New measurements of the EMC effect in very light nuclei
A high precision measurement of the proton elastic form factor ratio $$\mu G_{\mathrm{E}}/G_{\mathrm{M}}$$ in the range of $Q^2$=0.3 - 0.7~GeV/$c^2$ has been made using recoil polarimetry method in Jefferson Lab Hall A. In this low $Q^2$$ range, previous data (Bates, LEDEX) along with many fits and calculations indicate substantial deviations of the ratio from unity, and continue to suggest that structures might be present in the individual form factors, and in the ratio. In E08-007, with 80\% polarized electron beam for 24 days, we are able to achieve $$\sim 0.5\%$ statistical uncertainty. This high precision result will confirm or reute all existing suggestions of few percent structures in the form factors ratio. Beyond the intrinsic interest in nucleon structure, the improved form factor measurements also have implications for DVCS, determinations of the proton Zemach radius and for parity violation experiments.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 979053
- Report Number(s):
- JLAB-PHY-09-956; DOE/OR/23177-0688; PRLTAO; TRN: US1003080
- Journal Information:
- Physical Review Letters, Vol. 103, Issue 20; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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