International Symposium on the Development of Detectors, 2006/4 at SLAC Time of Flight measurements with MCP-PMT - Very high resolution TOF counter - Lifetime of MCP-PMTs T.Ohshima, K.Inami, N.Kishimoto, M.Nagamine (Nagoya university, Japan)
Introduction Photon device for TOP counter Cherenkov ring imaging counter with precise time measurement (NIM A 440 (2000) 124) For super B-factory Linear-array type photon detector Single photon sensitivity X Good transit time resolution (<50ps) Operational under 1.5T B-field Position sensitive (~5mm) High detection efficiency z y x Quartz radiator L ~400mm 20mm MCP-PMT is a good solution. In the course of R&D, Idea of a few psec resolution TOF MCP-PMT for TOP counter 2006/4/3-6 SNIC at SLAC 2
High resolution TOF Structure Small-size quartz (cm~mm length) Cherenkov light (Decay time ~ 0) extremely reduce time dispersion compared to scintillation (τ ~ ns) MCP-PMT (multi-alkali photo-cathode) TTS < 50ps even for single photon gives enough time resolution for smaller number of detectable photons Test counter Arbitrary scale Arbitrary scale 600 400 200 0 0 0.1 0.2 0.3 0.4 40 30 20 Simulation Cherenkov light Nγ~240 Scintillation (BC408) Nγ~820 2006/4/3-6 SNIC at SLAC 3 10 0 0 2 4 6 Emission and propagation time (ns)
MCP-PMT Micro-Channel-Plate Tiny electron multipliers Diameter ~10µm, length ~400µm High gain ~10 6 for two-stage type Fast time response Pulse raise time ~500ps, TTS < 50ps can operate under high magnetic field (~1T) Channel φ~10µm Input electron Photo-cathode MCP plates Photon Anode Single photon ~400µm MCP channel HV 2006/4/3-6 SNIC at SLAC 4
MCP-PMT (2) Hamamatsu R3809U-50 (multi-alkali photo-cathode) R3809U-50-25X Number of Events 600 400 200 single photon peak Number of Events 1500 1000 500 σ=46ps for single photon Window size : 25mm φ MCP hole 10µm φ 0 100 120 140 ADC (count/0.25pc) 0-20 0 20 TDC (count/25psec) R3809U-50-11X Window : 11mm φ event 1200 1000 800 600 400 200 Gain ~ 10 6 event 1000 800 600 400 200 30.4psec MCP hole 6µm φ 0 100 110 120 130 ADC (1bin/0.25pC) 0-20 -10 0 10 20 TDC(25ps/count) 2006/4/3-6 SNIC at SLAC 5
Beam test 1 3GeV/c π beam at KEK-PS π2 line PMT: R3809U-50-25X Quartz radiator 16x16x40mm with Al evaporation 40mm Test counter TOF between two counters evaluate the time resolution TOF counter with and without quartz radiator To confirm MCP-PMT s behavior for passage of charged particles Beam Tile TOF counter Quartz Trigger counter MCP PMT Trigger counter 2006/4/3-6 SNIC at SLAC 6 x z x y z x y z 16 x16 x40 mm 5 x5 x10 mm Scinti. BC408 60cm HPK R3809U-50-25X Photo-Cathode φ25mm single-photon TTS 50psec
Beam test 1 result With quartz radiator Number of photons ~ 250 agree with expectation of simulation ~240 Time resolution ~ 10.6ps with radiator Without radiator Number of photons ~ 50 Cherenkov light from PMT window Time resolution ~ 13.6ps -50-25 0 25 50 tof (ps) without radiator Resolution is limited by readout electronics. (σ elec ~8.8ps) Expected intrinsic resolution ~5.9ps -50-25 0 25 50 tof (ps) 2006/4/3-6 SNIC at SLAC 7
Beam test 2 Confirmation of intrinsic time resolution Improvements Readout electronics σ elec. : 8.8ps 4ps Time-correlated Single Photon Counting Modules (SPC-134, Becker & Hickl GMbH s) CFD, TAC and ADC Channel width = 813fs Electrical time resolution = 4ps RMS MCP-PMT TTS: ~46ps ~30ps 10µm hole 6µm hole R3809U-50-25X -11X 2006/4/3-6 SNIC at SLAC 8
Beam test 2 setup 3GeV/c π beam at KEK-PS π2 line PMT: R3809U-50-11X Quartz radiator 10 φ x40 z mm with Al evaporation Trig.1 TOF1 30cm TOF2 Trig.2 Beam Trig.1 Divider Discri. Coinc. Discri. TOF1 TOF2 Trig.2 Divider Start SPC-134 Discri. Stop Power Spliter π, - 3GeV/c Events 300 200 100 0 Elec. resolution 4.1ps 40 80 120 TDC (ch/0.814ps) 2006/4/3-6 SNIC at SLAC 9
Beam test 2 setup photo Trigger TOF2 TOF1 Trigger 2006/4/3-6 SNIC at SLAC 10
Beam test 2 result With 10mm quartz radiator +3mm quartz window Number of photons ~ 180 Time resolution = 6.2ps Intrinsic resolution ~ 4.7ps Without quartz radiator 3mm quartz window Number of photons ~ 80 Expectation ~ 20 photo-electrons Time resolution = 7.7ps Events Events 400 300 200 100 0 300 200 100 0 6.2ps 40 80 120 140 TDC (ch/0.814ps) 7.7ps 40 80 120 140 TDC (ch/0.814ps) 2006/4/3-6 SNIC at SLAC 11
Beam test 2 result (cont d) Nγ, σ TOF v.s. radiator thickness 14 Np.e. 300 200 100 Counter-1 Counter-2 Simulation σ TOF (ps) 12 10 8 6 4 2 Beam-test Simulation 0 10 20 30 40 50 Quartz thickness (mm) Extra photo-electrons 0 10 20 30 40 50 Quartz thickness (mm) N p.e. from short distance is larger than that of expected. Time-resolution behavior Resolution is gradually worse. Extra p.e. would affect the resolution dependence. 2006/4/3-6 SNIC at SLAC 12
Lifetime How long can we use MCP-PMT under high hit rate? HPK (x2) Russian (x5) Al protection O X O X Correction eff. 37% 65% 40-60% 55-60% Effective area 11mm φ 18mm φ Gain 1.9x10 6 1.5x10 6 3-4x10 6 TTS 34ps 29ps 30-40ps Photo-cathode Multi-alkali (NaKSbCs) Quantum eff. at 400nm 21% 19% 16-20% Bias angle 13deg 5deg Light load by LED pulse (1~5kHz) 20~100 p.e. /pulse (monitored by normal PMT) 2006/4/3-6 SNIC at SLAC 13
Relative gain Gain & TTS for single photon Gain TTS 1.2 1 0.8 Russian w/ Al(#32) before after σ=31ps σ=36ps Russian w/o Al (#6) σ=43ps σ=32ps 0.6 HPK w/ Al HPK w/o Al 0.4 0.2 0 200 400 600 800 1000 1200 Output charge (mc/cm 2 ) ~10 12 p.e./cm 2 with 10 6 gain HPK w/ Al HPK w/o Al Russian w/ Al (#32) Russian w/ Al (#35) Russian w/ Al (#38) Russian w/o Al (#6) Russian w/o Al (#11) σ=29ps σ=33ps TTS is stable within the gain drops. σ=34ps σ=34ps 2006/4/3-6 SNIC at SLAC 14
Relative Q.E. Quantum efficiency Q.E. Before/After λ=400nm 1.2 1 0.8 Q.E. ratio 1 10-1 0.6 0.4 0.2 HPK w/ Al HPK w/o Al 10-2 Russian w/ Al (#32) Russian w/ Al (#35) Russian 10-3 w/ Al (#38) Russian w/o Al (#6) Russian w/o Al (#11) 0 200 400 600 800 1000 1200 Output charge (mc/cm 2 ) ~10 12 p.e./cm 2 with 10 6 gain 200 300 400 500 600 700 800 900 λ(nm) Small Q.E. drop for HPK with protection Fast degradation for longer wavelength 2006/4/3-6 SNIC at SLAC 15
Summary High resolution TOF counter Small quartz as Cherenkov radiator MCP-PMT (TTS ~30ps for single photon) Readout system (time resolution ~4ps) Time resolution of 6.2ps have been measured. 4.7ps intrinsic resolution Lifetime test of MCP-PMTs Al protection layer works well to stop feedback ions. MCP-PMT by HPK with Al layer is best solution. For more detail, please refer NIM A 528, 763 (2004) and new paper to be published in NIM A. 2006/4/3-6 SNIC at SLAC 16
Separation power Separation 10 L=1.0m σ=5psec σ=10psec σ=20psec σ=50psec σ=100psec 3 1 0 2 4 6 Momentum (GeV) 2006/4/3-6 SNIC at SLAC 17
Fluctuation of Readout elec. 8 TDC channels with logic pulse Clock Generator Discri. 2 T1 = t stop1 t start T 2 = tstop2 tstart 2 2 σ T1 T 2 = σ stop1 + σ σ T8 = tstop8 t ( T1 T 2)/ 2 start σ stop 2 T 1+ T 2) ( T3+ T 4) ( tstop + tstop2) ( tstop3 + t = 2 2 ( T1+ T 2 T 3 T 4)/ 2 σ stop σ 4 ( 1 stop4 σ module T 1 T 2 = t stop 1 tstop2 = 8.8psec 0 0 2 4 6 8 Number of used channel 2006/4/3-6 SNIC at SLAC 18 stop2 ) RMS(psec) 16 14 12 10 8 6 4 2 8.8psec ADC TDC Gate CAMAC Diveder 8 8.8 # ch Discri. 1
Lifetime test (setup) 2006/4/3-6 SNIC at SLAC 19
Quantum efficiency Q.E.(%) 10 1 10-1 HPK w/ Al HPK w/o Al Russian w/ Al (#32) Russian w/ Al (#35) Russian w/ Al (#38) Russian w/o Al (#6) Russian w/o Al (#11) 10-2 200 300 400 500 600 700 800 900 λ(nm) 2006/4/3-6 SNIC at SLAC 20