10 psec Time-Of-Flight Counter

Transcription

1 10 psec Time-Of-Flight Counter T. Ohshima (Nagoya U.) oints for TOF counter Photo-detector easurements - Beam tests ew Approaches now-how Footnote: MCP-PMT 10 psec TOF counter R&D

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3 1.Points for TOF counter/ Photo-detectors (Transite Time Spread) TTS Multi-anode linear-array PMT (L16 & L24) ybrid Avalanche Photo-Diode icro-channel-plate PMT 70-80; 120 ps 150 ps ps HAPD(HPK R7110U-07) L16(HPK R5900-L16) PMT(HPK H7195) 1 ns/div L24(HPK R6135-L24X) MCP(HPK 3809U-50-25X) Footnote: TTS

4 1.Points for TOF counter Fluctuations of 1. TTS 2. Decay-time (T d TTS) 3. Light-path (T γ TTS) 4. N γ Photo-statistics 1/ Nγ is varied only at Td, Tγ << TTS. quartz: n=1.47; θ=45 o (for GeV/c particles) time photon signals ps (MCP-PMT), ps (L16) 2. Cherenkov light 3. Normal incidence σ = (30x2 30) ps /1cm/( 12N γ ) = 9 ps/ N γ / 1 cm) detected photons/1 cm quartz For short path, no chromaticity effect. σ = ps/ 50 = 5-6 ps Footnote: TOF MCP-PMY/Cherenkov/path/# photons

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6 2.Measurements MCP-TOF NIM A528 (2004) , by M. Akatsu et al, MCP-PMT timing property for single photons MCP(Micro-Channel Plate) Footnote: MCP-PMT

7 2.Measurements / MCP spectra HPK R3809U-50-25X Gain=10 6 σ=46ps BINP N4963 (pedestal = 100count) Gain=3x10 6 σ=34ps,hv:3.2kv (pedestal = 100count) Footnote: ADC & TDC spectra

8 2. R&D of MCP-PMT s (Gain vs TTS)

9 2. R&D of MCP-PMT s (TTS vs B)

10 2.Measurements / TOF by HPK10 TTS=46 ps, Nγ = 200/ 4 cm quartz, σ 0 = 46/ 200 = 3 ps σ expected = 9 ps including circuit fluctuation of 9 ps. σobserved = 10.6 ps With different TTS [ L16(TTS=80 ps) & MCP(TTS=46 ps) ] and similar Nγ s, σ observed = ps is attained,where the circuit fluctuations (7-9 ps) dominate the ambiguity. Footnote: HPK10 TOF

11 3.New Approaches / TOF-PMT w/o Radiator NIM submitted by Y.Enari et al, Cross-Talk of a Multi-Anode PMT and Attainment of a σ sim 10 ps TOF counter HPK10(TTS=46 ps) By hitting an MCP-PMT directly by charged beam, TOF resolution of σ = 13.6 ps was attained. Footnote: HPK10 psec

12 3. New Approaches / TOF-PMT w/o Radiator (continue) window thickness = 4 mm Nγ expected = 25 photons vs. Nγ detected = 50 photons 2 MCP (200µm t ) No path-fluctuation Transite-time from photocathode to MCP = 100 ps Inspection: σ0 = [ ] 1/2 = 10 ps = 46 ps/ 21 (photons) 21 photons vs. 25 / 50 photons Timing of photons from the 1 st MCP plate is 100 ps earlier than those from photo-cathode, but its gain would be lower so that effective # of photons would be less than 25. Yield of 25 photons is really from the MCP? Footnote: psec GaAs photo-cathode photon psec MCP-PMT TOF counter

13 3. New Approaches / TOF-PMT w/o Radiator (continue) In a case the most photons produced at the window, equipping thicker window, 10 mm, would improve TOF resolution better than 10 ps. 25x10/4=60 photons, 46 ps/ 60 =6 ps; σ = = 9 ps Circuit error MCP-PMT (TTS=46 ps) Footnote: MCP-PMT(HPK10) window 10 mm quartz psec MCP-PMT psec GaAsP photo-cathode HPK10(TTS= psec HPK6 TTS=30 psec window mm

14 3.New Approaches / 10 ps TOF-Counter σ=30ps/ 60(110) =3-4 ps with 7 ps circuit error MCP-PMT (TTS=30 ps) σ= 8 ps particle Quartz (10mm) Nγ=60(60+50) photons Footnote: 10 mm quartz Photon quartz PMT psec psec MCP-PMT HPK (TTS= psec HPK TTS= psec psec GaAsP photo-cathode

15 3.4 TOF counter 䚭(2nd BEAM-TEST: 5 ps TOF Beam-Test) Up to here, the attained resolution was limited mostly by the uncertainty of readout circuit.. Aims Study of TOF resolution using SPC (Becker & Hickl GmbH s) Time-Correlated Single Photon Counting Modules (SPC-134): - channel resolution = 813 fs - electrical time resolution = 4 ps RMS - repetition rates upto 200 MHz This SPC includes CFD, TAC, ADC, and MCA (Multi-Channel Analyzer). (2) Study of extra photons (from MCP itself?) ᅂ 䛴ฦよ 7-8 ps䚯䛙䜒䛒ฦよ 䜘Ử䜇䛬䛊䜑䚯SPC䟺ฦよ 䠆䡂䡅䟻䜘ᙔ㟻 䛝䛬䚮MCP-PMT䛴ฦよ 䜘study䚯

16 Using HPK6 (TTS=30 ps) with 3 mm-thick window instead HPK10. SET-UP LOGIC CIRCUIT The thickness of quartz radiator is varied. We don t need any other readout electronics for MCP s; only the common stop signal is prepared by scintillation counters. - cable: SMA, BNC - discri: 300 MHz - SPC-134: 0.86/count (CFD-TAC-ADC) - AMP: 50 k-1.5 GHz - ATTN: < 18 GHz - power splitter:

17 2 nd BEAM-TEST: 5 ps TOF Beam-Test (cont.) For SINGLE PHOTONS raw signals ADC, TDC and σ t (~30 ps) (CAMAC) GAIN, TTS and CE vs HV σ t for single photons(spc used) Pulser (single photon)

18 2 nd BEAM-TEST: 5 ps TOF Beam-Test (cont.) For 3 GeV/c PIONS Circuit resolution ( σ t = 4.1 ps ) TOF w/o radiator ( σ t = 7.7 ps ) TOF w radiator ( σ t = 6.2 ps ) Beam SPC No radiator & 10 mm crystal 6.2(ps) (ps) 2 = 4.7 (ps) 2

19 Although the number of the photo-electrons increases by using thicker quartz, the resolution gradually deteriorates. It is because the uncertainty of the light path due to the quartz thickness. σ t vs RADIATOR THICKNESS 䕋䚭Nγ vs RADIATOR THICKNESS ADC distribution of MCP-plate alone Almost 1 photo-electrons is seen on an average. The extra photo-electrons are not produced at MCP, it might be at the MCP window.

20 3.New Approaches Photon TOF-Counter Tungsten photon-convertor (2 rad.=2x3.5 mm) MCP-PMT (TTS=30 ps) particle Quartz (1 cm=0.08 rad.) Footnote: photon convertor rad. conversion rate = 95% Secondary track Cherenkov charged particle psec photon flight distance 3 mm photon production vertex Decay vertex

21 4. Know-How real TTS Shorter the pulse shot-duration of light-pulser yields smaller TTS. Real TTS might be better. HPK6 TTS=30 ps 20 ps Footnote: TTS

22 4. Know-How Window materials " 1! 2 Quartz/ Borosilicate Footnote: quartz, borosilicate window chromaticity quartz

23 4. Know-How Photocathode materials Cherenkov 1 /λ 2 Not only QE but also λ-range depend on material. Footnote: Bi-alkali multi-alkali quartz

24 Summary 1. TOF resolution = 10 ps achieved! 2. K/pi separation at Belle (Belle is a relatively small spectrometer) ~ σ at 4 GeV/c 1. Photon-TOF Δr=3 mm π 0, Ks, B reconstraction (B π 0 π 0 and vertexing: high signal extraction 3. Issues to be solved: (1) MCP-PMT lifetime (2) enlargement of radiator (3) precise circuit

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32 1.Points for TOF counter (continue) 8.8psec Divider Divider Footnote: TOF 7-9 psec att.&amp

33 2.Measurements L16-TOF NIM submitted by Y.Enari et al, Cross-Talk of a Multi-Anode PMT and Attainment of a σ sim 10 ps TOF counter TTS=80 ps, Nγ = / 4 cm quartz, 16 independent measures σ0= 80/ 9 (photons/channel) / 16 = 7 ps σ expected = 11 ps including circuit fluctuation of 9 ps. Two detectors Footnote: L16-PMT TOF 11 psec

34 Single channel Resolution σ = 30 ps Total Resolution σ observed = 12.1 ps Footnote: 30 psec 12.1 psec

35 Footnote: Systematic error j

36 Amp HPK C5594: bandwidth=50 khz-1.5 GHz gain=36db GHz) NF = 5 db Cable HUBER+SUHNER SMA MULTIFLEX MF 141 Impedance=50 ohm Operating frequency= 18 GHz Capacitance=95 pf/m Time delay= 4.7 ns/m Attenuation= a f(ghz)^1/2 + b f(ghz) (a= ), (b= ) No time to talk

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