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Performance test of a RICH with time-of-flight information

This study evaluates the performance of a proximity focusing aerogel Ring Imaging Cherenkov (RICH) detector with high precision timing measurement. The results suggest that adding Time-of-Flight (TOF) information improves the particle separation capabilities of the RICH detector.

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Performance test of a RICH with time-of-flight information

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  1. Performance test of a RICH with time-of-flight information Daiji Hayashi Nagoya Univ. Contents Introduction Setup for beam test Measurement contents Results Summary

  2. Introduction Proximity focusing RICH with Aerogel radiator For upgrade of Belle detector • Kinematic region 0.7~4 GeV/c, K/π separation>4σ • Due to a limited space available →Proximity focusing Aerogel RICH Considered to cover forward region

  3. R&D studies ; history Multi radiator Aerogel RICH First Aerogel RICH RICH with TOF (X,Y,T) sθ : 13mrad Npe/ring : 8.5 K/π separation per track :5.0σ @ 4 GeV/c sθ : 14mrad Npe/ring : 6.4

  4. Research interest Can we improve the performance of Aerogel RICH by adding high precision timing measurement ? RICH with TOF (X,Y,T) Aerogel RICH (X,Y)

  5. New type Aerogel RICH RICH with TOF ΔTOF1(K-π)=42psec ⊿TOFR=42psec (1 photon) R Aeroｇel ⊿TOFG=47psec (Multi photons) 4GeV G IP 1.8m 0.2m Cherenkov photons generate in glass PMT Multi anode MCP-PMT from BURLE at later can reach 19 psec for multi photons. More than 2.4σ for multi photons? Investigated possibility of ‘RICH with TOF’ with Beam test

  6. Beam test setup Estimate time resolution of ‘RICH with TOF’ by measuring time difference between start counter. Multi-anode MCP-PMT BURLE 85011-501 R Start counter R Aerogel radiator Cherenkov photon from aerogel MWPC MWPC 1.045 1.053 G MCP-PMT HPK R3809U G Beam(p) Cherenkov photon from window Quartz Scintillation trigger counter • Multi-anode MCP-PMT : Burle 85011-501 MCP-PMT (13 pixels readout by KC3781A TDC(Kaizu works) via FTA820 amplifier(ORTEC)) • Start counter : HPK R3809U MCP-PMT attached quartz bar on window (TTS : s=10 psec)

  7. Start counter BURLE MCP-PMT Trigger counter

  8. 64 anode BURLE MCP-PMT Dependence of # of detected photons • BURLE 85011-501 MCP-PMT: • 64(8×8) anode pads • pitch : 6.45mm, gap : 0.5mm • 2 MCPs • 25 mm pores • bialkali photocathode • gain : 0.6x106 • collection efficiency : 60% • box dimensions : 71mm square • active area fraction : 52% Measured by laser pulse @ Nagoya Expectation: @ glass hit point(G) Npe : 12(simulation) Time resolution : 35psec @ ring image point(R) Time resolution : 56 psec

  9. Beam test measurement contents 1.Time resolution for 1 pixel @ glass hit point(G). 2. Proton / p separation demonstration @ (G). 3. Time resolution for 1 track @ (G) 4.Time resolution @ ring image point(R).

  10. Time resolution @ glass hit point(G) Measured time resolution at the pixel hit by beam. Parameters were adjusted with threshold scan & HV scan. Threshold scan @ HV=2.4kV HV scan @ threshold=150mV TDCBURLE-TDCSTART COUNTER Time resolution(psec) Time resolution(psec) Event Gain:0.49x106 Threshold(mV) HV(kV) 1 photon Pulse height Time resolution :34psec TDC count(/25psec) (Time walk corrected)

  11. Proton / p separation demonstration (1) To examine TOF capability of ‘RICH with TOF’, measured TOF of proton and p at glass hit point(G) between start counter and BURLE MCP-PMT. Distance between start counter and Burle PMT : 65 cm Setup MCP-PMT BURLE 85011-501 MWPC MWPC MCP-PMT HPK R3809U ACC Beam(p/p) G Trigger counter Quartz

  12. Proton / p separation demonstration (2) Irradiated proton and p of momenta 2 GeV/c, 2.4 GeV/c, and 3.4 GeV/c. TDCBURLE-TDCSTART COUNTER @ 2 GeV/c Expected DTOFp-p and measured points p DTOFp-p Event p TDC count(/25psec) Time resolution : 38psec Confirmed separation of proton and p with TOF. TOF information is correctly measured.

  13. Expansion of photon detection area At glass hit point(G), not only 1 pixel but also neighboring pixels detect Cherenkov photons. BURLE PMT pixel map # of detected pixels ADC mean of each pixels Beam pass pixel Event Read out 13 pixels # of pixels Multi pixels detect Cherenkov photons for 1 track. Can multi pixel information improve time resolution?

  14. Time resolution @(G) for 1 track Estimated time resolution which information of neighboring pixel was included. TDC average of 5 pixels Evaluate TDC average of neighbor 5 pixels. Event 28psec BURLE PMT pixel map Beam pass pixel TDC count(/25psec) Time resolutionfor 1 track : 28psec (Time resolutionfor 1 pixel : 34psec)

  15. Time resolution @ ring image point(R) Measured time resolution @ ring image point(R) Parameters : HV=2.6kV, threshold=20mV PMT TDCBURLE-TDCSTART COUNTER Aerogel Event Time resolution for 1 pixel : 51psec(1 photon) TDC count(/25psec)

  16. Summary Possibility of ‘RICH with TOF’ was estimated with beam test. Results: Time resolution @ glass hit point(G) : 34psec Time resolution @ (G) for 1 track : 28psec Time resolution @ ring image point(R) : 51psec/pe Test with p/p beam demonstrated TOF capability. If uncorrelate 51/√Npe (Npe=6; 21psec) Results are consistent with expectation. (Expectation value: Point(G) : 35psec, Point(R) : 56psec) Separation power of TOF ▼TOF @ (G) Separation power of TOF(R & G) with Burle MCP-PMT STOF= 2.4s @ 4GeV/c SEPARATION POWER(s) Aerogel threshold MOMENTUM(GeV/c)

  17. Backup Backup slides

  18. Proton / p separation with 1 pixel Expected TOF distance and measured points P=+2.0GeV/c P=+2.4GeV/c P=+3.4GeV/c p 36psec 38psec 46psec p 41psec 38psec 37psec

  19. Separation power estimation Separation power with TOF at (R) and (G) Total separation with TOF of (R) and (G)

  20. Time walk correction Before correction After correction

  21. Number of detected photons adc(ch1) ~120

  22. Time resolution of start counter Measured time resolution by putting 2 identical PMTs in the beam. Adjusted threshold value with threshold scan. Parameters：HV=3.4kV, ATTN=30dB, Quartz 1cm Time resolution(psec) 2ns 200mV Start counter signal（before ADC） Threshold(mV) 1 photon Reason of time resolution-deterioration Lower threshold: Small slope of signal form. Higher threshold: Miss photons which arrive on photocathode at early timing. Time resolution of start counter 10.0psec

  23. Set up (Circuit)

  24. Circuit fluctuation Circuit HPK threshold[mV] HPK ATTN[dB] Burle threshold[mV] Time resolution [psec] HPK-HPK -20 W/O 8.6※1 Burle-HPK -50 10 -20 12.9 Input signal is clock signal via differential circuit. RESULT ※1Divided by Circuit fluctuation of CAMAC sistem is usually 9 ~ 10 psec.

  25. Analysis process p • At first, both p & p events are mixed. • Because protons are not detected with ACC-trigger, we can select only p events from the mixed events by cutting ADC pedestal of ACC-trigger. • Decide parameters of function for time walk correction by fitting ADC-TDC 2d distribution of p events. • Apply the parameters for both p & p events, and we can get corrected TDC distribution of both p & p events. p p p p

  26. Start counter • High-resolution TOF using Cherenkov light • Small-size quartz : Cherenkov light (Decay time ~ 0) • MCP-PMT : TTS < 50ps for single photon • Test counter • Num. of photo-electron ~ 260 •  Time resolution = 10.6 psec (including 8.8psec readout fluctuation)

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