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Title: First measurement of the polarization observable E in the p (y π +)n reaction up to 2.25 GeV

First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E , for the reaction y p →π +n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. Lastly, we report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.
  1. Univ. of South Carolina, Columbia, SC (United States). et al.
Publication Date:
Report Number(s):
JLAB-PHY-15-2025; DOE/OR/23177-3325; arXiv:1503.05163
Journal ID: ISSN 0370-2693; PII: S0370269315006541
Grant/Contract Number:
SFB/TR16; AC05-060R23177; AC05-06OR23177
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 750; Journal Issue: C; Conference: Grindelwald (Switzlerland), 8-12 Oct 2010; Journal ID: ISSN 0370-2693
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Jefferson Science Associates, LLC, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Orgs:
Jefferson Lab CLAS Collaboration; The CLAS Collaboration
Country of Publication:
United States
Baryon spectroscopy; pion photoproduction; polarization observables; FROST experiment; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1213680; OSTI ID: 1241245