October-November 2003 China - ALICE meeting 1

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

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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 (~ 1.5% @ 10 GeV) And high position resolution (~ 1.25mm @10 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

22

2

2

cE

b

E

a

E

E

a = 0.013 ± 0.007 GeVb = 0.036 ± 0.002 GeV1/2

c = 0.0112 ± 0.0003

Energy resolution Position resolution

Detection with PHOS

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Identification with PHOS 1/3

Photons

Shower topology

Efficien

cy

90%

Purity5%

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Identification with PHOS 2/3

Soft neutral hadrons (pt < 20 GeV/c)

Invariant mass

0

October-November 2003 China - ALICE meeting 8

Identification with PHOS 3/3

Hard direct photon (pt > 20 GeV/c)

Shower topology & isolation cut

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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 hadrons @ pt 20-100 GeV/c) Hot partonic phase (Quark-Gluon Plasma)

Thermal EM radiation (black body, photons @ pt < 2 GeV) Medium effects on jets (jet quenching, 0 @ pt > 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 production @ LHC

Prompt photons

Decay photons

October-November 2003 China - ALICE meeting 11

PHOS hardware Elementary detection cell

PWO4 crystal: 22 22180 mm3 (20 X0) Photo-readout: Avalanche Photo-Diodes

(APD)

Modular structure 17920 lead-tungstate crystals (PWO) 5 independent modules each of 3584 crystal

detector units: Total area: 8m2 Total crystal weight: 12.5t

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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 pT 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

DCSEthernet

CONTROL

ALICETriggerSystem

PHOS L0/L1

ALICE L0/L1/L2/TTC

Optical links, coax

PHOSpower+ bias400V, 12V, 6V, 3.3V

Cabling

FEE

PW

O c

rysta

ls

Counting room area

October-November 2003 China - ALICE meeting 14

PHOS FE & RO electronics: details4 x 8

crystals

FEE board 32 crystals

Trigger/RouterBoard TRU

energy

trigger

control

RCUcontrol

data

L0, L1

ALICEDAQ

TriggerDCS

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UV Photon Detector Avalanche Photodiode from Hamamatsu

55 mm2 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

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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

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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

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Readout Control Unit

Functions: Main Controller,

DDL to ALICE DAQ,

DCS Ethernet Provides timing

information

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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 crystal

s

FEE board 32 crystals

Trigger/RouterBoard TRU

energy

trigger

control

RCUcontrol

data

L0, L1

ALICEDAQ

TriggerDCS

Unit # module chs/unit Status / commentsAPD 3584 1 OKPreamplifier 3584 1 OKT-card 448 8 OKFEE board 112 32 Partly prototypedTrigger/Router board TRU 8 448 DesigningReadout Controller Unit 2 1792 TPC RCU

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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