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Title: The Heavy Photon Search test detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment's technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e⁺e⁻invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW04 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allowsmore » clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e⁺e⁻ pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. In addition, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab.« less
Authors:
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  1. Sezione di Genova e Dipartimento di Fisica dell'Universita, Genova (Italy)
  2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  3. Old Dominion Univ., Norfolk, VA (United States)
  4. CNRS/IN2P3 and Univ. Paris Sud, Orsay (France)
  5. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
  6. Yerevan Physics Inst. (YerPhI), Yerevan (Armenia)
  7. Stony Brook Univ., Stony Brook, NY (United States)
  8. Univ. of California, Santa Cruz, CA (United States)
  9. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  10. Rutgers Univ., Piscataway, NJ (United States)
  11. College of William and Mary, Williamsburg, VA (United States)
  12. Univ. of New Hampshire, Durham, NH (United States)
  13. Norfolk State Univ., Norfolk, VA (United States)
  14. Rensselaer Polytechnic Inst., Troy, NY (United States)
  15. Perimeter Institute, Ontario (Canada)
  16. Univ. of Glasgow, Glasgow (United Kingdom)
Publication Date:
OSTI Identifier:
1197784
Report Number(s):
SLAC-PUB-15999; JLAB-PHY-14-1994; DOE/OR/23177-3263; arXiv:1406.6115
Journal ID: ISSN 0168-9002; PII: S0168900214014582
Grant/Contract Number:
AC02-76SF00515; SC0008061; AC05-06OR23177; DESC0008061
Type:
Published Article
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 777; Journal Issue: C; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; experiment-HEP; HEPEX; silicon; tracking; vertexing; heavy photon; dark photon; electromagnetic calorimeter