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Title: A scaler-based data acquisition system for measuring parity-violating asymmetry in deep inelastic scattering

An experiment that measured the parity violating asymmetries in deep inelastic scattering was completed at the Thomas Jefferson National Accelerator Facility in experimental Hall A. From these asymmetries, a combination of the quark weak axial charge could be extracted with a factor of five improvement in precision over world data. To achieve this, asymmetries at the 10^-4 level needed to be measured at event rates up to 500 kHz and the high pion background typical to deep inelastic scattering experiments needed to be rejected efficiently. A specialized data acquisition (DAQ) system with intrinsic particle identification (PID) was successfully developed and used: The pion contamination in the electron samples was controlled at the order of 2 × 10^-4 or below with an electron efficiency of higher than 91% throughout the production period of the experiment, the systematic uncertainty in the measured asymmetry due to DAQ deadtime was below 0.2%, and the statistical quality of the asymmetry measurement agreed with the Gaussian distribution to over five orders of magnitudes. The DAQ system is presented here with an emphasis on its design scheme, the achieved PID performance, deadtime effect and the capability of measuring small asymmetries.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [4] ;  [4]
  1. Virginia U.
  2. MIT
  3. Virginu U.
  4. JLAB
  5. Yerevan Institute
Publication Date:
OSTI Identifier:
1084335
Report Number(s):
JLAB-PHY-13-1697; DOE/OR/23177-2580
DOE Contract Number:
AC05-06OR23177
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments & Methods in Physics Research, Section A; Journal Volume: 724; Related Information: Experiment: JLAB-E-08-011
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY Jefferson Lab; Hall A; PVDIS; DAQ