Gbor I Veres and Conor Henderson

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A High-pT Spectrometer Trigger For phobos

• Gábor I Veres and Conor Henderson
• Massachusetts Institute of Technology
• For the PHOBOS Collaboration

Quark Matter 2004, 11-17 Jan 2004
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Acknowledgements

• Anna Maria Convertino, Alan Carroll, Jay
  Kane, Abby Bickley, Aaron Noell, Richard Bindel,
  Charles Pearson, James Anselmini, Conrad Koehler,
  Joe Scaduto, Wuzheng Meng, Dale Ross, George
  Stephans, Robert Pak, Nigel George, Gunther
  Roland, Mark Baker, Alice Mignerey, Lois
  Caligiuri, Wit Busza, Gerrit van Nieuwenhuizen,
  David Hofman, Erik Johnson, Piotr Kulinich, Bolek
  Wyslouch, Carla Vale, Wojtek Skulski, Jan Toke,
  Andrei Sukhanov, Corey Reed, Frank Wolfs,
  Marguerite Belt Tonjes, Kevin from KC
  Electronics, and Andreas Ruben from CAEN.

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Collaboration (Jan 2004)
Birger Back, Mark Baker, Maarten Ballintijn,
Donald Barton, Russell Betts, Abigail Bickley,
Richard Bindel, Wit Busza (Spokesperson), Alan
Carroll, Zhengwei Chai, Patrick Decowski,
Edmundo García, Tomasz Gburek, Nigel George,
Kristjan Gulbrandsen, Stephen Gushue, Clive
Halliwell, Joshua Hamblen, Adam Harrington, Conor
Henderson, David Hofman, Richard Hollis, Roman
Holynski, Burt Holzman, Aneta Iordanova, Erik
Johnson, Jay Kane, Nazim Khan, Piotr Kulinich,
Chia Ming Kuo, Willis Lin, Steven Manly, Alice
Mignerey, Gerrit van Nieuwenhuizen, Rachid
Nouicer, Andrzej Olszewski, Robert Pak, Inkyu
Park, Heinz Pernegger, Corey Reed, Michael Ricci,
Christof Roland, Gunther Roland, Joe Sagerer,
Iouri Sedykh, Wojtek Skulski, Chadd Smith, Peter
Steinberg, George Stephans, Andrei Sukhanov,
Marguerite Belt Tonjes, Adam Trzupek, Carla
Vale, Siarhei Vaurynovich, Robin Verdier, Gábor
Veres, Edward Wenger, Frank Wolfs, Barbara
Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek
Wyslouch, Jinlong Zhang ARGONNE NATIONAL
LABORATORY BROOKHAVEN NATIONAL LABORATORY INSTITU
TE OF NUCLEAR PHYSICS, KRAKOW MASSACHUSETTS
INSTITUTE OF TECHNOLOGY NATIONAL CENTRAL
UNIVERSITY, TAIWAN UNIVERSITY OF ILLINOIS AT
CHICAGO UNIVERSITY OF MARYLAND UNIVERSITY OF
ROCHESTER
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The Goal

• To create a high-pT trigger for PHOBOS
• For use in dAu and pp collisions these have
  low-multiplicity and high-rate
• Should enhance yields in Spectrometer and
  Time-of-Flight detector
• Physics motivation high-pT particle ID in TOF

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High-pT Trigger Concept
TOF
accepted
rejected
Low-pT tracks curve in magnetic field high-pT
tracks almost straight ? Segmented trigger
detectors online vertex can select high-pT
tracks
Trigger
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Allowed Trigger Combinations
Allowed segment combinations for straight tracks
from desired vertex range
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The PHOBOS Detector 2003
ToF moved far from IP
New trigger detectors
Tunnell wall
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Hard At Work!
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PMT and Scintillator Assembly

• Bicron BC-408 scintillator light-guide
• PMTs from AGS experiment E850
• Double-layer magnetic shield (not pictured)
• Operating voltage -1600 V

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The Finished SpecTrig
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SpecTrig ADC Signal

• Clean separation of pedestal and MIP peak
• Good trigger efficiency and purity

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LED Calibration System

• Used to monitor PMT health
• Optical fibers carry LED light directly
  into each PMT
• Pulser system to drive LED

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PMT Stability Over Time

• Monitor stability with the LED system
• Some runs had magnet on that is the source of
  the fluctuations!

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Trigger Logic
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Trigger Logic Module
XLM72 module from JTEC Instruments, Rochester, NY
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XLM72 Specifications

• Programmable logic
• Xilinx SpartanXL FPGA
• 72 user-configurable input/output ECL ports
• VME control interface
• 80 MHz internal clock

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Tracks with a Minimum Bias trigger
All tracks
TOF tracks
ToF Trigger tracks
ToFTriggerhigh pT logic
If we trigger on them
Illustration only
Raw, Uncorrected Spectrum
pT (GeV/c)
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And with the High-pT trigger
TOF tracks
All tracks
ToF Trigger tracks
ToFTriggerhigh pT logic
Illustration only
Raw, Uncorrected Spectrum
pT (GeV/c)
Factor of 15 more high pT tracks in TOF
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Summary

• High-pT trigger for PHOBOS in 2003 RHIC run
• 2 walls of 10 scintillators, at 45º and 90º
• Programmable Logic module makes online decisions
• 15x enhancement of high-pT TOF tracks