Model 269 Photomultiplier Base Operating and Service Manual
Contents
1. Nal TI scintillator on one side of the coincidence system 4 2 3 Fast Coincidence Using Ge Li Drifted Detectors Some recent experiments have been performed using a 1 5 x 1 5 in Nal TI scintillator in a gamma gamma coincidence arrangement with an ORTEC 10 cm Ge Li drifted coaxial detector as shown in Fig 4 4 In this case the radiant energy from the source was not collimated at all so that the time is given by collection from all parts of the detector The source viewed one end of the germanium detector Side channels selected the energy region of interest which was the photopeak on each side The full time spectrum is given in Fig 4 5 Full width at half maximum FWHM and full width at one tenth maximum FWTM are indicated Comparison of this spectrum with published timing curves indicates a very good detector design for timing purposes The counting efficiencies associated with the FWHM and FWTM points are approximately 6096 and 92 respectively R L Graham et al IEEE Trans Nucl Sci NS 13 1 72 1966 5 MAINTENANCE Since the ORTEC 269 is composed of only passive components very little maintenance is expected mainly replacement of components that have failed with age Table 5 1 lists approximate dynode voltages for comparative purposes for use at this Table 5 1 Set 10 3 kV be max aut af PS time Almost all failures of the divider string may be isolated by removing the PM and making the2. 5 WEIGHTS AND DIMENSIONS 2 Si INSTALLATION 5 du RR teen ee new A die dite Pa ae dedu ena A AAA AAA 2 3 1 DETEGTOR MOUNTING u 2222 02 aie haie babe babe baba Malta dub au aa adie eed 2 3 2 PHOTOMULTIPLIER INSERTION 0 00000 cece tee 2 3 3 INITIAL ADJUSTMENTS a2 teen tte ant er ued er at 2 3 4 CONNECTION INTO A SYSTEM e cee hr 3 4 OPERATION i iita deterret ee ma tete Dante annee Paco a ee AURA AUR RUE AUR AUR LAE 3 4 1 TIMING WITH PHOTOMULTIPLIERS 4 4444 eue 3 4 2 ABPEICA TIONS uie eon oe eril ee Rte Nee aati doeet A A A OM ONE At 4 4 2 1 Typical Fast Slow Coincidence System Using Plastic Scintillators 6 4 2 2 Typical Fast Slow Coincidence Using Nal Tl 9 4 2 3 Fast Coincidence Using Ge Li Drifted Detectors 9 D MAINTENANCE as a fan ca a a a hy AE pues nn PR RE auge angela on elt 9 SAFETY INSTRUCTIONS AND SYMBOLS This manual contains up to three levels of safety instructions that must be observed in order to avoid personal injury and or damage to equipment or other property These are DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not observed WARNING Indicates a hazard that could result in bodily harm if the safety instruction is not observed CAUTION Indicates a hazard tha
3. EC 235 100 Mir DISC For a complete discussion of timing with photomultipliers the reader is referred to some of the excellent literature available on the subject 4 2 APPLICATIONS The different applications for the 269 are essentially limitless but since the unit was designed primarily for timing applications block diagrams for two specific systems for this type of application are given Figs 4 1 and 4 4 Typical resolution curves are also given Figs 4 2 4 3 and 4 5 from which operational characteristics of other systems may be implied Figures 4 6 4 10 are block diagrams of typical timing systems A Schwarzchild Nucl Inst Methods 21 1 1963 2G Present et al Nucl Instruments Methods 31 71 1964 SE Gatti and V Svelto Nucl Inst Methods 30 213 1964 TIMING LINEAR GATI i i TIMING Sta ANALYZER _ Fig 4 1 Simple Fast Slow Timing System u Srt 1 s la Kae T XT MH Ale a ier 51027 8 Yan Maten 128 1375 Pare Z5 enc Sou ce Ge E 3500 f TR 0 Tien 285 mac ati ol E Wiese 20 Sumo lalin Want 35 XP 1071 Nate e Enr 5 00 LE x bite ARTNET ae f Bs ee Scuro Co Ww 7300 ty Wish al Ent DE CAR CEN Charset Nutt s AD pih PAM Z7 ques H PATH RA cuc Ei sw 10 156 Le i E 190 200 2160 m Tx Y Ins 38 350 Channel Mortar fessi PA ber Fig 4 2 Typical Coincidence Spectrum Fig 4 3 Typical Coincidenc
4. LATION 3 1 DETECTOR MOUNTING In order to obtain the ultimate in pulse fidelity the anode of the 269 is connected to ground potential that is the photocathode must be at negative high voltage The 269 assures that this high voltage is not dropped across the glass envelope of the photomultiplier by providing a shield voltage on the conductive external surface of the photomultiplier Care should be taken to prevent the scintillator from imposing a ground at the front surface of the photocathode A drawing of the suggested method of mounting a simple detector is shown in Figure 3 1 Note When used with the RCA 6810A the shorting jumper between pins 9 and 7 should be removed and placed between pins 9 and 8 3 2 PHOTOMULTIPLIER INSERTION The magnetic shield if used should be removed The tube may now be directly inserted into the Socket Place the felt washers around the photomultiplier and remount the magnetic shield 3 3 INITIAL ADJUSTMENTS The high voltage divider cover should be removed WARNING The voltages used in this network are dangerous Use caution when adjusting the controls The controls of the unit are trimmed for optimum operation with a specific PM at the factory BELUMINUM FOL AT ALAN AAT CATMEOL POTENTIAL TET 2 SEL s a PRINTED DOCKET EIREUIE RIE Fi AITAFTER RING L ALIMA TWE A A TWO LAYERS OF ELECTPPCAL TEP VEY PER LAYER 2 LAPS EU ET ROFDAN o
5. Model 269 Photomultiplier Base Operating and Service Manual This manual applies to instruments marked Rev 34 on rear panel Printed in U S A ORTEC Part No 733870 1202 Manual Revision B Advanced Measurement Technology Inc a k a ORTEC a subsidiary of AMETEK Inc WARRANTY ORTEC warrants that the items will be delivered free from defects in material or workmanship ORTEC makes no other warranties express or implied and specifically NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ORTEC s exclusive liability is limited to repairing or replacing at ORTEC s option items found by ORTEC to be defective in workmanship or materials within one year from the date of delivery ORTEC s liability on any claim of any kind including negligence loss or damages arising out of connected with or from the performance or breach thereof or from the manufacture sale delivery resale repair or use of any item or services covered by this agreement or purchase order shall in no case exceed the price allocable to the item or service furnished or any part thereof that gives rise to the claim In the event ORTEC fails to manufacture or deliver items called for in this agreement or purchase order ORTEC s exclusive liability and buyer s exclusive remedy shall be release of the buyer from the obligation to pay the purchase price In no event shall ORTEC be liable for special or consequential damages Quality Control Befor
6. TO2E 12 108 Bendix PMT Socket A 20 pin Jedec B20 102 type 2 4 RELATED EQUIPMENT The Anode timing signal can be furnished to an ORTEC Fast Discriminator when using either a Nal TI or plastic scintillator For plastic scintillators only the Anode signal can be fed directly to the Start or Stop input of an ORTEC Time to Pulse Height Converter for time spectroscopy The linear output from the 10th dynode is normally processed through an ORTEC Scintillation Preamplifier and a Shaping Amplifier for energy spectroscopy An ORTEC 216 Magnetic Shield for 2 in diam PM tubes or a 217 for 5 in diam tubes is recommended for reduction of interference from magnetic fields High voltage at the level recommended by the manufacturer of the PM tube can be furnished from an ORTEC High Voltage Power Supply The complete cable ORTEC C36 12 is available for this connection 2 5 WEIGHTS AND DIMENSIONS See Table 2 1 below Table 2 1 Ari ORTEC 259 PM Baer 1 4 00 63 ig QORTEC 2 I6 Shi 1 LAE kl DRTEC 21 zhild 2r 125 kgl ORTEC CIE 12 Cable i 045 eg DATES geo b CDS kg an E 10 bgi ECS eg 21 0045 bal D rmen Sin dis amp in on Sin dis mammig 209 and 218 15 in hong Cn dis embed 205 3nd 217 12 in long 1 0085 bol 12 Sin d a Y in Vows a modibed Pia 540 chee ur hal in a racer ocre weh ir fie A a with the OATES 368 Goth the AC Ln SET and tha ROA i367 ans ro longer In proai 3 INSTAL
7. al assembly and resistive voltage divider network with appropriate capacity decoupling for operation of the Amperex 56 AVP UVP etc and the 58 AVP UVP XP 1040 types of photomultipliers and RCA tubes of the 6810 Series These tubes are specifically designed for high pulse current timing applications and therefore this base structure complements them by maintaining good pulse fidelity over a wide range of signal currents see Fig 1 1 The unit provides two outputs the negative anode signal for timing applications and a linear signal from the tenth dynode The linear signal is of special importance in any experiment in which energy measurements are desired HH ot Wy HHH Fi g 1 1 Conditions High vVnitaga 2200 V C Phosphor Maton 136 Hisizantal Cab D reten Vertical Cal 10 m cm Serres eco Anode Output Pulse 2 SPECIFICATIONS 2 1 BASE High Voltage Negative 3 kV max Bleeder Current 2 mA max last 4 dynodes available for optional voltage stabilization 2 2 SIGNALS Anode Negative timing signal 50Q dc coupled back terminated very good pulse quality for signal currents to 0 5 for Amperex tubes Dynode Positive linear signal from 10 dynode capacity coupled impedance 1 MQ Internal Controls Voltage adjustment for focus and deflection electrodes and for 14 dynode 2 3 CONNECTORS Anode BNC Dynode BNC High Voltage SHV AMP type 51494 2 Auxiliary MS3112E12 10s or P
8. ast Timing System Semiconductor Detector Photomultiplier Tube for Coincidence Using Crossover Pickoff Techniques Power Crete mamma TING Ave Ha node LINEAR DELAY MNCTI CRYSTALS GAT60 base a CA m parma SS ZA i ANALYZER 100 Nie Oc Fic 4 8 Gamma Ray Pair Spectrometer PRECISION PULSE GENERATOR L ORTEC 260 TIME TIME PICKOFF ACKOFF CONTROL STMICOND DETECTOR A ANALYZER Power SINGLE CHANNEL ANALYZER Power m onrec ii PICKDFT FOIL SEMICONDUCTOR 3 TERMIN ne de N DETECTOR EF Adttimil Chaque Partidas iam COINCIDENCE Ff M Ceule on Seen SAMPLE um Neutron Beam poda LINEAR Sa T CONVERTER os VA ADE ORTEC High Voltage 436 a MULTI t CHANNEL M oe har ANALYZER b SINGLE SOIN ANALYZER 7909003 Fig 4 10 Associated Particle Neutron Time of Flight System 4 2 2 Typical Fast Slow Coincidence Using Nal TI The block diagram of Fig 4 1 applies equally well here The difference in the two systems is the scintillator and its decay characteristic This decay time constant is 0 25 usec whereas the same time constant for Naton 136 is approximately 2 nsec With Nal TI much more total light is produced per equivalent energy event but the collection of this light is over such a wide period of time as indicated that the time resolution is poorer than that of plastic Figure 4 3 is a typical spectrum taken with a 1 5 x 1 5 in
9. ciated with the specific experiment The gain will vary by approximately a factor of 2 with voltage change of 100 V 4 1 TIMING WITH PHOTOMULTIPLIERS Timing with photomultipliers implies some type of coincidence measurement This measurement may be performed with standard coincidence circuits such as the pulse overlap type which are essentially signal channel time analyzers or with time to pulse height converters which are differential or multi channel time analyzers The response of the coincidence system to a prompt cascade always has finite width which comes from a variety of sources The most important of these are as follows 1 Variation of time of interaction of radiation with the scintillator and the amount of energy deposited therein 2 Finite decay time of light emitting states in the phosphor and variation of times of photon arrival at the multiplier cathode 3 Variation of transit time of photoelectrons in the photomultiplier due to different path lengths and to variation of initial energy and angle of the secondary electrons 4 Jitter and uncertainties of times of triggering of the associated electronics The variation in the time of interaction can be minimized by appropriate geometry and small scintillators at a corresponding loss in efficiency and average energy deposition Dysode 265 or 260 PM BASE ORTEC 436 100 MHz DISC SCINTILLATOR seinrie aron CEST PM TUBE ORT
10. e Spectrum Using Using Plastic Scintillators NaH TI Seintiligtor iiL DETECTION sounce Halt 1l sciri catar LES ANALYZER 16090041 Fig 4 4 Gamma Gammo Coincidence System with a GelLiDrifted Detector 37722 eee 4 2 1 Typical Fast Slow Coincidence System Using Plastic Scintillators Figure 4 1 is a block diagram of a system that might be used to perform lifetime measurements or to study the time dispersion associated with some prescribed coincidence events lt does not represent an optimum system if clean slopes of the coincidence curves are required to four or five decades but will give clean spectra to at least three decades at moderately high count rates The time spectrum shown in Fig 4 2 represents what may easily be obtained under laboratory conditions using the 269 and other appropriate equipment It is important to remember that the resolution obtainable varies as 1 n where n represents the number of photoelectrons created by the event and is therefore representative of the amount of energy deposited in the scintillation phosphor and is strongly influenced by PM optics ANALYZER ADC zi acc 22 100 MHz DASS STILSENE NEJI Pulse Shupe Separation Spectra TIMING SCA Timina Sz Fig 4 6 Fast Fast Coincidence Photomultiplier Tube with Pulse Shape Discrimination SEMICOND DET 7774 436 100 NH DISC 201 Fig 4 7 F
11. e being approved for shipment each ORTEC instrument must pass a stringent set of quality control tests designed to expose any flaws in materials or workmanship Permanent records of these tests are maintained for use in warranty repair and as a source of statistical information for design improvements Repair Service If it becomes necessary to return this instrument for repair it is essential that Customer Services be contacted in advance of its return so that a Return Authorization Number can be assigned to the unit Also ORTEC must be informed either in writing by telephone 865 482 4411 or by facsimile transmission 865 483 2133 of the nature of the fault of the instrument being returned and of the model serial and revision Rev on rear panel numbers Failure to do so may cause unnecessary delays in getting the unit repaired The ORTEC standard procedure requires that instruments returned for repair pass the same quality control tests that are used for new production instruments Instruments that are returned should be packed so that they will withstand normal transit handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the designated ORTEC repair center The address label and the package should include the Return Authorization Number assigned Instruments being returned that are damaged in transit due to inadequate packing will be repaired at the sender s expense and it will be the sender s responsibility
12. se measurements Potentiometer R 26 was set fully clockwise for the voltages given in Table 5 1 18 Should very from 2750 wv ta 3 kY WRT 1 Should vary from 2525 Y to 2750 w WiRT15 6 1500 2 2525 13 326 17 2409 1200 3 2775 12 900 16 2123 8 0 4 2001 11 475 1875 10
13. t could result in property damage if the safety instruction is not observed Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product In addition the following symbol may appear on the product ATTENTION Refer to Manual DANGER High Voltage Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product SAFETY WARNINGS AND CLEANING INSTRUCTIONS DANGER Opening the cover of this instrument is likely to expose dangerous voltages Disconnect the instrument from all voltage sources while it is being opened WARNING Using this instrument in a manner not specified by the manufacturer may impair the protection provided by the instrument Cleaning Instructions To clean the instrument exterior Unplug the instrument from the ac power supply Remove loose dust on the outside of the instrument with a lint free cloth Remove remaining dirt with a lint free cloth dampened in a general purpose detergent and water solution Do not use abrasive cleaners CAUTION To prevent moisture inside of the instrument during external cleaning use only enough liquid to dampen the cloth or applicator Allow the instrument to dry completely before reconnecting it to the power source vi ORTEC 269 PHOTOMULTIPLIER BASE 1 DESCRIPTION The ORTEC 269 Photomultiplier Base structure provides a mechanic
14. to make claim with the shipper Instruments not in warranty should follow the same procedure and ORTEC will provide a quotation Damage in Transit Shipments should be examined immediately upon receipt for evidence of external or concealed damage The carrier making delivery should be notified immediately of any such damage since the carrier is normally liable for damage in shipment Packing materials waybills and other such documentation should be preserved in order to establish claims After such notification to the carrier please notify ORTEC of the circumstances so that assistance can be provided in making damage claims and in providing replacement equipment if necessary Copyright 2002 Advanced Measurement Technology Inc All rights reserved ORTEC is a registered trademark of Advanced Measurement Technology Inc All other trademarks used herein are the property of their respective owners CONTENTS WARRANTS ii SAFETY INSTRUCTIONS AND SYMBOLS iv SAFETY WARNINGS AND CLEANING INSTRUCTIONS V TS DESCRIPTION G ce sear fie Bo Baer aereo out D e oe AT Be peau acude dua ets 1 2 SPECIFICATIONS 2 rtr o t er eee boe bee eee e been een 1 2 1 BASE tete et et Les tet eet Lastest ee aru p pe sd di eL 1 2 2 SIGNALS eu EE EE EE EE EE ER X E EE EVERY XE EXE EXE 1 2 3 CONNEGTORS sus cansarse 1 2 4 RELATED EQUIPMENT 4 4 hr rr 2 2
15. ver i eal P al POCO CEMENT 2 BCRITILLA TES ERVETAL Fig 31 Gutsy Drawing of PakSont llisor Mount rg However the unit will probably need trimming again if a different PM is used The following adjustments need to be performed rarely more than once with a specific PM unless the operating HV is varied more that 200 V 1 Observe the anode output on a fast rise time oscilloscope if coaxial cables are used they should be terminated 2 Apply negative 2200 V or the voltage at which the tube is to be operated to the high voltage connector 3 Place a radiation source appropriate to the chosen scintillator near the detector 4 Observe the output waveform and adjust the three controls for optimum gain and pulse shape The deflector adjustment will have no effect when RCA photomultipliers are used 5 Turn off the high voltage and replace the HV divider cover The unit is now ready for operation 3 4 CONNECTION INTO A SYSTEM The dynode signal should be coupled via a scintillation preamplifier such as the ORTEC 113 to a shaping amplifier if linear energy information is desired The anode signal should then be coupled via 50 O coaxial cable to the instrument desired care should be taken to assure that the coaxial cable is terminated 4 OPERATION Once the steps outlined in Section 3 of this manual are performed the unit is ready for use High voltage may be applied and adjusted for the appropriate gain asso
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