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PMT characterisation for the KM3NeT Project

PMT characterisation for the KM3NeT Project. Oleg Kalekin Representing the KM3NeT Consortium VLVnT 2009, Athens 14.10.2009. Photomultipliers for KM3NeT optical modules 3 (2+1) main options for optical modules (OM) in the KM3NeT OM with 1 photomultiplier tube (PMT) 10 or 8 inch diameter

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PMT characterisation for the KM3NeT Project

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  1. PMT characterisation for the KM3NeT Project Oleg Kalekin Representing the KM3NeT Consortium VLVnT 2009, Athens 14.10.2009

  2. Photomultipliers for KM3NeT • optical modules • 3 (2+1) main options for optical modules (OM) in the KM3NeT • OM with 1 photomultiplier tube (PMT) 10 or 8 inch diameter • OM with two 8-inch PMTs • Multi-PMT OM with 31 three-inch PMTs PMTs considered as candidates 10-inch: Hamamatsu R7081 8-inch: Hamamatsu R5912 ET Enterprises 9354 3-inch: Hamamatsu R6233 - prototype ET Enterprises 9822 - prototype O.Kalekin, VLVnT 09, Athens, 15.10.2009

  3. PMT parameters Quantum efficiency (QE) Effective photocathode area Time resolution – Transit time spread (TTS) Amplification Dark rate Peak to valley ratio All parameters are measured on the PMT test bench At the Erlangen Centre for Astroparticle Physics O.Kalekin, VLVnT 09, Athens, 15.10.2009

  4. Quantum efficiency All dynodes and anode connected electrically and at a few hundred volts relative to the cathode No amplification 100% collection efficiency Photocathode current measured Comparison with absolute calibrated photodiode Photocathode QE O.Kalekin, VLVnT 09, Athens, 15.10.2009

  5. Quantum efficiency O.Kalekin, VLVnT 09, Athens, 15.10.2009

  6. Scan of PMT surfaces X-Y scanner Step motors, min step 7.5 μm Optical fibre 1mm diameter LED pulses, ~10 ns FWHM A few tens photoelectrons (phe) A few hundred pulses in each measured point Charge and peak position recorded Effective area: Integral of scanned points with weights S=π∙ΔrΣf∙r Transit time spread over surface: Arrival time distribution weighted with radius and charge O.Kalekin, VLVnT 09, Athens, 15.10.2009

  7. Effective area Effective area 27sq.cm Effective diameter 58mm O.Kalekin, VLVnT 09, Athens, 15.10.2009

  8. Transit time spread TTS=0.73ns O.Kalekin, VLVnT 09, Athens, 15.10.2009

  9. Effective area and TTS (A few tens of photoelectrons signal) Measured eff. photocathode Specified photocath. TTS, ns Area,cm2 Diameter, mm diameter, mm R7081 1.0 380 220 220 9354KB 0.62 264 183 R6233MOD 3.1 35 67 70 9822B 0.73 27 58 O.Kalekin, VLVnT 09, Athens, 15.10.2009

  10. TTS of R6233MOD R6233 modified on demand of the KM3NeT from flat input window to plano-concave Further modification needed/planed: Convex-concave window O.Kalekin, VLVnT 09, Athens, 15.10.2009

  11. Single photoelectron jitter ECAP test bench for PANDA experiment Picosecond laser, 20ps FWHM LeCroy TDC 2228A, 50ps/ch LeCroy ADC 2249A, 0.25pC/ch PMTs illuminated at single photoelectron level O.Kalekin, VLVnT 09, Athens, 15.10.2009

  12. Single photoelectron jitter Time RMS = 1.45ns Long noise tail O.Kalekin, VLVnT 09, Athens, 15.10.2009

  13. Single photoelectron jitter Tail 17.5-19ns Non single phe Time RMS = 1.45ns Gauss sigma=0.55ns FWHM=1.5ns Long noise tail O.Kalekin, VLVnT 09, Athens, 15.10.2009

  14. Single photoelectron jitter single phe TTS, ns Gauss sigma FWHM R7081 1.2 3.1 R5912 0.57 1.4 9354KB 0.67 1.6 R6233MOD 1.5 3.2 9822B 0.55 1.5 O.Kalekin, VLVnT 09, Athens, 15.10.2009

  15. Single photoelectron jitter Peak at 23-30 ns Real late peaks O.Kalekin, VLVnT 09, Athens, 15.10.2009

  16. Summary The most part of evaluated PMTs meets KM3NeT specifications Variations of parameters observed Detailed calibration of the PMT’s subset will be needed O.Kalekin, VLVnT 09, Athens, 15.10.2009

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