A proposal of simple system for testing huge number of MPPC

1. A proposal of simple system for testing huge number of MPPC 2007/Feb/5 ACFA ILC Workshop ICEPP , University of Tokyo Hidetoshi OTONO and The GLD calorimeter group

2. Contents • Motivation • Hardware improvement • Issue of present method • A proposal of new method • Software improvement • Issue of present method • A proposal of new method • Summary

3. Motivation Num. of MPPCs 10M We have no available AMP For this period. 1M 100k 10k KEK is developing electronics for the GLD calorimeter. 1k 100 ASD was expected for MPPC AMP, but it was stopped producing. 10 AMP recommended by HPK is too expensive. 1 Time

4. Motivation From now on ,the number of MPPC is increasing toward 10Mega. We want to establish a simple, efficient and cheap system for treating many MPPCs . If some institutes has same system, double checking is easy and it makes good progress with checking numerous MPPCs

5. Hardware improvement • Issue of present method • A proposal of new method

6. Issue of present method Control PC RS232C HV Modules ＭＰＰＣ AMP ＭＰＰＣ AMP Present method need many AMP and modules AMP ＭＰＰＣ ＭＰＰＣ AMP

7. Our method Control PC RS232C HV DC Supply Measurement target ＭＰＰＣ relayOFF ＭＰＰＣ relayOn relayOFF AMP modules ＭＰＰＣ relayOFF ＭＰＰＣ relayOFF

8. Requirements for a relay MPPC’s typical pulse is as follows. A relay must be good performance between 100MHz~1GHz 1GHz pulse 10ns 100 relayOFF 0? A high isolation is required. 1GHz pulse 100 100? relayOn A low insertion loss is required. Isolation is the degree how the pulse can be stopped when a relay OFF. Insertion loss is the degree how the pulse can be passed when a relay is ON.

9. Relay selection Isolation Insertion loss 0.5dB 0.3dB 10dB Isolation Insertion loss GOOD GOOD 30dB (GHz) (GHz) The relay described by orange line is the most suitable one. Even at 1GHz , Isolation = 10dB and Insertion loss = 0.5dB. This relay is G3VM-LR10 produced by OMRON.

10. Typical pulse

11. Without relay v.s. With relay 1p.e rate 2p.e rate gain With relay (kHz) With relay (kHz) With relay (kHz) No relay (kHz) No relay (kHz) No relay (kHz) correlation We can find insertion loss of a relay. But correct gain can be got by calibration. We can use a relay element for MPPC mass check !!

12. Software improvement • Issue of present method • A proposal of new method

13. Issue of preset method Dark Box MPPC output 3281 １０４２３ ８ liner amp. MPPC oscilloscopefrequency counter Change voltage Searching 1p.e and 2p.e height →Threshold = 0.5p.e height →pulse counting for 1p.e rate →Threshold = 1.5p.e height →pulse counting for 2p.e rate Threshold value must be changed.

14. Our measurement method We proposal more simple method which can be done at any institute. • GAIN measurement without light source • 1p.e rate measurement by CAMAC scaler • 2p.e rate measurement by OFFLINE analysis Our method makes it possible to measure these three at the same time

15. Our method GAIN Use scaler together 1p.e rate 1p.e rate/2p.e rate

16. Gain measurement method test Measurement with light source = 2.75 (10^5) Gain We checked 10 MPPCs Measurement without light source = 2.7 + 0.07 (10^5) _ Thus we decide not to use light source. Gain(10^5)

17. Our circuit Dark Box NIM CAMAC Clock Scaler AMP MPPC AMP Disc. x 63 x 10 Output register G.G veto latch Disc. Charge ADC 35ns gate CCNET HV Our measurement system is very simple

18. Test result 1p.e rate (kHz) 2p.e rate (kHz) Bias Voltage Bias Voltage gain (10^5) HPK 2p.e data isn’t discreditable Bias Voltage

19. Summary We proposed simple method of checking MPPCs. And if it is accept at each institute, checking numerous number of MPPC become more easier works.