Photon Detector Workshop at Kobe 27 29 June
Photon Detector Workshop at Kobe, 27 -29 June 2007 Timing properties of MCP-PMT - Time resolution - Lifetime - Rate dependence K. Inami (Nagoya university, Japan) 2007/6/27 -29 Photon Detector WS at Kobe
Introduction l Photon device for TOP counter l Cherenkov ring imaging counter with precise timing measurement (NIM A 440 (2000) 124) l l l l Barrel PID upgrade for Super B factory Single photon sensitivity Good transit time spread (TTS<50 ps) Operational under 1. 5 T B-field Position sensitive (~5 mm) High detection efficiency MCP-PMT is a best solution! 2007/6/27 -29 Photon Detector WS at Kobe 2
MCP-PMT l Micro-Channel-Plate l Tiny electron multipliers l l Diameter ~10 mm, length ~400 mm High gain l ~106 for two-stage type Fast time response l Pulse raise time ~500 ps, TTS < 50 ps can operate under high magnetic field (~1 T) Channel f~10 mm Single photon ~400 mm 2007/6/27 -29 Photon Detector WS at Kobe 3
MCP-PMT for single photon l Timing properties under B=0~1. 5 T parallel to PMT HPK 6 BINP 8 MCP-PMT HPK 10 Burle 25 HPK 6 BINP 8 N 4428 R 3809 U-50 -25 X 85011 -501 PMT size(mm) 45 30. 5 52 71 x 71 Effective size(mm) 11 18 25 50 x 50 MCP hole diameter(mm) 6 8 10 25 Length-diameter ratio 40 40 43 40 Bias angle (deg. ) 13 5 12 10 Max. H. V. (V) 3600 3200 3600 2500 photo-cathode multi-alkali bi-alkali 18 26 24 R 3809 U-50 -11 X Q. E. (%) (l=408 nm) 26 2007/6/27 -29 Photon Detector WS at Kobe HPK 10 Burle 25 4
MCP-PMT for single photon (2) l Setup l l Single photon is generated by laser (408 nm). B-field is parallel to tube axis. HPK PLP-02 Width 36 ps 18 GHz 0~10 d. B 1. 5 GHz 36 d. B Philips 708 2007/6/27 -29 Photon Detector WS at Kobe 5
MCP-PMT (output) l Hamamatsu R 3809 U-50 (multi-alkali photo-cathode) HPK 10 single photon peak s=46 ps for single photon Window size : 25 mmf MCP hole 10 mmf HPK 6 Gain ~ 106 Window : 11 mmf MCP hole 6 mmf 2007/6/27 -29 Photon Detector WS at Kobe 6
Pulse response l Pulse shape (B=0 T) l l Fast raise time (~500 ps) Broad shape for BINP 8 l l l Due to mismatch with H. V. supply and readout cable No influence for time resolution Gain v. s. B-field l l Small hole diameter shows high stability against B-field. Explained by relation btw hole size and Larmor radius of electron motion under B-field. 2007/6/27 -29 Photon Detector WS at Kobe 7
MCP-PMT in B-field l ADC spectra with different angles under B=1. 5 T l l Gain depends on the angle. Behaviors are slightly different. l B f Because of the different bias angle of MCP hole l HPK 6: 13 deg, 6 mm, BINP 8: 5 deg, 8 mm HPK 6 2007/6/27 -29 Photon Detector WS at Kobe BINP 8 8
Time response l TTS v. s. B-field l l Small hole diameter shows high stability and good resolution. TTS v. s. Gain l l l Single photon For several HV and B-field conditions 30~40 ps resolution was obtained for gain>106 Hole size need <~10 mm l to get time resolution of ~30 ps under 1. 5 T B-field. 2007/6/27 -29 Photon Detector WS at Kobe Single photon 9
Lifetime l How long can we use MCP-PMT under high hit rate? (Nucl. Instr. Meth. A 564 (2006) 204. ) HPK (x 2) Russian (x 5) Al protection O X Correction 55 eff. 37% 65% 40 -60 60% Effective area 11 mmf 18 mmf Gain 1. 9 x 106 1. 5 x 106 3~4 x 106 TTS 34 ps 29 ps 30~40 ps Photo-cathode Multi-alkali (Na. KSb. Cs) Quantum eff. at 400 nm 21% 19% 16 -20% Bias angle 13 deg 5 deg l Light load by LED pulse (1~5 k. Hz) l 20~100 p. e. /pulse (monitored by normal PMT) 2007/6/27 -29 Photon Detector WS at Kobe 10
Lifetime - Q. E. l l Relative Q. E. by single photon laser Without Al protection l l With Al protection l l l Drop <50% within 1 yr. Long life Not enough for Russian PMTs Enough lifetime for HPK’s MCP-PMT with Al protection layer 2007/6/27 -29 Photon Detector WS at Kobe 11
Lifetime - Q. E. vs wavelangth l l l Q. E. after lifetime test (Ratio of Q. E. btw. before, after) Large Q. E. drop at longer wavelength Number of Cherenkov photons;only 13% drop (HPK w/Al) l Number of generated Cherenkov photon: ~1/l 2 2007/6/27 -29 Photon Detector WS at Kobe 12
Lifetime - Gain l l Estimate from output charge for single photon irradiation <1013 photons/cm 2 l l >1013 photons/cm 2 l l l Drop fast Drop slowly Single photon detection: OK Can recover gain by increasing HV 2007/6/27 -29 Photon Detector WS at Kobe 13
Lifetime - T. T. S. l Time resolution for single photon l No degradation! l Keep ~35 ps Russian w/ Al(#32) Russian w/o Al (#6) -before s=31 ps s=36 ps -after HPK w/o Al HPK w/ Al s=29 ps s=33 ps 2007/6/27 -29 Photon Detector WS at Kobe s=43 ps s=32 ps s=34 ps 14
Multi-anode MCP-PMT (1) SL 10 R&D with Hamamatsu for TOP counter • Large effective area • Position information 2007/6/27 -29 Photon Detector WS at Kobe Size 27. 5 x 14. 8 mm Effective area 22 x 22 mm(64%) Photo cathode Multi-alkali Q. E. ~20%(l=350 nm) MCP Channel diameter 10 mm Number of MCP stage 2 Al protection layer No Aperture ~60% Anode 4 channel linear array Anode size (1 ch) 5. 3 x 22 mm Anode gaps 0. 3 mm 64% by square shape 4 ch linear anode (5 mm pitch) 15
Multi-anode (2) l l l Single photon detection Fast raise time: ~400 ps Gain=1. 5 x 106 @B=1. 5 T T. T. S. (single photon): ~30 ps @B=1. 5 T Position resoltion: <5 mm Correction eff. : ~50% l l Nucl. Instr. Meth. A 528 (2004) 768. Raise time ~ 400 ps T. T. S. : s~30 ps Basic performance is OK! l Same as single anode MCP-PMT 2007/6/27 -29 Photon Detector WS at Kobe 16
Rate dependence l Gain vs. photon rate l l For high intensity beam Gain drop for high rate l l l >105 count/cm 2/s Due to lack of elections inside MCP holes Depending on RC variables MCP resistance (M cm 2) SL 10 HPK 6 BINP 96 143 380~1000 31 24~39 MCP capacitance 16 (p. F/cm 2) Enough for TOP counter 2007/6/27 -29 Photon Detector WS at Kobe 17
High resolution TOF l Structure l Small-size quartz (cm~mm length) l l Cherenkov light (Decay time ~ 0) extremely reduce time dispersion compared to scintillation (t ~ ns) MCP-PMT (multi-alkali photo-cathode) l l Test counter TTS ~ 30 ps even for single photon gives enough time resolution for smaller number of detectable photons Readout electronics l l selec. : 4 ps Time-correlated Single Photon Counting Modules (SPC-134, Becker & Hickl GMb. H’s) l l l CFD, TAC and ADC Channel width = 813 fs Electrical time resolution = 4 ps RMS 2007/6/27 -29 Photon Detector WS at Kobe 18
Beam test setup l 3 Ge. V/c p- beam l l l at KEK-PS p 2 line PMT: R 3809 U-50 -11 X Quartz radiator l 10 fx 40 zmm with Al evaporation Elec. resolution 2007/6/27 -29 Photon Detector WS at Kobe 19
Beam test result l With 10 mm quartz radiator l l l +3 mm quartz window Number of photons ~ 180 Time resolution = 6. 2 ps Intrinsic resolution ~ 4. 7 ps Without quartz radiator l l 3 mm quartz window Number of photons ~ 80 l l Expectation ~ 20 photo-electrons Time resolution = 7. 7 ps 2007/6/27 -29 Photon Detector WS at Kobe 20
Summary l MCP-PMT studies l Good time resolution of ~35 ps for single photon l l l Gain~106 with <10 mm MCP hole Long lifetime (<10% QE drop) until 3 x 1014 photons/cm 2 l l Enough performance for TOP counter in super B factory High resolution TOF; ~5 ps time resolution l l Need Al protection layer Gain degradation if Ndet >105 counts/cm 2/s l l Even under B=1. 5 T An apprication of fast MCP-PMT References l M. Akatsu et. al. , Nucl. Instr. Meth. A 528 (2004) 768. l K. Inami et. al. , Nucl. Instr. Meth. A 560 (2006) 303. l N. Kishimoto et. al. , Nucl. Instr. Meth. A 564 (2006) 204. 2007/6/27 -29 Photon Detector WS at Kobe 21
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