The STAR Photon Multiplicity Detector

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 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

2. What does it do? We measure the multiplicity and spatial distribution of photons (h,f,dN/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). Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

3. 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. 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 Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

4. How does it work? • 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 • 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 • h coverage: 2.3 – 3.8 • Area of the detector : 4.2 m2 PreShower CPV Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

5. 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 144 • unit modules • Supermodules are Gas tightand HV isolated • Whole detector can be separated in two • halves Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

6. Single Cell Design 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. • Cathode Material: 0.2mm thick copper sheet • Anode wire: 20 mm gold plated Tungsten • Anode wire Tension : 25 grams • End caps: standard 1.6 mm thick FR4 PCB Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

7. Unit Module construction Unit Module Components • Each unit module contains • 24x24 array of cells (576) • Size of unit module: • Rhombus of side 255 mm • Weight of unit module: 700 gm Gas - 4 board plugged onto the connector Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

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

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

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

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

13. Supermodule Test Results I Pulse height spectrum Variation of Efficiency & Pulse height with Voltage # of cells hit = 1.091 Pion beam at 5 GeV/c Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

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

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

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

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

18. DAQ:Number of Chains and C-RAMS • 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. Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

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

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

21. Network Power Switch NIM Crate for Trigger Elec. NIM Crate for CLK,CLR,T/H VME Crate for DAQ(pmd01) VME Crate for HV Control VME Crate for DAQ(pmd02) Slow Control for PMD at STAR To Main DAQ Network Fibre Optic Ethernet Hub for DAQ Network To Main Slow Control Network Ethernet Hub for Slow Control Network Motor Movement Control(PMD) CAN BUS MVME 167B CAN BUS PL-500 LV unit PL-500 LV unit HV Serial LeCroy 1454 HV Unit RACK-1 RACK-2 RACK-3 CAN BUS CAN BUS CAN BUS HV Console PC-Ethernet Host PC PC-CAN-USB Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

22. 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. Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL

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

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

25. 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. Supriya Das : Junior’s Day, STAR Collaboration Meeting, BNL