October-November 2003China - ALICE meeting1 PHOS in ALICE A PHOton Spectrometer with unique capabilities for the detection/identification of photons and neutral hadrons

October-November 2003 China - ALICE meeting 2 PHOS

October-November 2003 China - ALICE meeting 3 Rails for PHOS

October-November 2003 China - ALICE meeting 4 What is PHOS ? PHOS is a photon spectrometer consisting of  A high resolution, highly granular EM calorimeter  Associated to a MWPC acting as a charge particle veto detector, … offering unique particle detection  With high energy resolution (~ 10 GeV)  And high position resolution (~ GeV) And particle identification from very low (0.5 GeV) to fairly high (100 GeV) transverse momentum:  Direct photon  Decay photon  Electrons  Charged hadrons  Neutral hadrons (  0 and  )  Neutral baryons (n and n)

October-November 2003 China - ALICE meeting 5 a = ± GeV b = ± GeV 1/2 c = ± Energy resolution Position resolution Detection with PHOS

October-November 2003 China - ALICE meeting 6 Identification with PHOS 1/3 Photons Shower topology Efficiency 90% Purity 5%

October-November 2003 China - ALICE meeting 7 Identification with PHOS 2/3 Soft neutral hadrons (p t < 20 GeV/c) Invariant mass 00 

October-November 2003 China - ALICE meeting 8 Identification with PHOS 3/3 Hard direct photon (p t > 20 GeV/c) Shower topology & isolation cut

October-November 2003 China - ALICE meeting 9 PHOS provides access to an unique scientific program Dynamical characterization of the medium by its radiation spectrum:  Early hard QCD processes: initial state structure (hard photons and neutral p t GeV/c)  Hot partonic phase (Quark-Gluon Plasma) Thermal EM radiation (black body, p t < 2 GeV) Medium effects on jets (jet quenching,  p t > 10 GeV/c, jet photon tagging)  Late hadronic phase (soft photons and neutral hadrons) To study soft QCD effects and medium effects  Hadrons gas – partons gas phase transition  Chiral symmetry restoration  Gluon saturation

October-November 2003 China - ALICE meeting 10 Photon LHC Prompt photons Decay photons

October-November 2003 China - ALICE meeting 11 PHOS hardware Elementary detection cell  PWO 4 crystal: 22  22  180 mm 3 (20 X0)  Photo-readout: Avalanche Photo-Diodes (APD) Modular structure  lead-tungstate crystals (PWO)  5 independent modules each of 3584 crystal detector units:  Total area: 8m 2  Total crystal weight: 12.5t

October-November 2003 China - ALICE meeting 12 PHOS FE & RO electronics A challenging project: convert weak light signal into energy and time signals and construct trigger signals.  Energy Dual gain energy channels and digitization for covering a very large dynamic range up to ~100 GeV Separate fast energy signal for trigger and timing  Time Resolution ~2 ns to discriminate against low energy baryons  Trigger L0 (< 900 ns) for min-bias pp, low threshold (  100 MeV) L1 (< 6.2  s) for high p T Pb-Pb, high threshold (5-10 GeV)

October-November 2003 China - ALICE meeting 13 PHOS FEE & RO electronics in ALICE EVENT DATA ALICE DDL (optical) DAQ PC DCS Ethernet CONTROL ALICE Trigger System PHOS L0/L1 ALICE L0/L1/L2/TTC Optical links, coax PHOS power + bias 400V, 12V, 6V, 3.3V Cabling FEE PWO crystals Counting room area

October-November 2003 China - ALICE meeting 14 PHOS FE & RO electronics: details 4 x 8 crystals FEE board 32 crystals Trigger / Router Board TRU energy trigger control RCU control data L0, L1 ALICE DAQ Trigger DCS

October-November 2003 China - ALICE meeting 15 UV Photon Detector Avalanche Photodiode from Hamamatsu  5  5 mm 2  C ~ 80 pF at 250 V bias Preamplifier (Bergen & Kurchatov)  Sensivity 1V/pC  Noise 470 e -  Rise time 10 ns  Dynamic range 1mV – 8 V T card (Bergen & Kurchatov)  Connection to FEB  2  2  8 analog signals

October-November 2003 China - ALICE meeting 16 FEE board 32 channels Functions:  Shaper/amplifier: slow dual gain outputs for energy, fast energy output for trigger  Energy digitization (10 bit, base-line restoration, zero suppression)  Quadlet (2x2) analog summing of fast energy signals for PHOS trigger  Timing  APD bias control (2%)+ other control channels T cards

October-November 2003 China - ALICE meeting 17 Trigger Router Card 448 channels Functions:  Data and Control GTL cable bus with FEE’s and RCU  Digitization of quadlets from FEE boards  PHOS L0/L1 Trigger generation  Router for event data stream via RCU to ALICE DAQ

October-November 2003 China - ALICE meeting 18 Readout Control Unit Functions:  Main Controller, DDL to ALICE DAQ,  DCS Ethernet  Provides timing information

October-November 2003 China - ALICE meeting 19 PHOS FE & RO electronics: Status R&D for a few elements has ended Most of the elements in design/development phase There is a lot of work in all areas Designed as state-of-the-art technologies (programmable logic) Construction sites not yet defined 4 x 8 crystals FEE board 32 crystals Trigger / Router Board TRU energy trigger control RCU control data L0, L1 ALICE DAQ Trigger DCS

October-November 2003 China - ALICE meeting 20 PHOS collaboration China:  Beijing, China Institute of Atomic Energy  Wuhan, Huazhong Normal University, Institute for Particle Physics Czech Republic:  Prague, Academy of Science of the Czech Republic, Institute of Physics France:  Nantes, Laboratoire de Physique Subatomic et des Technologies Associées Norway:  Bergen, University of Bergen, Department of Physics  Oslo, University of Oslo, Department of Physics Poland:  Warsaw, Soltan Institute for Nuclear Studies Russia:  Moscow, Russian Research Center ‘Kurchatov Institute’  Protvino, Institute for High Energy Physics  Sarov, Russian Federal Nuclear Center ‘VNIIEF’  Dubna, Joint Institute for Nuclear Research