24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 1 The STAR Photon Multiplicity Detector Supriya Das, VECC Kolkata For The STAR PMD Collaboration Junior’s Day STAR Collaboration Meeting, BNL - 2003 Outline of the talk: Physics goals Working principle of the detector Design and fabrication aspects Test results Installation DAQ, Trigger and Slow control Simulation and offline reconstruction software Summary
The STAR Photon Multiplicity Detector. Supriya Das, VECC Kolkata For The STAR PMD Collaboration Junior’s Day STAR Collaboration Meeting, BNL - 2003. Outline of the talk: Physics goals Working principle of the detector Design and fabrication aspects Test results Installation - PowerPoint PPT Presentation
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24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 1
The STAR Photon Multiplicity DetectorSupriya Das, VECC Kolkata
Outline of the talk: Physics goals Working principle of the detector Design and fabrication aspects Test results Installation DAQ, Trigger and Slow control Simulation and offline reconstruction software Summary
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 2
What does it do?
We measure the multiplicity and spatial distribution of photons (dN/detc) to study:
• The azimuthal anisotropy to determine the reaction plane and flow as the probes of thermalization.
• The event by event fluctuations in global observables like multiplicity and pseudorapidity distributions following critical phenomena near phase boundary.
• The distribution of Nand N/Nch with full azimuthal coverage ( the charged particles info will be taken from FTPC), looking for signals of chiral symmetry restoration (e.g. DCC).
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 3
Recollection from past…
Observation of collective flow Phys. Lett. B403 (1997) 390.•Scaling of particle production: Phys. Lett. B458 (1999) 422.•DCC Search:• Phys. Lett. B420 (1998) 169 • Phys.Rev.C64:011901,2001 Fluctuations: Phys. Rev. C, May 2002
Scintillator + CCD readout detector sitting 21.5 meters from the vertex covering to
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 4
• Two planes CPV+Preshower• Gas detector of hexagonal cells• Cell cross section : 1.0 cm2
• Cell depth : 0.8 cm• Gas used: Ar+CO2 in 70:30• Total number of channels : 82,944• Distance from vertex : 550 cm• coverage: 2.3 – 3.8• Area of the detector : 4.2 m2
CP
V
Pre
Sh
ower
Preshower detector : • 3X0 Pb convertor sandwiched between two planes of segmented gas detectors.
• Charged particle gives single cell signal in both the planes, photon gives restricted shower signal on the second plane
How does it work?
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 5
• One Unit Module has 576 cells.
• Different Supermodules has different number of unit modules (4,6,9 etc.) depending on the position on the detector
• Each plain has 12 Supermodules 144 unit modules
• Supermodules are Gas tight and HV isolated
• Whole detector can be separated in two halves
Different features of PMD
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• Cathode Material: 0.2mm thick copper sheet• Anode wire: 20 m gold plated Tungsten• Anode wire Tension : 25 grams• End caps: standard 1.6 mm thick FR4 PCB
The single cells (shown above) have solder coating on the outer surface. They are assembled on a special jig (shown on the right) and fused together under controlled heat.
Single Cell Design
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Unit ModuleComponents
Gas - 4 board pluggedonto the connector
• Each unit module contains 24x24 array of cells (576)• Size of unit module: Rhombus of side 255 mm• Weight of unit module: 700 gm
Unit Module construction
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STAR PMD Supermodule assembled in Laboratory
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Front-end Electronics
The front-end electronics for processing PMD signals uses 16-channel GASSIPLEX chips.
Gassiplex Chip Testing
10,000 chips have been tested for the full functionality of each channel.
Test board for GASSIPLEX
The chip
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 10
Translator Board:
Needed to shift the logic level of the control signals (CLK, CLR and T/H) from fast NIM to that of the GASSIPLEX chips.
Gas – 4 Boards:• Contains 4 GASSIPLEX boards and necessary discrete components.• Two protection boards with twin series diodes for each channel is also plugged in.
Buffer board:
Needed for the impedance matching of the analog signal and the input impedance of the ADC in C-RAMS.
Different Front end boards
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 11
Tests performed on the Supermodule:
• Gas leak test• HV test • Pedestal with FEE boards• Signal with cosmic muons
Supermodule under test in laboratory
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 12
Test Setup at CERN-PS
June 2002
STAR PMD Supermodule
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Supermodule Test Results IPion beam at 5 GeV/c
# of cells hit = 1.091
Pulse height spectrum
Variation of Efficiency &Pulse height with Voltage
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 14
Test with electron beams
Preshower spectra Calibration curve
Supermodule Test Results II
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 15
PMD in Wide Angle Hall
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The suspension mechanism for PMD
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PMD Installation
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One Unit Module (UM) consists of 24x24 = 576 cells
•One UM has 9 Gas - 4 Boards each with 4 chips (= 64 Multiplexed channels per board)•3 of UM are daisy chained in ONE FEE Chain
• In ONE Chain: 27 Nos. Gas-4 boards i.e. 27x64 = 1728 channels
• In total there are 72 UM per plane.•Two planes: 72 x 2 = 144 Unit Modules.
•Total Number of FEE chains 144/3 = 48
• One C-RAM has 2 Blocks• One Block = 2K Channels and Total 4K Channels/C-RAM• 1728 channels/Block i.e. ONE chain/Block will be used
• Total Nos. of C-RAMS required are 24.
DAQ:Number of Chains and C-RAMS
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PMD trigger timing diagram
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Typical pedestal plot for one FEE chain
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CA
N
BU
S
VME Crate for DAQ(pmd02)
VME Crate for DAQ(pmd01)
NIM Crate for CLK,CLR,T/H
NIM Crate for Trigger Elec.
Motor Movement Control(PMD)
PL-500 LV unit
PL-500 LV unit
VME Crate for HV Control
Network Power SwitchEthernet Hub for DAQ Network
Ethernet Hub for Slow Control Network
PC-Ethernet
PC-CAN-USB
HV Console
CA
N
BU
SC
AN
B
US
CAN BUSCAN BUS
Host PC
To Main DAQ Network
To Main Slow Control Network
Fibre Optic
RACK-1 RACK-2 RACK-3
HV Serial
Slow Control for PMD at STAR
LeCroy 1454 HV Unit
MVME 167B
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 22
• 10 Supermodules have been installed in the last shut down period.
• 7 FEE chains have been installed and tested.
• Pedestal taken for all seven FEE chains.
• Slow control for Cathode High Voltage, FEE Low Voltage and VME crates have been set up and working.
• Suspension and moving mechanism for PMD has been installed on the east wall of the WAH.
• The stainless steel support plate and lead converter plates have been installed.
Journey so far …
• All LV, HV and signal cables including various optical cables have been laid.
• Gas supply and distribution system has been installed.
24th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 23
Implementation in GSTAR
Front view of PMD in GSTAR
PMD with other detectors
PMD
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Offline reconstruction framework
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Summary
• Photon Multiplicity Detector is a preshower detector which measuresthe multiplicity and spatial distribution of photons in the forward regionof STAR.
• In combination with the charged particle data from the FTPC, it studies different important physics aspects.
• A major portion of the detector has already been installed.
Looking forward for data from d+Au and p+p runs for detector Calibration and understanding of the different aspects of the detector.
Getting ready for real physics data from Au+Au run.
• The DAQ, Trigger and Slow control systems has been set up.