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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 - PowerPoint PPT Presentation
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PMT characterisation for the KM3NeT Project
Oleg Kalekin
Representing the KM3NeT Consortium
VLVnT 2009, Athens
14.10.2009
Photomultipliers for KM3NeToptical 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 R5912ET Enterprises 9354
3-inch:Hamamatsu R6233 - prototypeET Enterprises 9822 - prototype
O.Kalekin, VLVnT 09, Athens, 15.10.2009
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
Quantum efficiency
All dynodes and anode connected electricallyand at a few hundred volts relative to the cathode
No amplification
100% collection efficiency
Photocathode current measured
Comparison with absolutecalibrated photodiode
Photocathode QE
O.Kalekin, VLVnT 09, Athens, 15.10.2009
Quantum efficiency
O.Kalekin, VLVnT 09, Athens, 15.10.2009
Scan of PMT surfaces
X-Y scanner
Step motors, min step 7.5 μmOptical fibre 1mm diameterLED pulses, ~10 ns FWHMA few tens photoelectrons (phe)
A few hundred pulses in each measured pointCharge and peak position recorded
Effective area: Integral of scanned points with weightsS= π∙ΔrΣf∙r
Transit time spread over surface:Arrival time distribution weighted with radius and charge
O.Kalekin, VLVnT 09, Athens, 15.10.2009
Effective area
Effective area27sq.cm
Effective diameter58mm
O.Kalekin, VLVnT 09, Athens, 15.10.2009
Transit time spread
TTS=0.73ns
O.Kalekin, VLVnT 09, Athens, 15.10.2009
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
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
Single photoelectron jitter
ECAP test bench for PANDA experiment
Picosecond laser, 20ps FWHMLeCroy TDC 2228A, 50ps/chLeCroy ADC 2249A, 0.25pC/ch
PMTs illuminated at single photoelectron level
O.Kalekin, VLVnT 09, Athens, 15.10.2009
Single photoelectron jitter
Time RMS = 1.45ns
Long noise tail
O.Kalekin, VLVnT 09, Athens, 15.10.2009
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
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
Single photoelectron jitter
Peak at
23-30 ns
Real late peaks
O.Kalekin, VLVnT 09, Athens, 15.10.2009
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