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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

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Contents MICE (Muon Ionization Cooling Experiment)

MICE SciFi Tracker 3HF doped 0.35mm-phi scintillating fiber

KEK Beam Test (T553) Setup Analysis Results

Summary

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MICE (Muon Ionization Cooling Experiment) Ionization cooling of muon

Neutrino Factory Never been practiced… 　　 demonstration by MICEMICE

MICE International collaboration experiment (starting from 2006 @RAL) Measurement of emittance reduction

Trackers back & forward cooling channel MICE Scintillating Fiber (SciFi) Tracker

Absorber（ liquid hydrogen）SC solenoid（ 5T）

Tracker TrackerＲＦ -cavity（ 200ＭＨｚ）[ emittance measuring ] [ emittance measuring ]

μ

Experimental Setup of MICE

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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

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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% efficiency @8p.e.

Checking light yield by beam test

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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: 3×10^6 @800V Quantum efficiency: 50% @530nm

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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

1.5m4m

1.2 GeV/c

TOF2 Sci-Fi TOF1D1

Dark boxD2

• p　•π+

Beam D3

mirror

PMT

Optical connector

scifi

clear fiber2cm×2cm

defined beam LED

Front viewSide view

420um

350um

Double layer

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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 4% @ 8 p.e.

1.5 p.e. cut

w/o cut

Light yield (p.e.)

sys.err.A

B

# o

f events

ADC count

ADC histogram Subtracted histogram

# o

f events

P.E.1.5TDC count

# of

eve

nts

TDC histogram

Off-time

ADC gate

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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.

2500 ppm 8.0 (0.4)

4500 ppm 8.3 (0.4)

5000 ppm 8.5 (0.5)

7500 ppm 7.1 (0.5)

10000 ppm 7.7 (0.4)

# o

f p.e

.

3HF concentration (ppm)

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Expected light yield at MICE scifi tracker At MICE scifi tracker

Double layer 5.2/3.8=1.37@5000ppm Difference of path length

Waveguide 3.8/5.2=0.45@5000ppm Attenuation of clear fiber

VLPC readout 5.2×80%÷50%=8.3 p.e. Efficiency

1-P(0,8)-P(1,8)=99.7% @8p.e.

P(n, μ) ＝ μn exp(-μ) / n!

Poisson distribution

3HF concentration 5000 ppm 2500 ppm

Single layer

w/o waveguide8.5 (0.5) 8.0 (0.4)

Single layer

w/ waveguide3.8 (0.6) 3.2 (0.5)

Double layer

w/o waveguide11.2 (0.5) 9.6 (0.4)

Double layer

w/ waveguide5.2 (0.4) 4.4 (0.5)

Expected light yield at MICE

8.3 (0.6) 7.0 (0.8)

Efficiency 99.7% 99.3%

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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 p.e. @5000ppm (double layer with 4m-long waveguide) 4.4 ± 0.5 p.e. @2500ppm (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 ppm 2500 ppm

T553 5.2 (0.4) 4.4 (0.5)

MICE (Expected) 8.3 (0.6) 7.0 (0.8)

Efficiency 99.7% 99.3%

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END

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Neutrino Factory Physics

Precise measurement of the MNS matrix element Observation of the matter effect

the sign of Δm232

leptonic CP violation

Neutrino production Goals

(Eν)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 !

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3HF scintillating fibers VLPC can detect green lights (500-600 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 vs PMT QE

01020304050607080

200 300 400 500 600 700 800

Wavelength [nm]

Quan

tum

Efficie

ncy

[%]

00.020.040.060.080.10.120.140.16

PMTQE [%]VLPCQE [%]ZD43233HF

VLPC quantum efficiency

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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 %

Num

ber

of

P.E

.

Run number

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Data from Scifis

Background

ADC-TDC scatter plot

TDC count

AD

C c

ou

nt

•Phosphorescence

ADC histogram

ADC count

Proton hit

Pion hit

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Effect of double layer

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30cm

Side view

Layout of SciFi Station

u

V

W

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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