T. Sugitate / Hiroshima / PHX031 / Nov.01 The Photon Spectrometer for RHIC and beyond PbWO 4 Crystal Density 8.29 g/cm 3 Radiation length 0.89 cm Moliere radius 2.2 cm Presented by Toru Sugitate Hiroshima University Y.Furuhashi T.Sugitate K.HommaR.Kohara 20×20× 200 mm 3 produced by Furukawa co.

T. Sugitate / Hiroshima / PHX031 / Nov.01 Motivation of the project Motivation Photon 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 work Choice 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 costs To be discussed in the workshop.

T. Sugitate / Hiroshima / PHX031 / Nov.01 A PWO signal for a MeV photon PMT Hamamatsu R7056 single photon sensitive (10 PWO crystal (Covered with Aluminum) 60 Co  -source plastic scintillator BC-404 PMT Hamamatsu 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 60 Co-  photo peak crystalLight Yield [p.e./MeV]Decay Time [nsec]Light outputs in 50 ns PWO (A) (23%)+5.0 (72%)+21.9 (5%)97.8 % PWO (B) (16%)+5.9 (81%)+38.2 (3%) 94.9 % BGO % 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 E e = 117 MeV  /E = 13 % Crystal response to the 150 MeV electrons Deposit energy 77 % Energy resolution 16 % double electron peak E e = 231 MeV Single electron peak E e = 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 Spectrometer coverage: 1m ×1 m crystal size: 20×20×200 mm 3 array size: 50 × 50 distance from IP: 3 m  coverage:  0.17 π 0 → γγ GEANT4 Simulation 10  0 ’s in the acceptance (dN/d  ~76) d  /dp  exp(-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/c 2 ]. A sophisticated clustering algorithm may considerably improve the mass resolution

T. Sugitate / Hiroshima / PHX031 / Nov.01 Snapshots of APD readout from the crystal Charge amplifier Hamamatsu H4083 Gain: 0.5V/coulomb Blue-enhanced APD Hamamatsu S5345 active area: 5mm  Photon signal for 137 Cs source

T. Sugitate / Hiroshima / PHX031 / Nov.01 Summary and outlook of the “Hiroshima” project Summary A crystal produced by Furukawa was tested: Transmission; and Light yield; 4-8 p.e./MeV. Decay constant;  1 = ns (16-23%),  2 = ns (72-81%), and  3 = ns (3-5%). Light output in 50 (100) ns; 94.9 (98.6)%. Energy deposit in 20x20x200mm: 77% consistent with Geant4 Outlook in 1.5 years Build 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.