2005/3/271 3HF 蛍光体を添加した Sci-Fi の基礎 開発 阪大理 (A) 青木正治 有本靖 久野良孝 栗山靖敏 佐藤朗 田窪洋介 中丘末広 中原健吾 堀越篤 松島朋宏 吉田誠 高エ研 (B) 五十嵐洋一 横井武一郎 吉村浩司 FNAL (C) Alan Bross Imperial College London (D) Ken Long, Malcolm Ellis 大阪大学大学院理学研究科 坂本英之

2005/3/27 2 Contents  MICE (Muon Ionization Cooling Experiment)  MICE SciFi Tracker  3HF doped 0.35mm-phi scintillating fiber  KEK Beam Test (T553)  Setup  Analysis  Results  Summary

2005/3/27 3 MICE (Muon Ionization Cooling Experiment)  Ionization cooling of muon  Neutrino Factory MICE  Never been practiced… demonstration by MICE  MICE  International collaboration experiment (starting from  Measurement of emittance reduction Trackers back & forward cooling channel MICE Scintillating Fiber (SciFi) Tracker Absorber （ liquid hydrogen ） SC solenoid （ 5T ） Tracker ＲＦ -cavity （ 200 ＭＨｚ） [ emittance measuring ] μ Experimental Setup of MICE

2005/3/27 4 The MICE collaboration  141 physicists and engineers from 40 institutions in 9 countries  Belgium: UC Louvain  France: CEA/Saclay  Italy: INFN Bari, Frascati, Genoa, Legnaro, Milano, Napoli, Padova, Roma, III, Trieste  Japan: KEK, Osaka U  Netherlands: NIKHEF  Russian Federation: BINP  CERN  Switzerland: U Geneve, ETH-Zurich, PSI  UK: Brunel, Edinburgh, Glasgow, Liverpool, Imperial, Oxford, Sheffield  USA: ANL, BNL, Fairfield, Chicago, Fermilab, IIT, JLab, LBNL, UCLA, Northern Illinois, Iowa, Mississippi, UC Riverside

2005/3/27 5 To photon detector Waveguide Station MICE SciFi Tracker  R&D with UK, US and Japan  Components  Station 3HF doped 0.35mm-phi scintillating fiber  Waveguide 4m-long optical clear fiber  Photon detector VLPC (Visible Light Photon Counter)  High Q.E. 80% at 3HF emission peak (530nm)  Requirement  Higher efficiency e.g., 99.7% Checking light yield by beam test

2005/3/27 6 T553 beam test  KEK-PS T1 beam line, April-May 2004  Purpose  Selecting best 3HF concentration on light yield  And confirming enough high light yield  Scintillating fibers  Kuraray SCSF-3HF, 0.35mm-phi, multi-cladding and S-type  Base: polystyrene (99%)  First dopant: p-terphenyl (1%)  Second dopant: 3HF (2500, 4500, 5000, 7500, 10000ppm)  Photon detector  PMT (HAMAMATSU R7411U-40MOD) Cathode: GaAsP (5mm-phi effective area) Anode: 8 stages Gain: Quantum efficiency:

2005/3/27 7  Beam  1.2 GeV/c  Pion, proton, ….  Trigger  TOF & Defining counters  Setup of scintillating fibers  0.42-mm pitch with double layer and 4m-long waveguide  PMT gain monitor by LED  Mounted in dark box Experimental setup 1.5m 4m 1.2 GeV/c TOF2 Sci-Fi TOF1 D1 Dark box D2 p π + Beam D3 mirror PMT Optical connector scifi clear fiber 2cm×2cm defined beam LED Front view Side view 420um 350um Double layer

2005/3/27 8 Analysis  Pion selection by TOF → Events in ADC gate → P.E. conversion by LED calibration  Background rejection  Subtracting using off-time ADC spectrum  But still remains… ⇒ cutting under 1.5 p.e.  Number of p.e.  Mean of A (w/ cut) and B (w/o cut)  Systematic error is 8 p.e. 1.5 p.e. cut w/o cut Light yield (p.e.) sys.err. A B # of events ADC count ADC histogramSubtracted histogram # of events P.E. 1.5 TDC count # of events TDC histogram Off-time ADC gate

2005/3/27 9 3HF concentration dependence  Selecting best 3HF concentration on light yield  5000 ppm has highest light yield  But there was no significant difference among other concentrations 3HF concentration # of p.e ppm 8.0 (0.4) 4500 ppm 8.3 (0.4) 5000 ppm 8.5 (0.5) 7500 ppm 7.1 (0.5) ppm 7.7 (0.4) # of p.e. 3HF concentration (ppm)

2005/3/27 10 Expected light yield at MICE scifi tracker  At MICE scifi tracker  Double layer Difference of path length  Waveguide Attenuation of clear fiber  VLPC readout  5.2×80%÷50%=8.3 p.e.  Efficiency P(n, μ) ＝ μ n exp(-μ) / n! Poisson distribution 3HF concentration5000 ppm2500 ppm Single layer w/o waveguide 8.5 (0.5)8.0 (0.4) Single layer w/ waveguide 3.8 (0.6)3.2 (0.5) Double layer w/o waveguide 11.2 (0.5)9.6 (0.4) Double layer w/ waveguide 5.2 (0.4)4.4 (0.5) Expected light yield at MICE 8.3 (0.6)7.0 (0.8) Efficiency 99.7%99.3%

2005/3/27 11 Summary  MICE scifi tracker based on 3HF doped 0.35mm scintillating fibers will be used  KEK beam test (T553) was performed in April-May 2004  5.2 ± 0.4 (double layer with 4m-long waveguide)  4.4 ± 0.5 (double layer with 4m-long waveguide)  From T553,  Over 99% efficiency will be expected at MICE with 5000ppm and also 2500ppm  These meet the requirement of MICE scifi tracker 3HF concentration 5000 ppm2500 ppm T (0.4)4.4 (0.5) MICE (Expected)8.3 (0.6)7.0 (0.8) Efficiency99.7%99.3%

2005/3/27 12 END

2005/3/27 13 Neutrino Factory  Physics  Precise measurement of the MNS matrix element  Observation of the matter effect the sign of Δm 23 2 leptonic CP violation  Neutrino production  Goals  (E ν ) max = 50 GeV  10^20 muon decays/year  Advantages  Precise known energy spectrum and flavor composition  High-energy electron neutrinos  Need “cooling” of muons  Accelerating intense muon beam by reduction of emittance (cooling)  Fast cooling is essential before decaying of muons  Ionization cooling ! μ → e νν Cooling !

2005/3/ HF scintillating fibers  VLPC can detect green lights ( nm) at most.  Doping 3HF as a wavelength shifter; 350 nm ⇒ 530 nm  Doping with high concentration in order to improve the absorption efficiency. Absorption and emission spectrum of 3HFVLPC quantum efficiency

2005/3/27 15 PMT gain calibration  Purpose  Measuring the gain  Monitoring of gain stability  Gain  # of p.e. per ADC count  # of p.e. = (MEAN/RMS)^2 From Poisson distribution  10 % discrepancy was confirmed by position dependence of gain  Systematic error from PMT is less than 5 % Number of P.E. Run number

2005/3/27 16 Data from Scifis Background ADC-TDC scatter plot TDC count ADC count Phosphorescence ADC histogram ADC count Proton hit Pion hit

2005/3/27 17 Effect of double layer

2005/3/ cm Side view Layout of SciFi Station u V W

2005/3/27 19 Ionization Cooling  Fast cooling is possible  Best method for muon cooling  Principle  Passing through absorber (loss total momentum) followed by RF (restore longitudinal momentum)  Result in reduction in p ⊥ spread,i.e. (transverse) cooling Z X