ALICE

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ALICE Photon Multiplicity Detector (PMD)

• OUTLINE
• Layout and Design
• Test Beam setup and Results
• Experience with PMD _at_ STAR
• Front-End Electronics
• Cooling
• Integration
• Offline Simulation
• PMD Milestones and Planning

Tapan Nayak LHCC Review, March 2002
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ALICE PMD
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PMD Layout and Design
CPV
PreShower

• Two planes Veto PreShower
• Gas detector with hexagonal cells
• Cell cross section 0.22 cm2
• Cell depth 0.5 cm
• Total No. of channels 169,344
• Distance from vertex 355cm
• h Coverage 2.3 3.5
• Area of the detector 1.8m2
• Ave. Occ 13 for CPV 28 for PMD
• Photon counting Efficiency 64
• purity 60

FRONT VIEW
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PMD Prototypes
Extended cathode
Two Prototypes Prototype-4
Prototype-3
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Test Setup at T-10 beam-line

• The setup shown is for finding the response of
  the PMD to pion beam
• For Pre-shower studies with electrons
• a Lead plate is placed in front of and close to
  the PMD
• Scintillator 1-2 is moved to the front of the
  PMD
• A Cherenkov counter is placed upstream for the
  Electron Trigger

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Response to pion Beam
Prototype-4
CERN-PS Beam line T10 5 GeV pion Beam
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Detector Efficiency for pions
Prototype-4

• Efficiency is calculated
• using 5-fold coincidences
• Tests with
• ArCO2 KrCO2
• Final decision to use
• ArCO2 at 7030
• Efficiency close to 97
• achieved for pions.

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Efficiencies and Gains
Prototype-4
(mm)
Variation of efficiency as a function of
position within a cell. Efficiency drops at the
boundary. The arrows show the center of cell.
Relative gains of various cells in the prototype.
(32 cells tested).
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Transverse shower spread
Prototype-4
Response to Electrons at 2GeV/c
3GeV/c 4GeV/C
Number of cells affected Data 5.0
6.5
7.6 Geant 5.2
6.2 6.8
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Results from SPS test

• Tests performed with two readout chips
• Old gassiplex 1.2
• New gassiplex 0.7-3 (same spec. as MANAS)
• Gain of New gassiplex (or MANAS) is 3 times lower

Prototype-3 100 GeV electron Beam
Old chip 1500 V Peak 64
New chip 1550 V Peak 27
Comparison of Old and New chip.
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Count Rate Study
Prototype-3
Max. Count Rate Expected 5 KHz.
Efficiency and peak pulse height for 100GeV/c
electrons as a function of the incident flux.
Beam tests are done up to 3 KHz. 5-fold trigger
was used for this study.
(103 particles/cm2/sec)
Efficiency and peak ADC are stable with count
rate up to 3KHz.
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PMD Fabrication for STAR Experiment at RHIC

• STAR-PMD design is identical to
• ALICE-PMD
  TDR version
• STAR-PMD Fabrication is in progress
• STAR-PMD to be installed between July-Sept.
  2002
• STAR-PMD data taking will start from Nov. 2002
• STAR-PMD experience will be very useful in
  ALICE

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PMD _at_ STAR

• Preshower Detector with fine granularity
• Two planes Veto Pre-shower
• Total no. of cells 82,944
• Distance from vertex 550cm
• PMD is outside STAR magnet
• Gas detector with hexagonal cells
• h Coverage 2.3 3.9
• Cell cross section 1.0 cm2, depth 0.8 cm
• Area of the detector 4.2m2
• Readout Gassiplex 0.7-3 chip

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Unit Module Fabrication in progress
200 Unit Modules to be Fabricated for STAR-PMD

• 6 Stations are operational
• 3 at VECC (shown)
• 2 at Jammu
• 1 at Bhubaneshwar

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CHIP TESTING
4-chip Gassiplex Board
2000 boards to be made

• 10,000 chips in hand
• 8,000 already tested
• MANAS will be identical to Gassiplex,
• All setups to be used for ALICE-PMD.

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PMD Front-End Electronics
FEE Board Mounting and Cooling
4 chip MCM board with MANAS-16 (similar to that
of station 3-4-5 of Dimuon Tracking)
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(No Transcript)
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PMD Cooling
Setup to find out if Air Cooling is adequate for
the PMD-FEE.
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Effectiveness of forced air cooling can be seen
here.
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PMD Integration
V0
T0L
PMD
T0R
FMD
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PMD Offline simulation

• STATUS
• Geometry implemented
• Cell-wise hit information
• Reconstruction
• Clustering
• Photon-hadron discrimination
• Ready for PPR production
• Physics Simulation
• Centrality Trigger

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PMD Milestones (page - 1)
Prototype tests Jun. 02 Results of
Count-rate studies Nov. 02 Design
freeze Nov. 02 Design of production
jigs Mar. 03 Fabrication of jigs and
fixtures May.03 Pre-production unit module
prototype and tests July 03 PRR Aug.
03 Material procurement for unit modules Dec.
03 Unit module production starts Jan.
04 Unit module production ends Dec.
04   Supermodule assembly starts Jan.
05 Supermodule assembly ends Apr.
05 Packing/transportation to CERN May 05
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PMD Milestones (page - 2)
PCB Layout design Aug. 02 MCM Prototype
(gassiplex/manas) June 03 Test
facilities May 03 MANAS delivery Dec.
03 MCM production ends Jun. 04 MCM board
tests complete Mar. 05 Shipping of MCM boards
to CERN Apr. 05   Final mechanical layout
design Dec. 03 Cooling system design
freeze July 03 Cooling system
fabrication/assembly Dec. 04 Support
structure June 04 Lead plates July
04 Shipping of support structure and lead
plates Aug. 04 Arrival of support structure and
lead plates at CERN Oct. 04
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PMD Milestones (page - 3)
Design of gas system Oct. 03 Gas system
control May 04 Gas system commissioning Sep
t. 04   Slow control MMI design Oct.
02 Slow control design freeze Oct. 03 Slow
control fabrications and tests June
04     Tests and calibration of
supermodules Aug. 05 Installation of
services July 05 Pre-installation at
point-2 Sep. 05 Installation within L3
cave Nov. 05 Offline tests and
commissioning Dec. 05
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Planning

• 1. ALICE Note summarizing the detector
  performances up to
• 3 KHz count rate will be ready by end of
  March.
• 2. Beam tests for count rate study up to 5 KHz
  are planned
• for June-July 2002.
• 3. Final PMD document available November 2002
• 4. Full scale prototype module to be ready by
  Spring 2003
• 5. Test of full scale prototype module Summer
  2003
• PRR August 2003.