1. 1Shanghai 14-20/11/06QM2006 Daicui Zhou PHOSPHO S PHOS, the ALICE PHOton Spectrometer The scientific objectives The design Status & Performance Daicui Zhou ( for the ALICE/PHOS Collaboration ) Institute of Particle Physics, Central China Normal University, Wuhan,China

2. 2Shanghai 14-20/11/06QM2006 Daicui Zhou The role of photons –Jet quenching first observed through high p t  0 suppression –Observation of high p t direct photon, constraining pQCD –Observation of low p t photon excess which could be interpreted in terms of thermal photons emission PHENIX Phys. Rev. Lett. 88 (2002) 022301 WA98, Phys. Rev. Lett. 85 (2000) 3595 PHENIX, Nucl-Exp/0605005 SPS and RHIC data have shown the importance of the photon signal to diagnose the properties of matter formed in heavy-ion collisions.

3. 3Shanghai 14-20/11/06QM2006 Daicui Zhou … and at LHC Extending the photon measurement in the very hard regime ( ~ 100 GeV/c) More favorable environment for direct photon identification (larger  /  0, isolation cuts) Provide a calibration of the jets through photon-tagged jet measurements A hotter and longer lived QGP should emit a measurable thermal radiation

4. 4Shanghai 14-20/11/06QM2006 Daicui Zhou Requirements High quality photon identification in a hadron dominated environment (dN/dy ~ 2000-4000) – CPV for h ± and e ± -  discrimination – time of flight for h (mainly n and n) -  discrimination – Shower shape and isolation cut for  0 -  discrimination This can be provided by –A high granularity EM calorimeter providing excellent energy and position resolution and timing measurement –Associated to a charged particle detector

5. 5Shanghai 14-20/11/06QM2006 Daicui Zhou ALICE-PHOS Detector EMCA: 5 arrays of 56×64 Lead tungstate crystals ( small radiation length and Moliere radius ) CPV: multi-wire chamber with pad readout matching the granularity of EMCA PHOS ALICE

6. 6Shanghai 14-20/11/06QM2006 Daicui Zhou Technical data 17920 PWO crystals distance to IP: 4.6m coverage in pseudo-rapidity: |  | < 0.12 coverage in azimuthal angle:  < 100° crystal size: 22×22×180 mm 3 Depth ： 20X 0 photo readout: APD + CSP operating temperature: -25 o C PHOS Module Avalanche Pin-Diode Crystal Preamplifier module Support structure Strip unit

7. 7Shanghai 14-20/11/06QM2006 Daicui Zhou Readout and electronics 112 FEEs / 8 TRUs / 4 RCUs / 3584 CSP-APD Cold volume: PWO strips 2x16=32 channels array APD+CSP FEE boards working at room temperature

8. 8Shanghai 14-20/11/06QM2006 Daicui Zhou Signal Processing Scheme NIM A565(2006) 768 CERN/ALICE 99-4, ALICE TDR2

9. 9Shanghai 14-20/11/06QM2006 Daicui Zhou 32 channel FEE card V1.0 prototype in Aug. 2004 and test beam at CERN V1.1 version in Jan. 2005 and review in May 2005 130 cards production and testing at Wuhan in Jan 2006 Commissioning and test beam at CERN from June-Sept 2006 FEE Card FEE card hardware properties FEE Card 32 ch.dual gain shapers τ=1μs RMS noise 2 us: 615 e-(3.1MeV) 14 bit dyn range 5 MeV-80GeV 32 APD bias regulators ±0.1V Fast OR (2*2 Xtals) for trigger Board controller FPGA (PCM) USB controller TPC-like readout and control bus DAQ and DCS via RCU 5.5 Watt,349*210 mm 2 NIM A565(2006) 768 CERN/ALICE 99-4, ALICE TDR2

10. 10Shanghai 14-20/11/06QM2006 Daicui Zhou

11. 11Shanghai 14-20/11/06QM2006 Daicui Zhou ALICE-PHOS first Module 3584 crystals112 FEE cards 1 st Module beam test at PS-T10 First PHOS module Cooling system Assistant cooling

12. 12Shanghai 14-20/11/06QM2006 Daicui Zhou Calibration Stability Gain 1 / Gain 2 The balance test of ratio of different APD channels was carried from 2 calibrations runs under the condition that the prototype was warmed up and cooled down again The balance value of ratio of the gains: Mean  0.99   0.02

13. 13Shanghai 14-20/11/06QM2006 Daicui Zhou Energy and Position resolution ~ 3%,  (  (E)/E) ~ 0.1% @ 2 GeV ~ 2.7mm @ 2 GeV

14. 14Shanghai 14-20/11/06QM2006 Daicui Zhou Timing and Mass Resolution  (  0 ) =4.7 MeV/c 2   + 12 C →  0 + X → 2  + X Invariant mass spectrum  ~ 0.5 ns at E > 1.5 GeV Timing resolution measurement with the electron beam. Standard start-stop method with an external trigger Hysayuki Torii’s poster for ALICE-PHOS(138)

15. 15Shanghai 14-20/11/06QM2006 Daicui Zhou Installation plan The first PHOS module will be installed in ALICE for the first pp run in 2007 The 2 nd and 3 rd modules will be installed during the first winter shutdown after pp run The 4 th and 5 th modules will be installed for the first long heavy- ion run

16. 16Shanghai 14-20/11/06QM2006 Daicui Zhou ALICE-PHOS project-organization - China, Beijing, China Institute of Atomic Energy - China, Wuhan, Central China Normal University, Institute for Particle Physics - China, Wuhan, Huazhong University of Science and Technology - Czech Republic, Prague, Academy of Science of the Czech Republic, Institute of Physics - Germany, Münster, Westfälische Wilhelms Universität, Institute für Kernphysik - Japan, Hiroshima, Hiroshima University - Norway, Bergen, University of Bergen, Department of Physics - Norway, Oslo, University of Oslo, Department of Physics - Poland, Warsaw, Soltan Institute for Nuclear Studies - Russia, Moscow, Russian Research Center ‘Kurchatov Institute’ - Russia, Protvino, Institute for High Energy Physics - Russia, Sarov, Russian Federal Nuclear Center ‘VNIIEF’ - Russia, Dubna, Joint Institute for Nuclear Research - Switzerland, Geneva, CERN All the PHOS colleagues are acknowledged for the slides Thanks !

17. 17Shanghai 14-20/11/06QM2006 Daicui Zhou Importance of the TOF Different time resolutions of the TOF system were studied to estimate the contamination of the photon spectrum by hadrons. TOF 2ns/E reduces significantly the contamination from hadrons below ~0.1