The STAR Photon Multiplicity Detector Supriya Das VECC

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 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 1

What does it do? We measure the multiplicity and spatial distribution of photons (h, f, d. N/dh etc) 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 Ng and Ng/Nch with full azimuthal coverage ( the charged particles info will be taken from FTPC), looking for signals of chiral symmetry restoration (e. g. DCC). 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 2

Recollection from past… Scintillator + CCD readout detector sitting 21. 5 meters from the vertex covering h = 2. 9 to 4. 2 Observation of collective flow Phys. Lett. B 403 (1997) 390. • Scaling of particle production: Phys. Lett. B 458 (1999) 422. • DCC Search: • Phys. Lett. B 420 (1998) 169 • Phys. Rev. C 64: 011901, 2001 Fluctuations: Phys. Rev. C, May 2002 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 3

How does it work? Preshower detector : • 3 X 0 Pb convertor sandwiched between two planes of segmented gas detectors. 24 th. February, 2003 • Two planes CPV+Preshower CPV Pre. Shower • Charged particle gives single cell signal in both the planes, photon gives restricted shower signal on the second plane • Gas detector of hexagonal cells • Cell cross section : 1. 0 cm 2 • Cell depth : 0. 8 cm • Gas used: Ar+CO 2 in 70: 30 • Total number of channels : 82, 944 • Distance from vertex : 550 cm • h coverage: 2. 3 – 3. 8 • Area of the detector : 4. 2 m 2 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 4

Different features of PMD • 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 unit modules 144 • Supermodules are Gas tight and HV isolated • Whole detector can be separated in two halves 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 5

Single Cell Design • Cathode Material: 0. 2 mm thick copper sheet • Anode wire: 20 mm gold plated Tungsten • Anode wire Tension : 25 grams • End caps: standard 1. 6 mm thick FR 4 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. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 6

Unit Module construction Unit Module Components • Each unit module contains Gas - 4 board plugged onto the connector 24 th. February, 2003 24 x 24 array of cells (576) • Size of unit module: Rhombus of side 255 mm • Weight of unit module: 700 gm Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 7

STAR PMD Supermodule assembled in Laboratory 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 8

Front-end Electronics The front-end electronics for processing PMD signals uses 16 -channel GASSIPLEX chips. The chip Test board for GASSIPLEX Gassiplex Chip Testing 10, 000 chips have been tested for the full functionality of each channel. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 9

Different Front end boards 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. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 10

Supermodule under test in laboratory Tests performed on the Supermodule: • Gas leak test • HV test • Pedestal with FEE boards • Signal with cosmic muons 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 11

Test Setup at CERN-PS June 2002 STAR PMD Supermodule 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 12

Supermodule Test Results I Pion beam at 5 Ge. V/c # of cells hit = 1. 091 Pulse height spectrum 24 th. February, 2003 Variation of Efficiency & Pulse height with Voltage Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 13

Supermodule Test Results II Test with electron beams Preshower spectra 24 th. February, 2003 Calibration curve Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 14

PMD in Wide Angle Hall 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 15

The suspension mechanism for PMD 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 16

PMD Installation 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 17

DAQ: Number of Chains and C-RAMS One Unit Module (UM) consists of 24 x 24 = 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. 27 x 64 = 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 = 2 K Channels and Total 4 K Channels/C-RAM • 1728 channels/Block i. e. ONE chain/Block will be used • Total Nos. of C-RAMS required are 24. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 18

PMD trigger timing diagram 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 19

Typical pedestal plot for one FEE chain 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 20

Slow Control for PMD at STAR To Main DAQ Network Fibre Optic Ethernet Hub for DAQ Network Power Switch To Main Slow Control Network Ethernet Hub for Slow Control Network NIM Crate for Trigger Elec. Motor Movement Control(PMD) NIM Crate for CLK, CLR, T/H CAN BUS MVME 167 B PL-500 LV unit VME Crate for DAQ(pmd 01) PL-500 LV unit HV Serial VME Crate for DAQ(pmd 02) RACK-1 RACK-2 RACK-3 CAN BUS HV Console Host PC Le. Croy 1454 HV Unit CAN BUS VME Crate for HV Control PC-Ethernet PC-CAN-USB 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 21

Journey so far … • 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. • All LV, HV and signal cables including various optical cables have been laid. • Gas supply and distribution system has been installed. • 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. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 22

Implementation in GSTAR Front view of PMD in GSTAR PMD with other detectors PMD 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 23

Offline reconstruction framework 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 24

Summary • Photon Multiplicity Detector is a preshower detector which measures the multiplicity and spatial distribution of photons in the forward region of 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. • The DAQ, Trigger and Slow control systems has been set up. 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. 24 th. February, 2003 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL 25