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T. Sugitate / Hiroshima / PHX031 / Nov.01
The Photon Spectrometer for RHIC and beyond
PbWO4 CrystalDensity 8.29 g/cm3
Radiation length 0.89 cm Moliere radius 2.2 cm
Presented by Toru Sugitate
Hiroshima University
Y.Furuhashi T.SugitateK.Homma R.Kohara
20×20× 200 mm3
produced by Furukawa co.
T. Sugitate / Hiroshima / PHX031 / Nov.01
Motivation of the project
MotivationPhoton is an unique signal to explore the QGP matter.
higher granularity in a large multiplicity environment. higher energy resolution for better PID capabilities. PWO crystal is a good candidate for the EMCal upgrade.
Scope of the workChoice of the crystal; Apatity, Shanghai, Japan.Optimize the optical readout device; PMT, PIN, APD.Design and fabricate a FEE prototype.Prototyping of an array and testing with beams.Physics measurements in a RHIC experiment.
Time profile and costsTo be discussed in the workshop.
T. Sugitate / Hiroshima / PHX031 / Nov.01
A PWO signal for a MeV photon
PMT Hamamatsu R7056
single photon sensitive (107 @1900V)
PWO crystal(Covered with Aluminum)
60Co -source
plastic scintillatorBC-404
PMTHamamatsu R2083
T. Sugitate / Hiroshima / PHX031 / Nov.01
PWO light yield and decay time constant
single p.e. peak
Scintillation decay curve
Sample (B)
double p.e. peak
60Co- photo peak
crystal Light Yield [p.e./MeV] Decay Time [nsec] Light outputs in 50 ns
PWO (A) 4.5 1.5 (23%)+5.0 (72%)+21.9 (5%) 97.8 %
PWO (B) 8.2 1.2 (16%)+5.9 (81%)+38.2 (3%) 94.9 %
BGO 404 185 23.7 %
Time spectrum [ns]
Pulse height distribution
T. Sugitate / Hiroshima / PHX031 / Nov.01
A beam test with 150 MeV electron at the Hiroshima VBL
A 150 MeV electron microtron and a storage ring
T. Sugitate / Hiroshima / PHX031 / Nov.01
Ee = 117 MeV/E = 13 %
Crystal response to the 150 MeV electrons
Deposit energy 77 %Energy resolution 16 %
double electron peak Ee = 231 MeV
Single electron peak Ee = 116 MeV
Geant4 simulation of a 150 MeV electron
injection in a crystal
The simulation does not include; photon and p.e. statistics, backgrounds, PMT and electronics noises, and the beam energy fluctuation.
T. Sugitate / Hiroshima / PHX031 / Nov.01
A Monte Carlo simulation of the PWO photon spectrometer
The Photon Spectrometercoverage: 1m ×1 m
crystal size: 20×20×200 mm3
array size: 50 × 50distance from IP: 3 m
coverage: 0.17
π0 → γγ
GEANT4 Simulation
10 0 ’s in the acceptance (dN/d~76)
d/dpexp(-p/0.3) (1<p<5 GeV/c)
flat distribution in y and
T. Sugitate / Hiroshima / PHX031 / Nov.01
Invariant mass spectrum
Deposit Energy vs. Hit Position at the PWO Spectrometer
The invariant mass spectrum shows the mass reconstruction
resolution of 3.2%
Invariant Mass [MeV/c2]
.A sophisticated clustering
algorithm may considerably improve the mass resolution
T. Sugitate / Hiroshima / PHX031 / Nov.01
Snapshots of APD readout from the crystal
Charge amplifierHamamatsu H4083Gain: 0.5V/coulomb
Blue-enhanced APDHamamatsu S5345active area: 5mm
Photon signal for 137Cs source
T. Sugitate / Hiroshima / PHX031 / Nov.01
Summary and outlook of the “Hiroshima” project
SummaryA crystal produced by Furukawa was tested:
Transmission; 50%@350nm and 80%@400nm. Light yield; 4-8 p.e./MeV. Decay constant; 1=1.2-1.5ns (16-23%), 2= 5.0-5.6ns
(72-81%), and 3= 21.9-38.2ns (3-5%). Light output in 50 (100) ns; 94.9 (98.6)%. Energy deposit in 20x20x200mm: 77% consistent with
Geant4
Outlook in 1.5 yearsBuild a mini-tower (3x3) in this Dec. Mini-tower tests with PMT at Hiroshima and at
KEK-PS. Improve the clustering algorithm in the MC
code.Continue to study the APD readout.Evaluation of crystals from Apatity and Shanghai.Mini-tower tests with APD readout in the next JFY. Optimization of APD device.
A MC simulation code was setup. APD readout underway.