 Measurement The first graphic screen is the ACQUIRE screen which contains operative inf
6. a frequency of about 0 5 Hz If there is a voltage drop of more than 10 then the LED starts blinking fast 3 Hz and if this persists for more than 1 5 seconds the power supply is switched off To reset the power supply switch it off wait a second and then switch it on again Charge input connector 4 charge voltage 8 4V 1A max MCA Batt output connector 6 6 8 2V depending on Battery charge state 1A max Wiring of Output connector same as input connector Power Supply Connectors D9 female BNC Contact Voltage warranted max Current Current for before output voltage switching of within 5 D9 1 D9 2 D9 3 D9 4 D9 5 D9 7 D9 8 BNC Connected to D9 3 all current under condition that the total power output limit is not exceeded 12 lt E amp ELEKTRONIK 3 0 Software 3 1 System Requirements Software Installation and Overview Minimal system and software requirements for MS DOS based user programs PC XT compatible computer CGA compatible display adapter 640 KB conventional RAM 550 KB free lower DOS memory 1 MB disk space COM 1 port 16550 compatible UART recommended MS DOS V5 0 or higher For PCs running Windows 3 xx it is strongly recommended to start the MCA software in MS DOS mode to prevent problems in serial communication See also chapter 5 troubleshooting Minimal system requirements for the Windows based user programs Any PC able to run Windows 95 98 COM po
7. channel energy pairs as cursor position or as peak centroid using the graphic screen E Calibration Use the spacebar to turn the energy calibration on or off Peak Position Use the space bar to switch between the use of the peak centroid the cursor position to determine the peak location or manual input of coefficients Do calibration now Switches to a graphic screen to do the energy calibration Input Channel 1 Enter lower channel number in manual mode only and corresponding energy Input Channel 2 Enter upper channel number in manual mode only and corresponding energy Input Coefficients manual mode only Enter the slope in keV channel and the offset in keV 3 2 4 2 Smooth Allows to smooth a spectrum The smoothed spectrum overwrites the original spectrum Use the space bar to switch between a 3 or 5 point smoothing 3 2 4 3 Strip Allows to subtract or add two spectra which must be stored in two groups of the MMCA memory The resulting spectrum overwrites the spectrum in the first group Sign of stripping factor A positive sign default leads to the subtraction of the spectrum stored in the background group a negative sign adds the spectrum You can input a stripping factor default 1 The spectrum stored in the background group will be multiplied with this factor before it is subtracted or added to the spectrum stored 22 ELEKTRONIK in the sample group Use the spacebar to select the number of the
8. higher with the GUI Graphical User Interface optimized for the LCD screen of the HP200LX For Win 95 98 NT the programs WINMCA WINSPEC WINSCAN MCAPLOT IDENTIFY and SFATWIN are available More Windows programs are under development the actual status can be found on the GBS homepage http www gbs elektronik de mca software index_e htm The device can also be operated with the ORTEC software MAESTRO GammaVision ScintiVision etc contact ORTEC for details The firmware of the MCA 166 the software for the internal processor in the MCA is described in Appendix 3 and 4 Instructions how to change firmware can be found in Appendix 5 1 1 1 General DOS software concept e to the extend possible setup menus provide MS Windows pull down menu s and navigation look and feel e easy navigation is also present at the level of the HP 200LX e screens are easy to read on the HP 200LX palmtop computer LCD e special display to control and supervise the measurements 1 1 2 Basic software functions e File menu write read functions with drive path and file picklist functions e Setup menu ADC Amplifier Presets Memory splitting MCA mode MCS mode Multi spectral recording mode automated instrument configuration using setup files e Acquire control Start Stop Clear Presets Automated repeated measurement functions e Display functions Automated linear and logarithmic manual linear Y scale X axis expansion and scrolling Cursor
9. the device off afterwards or connect the charger If the user does not respond and the battery life time is nearly used up battery voltage 6 5 Volts the device switches off 7 eee S automatically It is made sure that the set up and the spectrum previously gathered is saved in the memory of the MCA 166 for at least several month The remaining battery life time is sufficient to transfer the measured spectrum to a computer It is recommended before reading out the MCA 166 to connect it to the charger In the case that the battery voltage drops below its lowest value the battery itself switches off This can be for example the result of a lasting short circuit at the preamplifier power supply As a consequence the internal setup and the measured values are lost The MCA 166 has to be connected to the charger to recharge the battery 2 2 2 Switching on The MCA 166 is set into operation by turning the power switch on see Fig 1 for it s location After a waiting time of a few seconds for the internal reset and check up the green power ON LED flashes with a frequency of 2 5 Hz if no MMCA software runs on the connected computer If the power switch is already in position ON for example after an automatic switch off due to a complete loss of battery power switch OFF and to ON again When the power ON LED does not flash connect the MCA 166 with the charger and repeat once more The MCA166 is online with the computer if the LED flas
10. the appearance of the file and turn on the high voltage Menu Setup Detector high voltage ENTER verify that the HV value and sign correspond to what is written on the detector and follow the instructions in the dialogue box 5 Go to File Autosave to check or set the File saving options Default settings are Autosave no Save also ampl spectrum yes and Remarks yes If Autosave is turned on a startup file name must be saved first e g mba 0001 spe During the automated measurement existing files will be overwritten without or after a warning You can control this by setting Autosave Prompt before overwrite yes or no To avoid data losses give a new name e g MBA 0100 spe to start a new series of measurements The amplitude spectrum information if save is desired is contained in the same file The amplitude spectrum is always acquired in 512 channels regardless of the number of time channels used by the MCS 6 Go to Setup mcS and check the input mode the number of time channels and the time channel dwell time The total measurement time will be calculated automatically when you leave the input field MCA and amplifier settings are not available if the external TTL mode is chosen If the cps or ULD ULD input mode is chosen check the MCA setup parameters against your calibration sheet 7 In case the amplifier or MCA is used cps or LLD ULD options of the MCS input put a source on the detector Go to Ampli
11. with up to 4096 channels can be measured in series which results in a theoretical maximum of 256 M channels in total e MCS mode offers the possibility to measure simultaneous MCS and amplitude spectrum Some bugs concerning the active groups strip compare and move have been fixed PZC offers now also an automatic option SCANDU option CdTe detector test option Supports using signals at the HV inhibit connector for triggering 3 6 2 WinSPEC I for Inspectors WinSPEC was developed for the IAEA It is derived from WinMCA It is used for spectrum measurements equivalent to SPEC DOS programs but with more advanced features as e g integration of MGAU for U enrichment measurements Special attention was spent to the design of the GUI to make its use intuitive and easy 3 6 3 WinSPEC A for Automation WinSPEC A is an extended variant of WinSPEC l It was designed for unattended measurements Special features of this variant are 38 errr aA e Automatic restart of the program after lost of mains power program or operating system crash e Sending commands to a special hardware module on LPT1 for monitoring the State of health already integrated and other states not integrated yet Writing zip files Data file retrieval to a flashcard Archiving of data files Writing a log file This new variant of WinSPEC contains all features of WinSPEC I except the firmware repeat mode 1 3 6 4 WinSCAN WinSCAN is used for can
12. y n 43 X Z amp ELEKTRONIK General use of the software To navigate use the arrow keys To enter a menu or to confirm something use the Enter key To toggle between settings use the space key big key in the lowermost line To exit a menu use the ESC key Step 4 Loading settings Navigate with the arrow keys to setup menu press Enter go to read setup file press Enter Choose by using the arrow keys the setup file for the detector press Enter Enter ESC ESC All parameters can also be set manually they are Detector high voltage see detector in most cases 2000 or 3000V negative or positive check polarity Presets Choice None MCA setup channels 4096 Threshold 2 LLD 0 ULD 3967 ADC Input Amplifier Amplifier setup Coarse gain try at first something between 5 and 50 fine gain 1 Shaping time us 1 or 2 Input polarity look detector manual or just try Stabilization setup Stabilization off Step 5 Switching on high voltage Chose Detector high voltage setup in the setup menu behind high voltage should appear the correct voltage and polarity for the detector check this Press ESC and Enter to switch on high voltage In the lowermost line on the screen should appear the actual voltage now Step 6 Starting measurement Now choose Data acquisition Measurement press Enter The acquisition screen should appear F4 starts a measureme
13. 2 2 1 Power management 2 2 Switching on 2 2 8 Connecting the MCA166 to the Charger 2 2 4 Connecting the MCA166 to a Computer 2 2 5 Connecting the Detectors 2 2 06 Connecting the external additional battery pack 2 2 7 Connecting the Power Pack Software System requirements software installation and overview The DOS program MCA for operating the Mini MCA 3 2 1 File menu 3 2 1 1 Open 3 2 1 2 Save 3 2 1 3 Exit 3 2 2 Acquire menu 3 2 2 1 Start 3 2 2 2 Setup 3 2 2 3 Clear 3 2 2 4 Active group 3 2 2 5 Mode 3 2 8 Setup 3 2 3 1 Detector High voltage setup 3 2 3 2 Amplifier setup 3 2 3 3 Stabilisation setup 3 2 3 4 Preamplifier power setup 3 2 3 5 Setup summary 3 2 4 Analysis 3 2 4 1 E Calibration 3 2 4 2 Smooth 3 2 4 3 Strip 3 2 4 4 Move 3 2 5 Help 3 2 5 1 Diagnostics The DOS program SPEC for measuring spectra 3 3 1 File menu 3 3 1 1 Open 3 3 1 2 Save 3 3 1 3 Autosave 3 3 1 4 Exit 3 3 2 Setup 3 3 2 1 Read setup file 3 3 2 2 Detector High voltage setup 3 3 2 3 Presets 3 3 2 4 MCA setup 3 3 2 5 Amplifier setup 3 3 2 6 Stabilisation setup 3 3 2 7 Setup Summary 3 3 3 Data acquisition menu 3 3 3 1 Start 3 3 3 2 Energy calibration 3 3 4 Help 3 3 4 1 Diagnostics The DOS program MCS for multi channel scaling 3 4 1 File menu 3 4 1 1 Open ELEKTRONIK T a o GBS ELEKTRONIK 3 5 3 6 A i acc Pe 0210000 C005 ero 4 2 3 4 1 2 Save 3 4 1 3 Autosave 3 4 2 Setup 3 4 2 1 Read setup file 3 4
14. 2 2 Detector High voltage setup 3 4 2 3 MCS setup 3 4 2 4 Amplifier setup 3 4 2 5 MCA Setup 3 4 2 6 Setup summary 3 4 3 Data acquisition menu 3 4 3 1 Measurement 3 4 3 2 Smooth 3 4 3 3 Energy calibration 3 4 4 Help 3 4 4 1 Diagnostics 3 4 4 2 About Other DOS software 3 5 1 U235 3 5 2 UF6 3 5 3 LENG 3 5 4 RATE Windows software 3 6 1 The program WinMCA 3 6 2 WinSPEC 3 6 8 WinSPEC A 3 6 4 WinSCAN 3 6 5 WinU235 and WinUF6 3 6 6 Identify 3 6 7 MCAPlIot and MCAPrint 3 6 8 MMCAEVAL 3 6 9 MCAWAND Other operating systems 3 7 1 WinSpec CE 3 7 2 SPEC for EPOC Example for Making a Measurement with a Nal Detector Example for a Measurement with a CdZnTe Detector Example for a Measurement with a HPGe Detector Some examples for parameters of MCA used with different detectors Some of the most important photon energies Technical Data Mini MCA MCA 166 Hardware Specifications 4 1 1 Amplifier ADC Power Supply Preamplifier Voltages High Voltage Battery Computer Interface Mechanical Specifications 4 1 9 Environmental Ratings Block Diagram of the MCA 166 and wiring tables of the connectors BRRRBRBRA sch sch sch sch sch Ge Ain ik Lo ha 5 Troubleshooting APPENDIX 1 MCA 166 spectral format APPENDIX 2 MCA 166 algorithm formulas APPENDIX 3 Description of the MCA 166 Windows DLL command set APPENDIX 4 Description of the MCA 166 firmware functions APPENDIX 5 Changing the MCA 16
15. 20 an indicated change of 10096 means a change of gain by a factor 1 2 y represents the current number of the stabilization cycles Every 25000 counts in the peak area the centroid of this period is recalculated the gain adjusted and the stabilization counter is advanced by one unit 3 3 2 7 Setup Summary This feature provides an overview on the setup parameters It does not allow any editing and is meant to give an overview on the current setup parameters 3 3 3 Data acquisition menu The acquire menu provides a start function to start data collection The data gathering is controlled from the graphic screen It further provides an energy calibration menu 3 3 3 1 Measurement The first graphic screen is the ACQUIRE screen which contains operative information like count rate stabilization status presets for the measurement and which provides a quickly updated live display of the spectrum To start a measurement press F4 During a measurement only 256 channels the width of the spectral display are transferred automatically every 2 sec from the Mini MCA to the Palmtop PC MCA 166 L unzaved 1 Mode MCA Acquire UFS 64 aLin Bat 66 Cursor 0 Window o 4095 Pres LTI Isecl io000 OCps DT 0 0 Elap LTIzecl o HU 500U Help Eval Start Y Exp Menu Figure 9 Acquire Screen that will appear after selecting START from the Acquire menu If an intermediate evaluation is needed a full spectrum snap shot not updated unless reques
16. 3 3 2 Setup The setup menu provides hardware setup functions related to the amplifier and detector preamplifier power supply The default values for different settings are pos 3 3 2 1 Read setup file Read setup file from memory Default directory is GETUP 3 3 2 2 Detector High voltage setup Allows to set the value for the high voltage which is used by the detector Input the value for the detector high voltage here The polarity is automatically set by the hardware depending on which bias module is plugged in The high voltage is turned on after this dialogue box is left with ESC and the corresponding message to turn the high voltage on is acknowledged The default value is the value of the setup file or the last used value or OV after reset The status of the high voltage is shown on the status bar at the lowest line of the screen The voltage as well as the polarity necessary is normally indicated on the detector or at least in the detector s manual Do not exceed the maximum voltage for the detector Use the right polarity Using lower voltages is possible in the case of HPGe detectors the resolution will degrade a bit using lower voltages For a Nal detector with a photomultiplier the amplification will change with high voltage The MCA also supports the possibility of shutting down the high voltage if a detector warm up or another malfunction is registered For enabling this the HV inhibit adapter cable may be connected and the app
17. 32 Connector female Lemo 0S 303 HV Inhibit Signal ext Trigger NL GE EE 7 Table 3 Preamplifier Power Supply Connector D9 female see Table 4 52 High Voltage Inhibit Signal for HV shutdown HV Inhibit mode Voltage at Pin 5 off E Canberra DFG Table 4 HV Inhibit Signal see Windows DLL description 53 ELEKTRONIK r a o z amp ELEKTRONIK 5 Troubleshooting General Remark Before changing anything concerning the hardware plugging or pulling cables etc shut down the high voltage and switch off the MCA Soldering or manipulating with the SMD boards is strongly not recommended for users We have specialists for that If you have a problem which cannot be solved by the table below contact us If it is really a hardware fault we can repair this for a fair price Software tells MCA not connected e Switch on the MCA e Check cable between MCA and Computer Serial cable at HP200LX may be loose or connected upside down Connect cable correctly e Check MCA battery Charge MCA battery The MCA is not recognized MCA not connected running MCA DOS Software in a DOS Box on Notebooks e Disable Power Save Mode for COM1 Port MCA lamp does not flash regardless if the switch is on or off e MCA battery empty Charge MCA battery e The MCA firmware programming switches are in a wrong position The firmware programming switches must be all in off position Do
18. 6 Firmware beer eme 1 0 Introduction The Mini MCA MMCA model MCA 166 is a battery powered high performance 4K Multi Channel Analyzer Multi Channel Scaler module comparable in its performance with laboratory grade MCAs High voltage supply for detector and preamplifier power supply are integrated as well as an internal amplifier and pulse shaping network The MCA is optimized in its shape for use with a HP 200 Palmtop but can also be used with any other Laptop or standard PC Together with a small detector it forms a pocket size gamma spectroscopy system and timer counter which is well suited to the demands of field measurements for international safeguards environmental monitoring nuclear waste treatment facilities radioactive transport control and similar applications Furthermore the MCA 166 supports a vast number of different detectors and its 4k resolution is adequate to support high resolution gamma spectrometry with HPGe detectors 1 1 Mini MCA MCA 166 Software The Mini MCA software allows to operate the device as a general purpose multi channel analyzer MCA SPEC and multi scaler analyzer MCS Additional user programs which support safeguards specific applications as U 235 enrichment verification U235 spectral radiation survey meter mode supporting active length determination LENG UF6 RATE are available Since the lowest computer platform is the HP 100LX palmtop computer the software works under MS DOS 5 0 or
19. Miniature Multi Channel Analyser MMCA Model MCA 166 User s Manual Version 2 2 Peak Centroid 242 95 FUHM 17 41 UFS 4K aLin Cursor dd ROI 4 226 260 Counts 1848 ElaptLzs o DT 6 0 Int 39277 Area 30483 1 439 Help MN Exp Menu GBS ELEKTRONIK mbH o ELEKTRONIK Exclusion of liability The GBS Elektronik GmbH is not liable for errors and does not guarantee the specific utility of the MCA 166 software or firmware In particular the GBS Elektronik GmbH is not liable for indirect or subsequent damages due to errors of the MCA 166 software or firmware The information in this manual has been carefully reviewed and is believed to be accurate and reliable However the GBS Elektronik GmbH assumes no liabilities for inaccuracies in this manual This manual is subject to change without notice Last update 15 1 2001 Address GBS Elektronik GmbH Bautzner LandstraBe 22 01454 GroBerkmannsdorf Tel 0351 217007 0 Fax 0351 217007 21 For software updates or problems exceeding the frame of this manual refer to Internet http www gbs elektronik de or send email to kontakt 2gbs elektronik de Table of Contents 1 0 1 1 2 0 2 1 2 2 3 0 3 1 3 2 3 3 3 4 Introduction Mini MCA MCA 166 Software Specification 1 1 1 General Concept 1 1 2 Basic Software Functions Hardware Users safety information 2 1 1 Power source 2 1 2 High Voltage supply General description
20. al screen which visualizes the pole zero adjustment For adjusting PZC a count rate of 1000 10000 should be optimum and the majority of these pulses should fill the measurement range at least to the half The bar indicates the voltage at the ADC 8us after the pulse peak maximum This voltage should be adjusted to zero A wrong PZC setting may lead to a degraded resolution 3 3 2 6 Stabilization setup This function is mainly useful for scintillation detectors as Nal The pulse amplitude of these detectors depends not only on photon energy but is also sensitive to 28 e i bereest photomultiplier voltage and temperature This drift can be compensated by regulating the fine gain of the amplifier on the position of a reference peak The reference peak has to be marked as a ROI Usual is to use the 60 keV Peak of an Am241 source Some detectors have for this purpose a built in Am241 source In enrichment measurements it is also possible to stabilize on the 186 keV peak of U235 To activate stabilization turn on stabilization by toggling the stabilization on off setting with the spacebar With Do visual Stab you can adjust the values for Stabilization ROI begin Stabilization ROI end and Stabilization Centroid target channel where the peak should be When stabilization is enabled in the acquisition screen can be found Stab x y Here x is the change in gain in percent of the regulation range As the regulation range is
21. aphic screen is the ACQUIRE screen which contains operative information like count rate presets for the measurement and which provides a quickly updated live display of the spectrum To start a measurement press F4 During a measurement only 256 channels the width of the spectral display are transferred automatically every 2 sec from the Mini MCA to the Palmtop PC 16 2 o MCA 166 unsaved 1 Mode MCA Acquire ROSTER ta a UFS 64 aLin Bat 66 Curzor o Window o 40905 Pres LTIsecl 1io0000 OCps DT O 0z Elap LTIsecl o HU 500u Help Eval Start Y Exp Menu Figure 6 Aquire Screen that will appear after selecting START from the Acquire menu If an intermediate evaluation is needed a full spectrum snap shot no life spectrum display not updated unless requested by pressing F2 again is presented on a second graphical screen EVALUATION screen showing the evaluation information peak information numeric calculations To enter the evaluation screen press F2 Peak Centroid 242 95 FWHM 17 41 UFS TS EE 4K aLin Cursor d ROI 4a 226 260 Counts 1846 ElaptLs 0 DT O 0x Int 3927TT firea go483 r 439 Help Y Exp Menu Figure 7 Evaluation Screen A cursor bold dotted line is available on both screens and ROls are indicated intense regions in between two dotted lines e To move the cursor use right and left arrow key e To mark a ROI press the SHIFT key while moving the cursor and release SHIFT an
22. ave the file Afterwards you can enter a comment or a short description of the spectrum 3 4 1 3 Autosave The autosave option causes a measured spectrum to be immediately saved after recording Options are to prompt before overwriting an existing spectrum to include also the amplitude spectrum and to ask for a remark before saving The spectra are saved in the format XXXX0000 SPE XXXX0001 SPE Before the first spectrum in autosave mode is recorded it is asked for an appropriate name Defaults are no for autosave and yes for remarks amplitude spectrum and prompt before overwrite 3 4 2 Setup The setup menu provides hardware setup functions related to the MCS settings and amplifier 3 4 2 1 Read setup file Read setup file from memory Default directory is SETUP 3 4 2 2 Detector High voltage setup Allows to set the value for the high voltage which is used by the detector Input the value for the detector high voltage here The polarity is automatically set through the hardware depending on which bias module is plugged in The high voltage is turned on after this dialogue box is left with ESC and the corresponding message to turn the high voltage on is acknowledged The default value is the value of the setup file or the last used value or OV after reset The status of the high voltage is shown on the status bar at the lowest line of the screen The voltage as well as the polarity necessary is normally indicated on the detector
23. crystal temperature This drift can be compensated by regulating the fine gain of the amplifier to keep the position of a reference peak The reference peak has to be marked as a ROI Usual is to use the alpha peak of an Am241 source Some detectors have for this purpose a built in Am241 source In enrichment measurements it is also possible to stabilize on the 186 keV peak of U235 To activate stabilization turn on stabilization by toggling the stabilization on off setting with the spacebar You are then asked to accept or to change the stabilization ROI settings 3 2 3 4 Preamplifier power setup Allows to turn certain preamplifier supply voltages off to extend battery life by about 1096 Use the spacebar to turn a preamplifier supply voltage off in case the used preamplifier 21 GmbH ELEKTRONIK does not use a certain voltage If supply voltages which are not needed are turned off the battery lasts longer 3 2 3 5 Setup Summary This feature provides an overview on the setup parameters It does not allow any editing and is meant to give an overview on the current setup parameters 3 2 4 Analysis The analysis menu allows to perform basic MCA analysis functions like energy calibration the movement of a spectrum from one memory group to another smoothing of a spectrum and subtraction of spectra 3 2 4 1 E Calibration Allows to perform a two point energy calibration The calibration coefficients can be set as numeric values
24. d then the arrow key after the end of the ROI has been reached e To delete a ROI move the cursor into the ROI and press the DELETE key Both screens have the same principal layout The top line shows the path and filename of the spectrum On the left side the vertical full scale VFS is displayed together with the Y scale mode either automated linear logarithmic or manual linear change this with F6 In addition the ACQUIRE screen shows the remaining battery capacity of the MCA Under the spectra display there are four lines with status information some of them appearing on both the ACQUIRE and EVALUATION screens e g the cursor information ROI resp X range and the dead time If the cursor is within a ROI its number and boundaries are shown On the EVALUATION screen is then additionally the peak 17 mbH ELEKTRONIK information integral area centroid and FWHM shown If the MCA is calibrated peak information is shown in keV otherwise in channels The last row of the graphics screens shows the actual functions of the function keys From left F1 to right F10 on the HP200LX the corresponding function keys are just below the screen 3 2 2 2 Setup Allows to setup the acquire functions like Presets MCA channels Threshold Upper and lower Level discriminators LLD ULD ADC input and automated repetitive measurements The parameters asked for depend on if the MCA is set to MCA or MCS mode Stop condition O
25. du bundle verifications WinSCAN is in its features somewhere between MCA and MCS It can measure up to 500 Spectra and save them in one file Evaluation is similar to MCS just that there is not only an integral spectrum but one spectrum for every point so it is possible to evaluate courses off arbitrary net or integral ROI areas 3 6 5 WinU235 and WinUF6 WinU235 and WinUF6 are the corresponding Windows applications for the DOS applications U235 and UF6 3 6 6 Identify Identify is an intelligent interactive software tool to evaluate spectra measured with the MCA 166 or other MCAs It does peak search and nuclide identification HPGe CdZnTe and Nal detector gamma spectra are supported For correct peak search a starting point for the detector resolution and efficiency is assumed based on detector type and size Features includes full master library of gamma lines derived from table of radioactive isotopes e editor for creating application specific evaluation libraries e detector function is calculated from detector data sheet no efficiency calibration needed e automatic determination of FWHM of the peaks found in a spectrum as function of energy supports 1 to 3 point energy calibration linear logarithmic square root and double log representation possible e error estimations confidence assessment for identified isotopes and visualization by overlay of calculated spectrum for a certain isotope e switching between Eng
26. e end of the peak Release the shift key and keep moving one or two channels Now move the cursor back into the ROI highlighted region to see peak characteristics such as Centroid FWHM Area Area error and Integral Step 9 Try other functions such as F7 expand Y vertical full scale Press F1 for help on the options available Step 10 e Press ESC or F10 to return to the main menu Step 11 Go to the File menu select Exit and press Enter Select yes and press ENTER when the question Turn HV off now will pop up Press ENTER again to leave the spectrum unsaved Step 12 e Turn off the MCA You are now back to the MS DOS prompt 3 9 Example for a Measurement with a CdZnTe Detector Used in this case SDP310 Z 60 from Ritec Step 1 Connecting cables The Palmtop 200 LX has to be connected by cable to the MCA 166 the detector SDP310 Z 60 with its 3 different connectors has also to be connected to the MCA 166 Step 2 Switching on Switch on MCA the green lamp should start to flash Switch on Palmtop the key in the uppermost right edge ON A menu with options for different programs should appear If not try Ctrl Alt Del or Shift yellow arrow Ctrl ON Step 3 Starting program Type 3 to start SPEC program Answer y and Enter The big key with the left arrow on the question Reset MMCA to SPEC defaults and clear all spectra y n General use of the software To navigate use the arr
27. e figure 1 with a scope A typical signal which should be seen is shown in figure 2 0 01 0 02 0 03 l wa Detector Signal V Amplifier V Time us Figure 2 Typical signals which can be seen at the detector preamplifier out and the amplifier test out This example CdZnTe Detector SDP310 Z 60 measuring a Cs137 mbH o ELEKTRONIK sample amplifier setting 200 0 91 negative pulses 1us shaping time pulse height equals to about channel 662 of 1024 channels Typical errors which may be observed with the detector preamp signal are Rise time is too slow 20 5 us This may cause the pile up rejector not to work correctly There may be even a large amount of regular pulses rejected and especially the high energetic part of the spectrum seriously affected When using such detectors switch pile up rejection off The fall time is too fast time constant resp 1 e fall time lt 40us This causes that the pole zero setting cannot be correctly adjusted Consequences may be peak shift and peak broadening with higher countrates and increased low energy spectrum cutoff Try to used another preamplifier 2 2 6 Connecting the external additional battery pack The additional battery pack can be used to extend measuring time up to 250 of that of the stand alone MCA e g to 20 hours with a HPGe detector and to about 35 hours with a Nal or CdZnTe detector The MCA cable has to be plugged into the
28. ea centroid and FWHM shown If the MCA is calibrated peak information is shown in keV with F9 can be toggled between channels and keV otherwise in channels The last row of the graphics screens shows the actual functions of the function keys From left F1 to right F10 on the HP200LX the corresponding function keys are just below the screen 3 3 3 2 Energy calibration Allows to perform a two point energy calibration The calibration coefficients can be set as numeric values manual input channel energy pairs as cursor positions or as peak centroids using the graphic screen E Calibration Use the spacebar to turn the energy calibration on or off Peak Position Use the space bar to switch between the use of the peak centroid the cursor position to determine the peak location or manual input of coefficients 30 ELEKTRONIK Channel 1 Enter lower channel number in manual mode only and the corresponding energy Channel 2 Enter upper channel number in manual mode only and the corresponding energy Do visual calibration not in manual mode Switches to a graphic screen to do the energy calibration In cursor mode it is asked for two cursor positions in centroid mode it is asked for two calibration peak ROls Input Coefficients manual mode only Enter the slope in keV channel and the offset in keV Actual Calibration shows the actual used calibration coefficients 3 3 4 Help You can get a short help sc
29. ector with a photomultiplier the amplification will change with high voltage 3 2 3 2 Amplifier setup This submenu can only be activated if ADC input see 3 2 2 2 is set to Amplifier Allows to setup the amplifier parameters like gain shaping time input polarity pile up rejector PUR and pole zero cancellation PZC PZC and gain can also be adjusted using a graphic screen to support fine tuning Coarse gain Use space bar to select the value for the coarse gain 2 1000 Fine Gain Input the value for the fine gain 0 5000 1 5000 Do visual gain adjustment Press Enter to switch to a graphical screen with the spectrum Use the screen to adjust the fine gain while observing the spectrum If the cursor is currently in a ROI then the peak centroid will be shown This is useful to do some coarse calibration by adjusting fine gain in a way that an even proportion between channel numbers and photon energy is achieved 20 lt E amp ELEKTRONIK Shaping time Use the space bar to toggle between the two time constants 1 and 2 microseconds The shaping time is the time constant of the RC in the pulse shaping network The pulse FWHM time is about 3 5 times the shaping time the total pulse time from 1 peak amplitude to 1 peak amplitude may be as long as 10 times the shaping time Use 2 microsec for low countrate measurements with a HPGe detector where the best resolution is needed and 1 microsec in all other cases Polarity
30. ents are battery currents and not the actual currents at 12V and 24V or high voltage currents To get an idea of the actual currents a converter efficiency of about 80 can be assumed The following formula will help Tagg O8 I SC aus Batt U aus If now for example a current off 120 mA is shown for the 24V and the actual battery voltage is 7 5 V then the current at the 24V output is approximately 30mA I 08 120mA V 24V aus 3 3 The DOS program SPEC for measuring spectra The user program SPEC is the default program for measuring spectra It supports semiautomated measurements of gamma ray spectra e g for the IAEA safeguards procedures MGA and MGAU with the portable multi channel analyzer MCA 166 The spectra are stored on mass storage media on a PC and can be analyzed with standard codes like VBMGAU Getting Started 23 mbH o ELEKTRONIK The MCA 166 must be connected to the detector of your choice usually HPGe or other high resolution detector and to the computer see chapter 2 Place the detector in correct position for a measurement Switch on the MCA 166 and the computer and start the SPEC User Program Usually you will have a setup file prepared and stored on your computer which is specific for your task and the detector to be used By reading this file the correct settings of the MMCA will automatically be restored You will need only switch on the HV and a fine tuning of the
31. er now and press ENTER You will now be prompted with a graphic screen If the radio active probe was placed near the detector a growing spectrum will appear If you can not see the spectrum change the coarse gain You may adjust the fine gain to shift the peak by using the and keys Once you have finished press ESC and Y to save the value Step 5 Move on to Do PZC and press ENTER You will be prompted with the screen Manual PZC Adjustment Press or to minimize the zero offset minimize the deviations of the shaded bar on the left from the middle Once the offset is equal or close to 0 press ESC and Y to save the value Step 6 Press ESC and ENTER to accept the amplifier settings and quit the Setup menu by pressing ESC again Step 7 Go to the Acquire menu select Start and press ENTER You will now see the graphical Acquire screen e Press the F4 softkey to start the measurement You will now see the growing spectrum and other frequently updated values such as elapsed time dead time countrate in counts per second etc 41 X Z amp ELEKTRONIK Step 8 Press the F5 softkey to stop the measurement and to transfer the spectrum to the PC The acquire screen will change to the evaluation screen and you will see the entire spectrum e Move the cursor to the begin of a peak use arrow keys and while holding down the shift key move to th
32. et an idea of the actual currents a converter efficiency of about 80 can be assumed The following formula will help Ip OB Ipa U nas U aus If now for example a current off 120 mA is shown for the 24V and the actual battery voltage is 7 5 V then the current at the 24V output is approximately I 0 8 120mA le 30mA 24V aus The settings of Discriminator threshold fast and slow are also shown These settings have influence on pile up count rate dead time and noise suppression performance and are normally fixed with the software There may be differences between some older software versions and values may only be influenced by setup files 3 4 1 2 About Gives Program version information 3 5 Other DOS software For a detailed description of the following programs look at their specific documentation help files included 3 5 1 U235 This program supports stabilized U 235 enrichment verification measurements with a Nal or CdZnTe detector PMCN PMCC The algorithm bases on absolute intensity measurement of the 186 keV photon energy It also needs a two point intensity calibration with two standards Re evaluation re calibration using previously recorded spectra is possible Verification results are documented in a report file which is automatically saved with the extension rep if the the dialogue box 3 5 4 UF6 37 GmbH ELEKTRONIK Similar to U235 but optimized for HPGe detectors Only one i
33. etween 2 and 60 of the current MCA scale Default is 296 This analogue threshold cuts the pulses before they reach the ADC Setting the threshold high discriminates unwanted pulses and reduces the dead time of the ADC Do visual threshold adjustment Allows to adjust the threshold using visual control of the spectrum 18 LLD ULD eee LLD allows to set the lower level discriminator of the ADC All channels below the LLD value remain empty The ADC deadtime however is not reduced The value for LLD must be lt ULD Default is 0 ULD allows to set the upper level discriminator ULD of the ADC All channels above the ULD value remain empty The ADC deadtime is not reduced The value for ULD must be gt LLD Default is highest possible channel In MCS mode main application for this if LLD ULD is set LLD and ULD define the limits within impulses are counted In MCA mode it is more recommended to use Threshold than LLD to remove noise and low energy components of the spectrum ADC input MCA mode Use the spacebar to toggle between the 2 different direct inputs 3V dir 3 V dir if you want to use for e g an external amplifier or select Amplifier in order to use the internal amplifier Default is amplifier Input Type MCS mode Use the spacebar to select between extern TTL pulses Input Rate from the MMCA count rate meter or LLD ULD Only impulses between the LLD ULD limit are counted Default is TTL Thi
34. ext editor for this Too high background rate with BICRON detectors e Set Fast Threshold to 600 You have to edit a setup file with a text editor for this for gain gt 50 Edit setup file MCA battery does not charge correctly e You have connected charger in a wrong order Connect charger first to MCA and then charger to mains HP 200 tells main battery low or Hauptbatter schwach e This is the battery of the HP and not the MCA battery You can continue measuring but should switch the HP off most of the time to save its battery Charge or change HP battery Everything should be okay but the MCA gets no signals or just measures strange spectra e wrong input polarity Check input polarity just toggle it for a test e The amplification is severely wrong set e wrong input mode Check also ADC input mode Strange error messages e MCA opened recently flat cables loose Connect flat cable again Very bad resolution in a HPGe spectrum e Detector worn out or defective Change and regenerate detector e Problems with the high voltage module Try another high voltage module Bad resolution in a HPGe spectrum or from a test generator specially at high amplification factors e Check electrical noise and EMC compatibility of surroundings Some laptops and also some switch mode power supply battery chargers may disturb Remove all connections from the MCA to ground or to mains voltages Try a different computer laptop palmtop e Wi
35. fier Setup Switch to visual gain adjustment Enter Use keys to move the peak into the desired channel Press ESC Y to check the PZC adjustment by minimizing the vertical bar on the left side of the screen using the keys The source strength must be between 300 and 30000 cps and the spectrum must reach at least 50 of the MCA range Leave the dialogue box accepting all settings 8 Go to Data acquisition Measurement to start a MCS measurement Description of the MCS program in order of the commands 3 4 1 File menu The file menu allows to open and to save files Files contain MCS spectrum data with setup information and may also contain amplitude spectrum data 32 bereest 3 4 1 1 Open This leads to a file selection box Under Dir you can type the drive letter for e g a In the right part of the box the roots directory and subdirectories of the drive are shown Move the cursor bar to the desired subdirectory and press Enter to select it Pick the file in the left box with the cursor bar and press Enter to retrieve it You first can read the comment to the spectrum ESC then leads to the evaluation screen with opened spectrum 3 4 1 2 Save Here you enter a drive and file box Under Dir you can type the drive letter e g a and press Enter Using the Arrow and Enter keys select the subdirectory into which the file is to be saved Type the filename under File Move the cursor bar to OK and press Enter to s
36. four lines with status information some of them appearing on both the ACQUIRE and EVALUATION screen e g the cursor information ROI resp X range If the cursor is within a ROI its number and boundaries are shown On the EVALUATION screen is then additionally information integral ROI integral shown The MCA evaluation screen shows amplitude information If the MCA is calibrated peak information is shown in keV F9 toggles between channels and keV otherwise in channels The last row of the graphics screens shows the actual functions of the function keys From left F1 to right F10 on the HP200LX the corresponding function keys are just below the screen 3 4 3 2 Smooth Allows to smooth a spectrum The smoothed spectrum overwrites the original spectrum Use the space bar to switch between a 3 or 5 point smoothing 3 4 3 3 Energy calibration Allows to perform a two point energy calibration The calibration coefficients can be set as numeric values manual input channel energy pairs as cursor positions or as peak centroids using the graphic screen E Calibration Use the spacebar to turn the energy calibration on or off Peak Position Use the space bar to switch between the use of the peak centroid the cursor position to determine the peak location or manual input of coefficients Channel 1 Enter lower channel number in manual mode only and the corresponding energy Channel 2 Enter upper channel number in manual
37. function ROI setting and processing 5 mbH o ELEKTRONIK Peak stabilization Analysis functions ROI peak area and integral FWHM calculation Analysis report function Energy calibration function linear calibration curve using 2 peaks Incorporated Help texts Print screen for quick documentation lt E amp ELEKTRONIK 2 0 Hardware 2 1 Users safety information Read all these instructions first Save these instructions for later use Do Not Remove Connectors To avoid personal injury or damage of equipment do not remove the connectors for the High Voltage supply preamplifier supply and the input connector until the High Voltage is shut down and the device is switched off at least for 1 minute Do Not Remove Covers Do not open the device before the power is switched off 2 1 1 Power Source This device is intended to operate from an internal accumulator set high performance Li lon battery or together with the external charger from a power source Do not apply more than 240 volts rms between the supply conductors of the charger The power cord and the connector must be in a good condition Do not allow anything to rest on the power cord 2 1 2 High Voltage Supply Make sure that the High Voltage connector and the High Voltage supply cable of the detector are in a good condition before connecting them to the MCA 166 or before switching the High Voltage on Do not allow anything to rest on the HV cable Never
38. gain in case of high resolution measurements also of the pole zero adjustment before starting a measurement Once SPEC is started you should reset the MMCA answer the corresponding question in the startup screen with Yes Navigate through the menus with the Arrow and Tab keys open a menu with the Enter key accept settings by leaving a menu with the Escape and Enter keys Use the context sensitive on line help which is available if you press the function key F1 In the menu screens which are used to define or change settings the active fields are highlighted You will find information on how to change the highlighted parameter in the bottom line of the active menu screen The user interface of the SPEC program is almost identical with the generic multi channel analyzer program MCA which is described in chapter 3 2 To start a measurement proceed as follows e Read the setup file prepared previously Setup gt Read setup file e Switch on the HV Setup gt Detector high voltage setup e Choose your preset life time real time or none Setup gt Presets e Check or change if necessary the MCA resolution channels thresholds lower upper levels for spectrum collection Setup gt MCA Setup The optimum choice for your task is probably already defined in the setup you read in but you have access to all of these parameters Here you can also toggle the options for the signal input internal amplifier direct input of positive o
39. he interface cable with the standard D9 connector of the computer will be used For use with the HP680 request a special cable For proper wiring see 4 2 2 2 5 Connection of detectors To connect a detector switch the device off Before connecting the high voltage connector of the detector Make sure that the built in High Voltage supply has the right polarity and that the power consumption of the detector does not exceed the maximum value 0 5 mA or 0 25 Waitt Polarity can be checked by Software go to the menu setup high voltage and look at indicated polarity You can also open the MCA and check the HV module itself red HV module positive blue HV module negative The correct values for HV polarity and power consumption should be found in the detectors manual e Check by the detector manual that the pin assignment of the preamplifier power supply connector is compatible with the MCA 166 and that the power consumption does not exceed the maximum ratings see Table 3 Chapter 4 2 e Connect the cable for the preamplifier power supply of the detector to the concerning female D9 connector on the MCA 166 and attach it by the clamps e Plug the BNC Signal connector of the detector to the female BNC input connector of MCA 166 e Plug the High Voltage connector of detector into the female SHV connector of MCA 166 If problems occur it is possible to check the detector signal and the main amplifier signal Amplifier Test out se
40. hes with 1 2 Hz Irregular flashing of the lamp indicates an error Detector Signal IN Preamplifier Power High Voltage OUT 350 5000V Figure 1 Front Panel of MCA 166 2 2 3 Connecting the MCA 166 to the Charger Before connecting the charger to the MCA 166 pull out the mains power connector of the charger Otherwise the charger does not work properly In one version of the charger make sure that the switch is in the charge position First connect the Lemo see Table 1 in chapter 4 2 for a wiring diagram to the MCA166 Then plug the power connector see Fig 12 in chapter 4 2 for a block diagram into the power socket The CHARGE lamp orange of the charger will light and charging will begin When the charging is completed the CHARGE lamp will switch off If the CHARGE lamp flashes permanently check the connection to the MCA 166 and disconnect and connect the power connector to the power socket again It is possible to work with the charger permanently connected to the MCA 166 2 2 4 Connecting the MCA166 to a Computer The MCA166 is interfaced to the serial port Table 2 with a fixed baudrate of 38 4 kBaud The baudrate on the computer is set automatically by the MMCA software The special short serial interface cable is used to connect the HP 200LX proprietary connector to the 8 serial interface Lemo connector type 0S 303 of MCA 166 To EE connect the MCA 166 with a notebook PC or any other industry standard PC t
41. insert objects of any kind into the High Voltage connector as they may touch the dangerous voltage point This might cause an electric shock or a damage of the device 2 2 General Description The MCA 166 is an autonomous module The device has its own battery and provides power supply to radiation detectors Together with a computer the MCA 166 forms a multi channel analyzer The spectra are collected in the memory of the MCA 166 and are transferred via a serial interface periodically to the computer The computer is used to setup the MCA 166 to display and process the measurement results and to store the data The design concept of the MCA 166 also supports a Multi Channel Scaler mode For operation the MCA 166 itself has only a power switch and a green LED indicator 2 2 1 Power management The MCA 166 works with a built in re chargeable Li lon battery which has no memory effect and is deep discharge and short circuit protected If the device is working the remaining battery life time is permanently checked When the battery voltage has dropped down to 6 8 Volts while a data collection is in progress the MCA 166 gives out a warning to the user the lamp will flash irregularly and the software will show an error message The running measurement is automatically stopped and the detector high voltage together with the preamplifier power supply will be switched off The user can now transfer the measured spectrum to the computer but should switch
42. lish and German languages e interactive nuclide pattern identification e nuclide assignment suggestions also for each single peak instant graphical comparison to simulated spectra by clicking on a nuclide e Win 3 1 version also available IDENTIFY is not included in the MCA price 3 6 7 MCAPlot and MCAPrint MCAPIot and MCAPrint are programs to view and print spectra recorded with the MCA 166 Up to 32 spectra can be viewed at the same time and be printed on one page Also 39 mbH o ELEKTRONIK some evaluation functions are available MCAPlot is not included in the MCA price MCAPrint is a free downgraded version of MCAPIot 3 6 8 MMCAEVAL MMCAEVAL is a program for evaluating groups of spectra and extracting information to a MS Access style data base 3 6 9 MCAWAND MCAWand is a program for converting different file formats Please note that there may be always a loss of information as not all kind of information about the spectrum is supported by every file format The following information is converted e Channel Data Energy Calibration Energy Calibration points Livetime Realtime Date and Time of measurement Spectrum Remark The following file formats are supported Source j Target OO spe Interwinner spe Interwinner spc Target PO dat two column energy Channel content 3 7 Other operating systems 3 7 1 WinSpec CE WinSpec CE is similar to Winspec bu
43. ll programs 13 X z amp ELEKTRONIK can also be used offline for data viewing and evaluation without a MMCA module connected The MCA software will fully use all the hardware and firmware features of the MCA This includes setup measurement control data display and analysis storage and retrieval of data In the MCA emulation software only data evaluation features are implemented For more advanced processing the data can be read in other software packages The program MCA was the first emulation program for the MCA all other programs are derived from it This program is mainly used for testing and general applications For measuring spectra the program SPEC is more recommended The program MCS allows to measure time dependent count rates there is also a mode where amplitude and time spectra can be recorded simultaneously There exist also further programs for special applications at IAEA such as U235 UF6 RATE LENG These programs are not described here in short form only Note that the MCA emulation software is DOS based written and optimized for the HP Palmtop hardware i80x86 CPU CGA VGA video adapter monochrome display and special keyboard layout Some features are therefore not optimum for desktop or laptop computers If you want a more convenient working with a desktop WINMCA or WINSPEC are recommended For creating own software for the MCA the MCA command set is described in appendix 3 and 4 For the
44. memory group where the sample spectrum is stored and where the background spectrum is stored There are still some bugs within the memory groups 3 2 4 4 Move Allows to move a spectrum from one memory group to another Using the space bar select the source group where the spectrum which you want to move is located The content of this group will be cleared after the transfer is complete Then select the destination group into which you want to move the spectrum The content of this group will be overwritten when Move is executed There are still some bugs within the memory groups 3 2 5 Help You can get a short help screen by moving the cursor to the menu item you want more information about and pressing F1 The help menu gives also information about the used software version command about The Help menu is context sensitive To get help on a certain function press F1 and a context sensitive message will pop up If the Help text exceeds the length of the screen use the arrow keys to scroll Use ESC to leave a Help screen and return to the menu The Help menu also includes a MCA Diagnostics screen 3 2 5 1 Diagnostics Shows useful information about the attached Mini MCA version voltages and currents Also displayed is the actual MCA Battery voltage and current A blinking current value means overload or low battery voltage All battery currents used for the preamplifier supply voltages and for high voltage are shown Remember The curr
45. mode only and the corresponding energy Do visual calibration not in manual mode Switches to a graphic screen to do the energy calibration In cursor mode it is asked for two cursor positions in centroid mode it is asked for two calibration peak ROls 36 beer ene Input Coefficients manual mode only Enter the slope in keV channel and the offset in keV Actual Calibration shows the actual used calibration coefficients 3 4 4 Help You can get a short help screen by moving the cursor to the menu item you want more information about and pressing F1 The help menu gives also information about the used software version command about The Help menu is context sensitive To get help ona certain function press F1 and a context sensitive message will pop up If the Help text exceeds the length of the screen use the arrow keys to scroll Use ESC to leave a Help screen and return to the menu The Help menu also includes a MCA Diagnostics screen 3 4 4 1 Diagnostics Shows useful information about the attached Mini MCA serial number hardware version firmware version voltages and currents Also displayed is the actual MCA Battery voltage and current A blinking current value means overload or low battery voltage All battery currents used for the preamplifier supply voltages and for high voltage are shown Remember The currents are battery currents and not the actual currents at 12V and 24V or high voltage currents To g
46. move the cursor around e Use the enter key to enter a menu or to confirm an action e Use the space key to toggle between settings e Use the ESC key to exit a menu you are then asked if you want to accept the settings this does not comply with Windows GUI standards but was caused by the DOS GUI development tool used to develop the software 3 2 1 File menu The file menu allows to open and to save files Files are spectral data files with setup information 3 2 1 1 Open Here you reach a submenu with the choices to open a drive and file selection box or to set file retrieve options Another Open leads to a file selection box Under Dir you can type the drive letter for e g a In the right part of the box the roots directory and subdirectories of the drive are shown Move the cursor bar to the desired subdirectory and press Enter to select it Pick the file in the left box with the cursor bar and press Enter to retrieve it Options leads to a menu to set the options for retrieving a file Normally all options are set to yes to retrieve a file with all setup ROI and calibration information If for e g only the ROI option would be set to yes only the ROI list would be retrieved and could be 15 mbH o ELEKTRONIK overlayed to a spectrum already stored in the memory Use the spacebar to toggle the options between yes and no 3 2 1 2 Save Here you reach a submenu offering the choice to open a drive box o
47. mum gain step 0 5 channel for 2K scale Gain tuning under visual control of spectrum Gain adjustment by peak stabilizer Integral linearity of amplifier 0 196 for full output range 3 Input e accepts positive and negative preamplifier signals input resistance 1 kOhm DC coupled accepting 200 mV DC levels maximum input signal corresponding to full ADC scale at minimum gain 3V 10V with external attenuator and input set to direct input With input set to amplifier the maximum voltage step from preamplifier corresponding to ADC full scale at gain 1 is 9 5 V corresponding to a peak voltage at the test point of 2 2V 4 Pulse shaping e active integrator and single pole zero compensated differentiator with two shaping time constants 1 and 2 usec 5 Base line restorer BLR Active gated Base Line Restorer 6 Pole Zero Cancellation PZC e settings automated by MCA software and manual setting option designed for decay time of the preamplifier pulses gt 40 usec screen indicator allows PZC without scope 7 Pile UP Rejector PUR e settings OFF and ON 4 1 2 ADC 1 Successive approximation ADC with sliding scale liniarization e Channel splitting 128 256 512 1K 2K or 4K Full input voltage range 3V positive and negative 10V with external attenuator 2 ADC Dead time including time needed to write into memory lt 8 usec 47 X Z amp ELEKTRONIK 3 Nonlinearities e Differen
48. nding the cable to the detector computer several times around a ferrite ring also may help While opening a spectrum the MCA program tells Wrong data format or data format error e spectrum was created by another program or another program version Check results do not mind too high count rate e Keep a bigger distance to radiation source Try a less sensitive detector Watch for your personal safety e Check detector Unexpected errors from the HP 200 Memory allocation error total system crash of the HP200LX 55 X Z amp ELEKTRONIK e There are some versions of SPEC with a bug which may cause this problem First try Control Alt Delete Strg Alt ENTF on german keyboard Try Shift Control On Shift Strg Ein on German keyboard Palmtop reset Last try remove batteries also the backup battery on the right side wait a moment and place them again The MCA DOS Software does not run on my WIN 95 computer e There are problems No problems with following notebooks Gateway 2000 HP800 Panasonic CF 25 CF 35 HP 4000 Toshiba Libretto Use WinMCA instead 56
49. newest software versions refer to the GBS homepage http www gbs elektronik de mca software index_e htm and ask for updates 3 2 The DOS program MCA for operating the Mini MCA The emulation software has one startup screen and three different screens one character based menu screen and two almost similar graphical screens showing the spectra This variety of screens might seem to be confusing but has advantages The screens are clearly separated according to their functions The start up screen Fig 4 shows general information about the software the attached Mini MCA and its state of operation Here you are asked whether you want to reset the MCA It also complains if MCA power is off or no MCA is connected but you can use the software also offline If you start the MCA program offline the start command is disabled and in all the setup menus changes are possible but will have no effect MCA Emulation Program Copyright C 1997 Forschungszentrum Rossendorf e V Software Version 1 61 Mini MCA Number 129 Hardware Release 9701 Firmware Release 9801 Reset MMCA to default setup 14 and clear all spectra y n eo ELEKTRONIK Figure 4 Startup Screen The MENU screen Fig 5 with the main menu bar and the sub menus is mainly used for instrument setup and control File Acquire Setup aNalysis Help MCA 166 online Figure 5 Menu Screen General Navigating through this program e Use the arrow keys to
50. nly in MCA mode Allows to set the preset choices Possible are Real time just the elapsed time sec live time the elapsed time subtracted by the MCA dead time in sec default Integral Peak Area peak integral subtracted by background see appendix 2 for the formula and infinite measurement For integral and peak area a ROI must be set Use the space bar to toggle between the choices Value only MCA mode Use this field to input a preset value this can either be set as the number of seconds or the number of counts The maximum number of preset seconds is 65536 the maximum number of preset counts is 10 000 000 Default is 300s or counts ROI only MCA mode Allows to select one of the ROIs which is used as preset for the integral counts or the peak area in that ROI Channels MCA mode Allows to set the number of MCA channels Use the space bar to toggle between 128 4096 channels Note that the last 128 channels of 4096 can not be used and remain empty and correspondingly the last 64 of 2048 etc Default is 4096 channels For a HPGe detector the choice will be in most cases 4096 channels whereas for a CdZnTe detector 1024 channels are enough For a Nal 256 channels are sufficient Channels MCS mode Use the spacebar to select between 128 4096 MCS channels Default is 4096 channels Time per Channel only MCS mode Enter the time per channel in increments of 10 msec Threshold Allows to set a threshold value b
51. not play around with them MCA lamp flashes irregularly Computer tells MCA power failure or beeps e MCA battery very low Charge MCA battery e MCA internal or communication error Switch off and on MCA restart software Power Supply Error Goto Diagnostics Measurement is not possible e MCA battery very low Charge MCA battery and switch on HV and preamplifier supplies again e Go to diagnostics blinking power supply currents indicate overload e Short circuit in detector Check if detector is defective Disconnect detector try again Do not pull or plug connectors when MCA is on Change detector e Too power hungry preamplifier A fully charged MCA battery may help sometimes Otherwise you have get a powerpack supply with increased current capability from GBS or you have to exchange the preamplifier e H the diagnostics menu shows irregular high currents or even overload although there is no detector connected to the MCA and the battery voltage is ok there may be a fault in the internal power supply Contact GBS for repair The threshold of the spectrum seems to be much higher than expected e The input polarity may be wrong Does the threshold depend on radioactive source and count rate Try some other input polarity e P Zmay not be set correctly Please check if P Z is correctly adjusted e If the lower cutoff rises by itself this is most probable caused by the autothreshold circuit which is responsible for detecting the noi
52. nt F5 stops it During the measurement the growing spectrum can be seen also some additional parameters e g elapsed time cursor position actual count rate are shown The arrow keys move the cursor and change vertical scale on this screen When a sufficient accurate spectrum is acquired maybe 300 s at 100 cps stop by F5 Step 7 Saving spectrum Leave measurement screen with ESC choose File Save press Enter Now a file menu should appear Choose a filename like xxxxxxxx spe and enter it in the line File Press Enter two times Another box appears where you can enter a remark to the spectrum Exit this box with ESC Press another time ESC to go back to the menus Step 8 Switching off Choose File eXit Press Enter Confirm Turn off HV yes by pressing Enter Confirm Don t forget to turn off MMCA by pressing Enter Switch off MCA 166 and Palmtop HP200LX Now you can disconnect the cables 44 lt z amp ELEKTRONIK 3 11 Some examples for parameters of MCA used with different detectors This table shall just give an overview of possible settings useful with the MCA It is far from being complete For actual settings with your detector see the detectors manual Type HV V Input annels Gain for 2 Shap 2 12 24 24 signal MeV full ing V polarity range us Ch CdZnTe SDP Z O Ier an x x neg 1024 CdZnTe SDP Z 20 Ritec np x x f
53. nt accurate spectrum is acquired maybe 300 s at 100 cps stop by F5 Step 7 Saving spectrum Leave measurement screen with ESC choose File Save press Enter Now a file menu should appear Choose a filename like xxxxxxxx spe and enter it in the line File Press Enter two times Another box appears where you can enter a remark to the spectrum Exit this box with ESC Press another time ESC to go back to the menus Step 8 Switching off Choose File eXit Press Enter Confirm Turn off HV yes by pressing Enter Confirm Don t forget to turn off MMCA by pressing Enter Switch off MCA 166 and Palmtop HP200LX Now you can disconnect the cables 3 10 Example for a Measurement with a HPGe Detector Step 1 Connecting cables The Palmtop 200 LX has to be connected by cable to the MCA 166 the HPGe detector S with its 3 different connectors has also to be connected to the MCA 166 There may be a fourth cable HV inhibit if so use the HV inhibit adapter to connect it Step 2 Switching on Switch on MCA the green lamp should start to flash Switch on Palmtop the key in the uppermost right edge ON A menu with options for different programs should appear If not try Ctrl Alt Del or Shift yellow arrow Ctrl ON Step 3 Starting program Type 3 to start SPEC program Answer y and Enter The big key with the left arrow to the question Reset MMCA to SPEC defaults and clear all spectra
54. ntensity calibration measurement is necessary 3 5 2 LENG This program supports semi automated active length measurement HM 4 using a miniature Nal or CdZnTe detector 3 5 3 RATE This program supports measurements of count rates with any radiation detector HPGe Nal CdTe CdZnTe and neutron counters In the most convenient mode of operation only the menu button measurement needs to be pressed to start a measurement and showing the count rates in form of a LCD display and a bar graph 3 6 Windows software 3 6 1 The program WinMCA The program WinMCA has mostly the same features as MCA but for a Windows 95 environment It is written under Visual Basic in 32 bit code To install copy all files to a temporary directory and then start setup exe or install from the floppy disks The main differences to DOS MCA are e supports saving of spectral data in tka format only ASCII string of channel data e g for use in a spread sheet e supports saving of report files no spectral data but all ROI information begin end centroid FWHM FWTM Integral Area Area error e Open Save options can be accessed via File Preferences e Also some more options concerning display graph style color and general program options are found e In MCS operation mode different firmware software acquisition modes can be found some of them offering absolute continuous measurements avoiding gaps for file saving So up to 65536 MCS spectra
55. o adjust the fine gain while observing the spectrum If the cursor is currently in a ROI then the peak centroid will be shown This is useful to do some coarse calibration e g adjust fine gain in a way that 1 channel corresponds to 0 5 keV energy using a germanium detector Shaping time Use the space bar to toggle between the two time constants 1 and 2 microseconds Use 2 microsec for low countrate measurements with a HPGe detector where the best resolution is needed and 1 microsec in all other cases Input polarity Use the spacebar to toggle between amplifier input pulses with negative or positive input polarity Remember Wrong polarity is a common reason for measuring strange spectra or getting no signal at all PZR Mode Is always manual Only in WINMCA there is a automatic option Adjust PZC now Press Enter to access the graphical screen which visualizes the pole zero adjustment For adjusting PZC a count rate of 1000 10000 should be optimum and the majority of these pulses should fill the measurement range at least to the half The bar indicates the voltage at the ADC 8us after the pulse peak maximum This voltage should be adjusted to zero A wrong PZC setting may lead to a degraded resolution 34 lt E amp ELEKTRONIK 3 4 2 5 MCA Setup only in LLD ULD mode Allows to setup the acquire functions like MCA channels Threshold Upper and lower Level discriminators LLD ULD and ADC input Channels In the
56. o use the internal amplifier Default is amplifier 3 3 2 5 Amplifier setup This submenu can only be activated if ADC input see 3 3 2 4 is set to Amplifier Allows to setup the amplifier parameters like gain shaping time input polarity and pole zero cancellation PZC PZC and gain can also be adjusted using a graphic screen to support fine tuning Coarse gain Use space bar to select the value for the coarse gain 2 1000 Fine Gain Input the value for the fine gain 0 5000 1 5000 Do visual gain adjustment Press Enter to switch to a graphical screen with the spectrum Use the screen to adjust the fine gain while observing the spectrum If the cursor is currently in a ROI then the peak centroid will be shown This is useful to do some coarse calibration e g adjust fine gain in a way that 1 channel corresponds to 0 5 keV energy using a germanium detector Shaping time Use the space bar to toggle between the two time constants 1 and 2 microseconds Use 2 microsec for low countrate measurements with a HPGe detector where the best resolution is needed and 1 microsec in all other cases Input polarity Use the spacebar to toggle between amplifier input pulses with negative or positive input polarity Remember Wrong polarity is a common reason for measuring strange spectra or getting no signal at all PZC Mode Is always manual Only in WINMCA there is a automatic option Adjust PZC now Press Enter to get access to the graphic
57. or at least in the detector s manual Do not exceed the maximum voltage for the detector Use the right polarity Using lower voltages is possible in the case of HPGe detectors the resolution will degrade a bit using lower voltages For a Nal detector with a photomultiplier the amplification will change with high voltage 3 4 2 3 MCS setup Time Channels Use the spacebar to select between 128 4096 MCS channels Default is 4096 channels Time per Channel Dwell time 33 bero inve Enter the time per channel Minimum step 10 msec Maximum value 500s The calculated total measuring time is then shown below the time per channel setting Input Type MCS mode Use the spacebar to select between extern TTL pulses Input Rate from the count rate meter or LLD ULD Only impulses between the LLD ULD limit are counted Default is TTL 3 4 2 4 Amplifier setup not available if input set to TTL This submenu can only be activated if input Type see 3 4 2 3 is set to LLD ULD or input rate Allows to setup the amplifier parameters like gain shaping time input polarity and pole zero cancellation PZC PZC and gain can also be adjusted using a graphic screen to support fine tuning Coarse gain Use the space bar to select the value for the coarse gain 2 1000 Fine Gain Input the value for the fine gain 0 5000 1 5000 Do visual gain adjustment Press Enter to switch to a graphical screen with the spectrum Use the screen t
58. ormation like actual counts per channel rate real time preset for the measurement and which provides a quickly updated live display of the spectrum To start a measurement press F4 During a measurement only 256 channels the width of the display are transferred automatically every 2 sec from the Mini MCA to the Palmtop PC If an intermediate evaluation is needed a full spectrum Snap shot not updated unless requested is presented on a second graphical screen EVALUATION screen showing the evaluation information integral counts ect To enter the evaluation screen press F2 35 mbH o ELEKTRONIK The amplitude spectrum is shown on a third graphical screen which can be entered from the evaluation screen by pressing F5 A cursor bold dotted line is available on all three screens and ROls are indicated intense regions in between two dotted lines To move the cursor use right and left arrow key e To mark a ROI press the SHIFT key while moving the cursor e To delete a ROI move the cursor into the ROI and press the DELETE key All three screens have the same principal layout The top line shows the path and filename of the spectrum On the left side the vertical full scale VFS is displayed together with the Y scale mode either automated linear logarithmic or manual linear change this with F6 In addition the ACQUIRE screen shows the remaining battery capacity of the MCA Under the spectra display there are
59. oved Then the voltage can be measured easily with a multimeter at the plug inserts of the connecting block 10 lt z amp ELEKTRONIK 2 2 6 Connecting the Power Pack The powerpack is an extension of the akkupack with an high performance integrated power supply Standard detector preamplifier voltages as well as an extra 5V supply are delivered The Powerpack may be used to manage also power hungry detectors or detectors with a 5V demand It may be used it as backup battery for the MCA166 similar as the akkupack Or use just as a stand alone versatile power supply for many nuclear electronics Preamp supply Powerpack charger input 84 wv MCA output B5 81w 24 BAY 4124 12w Sif ov DV BMC output voltage We output voltage monitor circuit Ga g 11 bero eto si Specifications All outputs are short circuit proof Overloading of any output leads to shutdown of all output supply voltages except the MCA Batt output Ripple on all regulated outputs lt 20mVpp on 5V 6 mVpp on all other outputs Ripple measured with outputs loaded to 100 mA Operating temperature 5 50 C Size 155 95 50 mm same as MCA166 Water and Dust protection IP42 6W total power output maximum Contains 3 camcorder type Li lon batteries 4 Ah 3OWh Standby current power supply switched on no load 35mA Overload recognition If all output voltages are correctly present the indicator LED is blinking with
60. ow keys To enter a menu or to confirm something use the Enter key To toggle between settings use the space key big key in the lowermost line 42 lt E amp ELEKTRONIK To exit a menu use the ESC key Step 4 Loading setup file Navigate with the arrow keys to setup menu press Enter goto read setup file press Enter Choose with the arrow keys sdp31060 spe press Enter Enter ESC ESC All parameters can also be modified manually they are Detector high voltage 300V Presets Choice None MCA setup channels 1024 Treshold 2 LLD 0 ULD 991 ADC Input Amplifier Amplifier setup Coarse gain 200 fine gain 0 9100 Shaping time us 1 Input polarity neg Stabilization setup Stabilization off Step 5 Switching on high voltage Choose Detector high voltage setup in the setup menu behind high voltage should appear 300 Press ESC and Enter to switch on high voltage In the lowermost line on the screen should appear now HV 300V Step 6 starting measurement Now choose Data acquisition Measurement press Enter The acquisition screen should appear F4 starts a measurement F5 stops it During the measurement the growing spectrum can be seen also some additional parameters e g elapsed time cursor position actual count rate are shown The arrow keys will move the cursor and change the vertical scale on this screen When a sufficie
61. pports semi automated measurements of time distributions with any radiation detector HPGe Nal CdTe CdZnTe and neutron counters as e g used for CANDU canister verification In the most convenient mode of operation only the F4 31 mbH o ELEKTRONIK Start key needs to be pressed to start and automatically save a measurement Optionally a remark can be saved For CANDU canister verification the averaged amplitude spectrum 512 channels is being collected simultaneously in the background for each scan The corresponding spectrum file is optionally recorded together with the time distribution The following input options are available for multi channel scaling cps MCS count proportional to input rate ULD ULD MCS count proportional to the rate between LLD and ULD and TTL MCS count proportional to rate of external TTL signal in this case no spectrum is recorded The first option is used for canister scanning and the last is used for criticality tests To use the MCS program 1 Connect the detector and afterwards turn the MMCA module on toggle switch at the front side 2 Turn on the computer right upper corner of the keyboard also used if the HP 200LX went into the sleep mode Start the program by pushing the corresponding numeric key and reset the MMCA 3 Read in the setup file for your detector Setup Read setup file use arrow down key to move the cursor bar to the setup file and press Enter twice 4 Check
62. r negative signals from external amplifier e Adjust the fine gain Setup gt Amplifier setup gt Do visual gain adjustment e Check the PZC adjustment Setup gt Amplifier setup gt Do visual PZC adjustment The displayed value of Zero offset should be 0 2 Correct if necessary Check again the fine gain adjustment if large changes were necessary in the PZC adjustment Now you are ready to measure a spectrum With Data acquisition gt Measurement you enter the graphics screen Acquire screen Possible operations like Start Stop Expand Change vertical full scale Y and others are indicated at the bottom text line which is adapted to the HP 200LX Palmtop computer and controlled by the function keys F2 F10 Use F1 to obtain more detailed information about possible operations in the Acquire Screen Other operations like saving spectra and getting information about peak areas centroids and integrals in regions of interest ROIs are possible only if you enter the Evaluation screen press F2 Once a measurement is finished either by pressing F5 or by reaching the chosen preset the Evaluation screen is automatically activated Now you may save a spectrum by pressing F4 To start the next measurement you must switch back to the Acquire Screen F2 Exiting the graphic screen is always possible press F10 even if a measurement is still running You may come back later to the Acquire Screen choose Data acquisition gt Mea
63. r to set file save options With Save you enter a drive and file box Under Dir you can type the drive letter e g a and press Enter Using the Arrow and Enter keys select the subdirectory into which the file is to be saved Type the filename under File Move the cursor bar to OK and press Enter to save the file With Option you reach an options setting menu for saving a file Normally all options are set to yes to save a file with all setup ROI and calibration information If for e g only the ROI option would be set to yes then only the ROI list would be saved Use the spacebar to toggle the options between yes and no 3 2 1 3 Exit Leaves the MCA emulation program and exits to the DOS prompt The MCA module however may continue to collect a spectrum So you can disconnect the computer and leave the MCA measuring on its own But if you want to do this leave the high voltage on when exiting and after connecting the MCA again and starting the MCA program do not reset the MCA otherwise the measurement will be deleted 3 2 2 Acquire menu The acquire menu provides a start function to begin data collection The data gathering is controlled from the graphic screen It further provides acquire presets and MCA or MCS mode selection including their setup One of the three memory groups of the MCA can be chosen as an active group for data collection A clear function allows to clear all ROIs and data 3 2 2 1 Start The first gr
64. reen by moving the cursor to the menu item you want more information about and pressing F1 The help menu gives also information about the used software version command about The Help menu is context sensitive To get help ona certain function press F1 and a context sensitive message will pop up If the Help text exceeds the length of the screen use the arrow keys to scroll Use ESC to leave a Help screen and return to the menu The Help menu also includes a MCA Diagnostics screen 3 3 4 1 Diagnostics Shows useful information about the attached Mini MCA serial number hardware version firmware version voltages and currents Also displayed is the actual MCA Battery voltage and current A blinking current value means overload or low battery voltage All battery currents used for the preamplifier supply voltages and for high voltage are shown Remember The currents are battery currents and not the actual currents at 12V and 24V or high voltage currents To get an idea of the actual currents a converter efficiency of about 80 can be assumed The following formula will help Tagg O8 Fy SC aus Batt U aus If now for example a current off 120 mA is shown for the 24V and the actual battery voltage is 7 5 V then the current at the 24V output is approximately 30mA I 08 120mA V 24V aus 3 4 The DOS program MCS for time dependent measurements Multi Channel Scaler Overview This program su
65. ropriate HV inhibit setting chosen setting HV inhibit HV is shut down at Detector cold unused jJnoacion LI o Canberra HPGe DFG HPGe EG amp G Ortec HPGe 3 3 2 3 Presets 26 beer eme Choice Allows to set the preset choices Possible are Real time just the elapsed time sec live time the elapsed time subtracted by the MCA dead time in sec default Integral the total number of counts in a ROI Peak Area peak integral subtracted by background see appendix 2 for the formula and None for an infinite measurement For integral and peak area a ROI must be set Use the space bar to toggle between the choices Default is live time Value Use this field to input a preset value this can either be set as the number of seconds or the number of counts The maximum number of preset seconds is 65536 the maximum number of preset counts is 10 000 000 Default is 300s or counts ROI Allows to select one of the ROIs which is used as preset for the integral counts or the peak area in that ROI 3 3 2 4 MCA setup Allows to setup the acquire functions like MCA channels Threshold Upper and lower Level discriminators LLD ULD and ADC input Channels Allows to set the number of MCA channels Use the space bar to toggle between 128 4096 channels Note that the last 128 channels of 4096 can not be used and remain empty and correspondingly the last 64 of 2048 etc Default is 512 channels For a HPGe detec
66. rt VGA Screen Windows 95 98 NT Some programs MCAPlot Identify are also available in Windows 3 1 version The MCA DOS software usually consists of the following 3 files e the executable file e g mca exe e the screen file e g mca Inf e the help file e g mca hlp To install the MCA software from the MS DOS prompt e Insert the MCA 166 distribution disk in drive A e Type A and press ENTER e Type XCOPY AA C S and press ENTER The programs must always be started from their directory in order to run correctly After starting the program it will try to detect the default data directory and creates one in the root of the actual drive e g c data On the HP200L X the software is preinstalled on the flashdisk a All programs are called from the Main Menu which appears automatically when the computer has booted or re booted for the HP 200LX from drive a Before you start measurements check or reset date and time on the computer and check its battery status If the HP main battery level is 2 4 V and the backup battery level is 2 7 V replace it At the DOS prompt use the dir a command to make sure that you have enough storage space on drive a or c if a notebook computer is used Use the Norton Commander to delete old files if there is less than 1 Mb free space CTRL ALT DEL resets the computer and brings up the Menu again CTRL ALT ON does a hard reset of the HP 200LX computer and brings also up the menu again A
67. s provides the highest countrate capability up to 10 cps Repeat MCA mode Allows automated data collection and saving of spectra After the preset is reached the spectrum is automatically recorded into a pre selected subdirectory and then the next measurement is started At first a file with a filename using the scheme XXX00000 spe 3 letters and 5 digits must be saved XXX is user selected to distinguish between measurement series kept in the same subdirectory File name and directory are set under File Save Up to 65535 files can be automatically recorded Default is O no repetitive measurements Sweeps MCS mode Allows automated repetitive MCS spectra collection like Repeat in MCA mode 3 2 2 3 Clear Allows to clear all ROIs and all data in either the active or all memory groups Clear ROIs Use the spacebar to select the right choice Note Set data option to no if only ROIs should be cleared Clear Data Use the spacebar to toggle between all and active group depending on which data should be deleted 3 2 2 4 Active group Allows to set one of 3 memory groups into which a spectrum is collected The first group is selected by default Use the spacebar to toggle between active group 1 2 and 3 There are still some bugs within this function 3 2 2 5 Mode You can set the acquisition mode here either to MCA or to MCS mode MCA mode measures pulse height spectra which corresponds almost always to measure energy spectra MCS mea
68. se level and adjusting the threshold to it This autothreshold circuit uses the negative part of the amplifier output pulses to estimate noise If now pole zero is severely misadjusted with strong undershoot the undershoot is misinterpreted as noise and the threshold is increased especially at medium and high count rates e Please check the detector preamplifier waveform The decay half time of the signal should be optimum 40 us but never shorter than 25 us If it is shorter as experienced with some Nal s then it is not possible to adjust P Z correctly the time constant of the preamp has to be adjusted instead The high energy part of the spectrum is reduced or even missing 54 lt i amp ELEKTRONIK e Check if the behavior changes if the pile up rejector is switched off Check the signal from the preamplifier If the preamplifier signal rise time is slower than 500ns then there is the danger that regular pulses especially the large ones are misinterpreted as pile up Try to use another preamplifier or just switch the pile up rejector off e Similar effects can be seen if detector cables longer than 50m are used Dead time shown is very high although the countrate is low e This problem occurred with some older firmware versions and Nal detectors connected Ignore it or install newer firmware e There may be some detectors with excessive electronic noise Try higher fast and slow threshold You have to edit a setup file with a t
69. supply Power supply adequate for commonly used Nal HPGe CdTe and proportional counters e Current limited mode with indication of overload condition through software short circuit protected and automated recovery after overload or shortening 4 1 4 Preamplifier Voltages e 12V e Maximum current 60 mA for each of the voltages e 24V 48 ELEKTRONIK e Maximum current 30 mA for each of the voltages e Maximum total power at least 2 W 41 5 High Voltage Single positive or negative modular HV supply reaching from 50 to 3000 V Indication of high voltage sign and value by software Calibration within 1 at maximum of bias voltage Maximum current 0 5 mA or 0 25 W e g 1000 V and 0 25 mA 4 1 6 Battery Rechargeable Li battery with no memory effect Deep discharge protected Battery capacity 2 5 Ah at 20 C Measured values of the battery life time If no detector connected 16 hours Expected battery life time with detection systems connected Standard IAEA Nal detector ORTEC SCIONIX 14 hours Bias 500 V 100 pA Preamplifier 100 mW Miniature CdTe detection probe SDP310 RITEC Latvia 12 hours Bias 400 V 100 nA Preamplifier 12 V 20 mA 12 V 9 5 mA Standard planar HPGe detector e g Canberra Ortec 6 hours Bias 2000V 1 nA Preamplifier 12 V 21 mA 12 V 7 mA 24 V 18 mA 24 V 8 mA 4 1 7 Computer Interface RS 232C port Baud rate 38400 proprietary software protocol
70. surement and inspect your running or finished measurement Here you find a brief list of features which are available in SPEC e Defining ROIs Move the cursor to the ROI begin press the Shift key move the cursor to the ROI end while pressing Shift release the Shift key The selected ROI is highlighted e Deleting ROIs Move the cursor into the ROI press the Del key 24 be metre ri e Autosave mode File gt Autosave You may initiate automatic file saving after each measurement If the options Prompt before overwrite and Remarks are switched off a one button regime to measure and store spectra is realized The file names in the format xxxxnnnn spe are automatically created if a first file xxxx0000 spe is saved nnnn means a number which is incremented after each saving MMCA Appl Program SPEC Version 1 20 Copyright C 1997 Forschungszentrum Rossendorf e V Previous appl mode was SPEC Reset MMCA to SPEC defaults and clear all spectra y n Figure 8 SPEC Startup Screen Description of the SPEC program by the order of the commands 3 3 1 File menu The file menu allows to open and to save files Files are spectral data files with setup information 3 3 1 1 Open This leads to a file selection box Under Dir you can type the drive letter for e g a In the right part of the box the roots directory and subdirectories of the drive are shown Move the cursor bar to the desired subdirectory and press En
71. sures time dependent count rates All channels correspond to an equidistant sequence of time windows the number of counts in the time window is stored 19 mbH o ELEKTRONIK in the corresponding channel Parameters can be adjusted in the acquisition setup menu A possible application for MCS mode are decay time measurements or unattended monitoring measurements 3 2 3 Setup The setup menu provides hardware setup functions related to the amplifier and detector preamplifier power supply The default values for different settings are Parameter default High voltage O0 1 1 0000 1 3 2 3 1 Detector High voltage setup Allows to set the value for the high voltage which is used by the detector Input the value for the detector high voltage here The polarity is automatically set through the hardware depending on what bias module is plugged in The high voltage is turned on after this dialogue box is left with ESC and the corresponding message to turn the high voltage on is acknowledged The status of the high voltage is shown on the status bar at the lowest line of the screen The voltage as well as the polarity necessary is normally indicated on the detector or at least in the detector s manual Do not exceed the maximum voltage for the detector Use the right polarity Using lower voltages is possible in the case of HPGe detectors the resolution will degrade a bit using lower voltages For a Nal det
72. t for Windows CE environment It was developed using a HP680 Palmtop Computer 3 7 2 SPEC for EPOC Spec for EPOC use with Psion 5 or similar devices is in preparation Check our homepage for availability 40 lt E amp ELEKTRONIK 3 8 Example for Making a Measurement with a Nal detector using the MCA program on the HP200LX Assuming that the Mini MCA with a positive HV module is connected to the PC and the detector and the software is installed Step 1 e Turn the MCA on and wait until the LED starts flashing Start the MCA emulation software mca exe from the DOS PROMPT current directory must contain all software components by typing mca On the HP 200 just press 1 in the menu to start the MCA program Press Y when you are prompted with Reset MMCA to default setup and clear all spectra y n Step 2 Go to the Acquire menu select Setup by using either letters or arrow keys and press ENTER Move down to Channels and set the value to 512 toggle Channel value with the space bar Press ESC and ENTER to store the Channel value Step 3 Go to the Setup menu select Detector high voltage setup and press ENTER Type in 500 for the value and press ESC and ENTER to turn the detector high voltage on Step 4 e Now move on to Amplifier setup and press ENTER Use the space bar to toggle the Coarse gain to a value suitable for the detector Now move to Adjust amplifi
73. ted is presented on a second graphical screen EVALUATION screen showing 29 GmbH ELEKTRONIK the evaluation information peak information numeric calculations To enter the evaluation screen press F2 Peak Centroid 242 95 FWHM 17 41 UFS Joe nee EE a f 4E aLin Cursor d ROI 4 226 260 Counts 1848 ElaptLs3 0 DO Oe Int 39277 Area 30483 1 439 He lp Y Exp Menu Figure 10 Evaluation Screen A cursor bold dotted line is available on both screens and ROls are indicated intense regions in between two dotted lines ROIs may not overlap e To move the cursor use right and left arrow key e To mark a ROI press the SHIFT key while moving the cursor e To delete a ROI move the cursor into the ROI and press the DELETE key Both screens have the same principal layout The top line shows the path and filename of the spectrum On the left side the vertical full scale VFS is displayed together with the Y scale mode either automated linear logarithmic or manual linear change this with F6 In addition the ACQUIRE screen shows the remaining battery capacity of the MCA Under the spectra display there are four lines with status information some of them appearing on both the ACQUIRE and EVALUATION screens e g the cursor information ROI resp X range and the dead time If the cursor is within a ROI its number and boundaries are shown On the EVALUATION screen is then additionally peak information integral ar
74. ter to select it Pick the file in the left box with the cursor bar and press Enter to retrieve it You first can read the comment to the spectrum ESC then leads to the evaluation screen with opened spectrum 3 3 1 2 Save Here you enter a drive and file box Under Dir you can type the drive letter e g aA and press Enter Using the Arrow and Enter keys select the subdirectory into which the file is to be saved Type the filename under File Move the cursor bar to OK and press Enter to save the file After that you can enter a comment or a short description of the spectrum 3 3 1 3 Autosave The autosave option causes a measured spectrum to be immediately saved after recording Options are to ask for a remark before saving and to prompt before overwriting an existing spectrum The spectra are saved in the format XXXX0000 SPE XXXX0001 SPE Before the first spectrum in autosave mode is recorded it is asked for an appropriate name Defaults are no for autosave and yes for remarks and prompt before overwrite 3 3 1 4 Exit 25 mbH ELEKTRONIK Leaves the SPEC program and exits to the DOS prompt The MCA module however may continue to collect a spectrum So you can disconnect the computer and leave the MCA measuring on its own If you want to do this leave the high voltage on when exiting and after connecting the MCA again and starting the SPEC program do not reset the MCA otherwise the measurement will be deleted
75. tial non linearity over 95 channel range lt 2 e Integral non linearity over 95 channel range lt 0 1 4 Peak capturing Works with pulse of gaussian shaping amplifier range of shaping time constant between 0 5 and 5 usec 5 Temperature Stability e TK 100 ADC TK 500 Amplifier 6 Discriminators and threshold e Digital LLD and ULD allows channel wise cutting e Analogue threshold 2 60 of ADC range 7 Multi Channel Scaling MCS mode allowing to count the following pulses TTL input pulses minimum width of flat top 0 2 usec not routed through the ADC maximum rate 1 MHz e LLD ULD counting mode counting pulses within a preset digital window Countrate derived from internal amplifier ICR signal maximum countrate determined by countrate limitation of amplifier Dwell time 0 01 500 sec 8 Spectrometric performance Resolution FWHM for typical 500 mm planar HPGe detector for countrates lt 10000 cps and a Co 57 source at 122 keV 610 20 eV at 1 usec shaping time 580 20 eV at 2 usec shaping time Peak shift lt 0 5 for 1 usec shaping time and count rates from 1000 to 70000 cps lt 0 2 for 2 usec shaping time and count rates from 1000 to 40000 cps deterioration of FWHM lt 5 for both conditions e Throughput in memory at least 25000 cps in memory at 50000 cps input rate and 1 usec shaping time at least 13000 cps in memory at 30000 cps input rate and 2 usec shaping time 4 1 3 Power
76. tor the choice will be in most cases 4096 channels whereas for a CdZnTe detector 1024 channels are enough For a Nal 256 channels are sufficient Threshold Allows to set a threshold value between 2 and 60 of the current MCA scale Default is 296 This analogue threshold cuts the pulses before they reach the ADC Setting the threshold high discriminates unwanted pulses and reduces the dead time of the ADC Do visual threshold adjustment Allows to adjust the threshold using visual control of the spectrum LLD ULD LLD allows to set the lower level discriminator of the ADC All channels below the LLD value remain empty The ADC dead time however is not reduced The value for LLD must be ULD Default is O ULD allows to set the upper level discriminator ULD of the ADC All channels above the ULD value remain empty The ADC dead time is not reduced The value for ULD must be gt LLD Default is the highest possible channel It is more recommended to use Threshold than LLD to remove noise and low energy components of the spectrum Do visual LLD ULD adjustment 27 mbH o ELEKTRONIK Starts acquiring a full spectrum by pressing F5 and by not accepting the current values you can enter new values by moving the cursor to LLD and ULD channel ADC input Use the spacebar to toggle between the 2 different direct inputs 3V dir 3 V dir if you want to use for e g an external amplifier or select Amplifier in order t

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