1. PMT test device setup functionality –reproducibility of output signal –dynamic range –limitations –test duration conclusion T. Wälchli, TT-Meeting Brussels, April 11. 2003

2. setup 8 boxes x 8 fibers no neighbors lighted @ the same time 2 LED/box increase dynamic range all 16 LEDs triggered individually 2 monitor PMTs Bi – sources for reference peak T. Wälchli, TT-Meeting Brussels, April 11. 2003

3. setup 8 boxes x 8 fibers no neighbors lighted @ the same time 2 LED/box increase dynamic range all 16 LEDs triggered individually 2 monitor PMTs Bi – sources for reference peak T. Wälchli, TT-Meeting Brussels, April 11. 2003

4. reproducibility of output signal LED drifts –monitored fiber quality –assumed stable positioning PM on cookie –done, redone… electronics –under control Ratio between anode charge of 2 runs with all the same settings PM removed and replaced, HV left on T. Wälchli, TT-Meeting Brussels, April 11. 2003 Ratio between anode charge of 2 runs with all the same settings PM removed and replaced, HV left on  repositioning stability better than 1%

5. using grease (SISS SI 7) +14% anode charge… using grease (SISS SI 7) …but very poor reproducibility! reproducibility of output signal T. Wälchli, TT-Meeting Brussels, April 11. 2003 HV down, PM removed, stored and replaced. Looks like tilted HV on for 2 hrs: anode charge decreases by 2.5%

6. absolute number of p.e. for GA0490 with lowest- and highest LED setting dyn.range ~ 4’300 Chn 37; 50 kEntries; 900V ADC counts 1p.e. G = 1.97 10 6 dynamic range each LED has dyn. range 200 factor 20 between the two LEDs in box → total dynamic range = 4’000 T. Wälchli, TT-Meeting Brussels, April 11. 2003

7. Chn 37; 50 kEntries; 900V ADC counts 1p.e. G = 1.97 10 6 dynamic range p.e. ID with “Bellamy” – function -> Strasbourg –number of photoelectrons is poisson-distributed –each p.e. is a Gaussian distribution T. Wälchli, TT-Meeting Brussels, April 11. 2003 absolute number of p.e. for GA0490 with lowest- and highest LED setting dyn.range ~ 4’300

8. T. Wälchli, TT-Meeting Brussels, April 11. 2003 dynamic range 1p.e. peak from first dynode?? Separate peaks from the two dynode systems??

9. T. Wälchli, TT-Meeting Brussels, April 11. 2003 limitations min 8 fibers lighted at the same time 11 bit FERA ADCs: 480pC full range = 25p.e. @ G = 10 6 HV-curve needed for more LED-power but HV-curve doesn’t help to measure saturation at high anode currents added 2 nd output on dynode 12  160 times less amplification  Measure up to 100p.e. @ G = 10 6 new, not yet tested rates of monitoring sources ~35Hz

10. T. Wälchli, TT-Meeting Brussels, April 11. 2003 test duration t 2kHz [min] = N run x N event / 9’000 e.g. N run = 10, N event = 18’000  t = 20’ But: dark-current is down on it’s final value only after 30’. Hz + t dc

11. T. Wälchli, TT-Meeting Brussels, April 11. 2003 test duration t 2kHz [min] = N run x N event / 9’000 e.g. N run = 10, N event = 18’000  t = 20’ + t dead Or: If accuracy should be on 1% level: Add deadtime before acquisition start?

12. T. Wälchli, TT-Meeting Brussels, April 11. 2003 test duration t 2kHz [min] = N run x N event / 9’000 e.g. N run = 10, N event = 18’000  t = 20’ What will be the number of runs? Do we need high voltage curves? HV log Gain G = a (HV) b …and specify saturation? log Gain LED power

13. T. Wälchli, TT-Meeting Brussels, April 11. 2003 test duration t 2kHz [min] = N run x N event / 9’000 e.g. N run = 10, N event = 18’000  t = 20’ What will be the number of runs? …should the final relative anode charge 1 0.8 0.6 be a combination from different runs

14. T. Wälchli, TT-Meeting Brussels, April 11. 2003 conclusion device is (as good as) ready to perform tests with dynamic range > 4’000 with repositioning accuracy > 99% within “reasonable” time should discuss required parameters soon maybe before June, when first series arrives