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 AA2009127004501.14001.55 LA141313503001.022001.19 LA205844503001.086001.45 LA209176004001.1713001.62 LA4457460 1.2315001.1 LA848772602001.127001.62 LA905753502501.087001.51 LA9772210 1.225000.96 LA9869102001501.335001.46 LB00311015009001.1115001.71 LB008698505001.086001.74 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 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:R7899-20 Serial Number CathodeAnodeBlueGainDark CurrentV-I (Shipping Month) Sens 1000V1250V1500V1800V Judgement (µA/lm)(A/lm)Index(E+06)(nA) 1800V/1250V AA2009 (Apr.2003) Shipping Data10013.99.530.140.150.250.390.692.8 Failed Retest Result98.151.99.510.532503444928552.5 LA1413 (Jan.2004) Shipping Data12715.110.90.121.322.842.0 Failed Retest Result13111210.90.8511401440186032902.3 LA2058 (Sep.2003) Shipping Data9813.49.420.140.390.590.961.93.2 Failed Retest Result12433.211.90.2732941750962.60.2 LA2091 (Sep.2003) Shipping Data10713.69.710.131.41.82.331.7 Failed Retest Result12819.111.30.153484475697911.8 LA4457 (Jan.2004) Shipping Data1314711.00.360.140.220.340.552.5 Failed Retest Result15916512.11.0456.5811161992.5 LA8487 (Jul.2004) Shipping Data12918.411.50.140.130.20.30.452.3 Failed Retest Result14431.211.80.221421872363021.6 LA9057 (Jul.2004) Shipping Data11616.510.70.140.380.6511.72.6 Failed Retest Result12354.611.20.441151531952571.7 LA9772 (Jul.2004) Shipping Data13140.511.80.310.130.220.350.612.8 Failed Retest Result12615311.71.2123.43140.458.11.9 LA9869 (Jul.2004) Shipping Data13724.610.80.180.110.280.752.17.5 Failed Retest Result15752.511.50.331111431923262.3 LB0031 (Jul.2004) Shipping Data11814.610.70.120.240.370.550.982.6 Failed Retest Result13416.511.60.1257372687810101.4 LB0086 (Jul.2004) Shipping Data10819.810.20.180.160.230.330.512.2 Failed Retest Result13137.111.80.282182873594571.6 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