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1. 27 Bunch Signal Processor IHR eite cadens nee ded mre re resp 28 POWER Supply conse uote eso eee dose duas te debet tue inae tuis he etie 28 CONNECTOR PINS ALLOCATION esses eren 20 BINCTeAECOBTIECEDOTS socios oso ont petes eE KLN adea ee 29 DB9 male Remote Control connector 29 Charge Amplifier and Calibration CAC DIN 41612 rear connector 30 Bunch Signal Processor BSP DIN 41612 rear connector 30 BACKPLANE WIRING DIAGRAM ee 31 Cont d next page BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 2 Fax 33 450 426 643 User s manual SUMMARY Cont d INSTALLATION ON THE VACUUM CHAMBER 32 Break in the vacuum chamber electrical continuity 32 Vacuum chamber impedance esci ie e ee eee ee 33 Wall current by pass and RF shield 33 Thermal protection of the IC Tusen 33 Keeping high harmonics of the beam out of the cavity 34 LONG CABLE LOSS ON SITE CALIBRATION 36 Proposed Methods ses nee eee eder 36 Establish the reference pulse eee e e e e ere ee eda mn aer RR 37 Cable loss core 38 Correcting the internal calibration generator for long cable 39 Annex I Test of Cable Leng
2. E m c o I AN lt lt fe nu T div 5us Top to bottom Memorized Timing View BSP Output View and BSD Input View BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 10 Fax 33 450 426 643 User s manual Waveforms cont d Adjust your oscilloscope time base to a slower sweep 50 us div It should look like this 9 Jun 95 18 23 14 Main Menu Chan 50us 2 V Gane SOus 1 V EXT 0 80 V LF REJ CH1 2 V pup cH 41 V T div 50 us The BSP IHR cycle Top to bottom Timing View BSP Output View and BSP Input View The complete BSP IHR cycle is visible on the oscilloscope including the BSP output reset to zero Explanation of the Timing View The Timing View is a signal to help the user a adjust the beam pulse in the integration window b adjust the timing of his readout ADC or sampling voltmeter with the BSP output signal The voltage levels of the Timing View are arbitrary Signal lowest level at the beginning of the trace The Beam Charge Monitor is ready to receive a Trigger First step up The BSP has received a Trigger the Trigger delay is elapsing 4us in ex factory conditions Second step up The trigger delay has elapsed the first integration window starts In ex factory conditions it lasts 4 us During this window the signal is summed in the output with a negative sign It is the
3. 2 The BCM output decreases considerably when the cable length increases This can be explained in this manner The charge collected by the ICT discharges into two paths The first path is the ICT internal load resistor The second is the resistance of the cable in series with the resistance of the virtual 0Q input impedance When the cable resistance increases the repartition of the collected charge between those two paths is modified Second test Test of ICT BCM linearity with long cable in the virtual 0Q input Pulse Generator O i Attenuator TEST SETUP 2nd Test A 20 1 ICT is connected to the BCM virtual 0Q input via 76 meters of low quality cable 74 meters of RG243 and 2 meters of RG58 The test consists in measuring the linearity of the system first with strong signals and the lowest BCM sensitivity then with weak signals and the highest BCM sensitivity A 96 nC pulse is applied to an HP calibrated attenuator The pulse charge remains constant throughout the whole test First the pulse is attenuated in the attenuator then measured in the 50Q internal termination of a LeCroy DSO The nVs is converted in nC nVs 50Q and entered in the tables Second the cable is disconnected from the LeCroy and and instead passed through the ICT The charge collected in the ICT is read by the BCM Each BCM reading is entered in the tables Conclusions The previous test showed a considerable decrease of the charge seen by the virtual 0Q in
4. 643 User s manual Establish the reference pulse Equipment needed BCM IHR DB9 Remote Control key Pulse generator with 50Q output 20 dB attenuator 2 channel 100 MHz oscilloscope Sampling voltmeter Make sure the jumper on the Charge Amplifier board is set to 50Q input Note In ex factory conditions this jumper is set to 50Q Install the DB9 Remote Control key on the BCM rear panel Set all switches to 1 Adjust the pulse generator voltage x time integral output to approximately 500 nVs Use the highest voltage output the generator can deliver thus minimizing the pulse duration Feed this pulse into the Beam Charge Monitor via the 20dB attenuator as shown Fit the pulse into the Subtracting window See Quick Check in this manual Adjust the voltmeter sampling 30us after the trigger and average over 2 300us Pulse Generator Sampling voltmeter 2 00 Volts Trigger Input O O CRC O O C O O Output Trigger out 20 dB attenuator Beam Charge Monitor Short cable Adjust the pulse generator to obtain 2 00 V output from the BCM The pulse generator is now adjusted to give the reference pulse This pulse will be used to compute the cable loss and the calibration correction factors BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 38 Fax 33 450 426 643 User s manual Cable loss correction Connect the pulse generator
5. ETS 7 Your BCM does not behave as described 11 Testing all other BCM functions esse e eee 11 GENERAL DESCRIPTION re nn sagten ere nd 12 Purpose nn re RU es EERE ds ENES 12 System componens 6225s rocade eat eee tue ne 12 ARCHITECTURE snr EN ei 13 OPERATING PRINCIPLES vic edel 14 Integrating Current Transformer spaserte 14 Fast Current Transformer ss ee ee ee e e e ee eee 15 Cable Connection ii edic 9 Y lt eos nedre de 15 SIONAL POESI covey de RE ee de KRN Ee AR R ARE RTS ue 16 Timing of the BSP IHR esse 17 Beam Charge Monitor OUuDUL xx e e e arsenal stone 18 Virtual zero O IMPUN sores sas Te 18 Ornsline calibration sccis S wees RE eee nn ain ne 19 SENSITIVITY OF THE BCM IHR 20 Full scale with 500 input mode cs x xe e e e ees ione ente he qns enne 20 Full scale with virtual OQ input mode 20 Most sensitive configuration nex vile e e e e e eee 20 Least sensitive configuration 20 REMOTE RANGE and CALIBRATION SWITCHING 21 MAKING PRECISE MEASUREMENTS WITH THE BCM 22 SETTINGS ee 23 Charge Amplifier serre sfr nn dir 24 Bunch Sipnal Processors seente Ha ni Tu NAT RR 25 Power SUP DI iiss xc a esse Ra assedic dre Nes 26 SPECIFICATIONS an 27 Integrating Current Transformer 27 Charge Amplifier and Calibration Generator
6. France Integrate Hold Reset Tel 33 450 426 642 Page 13 Fax 33 450 426 643 User s manual ARCHITECTURE Remote control Rang r 0dB 6dB 6dB 12dB 20dB tine 200B driver 1dB vL Gain CHARGE AMPLIFIER Non invert Invert Signal Input Output View Trigger input B Calibration enable Cdlibr tion ranges OL Trigger CALIBRATION GENERATOR 10 ye I E F Attenuators Calibration Delay alibration View Calibration On Off BUNCH SIGNAL PROCESSOR ignal View Output View Timing View Trigger View Trigger delay Trigger delay 11 ION 24 odor LA Window width Cycle time Output Output BNC POWER SUPPLY 15V Voltage selector Mains BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 14 Fax 33 450 426 643 User s manual OPERATING PRINCIPLE Integrating Current Transformer The Integrating Current Transformer ICT is a passive transformer designed to measure the charge in a very fast pulse with high accuracy It is capable of integrating a pulse with rise time in the order of picoseconds with no significant loss ra ICT lt User connection The ICT is a capacitively shorted transformer coupled to a fast readout transformer in a common magnetic circuit The ICT delivers a pulse with ca 20 ns rise time irrespective of t
7. for a InC calibrated pulse Note Gain may be slightly different with inverted signal The procedure hereafter establishes the correction factors The on site cable loss calibration consists of calculating ratio of BCM output voltage with the long cable and without it It does not consist of readjusting the calibrated levels of the BCM boards On site calibration is not required when the ICT to BCM cable loss is less than 0 1 dB 10 MHz For reference this condition is fulfilled by a 2 5 meter long RG58 cable or 30 meters of 015mm RF low loss cable like CERN C 50 11 1 or Suhner S 12272 04 A simple method is proposed hereafter It does not require calibrated instruments Proposed method A pulse generator is connected directly to the BCM IHR input The pulse is adjusted to produce a 2 00 Volts output on the BCM This pulse becomes the reference pulse Next pulse generator is connected to the BCM IHR via the long cable The reference pulse is fed into the long cable The resulting voltage is read from the BCM it serves to establish the cable loss ratio Then the ICT is connected to the BCM via the long cable The BCM internal pulse generator is activated The resulting voltage on the BCM serves to compute the correction factor to be applied to the BCM internal calibration pulse generator BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 37 Fax 33 450 426
8. include a detailed description of the defect or failure name and fax number of the user Contact Bergoz Instrumentation or your local distributor to determine where to return the product Returns must be notified by fax prior to shipment Return should be made prepaid Bergoz Instrumentation will not accept freight collect shipment Shipment should be made via Federal Express or United Parcel Service Within Europe the transportation service offered by the Post Offices EMS Chronopost Datapost etc can be used The delivery charges or customs clearance charges arising from the use of other carriers will be charged to the customer BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 4 Fax 33 450 426 643 User s manual YOU JUST RECEIVED YOUR BCM Check that the voltage corresponds to your mains voltage The power supply voltage is indicated on the plastic label located on the power supply module front panel If it does not correspond go to Annex III Delta Elektronika U Series linear power supply data sheet to adjust the power supply to your mains and change the fuse and front panel plastic label accordingly QUICK CHECK You can check immediately that your BCM is working This is what you need Beam Charge Monitor Integrate Hold Reset DB9 Remote control key Integrating Current Transformer or Fast Current Transformer 4 channel oscilloscope or 2 channe
9. on the Charge Amplifier front panel until the calibrated pulse fits into an integrating window If those adjustments cannot be effected the instrument s time constants have probably been changed after delivery of the instrument Either restore original values according to the schematics or contact manufacturer for recalibration Testing all other BCM functions You can test all gain ranges inverse the signal polarity change the value of the calibration pulse and its polarity Move the switches of the DB9 Remote control key Place the switches AO to A6 according to Remote Range and Calibration Switching Switch position 1 corresponds to bit HIGH Position 0 to bit LOW Note that Switch A7 is not connected The Calibration Enable command can be activated with the BCM front panel switch BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 12 Fax 33 450 426 643 User s manual GENERAL DESCRIPTION The BCM is made in two versions Integrate Hold Reset IHR version for pulse repetition rates from 1 kHz down to single pulses Continuous Averaging CA version for pulse repetition rates from 10 MHz down to 5 kHz This manual describes the Integrate Hold Reset IHR version Purpose The Integrate Hold Reset version measures the charge in a single selected pulse or macro pulse The Continuous Averaging version measures the average charge over time of repetiti
10. standard units with 70 ns output pulse Pulse Charge to output ratio Input current rise time Pulse length Eddy current loss ratio Droop in 50Q termination Droop in virtual 0Q load Linearity error Off centre position sensitivity Output connector Output rise time Output pulse duration 50 1 20 1 10 1 or 5 1 lt lps Limited by the droop lt 1 lt 10 us lt lt 1 us depending on cable ohmic resistance lt 0 1 lt 0 01 mm on axis SMA 50Q female ca 20 ns ca 70 ns 99 Idt Charge Amplifier and Calibration Generator Input charge Input rise time Gain steps Gain fine adjustment Output Front panel connectors Back panel connectors Front panel switch Front panel potentiometer On board jumpers On board potentiometer Calibration pulse absolute accuracy Card size 4 nC max lt Ins in 50Q termination 10 ns in 0Q virtual load 7 steps from 37 dB to 71 dB 1dB bipolar up to 10 V 500 SMA 50Q female Lemo on option Signal Input Trigger Input Calibration View for oscilloscope Output View for oscilloscope BNC Trigger Input DB9 male 8 TTL commands for Range control Calibration Control and Calibration Enable Calibration on off Calibration delay to fit the calibration pulse in the integrating window Input termination 50Q 0Q Fine gain adjust 1dB 2 Eurosize 100 x 160 mm 20mm wide BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426
11. 50 426 642 Page 18 Fax 33 450 426 643 User s manual Beam Charge Monitor Output The output is a DC level up to 7V proportional to the pulse charge The output voltage is the difference between the value of the Subtracting Integrator and the Adding Integrator The output may have an offset This output zero offset is user adjustable with the Zero Offset potentiometer P6 located on the BSP board To eliminate this offset and make precision measurement see chapter Making precise measurements with the BCM in this manual The output is available on the BNC at the rear of the Beam Charge Monitor See BCM Backplane Wiring Diagram chapter in this manual It is also available for oscilloscope viewing from the BSP front panel connector Output View In the IHR Integrate Hold Reset version the output is the value of the last selected pulse only The signal settles in lt 20 us after the end of the second window it is held at that level until the end of the cycle then it is reset to zero The Cycle time Tc or Hold time can be adjusted with the P4 potentiometer located on the BSP board Virtual zero Q input Not applicable when optional Wideband Amplifier is used In the Charge Amplifier a special feature makes the input impedance a virtual zero Q instead of 50Q This can only be used with slow rising signals because the active circuits are limited in slew rate In practice pulses with rise times down to 20 ns are well integrated Belo
12. 50 Hz mains the time interval must be equal to N x 20 ms BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 23 Fax 33 450 426 643 User s manual SETTINGS Pull the modules out of the crate The modules can be removed and inserted while the power in on Remove the shield LL I x nm To remove shield Remove screws 2 from under To adjust the potentiometers a card extender is necessary such as Schroff p n 20800 185 BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Fax 33 450 426 643 Charge Amplifier Page 24 User s manual CHARGE AMPLIFIER Calibration attenuators gm AMAA 1pC 10pC 100pC 1nC Input Termination 50Q 0Q Los Input Termination Jumper 500 Ex factory setting 0Q The charge collected by the beam current sensor splits equally between the 50Q load resistor integrated in the transformer sensor head and the 50Q input termination The charge amplifier receives exactly 1 2 of the collected charge The charge is passively integrated in a coil before it goes into any active circuit even very fast pulses lt Ins rise time are properly integrated The input termination is a virtual 0Q impedance As a consequence the charge collected by the beam current sensor is mostly going into the charge amplifier this increases the BCM sensitivity The o
13. 642 Page 28 Fax 33 450 426 643 Beam Charge Monitor Integrate Hold Reset User s manual SPECIFICATIONS Cont d Bunch Signal Processor Integrate Hold Reset BCM IHR Input voltage 10 V AC coupled Input impedance 10 kQ Trigger pulse Rising edge 10 ns min 22 4V Integrating windows width adjustable Output signal bipolar up to 7 V Output load 10 mA max Font panel connectors Back panel connectors Front panel potentiometers On board potentiometers Back panel connector Output settling time Output signal hold time Card size Power Supply Type Manufacturer Model Output Mains voltage Mains voltage selector Mains frequency Card size Back panel connector SMA 50Q female Lemo on option Signal View for oscilloscope Output View for oscilloscope Timing View for oscilloscope Trigger View for oscilloscope BNC Output signal Integration window width Tw adjustable Trigger delay adjustable Window balancing Cycle or Hold time Tc adjustable Output zero offset adjustable Voltage fine adjust adjustable BNC Output lt 30 us after the trigger up to 430 us after the trigger adjustable Eurosize 100 x 160 mm 20mm wide modular plug in 15V linear power supply Deleta Elektronika 4300A Zierikzee The Netherlands 5 U 15 15 15V 200 mA jumper selected 110 220Vac tested at 90 Vac 50 Hz for 100Vac Japanese mains voltage located under the power supply block AC 50 60 Hz Euros
14. 7 Volts output Sensitivity is ca 43 mV per nC of beam charge Noise is 0 4 mV rms 10 pC rms of beam charge Dynamic range is 16000 BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 21 Fax 33 450 426 643 User s manual REMOTE RANGE and CALIBRATION SWITCHING With the Remote range Switching BCM RRS B option installed all functions of the BCM IHR can be controlled by TTL levels It allows remote control of the Charge Amplifier gain level signal polarity selection of the Calibration pulse charge and Calibration pulse polarity C15 Function D O Q o Q fev Co a o Calibration Calibration Enable Pis gl belection e on 2nd stage 1st stage OdB 6dB 12dB OdB 6dB 20dB 12dB 20dB Signal polarity Non invert Invert Calibration pulse Positve Negative Calibration charge Calibration Enable Disable Calibration Enable and Calibration front panel switch ON are OR d Therefore the BCM will be in calibration mode whenever either Calibration Enable is High or Calibration switch is ON H H H H H L H L H L H H L H L H L L L L H L L L E L Notes The default status i e the status when no external control signal is applied is printed in BOLD The Remote Calibration Enable Pin C5 of the DIN41612 connector is installed on the Charge Amplifier board whether or not a BCM RRS option is installed BER
15. BERGOZ Instrumentation Espace Allondon Ouest 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 Visit our web site at http www bergoz com bergoz Instrumentation Beam Charge Monitor Integrate Hold Reset Japan REPIC Corporation 28 3 Kita Otsuka 1 Chome Toshima ku Tokyo 170 0004 Tel 03 3918 5326 Fax 03 3918 5712 sales repic co jp User s Manual Rev 1 8 1 U S A GMW Associates 955 Industrial Road San Carlos CA 94070 Tel 650 802 8292 Fax 650 802 8298 sales amp gmw com BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 email bergoz O bergoz com http www bergoz com Registre des M tiers Bourg en Bresse Registre des ing nieurs Zurich TIA X7 AT TYNT ATTA NIOTTD 00A1 Am DN ALT an AASE VORTE THAT EN EE nr ANT 50H55D BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 1 Fax 33 450 426 643 User s manual SUMMARY Page INITIAL INSPECTION eselet 3 WARRANTY T 3 ASSISTANCE serenon greene piese RAA oner a eee oee eop e une Redon 3 SERVICE amp RETURN PROCEDURES sse ee 3 YOU JUST RECEIVED YOUR BOM ions ce Eden nn R Taa neue Mende 4 QUICK CHECK sisi annee UHR or EEEE rade vends nn au 4 Front panel ss Sn Feed 3 Jumpers configuration for quick check 5 SCUD MR C 7 WAVOLORS uus EE
16. GOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 22 Fax 33 450 426 643 User s manual MAKING PRECISE MEASUREMENTS WITH THE BCM It is recommended to use a sampling voltmeter with programmable statistics capabilities to read the BCM output signal The Hewlett Packard sampling voltmeter HP 3458A is suitable for this application It exceeds specifications in terms of sampling rate therefore a suitable voltmeter at a lower cost can possibly be found The voltmeter reading must be started triggered when the BCM IHR output pulse is stable 1 e gt 20us after the BCM IHR trigger pulse For precise measurement the voltmeter should sample the BCM IHR output over 2 300us and calculate the average For ultimate precision the BCM IHR should execute two measurement cycles First measurement is with beam pulse Second measurement is without beam pulse Second measurement is deducted from the first measurement to obtain precise value This technique has two advantages A The value of the zero which depends on the balancing between the Adding and the Subtracting integrators is compensated Any drift of the zero due to temperature or aging is eliminated B The mains frequency noise can be eliminated For 60 Hz mains the noise can be rejected very effectively by making the two measurements at a time interval equal to N x 16 66ms where N is an integer 1 2 3 For
17. HE BCM IHR Full scale with 50Q input mode Bits Full scale with Full scale with Full scale with Full scale with Gain setting ICT XXX 070 ICT XXX 070 ICT XXX 070 ICT XXX 070 2 1 0 Full scale with virtual 0 input mode The sensitivity is almost doubled as compared to sensitivity in 50 input mode depending on the coax cable used between the ICT and the BCM IHR The corresponding full scales are divided by a factor lt 2 when using the virtual 0Q input Most sensitive configuration The most sensitive configuration is obtained when using also the most sensitive beam current transformer With an Integrating Current Transformer with 5 1 turns ratio and the charge amplifier adjusted for maximum gain 20 dB on first stage and 20 dB on second stage and the cable terminated in the virtual 0Q termination of the charge amplifier then Full scale is 400 pC for 7V output Sensitivity is ca 18 mV per pC of beam charge Noise is 10 mV rms 550 fC rms of beam charge Dynamic range is gt 700 Least sensitive configuration The least sensitive configuration without external signal attenuators is limited by the saturation of the circuits With an Integrating Current Transformer with 20 1 turns ratio and the charge amplifier at minimum gain 0 dB on first stage and 6 dB on second stage and the cable terminated in the 50Q termination of the charge amplifier then e Full scale is 160 nC for
18. N Now look at the signals with the oscilloscope All View points are on the front panel Waveforms Connect the BSP Trigger View output to the oscilloscope It should look like this 9 Jun 95 17341158 r Main Menu EXT 0 80 V LF REJ CH 2 V CH2 1 lt H H T div Sus Trigger View BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Page 7 Fax 33 450 426 643 Beam Charge Monitor Integrate Hold Reset User s manual Waveforms cont d Connect the Charge Amplifier Calibration View output to the oscilloscope It should look like this S Jun 95 17 44 08 Main Menu EXT 0 80 V LF REJ CH1 50mV 1 CH 1 V T div 5us Calibration View Connect the Charge Amplifier Output View to the oscilloscope It should look like this S Jun 95 17 45 48 Main Menu EXT 0 80 V LF REJ CH1 2 V r4 CH2 1 V T div 5us Charge Amplifier Output View Beam Charge Monitor BERGOZ Instrumentation 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 8 User s manual Fax 33 450 426 643 Waveforms cont d Connect the Bunch Signal Processor Signal View to the oscilloscope It should look like this 9 Jun 95 17 47 41 EXT 0 80 V LF REJ Gp 1 V T div Sus Bunch Signal Proc
19. Subtracting window Next step is down The first or Subtracting window has closed The second window starts In ex factory conditions this window has equal duration than the first window During this window the input signal is summed with a positive sign It is the Adding window Next step down The second window has closed The Hold time starts During the hold time the BSP output value is held In ex factory conditions the Hold time terminates 400 us after the trigger Next step down The Hold time is finished The BSP output is reset to zero The Beam Charge Monitor is ready to receive another Trigger BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 11 Fax 33 450 426 643 User s manual Your BCM IHR does not behave as described If your BCM IHR is in ex factory conditions it should behave as described If it does not check the switch settings on the Remote Control key All switches should be in the OFF position If your BCM IHR is not anymore in ex factory conditions the front panel potentiometers settings may have been changed To reestablish the ex factory settings Turn potentiometer delay located in the BSP front panel Trigger View frame until the Trigger delay equals 4 us Turn potentiometer Tw located in the BSP front panel Timing View frame until the integration window width equals 4 us Turn potentiometer Calibration Delay
20. User s manual Signal processing The signal is amplified by the Charge Amplifier The amplified signal is entered via the backplane into the Bunch Signal Processor BSP The BSP integrates this signal whenever the BCM is triggered by an external trigger This gives the possibility to measure only selected pulses not necessarily at a fixed repetition rate The trigger can be applied to the Charge Amplifier front panel or to the BNC connector located at the back of the BCM mini crate The signal processing is initiated by the external positive going trigger pulse A sequence timer creates three successive time windows a trigger delay a subtracting window and an adding window The pulse to be integrated must fall either in the adding window or the subtracting window Pulses falling in the first window or trigger delay are not integrated At the start of the first integration window the baseline is clamped to set the zero reference The two integration windows are used to integrate the input signal in two independent integrators offset erro correction sequence trigger timer gated integrator gated integrator Lowpass Out filter One integrator integrates the pulse signal The other integrates the input noise and baseline offset The pulse charge is obtained by summing the two integrators the first with negative sign the second with positive sign This particular combination of sampling window integrators give
21. ber electrical conductivity If the vacuum chamber does not require bake out and the vacuum requirements are moderate a polymer gasket in between two flanges is adequate to assure the desired galvanic isolation If the vacuum chamber needs bake out the most commonly use solution is to braze a section of ceramic on the vacuum chamber tube This is called a ceramic gap The ceramic gap may be installed on centre or off centre of a short pipe section Flanges m HM Ceramic gap BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 33 Fax 33 450 426 643 User s manual INSTALLATION ON THE VACUUM CHAMBER Cont d Vacuum chamber impedance The ceramic gap causes a disruption of the impedance seen by the beam This is particularly undesirable for leptons accelerators The most usual corrective measure consists of metallizing the inside of the ceramic gap Metallization has been used successfully on many electrons positrons accelerators Depending on the type of current transformer being installed AC or DC the resistance of the desirable metallization varies ICT current sensors tolerate a metallization with ca 1Q without problem provided the wall current bypass is of very low impedance If a DC current transformer PCT or MPCT S is installed over the same ceramic gap these latter instruments are adversely affected by an ohmic value R lt 100Q because it shorts
22. dinal profile with an oscilloscope and b measuring the beam charge with a Beam Charge Monitor But the Integrating Current Transformer is preferable The sensitivity of the Fast Current Transformer is also called the transfer impedance It depends on the FCT model It is expressed in terms of output pulse voltage as a function of the input pulse current therefore in V A or Q FCT Model Sensitivity Beam charge to Beam charge to in a 500 input charge ratio input charge ratio termination in BCM 5090 input in BCM OQ input FCT XXX 50 1 Cannot be used FCT XXX 20 1 Cannot be used FCT XXX 10 1 Cannot be used FCT XXX 05 1 Cannot be used Cable connection When a Fast Current Transformer is used as beam sensor the choice of the cable may be critical The cable must be capable of carrying the frequency spectrum of the signal with acceptable integration and differentiation With fast beam pulses the FCT limits the risetime Somewhere below Ins When using an Integrating Current Transformer as beam sensor the choice of the cable is much less critical because the ICT output pulse has a risetime of 20 ns unless it is a special model with short output pulse We made tests with long low quality cable Those tests are reported in Annex I Test of cable length incidence on BCM linearity BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 16 Fax 33 450 426 643
23. e recalibrated on site using the actual cable linking the ICT to the BCM Beam Current and Beam Lifetime Measurements at the HERA Proton Storage Ring W Sch tte and K B Unser Proceedings of the 4th Accelerators Instrumentation Workshop Berkeley 1992 to be published BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 19 Fax 33 450 426 643 User s manual On line calibration On line calibration is possible at any time when there is no beam Even when the no beam time is short on line calibration may still be possible The Calibration Generator is located on the Charge Amplifier board The Calibration generator is enabled when the front panel switch Calibration is turned ON The Calibration Generator can also be enabled by applying a high level to the Calibration pin on the BD9 connector When the Calibration Generator is enabled it sends two calibrated pulses one positive the other negative a short time after it receives a trigger The delay between the trigger and the first calibration pulse can be adjusted with the front panel potentiometer Calibration Delay The trigger signal is the same as the one applied to the BSP It is fed from the Charge Amplifier into the BSP module via the backplane The calibrated pulse is applied to the input of the charge amplifier For correct calibration the beam current transformer and its cable must be connected to the inp
24. eam out of the cavity The transformer the gap capacitance and the wall current bypass form together a cavity It is important to prevent unnecessary harmonics from entering the cavity The beam current flows thru the vacuum chamber The wall current follows the conductive vacuum chamber walls gt lt lw lb S PS Transformer Ceramic gap Wall current bypass The transformer sees the wall current Iw The higher frequencies of the wall current frequency spectrum will pass thru the capacitance of the ceramic gap while the lower frequencies will enter the cavity and induce a flux in the transformer core Note that the full charge of the wall current pulse passes thru the cavity irrespective of the value of the gap capacitance The value C of the gap capacitance determines the higher cutoff frequency of the wall current entering in the cavity The 3dB point is obtained when the impedance of the cavity Zeavity is equal to the impedance of the gap Zeap The impedance of the wall current bypass itself can be ignored because it is much lower than the transformer s reflected impedance therefore ICT lt User connection Zeavity R N2 where R is the load impedance of the transformer 25Q 50Q termination II 50Q internal load N is the transformer s turns ratio Example an ICT with 20 1 turns ratio i e ICT XXX 070 20 1 Zeavity 0 0625 Q BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Gen
25. essor Signal View Connect the Bunch Signal Processor Timing View to Channel 1 of the oscilloscope and Signal View to Channel 2 It should look like that 93 Jun 35 17 50 34 Main Menu SITE T div 5us Bunch Signal Processor Timing View and Signal View BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Page 9 Fax 33 450 426 643 Beam Charge Monitor Integrate Hold Reset User s manual Waveforms cont d To view the Bunch Signal Processor Output in relation to the other signals connect the Bunch Signal Processor Output View to channel 3 of your oscilloscope If you use a 2 channel oscilloscope memorize the Timing View waveform and connect Output view to Channel 1 It should looks like this 9 Jun 95 18 09 26 Main Menu EXT 0 80 V LF REJ CH1 2 N FL CH2 1 V T div Sus Top to bottom Memorized Timing View BSP Output View and BSP Input View Turn the Charge Amplifier front panel Calibration Delay 20 turn potentiometer It changes the delay between the trigger and the calibrated pulse The calibrated pulse can be moved from the second window the adding window into the first window the subtracting window When the calibrated pulse fits entirely into the first subtracting window it should look like this 9 Jun 95 18 12 48 Main Menu A o Q O lt
26. gs label affixed to the BCM crate P3 Trigger delay P3 x C34 adjusts the delay from the trigger until the beginning of the first integration window Factory set as shown on the Factory Settings label affixed to the BCM crate P4 Cycle time P4 x C37 determines the cycle duration Tc Tc must be greater than the or Hold time trigger delay 2x Tw Allows an adjustment from lt 15us up to gt 400us Factory set as shown on the Factory Settings label affixed to the BCM crate P6 Zero Offset Trims the Charge Amplifier s output signal zero offset Factory set to zero offset for 1 kHz trigger frequency BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 26 Fax 33 450 426 643 User s manual Power Supply See Annex III Delta Elektronika U Series linear power supply data sheet The mains voltage is factory set according to the label stuck on the front panel Please remove this label when you change the mains voltage selection The fuse and the spare fuse located in the IEC connector on the BCM back panel are factory installed 200 mA fast blow for 220 and 240 Vac jumper settings 100 mA fast blow for 110 and 130 Vac jumper settings BERGOZ Instrumentation 01630 Saint Genis Pouilly France Tel 33 450 426 642 Fax 33 450 426 643 SPECIFICATIONS Beam Charge Monitor Integrate Hold Reset Page 27 User s manual Integrating Current Transformer
27. he beam pulse rise time The ICT output pulse charge is in exact proportion to the beam pulse charge Integrating Current Transformer Beam pulse Output pulse The sensitivity of the Integrating Current Transformer is also called the transfer impedance It depends on the ICT model It is expressed in terms of the integral of the output pulse voltage as a function of the input pulse charge therefore in V s C or Q ICT Model Sensitivity Beam charge to Beam charge to in a 500 input charge ratio input charge ratio termination in BCM 5090 input in BCM OQ input ICT XXX XXX 50 1 ICT XXX XXX 20 1 ICT XXX XXX 10 1 ICT XXX XXX 05 1 1 Measuring Bunch Intensity Beam Loss and Bunch Lifetime in LEP K B Unser Proceedings of the 2nd European Particle Accelerator Conference 1990 Vol 1 p 786 BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 15 Fax 33 450 426 643 User s manual Fast Current Transformer The Fast Current Transformer FCT is a passive AC transformer with 1ns rise time and droop lower than 5 us Fast Current Transformers are made with 20 1 10 1 and 5 1 turns ratios into a 50Q load The FCT is specifically designed to observe bunched beams in particle accelerators Primary current FCT User connection It can be used as beam sensor in a Beam Charge Monitor when the sensor must have the dual purpose of a looking at the beam longitu
28. hmic resistance of the cable is becoming non negligible as compared to the transformer s load this makes the charge to output voltage ratio dependent on the cable length and quality See Annex I Test of Cable Length Incidence on BCM linearity The load R seen by the current transformer is very low This increases the transformer s L R differentiating time constant and the droop decreases Signals with risetime faster than 20 ns are not properly integrated because of slew rate limitations in the virtual OQ termination Fine Gain Potentiometer PI Continuous gain adjustment 1 dB Factory adjusted for 2 000 V BSP output corresponding to I nC in the 50Q input of the charge Amplifier at lowest gain 0 dB in first stage and 6 dB in second stage BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 25 Fax 33 450 426 643 User s manual Bunch Signal Processor te P6 Output E Mi EE P1 Window Balancing P4 Cycle Hold Time Es ba P2 Window width Tw P3 Trigger delay Dog adjust O Potentiometers P1 Window Balancing Balances the respective gains of the Adding and Subtracting Integrators Factory set as shown on the Factory Settings label affixed to the BCM crate P2 Window width P2 x C36 determines the width Tw of the integration windows Allows an adjustment from lt 0 15 us up to gt 8 us Factory set as shown on the Factory Settin
29. ied ives des etes en ie k ssnsti EEE B23 External commands Calibration Enable vsert SR eee ees C05 Calibration Charge Only with BCM RRS B DANG ST C16 Fs C15 Calibration Polarity Only with BCM RRS B C14 Signal Polarity Only with BCM RRS B C13 Signal Gain Only with BCM RRS B Sid i co RSS ee ee mE PE C12 2nd DIL rc ETE C11 LS T aa LRA C10 Power Supply FISM OE Ne me EE ER C31 IVE 0 Ree nee Gunes ME A31 1 Sa NE SE EE SE EE A15 Bunch Signal Processor BSP DIN 41612 rear connector Rear connector DIN 41612 form C 3 rows of 32 pins each Signal Path Signal put 0 SE een AE e nes Ros emis te lene DUI MUN B11 Signal Inp t round coset ee SS All AIS CT Input T 7 reete Gece ata SENERE B07 Tie ger Input omdr te A09 Output sipnalo Er au sve SE NGS B05 Output signal ground ee A09 Power supply BON ee C31 EN Ma MIEL Cu METER A31 be A15 BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 31 Fax 33 450 426 643 User s manual BACKPLANE WIRING DIAGRAM BCM Rev 3 0 Power Supply ES Remote Control 220 28 p 9 o L 4 ovo Le if 8 1 EN 3 of 7 fan 2 EN ES 6 Er T LT IT 1 5 Calibration 9 Ground Mating connector is 3M 8309 6009 S ba D Sub 09 Female Output BNC Trigger BNC B
30. is Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 35 Fax 33 450 426 643 User s manual Keeping high harmonics of the beam out of the cavity Cont d The gap impedance is determined by its capacitance Zap 1 OC and 2nf For Zeavity Zgap C N2 2nfR Example ICT with 20 1 turns ratio f 3as 1GHz R 25 C 2 54 nF Different laboratories use different techniques to obtain the required gap capacitance A simple method consists in building a capacitor over the ceramic gap with layers of copper foil separated by layers of 100um thick kapton foil To obtain the desired capacitance value the overlapping area is obtained by S Cd Er o Where C is the capacitance F S is the area m d is the dielectric thickness m Er is the relative dielectric constant 3 5 for Kapton polyimid o is the dielectric constant 8 86 x 10712 Example for C 2 54 nF and d 100um and r 3 5 S 82 cm2 BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 36 Fax 33 450 426 643 User s manual LONG CABLE LOSS ON SITE CALIBRATION The BCM IHR is factory calibrated at 2 000 Volt output for 1nC charge in the 50Q input at lowest gain Bits 2 1 0 High High High for non inverted signals Bit 3 High in either the adding window or the subtracting window The internal calibrated pulse generator is likewise factory set to produce 2 000 V output
31. ize 100 x 160 mm 50mm wide The Power supply mains are wired to a IEC connector via an EMI RFI filter and fuse The manufacturer s data sheet sheet is attached as Annex III BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 29 Fax 33 450 426 643 User s manual CONNECTOR PINS ALLOCATION BNC rear connectors Trigger input bussed with Charge Amplifier front panel connector BNC up His BNC DB9 male Remote Control connector Mating connector use any DB9 female connector Locking with 4 40 screws Gain selection BIO arrestere Billie Lx sed Mr Decade semua Re Bit2 se Tuba Annee Signal polarity OO SRE Ade ehe Coa SEA Unies XE RU d RN ZR T Calibration charge selection BEG NA SM ALVES AR TD are Bib oo e aea ee en Calibration polarity RE Ress re Ne rar NN nee TRE DM dd Calibration Enable sese eee COUN sA a hati HT I MD Lh LA BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 30 Fax 33 450 426 643 User s manual CONNECTOR PINS ALLOCATION Cont d Charge Amplifier and Calibration CAC DIN 41612 rear connector Rear connector DIN 41612 form C 3 rows of 32 pins each Trigger functions Trigger input bussed with front panel input C28 Trigger output DUNered se C27 Trigger input Sround v
32. l with memory with 100 MHz bandwidth or better Pulse generator capable of making the trigger pulse 210 ns 22 4V 1 kHz You will also need short 4 8 ns cables and SMA BNC adapters Verify that this manual corresponds to your BCM version The BCM version is marked on the front panel handle of the Bunch Signal Processor module e BSP CA for a BCM CA e BSF IHR for a BCM IHR Your configuration may include a Wideband Amplifier This manual covers the BCM IHR Beam Charge Monitor Integrate Hold Reset version order code BCM IHR It does not cover the BCM CA Another manual titled Beam Charge Monitor Continuous Averaging covers the BCM CA with and without the BCM WBA Wideband Amplifier DB9 Remote control key A DB9 Remote control key is supplied with the Beam Charge Monitor It is a small auxiliary printed board attached to a DB9 connector An 8 bit switch is mounted on the printed board It must be plugged to the DB9 Remote control connector at the rear of the BCM to allow range switching and calibration range switching during tests Switches AO A6 are active They correspond to Bits 0 6 of the remote control See Remote Range and Calibration Switching this manual Position 1 corresponds to bit HIGH Position 0 corresponds to bit LOW Switch A7 is not connected Bit 7 controls Calibration Enable This function can be enabled during tests by the BCM front panel switch DB9 Remote control key BERGOZ Instr
33. lack I White BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 32 Fax 33 450 426 643 User s manual INSTALLATION ON THE VACUUM CHAMBER The installation of an Integrating Current Transformer on the outside of a vacuum chamber requires some precautions a The electrical conductivity of the vacuum chamber must be interrupted in the vicinity of the ICT otherwise the wall current will flow thru the ICT aperture and cancel the beam current b The wall current must be diverted around the ICT thru a low impedance path c A fully enclosing shield must be installed over the ICT and vacuum chamber electrical break to avoid RF interference emission d The enclosing shield forms a cavity Cavity ringing at any of the beam harmonics must be avoided e The ICT must be protected from being heated beyond 80 C during vacuum chamber bake out f The higher harmonics of the beam should be prevented from escaping the vacuum chamber because 1 they are not seen by the ICT therefore unnecessary 2 they heat the ICT and any other conductive material inside the cavity 3 they cause quater wave mode ringing in the cavity Note The ICT does not need to be protected from external magnetic fields When it is exposed to external magnetic fields it may saturate this causes the droop to increase up to a factor of 2 It has no effect on the ICT linearity Break in the vacuum cham
34. on replace any product returned to Bergoz Instrumentation or its local distributor within the warranty period provided that the warrantor s examination discloses that the product is defective due to workmanship or materials and that the defect has not been caused by misuse neglect accident or abnormal conditions or operations Damages caused by ionizing radiations are specifically excluded from the warranty Bergoz Instrumentation and its local distributors shall not be responsible for any consequential incidental or special damages ASSISTANCE Assistance in installation use or calibration of Bergoz Instrumentation beam current monitors is available from Bergoz Instrumentation 01630 Saint Genis Pouilly France It is recommended to send a detailed description of the problem by fax SERVICE PROCEDURE Products requiring maintenance should be returned to Bergoz Instrumentation or its local distributor Bergoz Instrumentation will repair or replace any product under warranty at no charge The purchaser is only responsible for transportation charges For products in need of repair after the warranty period the customer must provide a purchase order before repairs can be initiated Bergoz Instrumentation can issue fixed price quotations for most repairs However depending on the damage it may be necessary to return the equipment to Bergoz Instrumentation to assess the cost of repair RETURN PROCEDURE All products returned for repair should
35. orresponding beam charge is obtained by Equivalent beam charge Nominal calibrated pulse charge x Beam charge to input charge ratio ANNEX I TEST OF CABLE LENGTH INCIDENCE ON BCM LINEARITY Conclusions THE INTEGRATING CURRENT TRANSFORMER CAN BE USED WITH LONG LOW QUALITY CABLES THE BCM REMAINS VERY LINEAR BUT THE SENSITIVITY OUTPUT VOLTS PER INPUT NANOCOULOMB MUST BE MEASURED WITH THE SENSOR AND THE CABLE PRIOR TO INSTALLATION Pulse Generator TEST SETUP EY Attenuator Various cable lengths and qualities First test A charge is injected in a 20 1 ICT This charge is constant throughout the whole test The test is is made for different cable lengths and qualities varying from 2 meters to 84 meters The test consists of a Disconnecting the cable from the ICT connecting it to a LeCroy DSO and reading the pulse integral in nVs These values are shown in the table under the heading ICT Output and converted in nC nVs 50Q b The BCM input is set to virtual 0Q input The BCM output is measured and the values are entered in the table under the heading BCM Output Name Linea of BCM Serial number BSP N 08 and Charge Ampl N 08 Date 15 01 93 Amplifier stage 0 6 dB 062 ICT Output after loss in cabl BCM Output 2m RG58 74m RG243 RG58 Conclusions 1 The signal is attenuated by the cable rather insignificantly because the ICT output is slow 20 ns risetime
36. put when the cable length increases This test shows for a fixed 76 meter cable length that the ICT BCM system remains perfectly linear throughout its entire dynamic range from a few pC to 100nC also when the virtual 0Q input is used Attached s BCM linearity test with 76 meter long cable in the virtual OQ input from 1 to 96 nC s BCM linearity test with 76 meter long cable in the virtual 0Q input from 32 pC to 2 2 nC BCM Output Y oks Name Linea of BCM CABLE 76 M Serial number BSP N 08 and Charge Ampl N 08 Date 15 01 93 Amplifier stage 0 6 dB 0Q Position Input Equivalent Output attenuateur ICT measured Charge BCM BCM linearity test with 76 meter cable gain 0 6dB 0 9 0000 8 0000 SAE EE NEN REN Se 1 0000 Ea 00 0 20 0 40 0 60 0 80 0 Charge passed through the ICT nC 100 0 BCM Output oks Name Linea of BCM CABLE 76 M Serial number BSP N 08 and Charge Ampl N 08 Date 15 01 93 Amplifier stage 20 20 dB 02 Position Input Equivalent Output attenuateur ICT measured Charge BCM BCM linearity test with 76 meter cable gain 20 20dB 0 10 0000 9 0000 6 0000 4 0000 0 500 1000 1500 2000 Charge passed through the ICT pC 2500
37. s a high degree of noise suppression All signals which do not correlate in frequency and in time with the window timing are rejected This is true for the amplifier noise and also for the general background The balance of integrators gains is user adjustable with the Window Balancing potentiometer PI BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 17 Fax 33 450 426 643 User s manual Timing of the BSP IHR Trigger 10ns min Jl Signal input EB Timing view s LE INN Output signal Medb l Trigger dela Trigger dela Tw Tw Baseli amp ubaausibujngmvovdo Base pinap le time The Trigger delay is adjustable with front panel potentiometer P3 labelled delay in Trigger View frame of the BSP The trigger delay is determined by the P3 x C34 time constant The two integration windows are of equal width Tw Tw is adjustable with front panel potentiometer P2 labelled Tw in the Timing View frame of the BSP module Tw is determined by the P2 x C36 time constant The Hold time or Cycle duration Tc is determined by the time constant P4 x C37 P4 is user adjustable It is located on the BSP board C37 can be changed to another value The cycle duration Tc must not be made shorter than the sum of the trigger delay and the two integration windows BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 4
38. th Incidence on BCM Linearity Annex II Delta Elektronika U Series Linear Power Supply data sheet Annex III Measuring Bunch Intensity in LEP K B Unser Annex IV Beam Current Measurement at the HERA Proton Ring W Sch tte K B Unser Annex V Fast Bunch to Bunch Current Sampling in the Cornell e e Collider C R Dunnam Annex VI Bunched Beam Measurement of Small Currents at ASTRID F Abildskov et al BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 3 Fax 33 450 426 643 User s manual INITIAL INSPECTION It is recommended that the shipment be inspected immediately upon delivery If it is damaged in any way contact Bergoz Instrumentation or your local distributor The content of the shipment should be compared to the items listed on the invoice Any discrepancy should be notified to Bergoz Instrumentation or its local distributor immediately Unless promptly notified Bergoz Instrumentation will not be responsible for such discrepancies WARRANTY Bergoz Instrumentation warrants its beam current monitors to operate within specifications under normal use for a period of 12 months from the date of shipment Spares repairs and replacement parts are warranted for 90 days Products not manufactured by Bergoz Instrumentation are covered solely by the warranty of the original manufacturer In exercising this warranty Bergoz Instrumentation will repair or at its opti
39. the PCT or MPCT sensor The commonly used solution is to etch a narrow groove in the metal deposit to prevent DC conductivity of the gap metallization Wall current bypass and RF shield The two functions of wall current by pass and RF shield can be performed by a solid metal shield attached to the vacuum chamber on either side of the electrical break The easiest is to make a cylindrical enclosure which splits into two half shells The shells can be firmly attached to the vacuum chamber with water hose clamps Material can be aluminium stainless steel or copper Copper oxidation does not seem to be a problem Thermal protection of the ICT The ICT must not be heated beyond 80 C If the vacuum chamber requires bake out a thermal shield must be installed between the vacuum chamber or the heating sleeves and the ICT The thermal shield can be a simple copper cylinder cooled by water circulating in a copper tube brazed onto the cylinder The water circuit must not pass thru the ICT aperture It must enter and go out on the same side of the ICT otherwise it makes a shorting loop around the ICT toroid MAXIMUM STORAGE AND OPEARTING TEMPERATURE 80 C 176 F AT ANY TIME The alloy looses its characteristics when heated beyond this temperature BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 34 Fax 33 450 426 643 User s manual Keeping high harmonics of the b
40. to the BCM IHR via the long cable Pulse Generator Sampling voltmeter Reference pulse Volts U O O O C Oo O Trigger O Output Trigger out 20 dB attenuator Beam Charge Monitor Actual cable to be laid in tunnel Read from the voltmeter the BCM output produced by the reference pulse The difference between this value and 2 00V is the loss due to the cable when the Charge Amplifier is used in 50Q input mode BCM read out Cable loss ratio 1 200 V This loss ratio can be applied to all BCM gain ranges to compute the actual bunch charge This is only valid when the Charge Amplifier is used in 509 input mode i e with the jumper set to 30 To calibrate the BCM IHR in virtual 0Q input mode a calibrated pulse must be fed directly into the ICT BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 39 Fax 33 450 426 643 User s manual Correcting the internal calibration generator for long cable When the BCM internal calibration generator is enabled Command Calibration Enable a calibrated pulse is sent into the Charge Amplifier input A small fraction of the pulse charge goes into the ICT it gets lost in the cable and ICT The remaining fraction which is measured by the BCM depends on the cable DC resistance The 1 nC internal calibration generator is adjusted to generate 2 00 V BCM output taking into account the loss ca
41. umentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 5 Fax 33 450 426 643 User s manual Front panel Charge Amplifier 3 On Off Calibration J Delay Calibration View Trigger Input Output View Signal Input C A C Font panel The modules have labels on the handles identifying the version IHR or CA WARNING Jumpers configuration amp Potentiometers settings Your BCM is in the Ex factory configuration Jumper and timing adjustments potentiometers have been configured according to your order Do not change those settings until you are familiar with the Beam Charge Monitor BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 6 Fax 33 450 426 643 User s manual Setup ICT or FCT Beam Charge Monitor Pulse Generator 10ns 2 4V 1 kHz Chl Trig O O OOOOO O Connect the beam current transformer to the Signal Input of the Charge Amplifier Insert the Remote Control key in the DB9 connector at the rear of the Beam Charge Monitor Note All Remote Control switches should be OFF Connect the BCM to the mains Apply to the Trigger Input a pulse Polarity Positive Width 2 lO ns Amplitude 22 4V v Repetition rate 1 KHz Impedance 50Q Apply same pulse to the oscilloscope trigger Turn the front panel Calibration switch O
42. used by a short cable and the ICT The other calibrated pulses are derived from 1 nC by trimmed attenuators When the ICT is connected to the BCM by a long cable the DC resistance of this path is higher and more charge goes into the Charge Amplifier The calibrated pulse therefore gives a higher output voltage A correction factor must therefore be applied Procedure e Stop the pulse generator e All switches of the DB9 Remote Control key must be on 1 Bits 6 0 High e Switch ON the Calibration Switch on the Charge Amplifier front panel e Read the value from the voltmeter The internal calibration pulse generator injects too much charge in the BCM when a long cable is used The correction factor is 2 00 V Calibrati tion factor 1 alibration pulse correction factor BCM read out The BCM read out is negative its absolute value is larger than 2 volts The Calibration pulse correction factor is a small few percent factor to be deducted from all BCM readings when calibration is enabled The corresponding beam charge depends on the sensor used Transformer Model Sensitivity Beam charge to Beam charge to ina 500 input charge ratio input charge ratio termination in BCM 509 input in BCM OQ input ICT XXX XXX 50 1 ICT XXX XXX 20 1 ICT XXX XXX 10 1 ICT XXX XXX 05 1 FCT XXX 50 1 Not applicable FCT XXX 20 1 Not applicable FCT XXX 10 1 Not applicable FCT XXX 05 1 Not applicable The c
43. ut of the charge amplifier The pulse charge splits in two parts One part is lost in the cable and the current transformer The remaining charge is amplified by the Charge Amplifier The calibration delay is so adjusted to make the calibrated pulse to fall into the integration window of the BSP The purpose of the pulse charge generator is not to provide accurate calibration The calibration pulse generator provides pulses calibrated at ca 2 The Calibration Enable command the calibration charge value from 1 pC 10 pC 100 pC up to nC and the calibration pulse polarity are selected by TTL external command line applied to the DB9 connector at the rear of the BCM Beware this is charge as applied to the input of the Charge Amplifier It is not beam pulse charge equivalent To obtain beam charge equivalents use the table below Equivalent beam pulse using the 500 input in pC With sensor ICT XXX XXX 50 1 ICT XXX XXX 20 1 ICT XXX XXX 10 1 ICT XXX XXX 05 1 Equivalent beam pulse using the virtual 00 input in pC With sensor ICT XXX 070 50 1 ICT XXX 070 20 1 ICT XXX 070 10 1 ICT XXX 070 05 1 With the virtual OO input the beam charge equivalent depends on the cable ohmic resistance from the sensor to the BCM It must be calibrated on site BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly France Integrate Hold Reset Tel 33 450 426 642 Page 20 Fax 33 450 426 643 User s manual SENSITIVITY OF T
44. ve selected pulses or macro pulses The Continuous Averaging version therefore measures currents System components In a beam line or particle accelerator application the BCM detects the beam signal with a non destructive sensor Integrating Current Transformer ICT or Fast Current Transformer FCT Note The Beam Charge Monitor virtual 0 input cannot be used when an FCT is used as sensor See Virtual 0Q Termination in Operating Principle chapter in this manual The signal may be amplified by an optional wideband amplifier BCM WBA before being delivered to an electronics mini crate by a user s supplied coaxial cable In this mini crate there are 3 modules Charge Amplifier and Calibration Generator CAC Bunch Signal Processor BSP and Power Supply The BCM output is delivered by the Bunch Signal Processor It is a voltage up to 7V proportional to the beam charge In the Integrate Hold Reset IHR version the voltage level it held up to 400us then reset In the Continuous Averaging CA version the voltage level averages the successive input pulses with a long time constant ICT or FCT Beam Charge Monitor neu Sampling voltmeter 9999999 On the BCM rear rigger pulse BCM output O To the BCM rear Range selection calibration selection and command BCM system represented without the optional wideband amplifier BERGOZ Instrumentation Beam Charge Monitor 01630 Saint Genis Pouilly
45. w 10 ns risetime there is significant non linearity Signals generated by an ICT with standard 70 ns output pulses are integrated without charge loss When using an FCT as beam sensor the signal can be too fast for the virtual 0 termination The portion of the signal which rises faster than 20 ns may not be properly integrated The virtual 00 termination feature can be selected with a jumper on the Charge Amplifier board Input termination 50 0Q When the virtual OQ input termination is selected this has three consequences a most of the charge collected by the current transformer flows only in the OQ termination and very little in the current transformer s internal load resistor This almost doubles the transformer s sensitivity The sensitivity is not really doubled because of the cable s impedance b the sensitivity being almost doubled without increase in the noise the signal to noise ratio is doubled and the resolution in terms of beam equivalent noise is improved by a factor of 2 c the impedance seen by the transformer is close to 0Q therefore the transformer differentiating time constant L R is getting much larger and the droop much smaller With a standard ICT the signal droop is lowered to 1 us instead of 5 us The Virtual 0 2 input has therefore many advantages Its only drawback is that the BCM overall gain depends on the cable ohmic resistance When the Virtual 0Q input is used the BCM must b

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