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LHCb HCAL PMT problems HAMAMATSU studies 1 Yu. Guz.

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Presentation on theme: "LHCb HCAL PMT problems HAMAMATSU studies 1 Yu. Guz."— Presentation transcript:

1 LHCb HCAL PMT problems HAMAMATSU studies 1 Yu. Guz

2 degraded PMTs sent to HAMAMATSU (11) 2 Yu. Guz PMT serial#gain degradationdark current rate effectworking currentworking HV factorat working HVat 1 kV2 hours after the(from collisions)before since 2009nA start of collisions nAreplacement, kV AA LA LA LA LA LA LA LA LA LB LB rate effect: measured in situ (on HCAL) with LED monitoring system during the LHC data taking, measured as a ratio of LED flash response 2 h after LHC collision start. dark current: measured in situ (on HCAL), no collisions, no LED flashes working current: the DC current caused by physics events during the LHC collisions gain degradation: ratio of LED amplitudes in 2009 to the LED amplitude right before the dismounting, recalculated for the same HV working HV before replacement: it is rather high for many of these PMTs because we had to compensate the gain degradation

3 DC test result at HAMAMATSU 3 Yu. Guz Type number:R Serial Number CathodeAnodeBlueGainDark CurrentV-I (Shipping Month) Sens 1000V1250V1500V1800V Judgement (µA/lm)(A/lm)Index(E+06)(nA) 1800V/1250V AA2009 (Apr.2003) Shipping Data Failed Retest Result LA1413 (Jan.2004) Shipping Data Failed Retest Result LA2058 (Sep.2003) Shipping Data Failed Retest Result LA2091 (Sep.2003) Shipping Data Failed Retest Result LA4457 (Jan.2004) Shipping Data Failed Retest Result LA8487 (Jul.2004) Shipping Data Failed Retest Result LA9057 (Jul.2004) Shipping Data Failed Retest Result LA9772 (Jul.2004) Shipping Data Failed Retest Result LA9869 (Jul.2004) Shipping Data Failed Retest Result LB0031 (Jul.2004) Shipping Data Failed Retest Result LB0086 (Jul.2004) Shipping Data Failed Retest Result Specifications 70 Min.9 Min.-2.5 Max.--

4 afterpulse test at HAMAMATSU (1/3) 4 Yu. Guz

5 afterpulse test at HAMAMATSU (2/3) 5 Yu. Guz

6 afterpulse test at HAMAMATSU (3/3) 6 Yu. Guz Conclusion: afterpulses are moderate, no problem with vacuum

7 black paint has been removed for further studies 7 Yu. Guz

8 emission studies (1/5) 8 Yu. Guz

9 emission studies (2/5) 9 Yu. Guz

10 emission studies (3/5) 10 Yu. Guz

11 emission studies (4/5) 11 Yu. Guz

12 emission studies (5/5) 12 Yu. Guz


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