Yu. Guz

LHCb HCAL PMT problems

HAMAMATSU studies

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Yu. Guz

degraded PMTs sent to HAMAMATSU (11)

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PMT serial# gain degradation dark current dark current rate effect working current working HVfactor at working HV at 1 kV 2 hours after the (from collisions) before

since 2009 nA nA start of collisions nA replacement, kVAA2009 12 700 450 1.1 400 1.55LA1413 1 350 300 1.02 200 1.19LA2058 4 450 300 1.08 600 1.45LA2091 7 600 400 1.17 1300 1.62LA4457 4 60 60 1.23 1500 1.1LA8487 7 260 200 1.12 700 1.62LA9057 5 350 250 1.08 700 1.51LA9772 2 10 10 1.2 2500 0.96LA9869 10 200 150 1.3 3500 1.46LB0031 10 1500 900 1.11 1500 1.71LB0086 9 850 500 1.08 600 1.74

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 flashesworking current: the DC current caused by physics events during the LHC collisionsgain degradation: ratio of LED amplitudes in 2009 to the LED amplitude right before the dismounting, recalculated for the same HVworking HV before replacement: it is rather high for many of these PMTs because we had to compensate the gain degradation

Yu. Guz

DC test result at HAMAMATSU

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Type number: R7899-20Serial Number Cathode Anode Blue Gain Dark Current V-I

(Shipping Month) Sens Sens Sens 1000V 1250V 1500V 1800V Judgement (µA/lm) (A/lm) Index (E+06) (nA) (nA) (nA) (nA) 1800V/1250V

AA2009(Apr.2003)

Shipping Data 100 13.9 9.53 0.14 0.15 0.25 0.39 0.69 2.8 FailedRetest Result 98.1 51.9 9.51 0.53 250 344 492 855 2.5

LA1413(Jan.2004)

Shipping Data 127 15.1 10.9 0.12 1.3 2 2.8 4 2.0 FailedRetest Result 131 112 10.9 0.85 1140 1440 1860 3290 2.3

LA2058(Sep.2003)

Shipping Data 98 13.4 9.42 0.14 0.39 0.59 0.96 1.9 3.2 FailedRetest Result 124 33.2 11.9 0.27 329 417 509 62.6 0.2

LA2091(Sep.2003)

Shipping Data 107 13.6 9.71 0.13 1.4 1.8 2.3 3 1.7 FailedRetest Result 128 19.1 11.3 0.15 348 447 569 791 1.8

LA4457(Jan.2004)

Shipping Data 131 47 11.0 0.36 0.14 0.22 0.34 0.55 2.5 FailedRetest Result 159 165 12.1 1.04 56.5 81 116 199 2.5

LA8487(Jul.2004)

Shipping Data 129 18.4 11.5 0.14 0.13 0.2 0.3 0.45 2.3 FailedRetest Result 144 31.2 11.8 0.22 142 187 236 302 1.6

LA9057(Jul.2004)

Shipping Data 116 16.5 10.7 0.14 0.38 0.65 1 1.7 2.6 FailedRetest Result 123 54.6 11.2 0.44 115 153 195 257 1.7

LA9772(Jul.2004)

Shipping Data 131 40.5 11.8 0.31 0.13 0.22 0.35 0.61 2.8 FailedRetest Result 126 153 11.7 1.21 23.4 31 40.4 58.1 1.9

LA9869(Jul.2004)

Shipping Data 137 24.6 10.8 0.18 0.11 0.28 0.75 2.1 7.5 FailedRetest Result 157 52.5 11.5 0.33 111 143 192 326 2.3

LB0031(Jul.2004)

Shipping Data 118 14.6 10.7 0.12 0.24 0.37 0.55 0.98 2.6 FailedRetest Result 134 16.5 11.6 0.12 573 726 878 1010 1.4

LB0086(Jul.2004)

Shipping Data 108 19.8 10.2 0.18 0.16 0.23 0.33 0.51 2.2 FailedRetest Result 131 37.1 11.8 0.28 218 287 359 457 1.6

Specifications 70 Min. 9 Min. - 2.5 Max. - -

Yu. Guz

afterpulse test at HAMAMATSU (1/3)

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Yu. Guz

afterpulse test at HAMAMATSU (2/3)

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Yu. Guz

afterpulse test at HAMAMATSU (3/3)

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Conclusion: afterpulses are moderate,no problem with vacuum

Yu. Guz

black paint has been removed for further studies

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Yu. Guz

emission studies (1/5)

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Yu. Guz

emission studies (2/5)

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Yu. Guz

emission studies (3/5)

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Yu. Guz

emission studies (4/5)

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Yu. Guz

emission studies (5/5)

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