Dynamics of the quasielastic {sup 16}O(e,e{sup '}p) reaction at Q{sup 2}{approx_equal}0.8 (GeV/c){sup 2}
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
- Kent State University, Kent, Ohio 44242 (United States)
- California State University Los Angeles, Los Angeles, California 90032 (United States)
- Temple University, Philadelphia, Pennsylvania 19122 (United States); and others
The physics program in Hall A at Jefferson Lab commenced in the summer of 1997 with a detailed investigation of the {sup 16}O(e,e{sup '}p) reaction in quasielastic, constant (q,{omega}) kinematics at Q{sup 2}{approx_equal}0.8 (GeV/c){sup 2}, q{approx_equal}1 GeV/c, and {omega}{approx_equal}445 MeV. Use of a self-calibrating, self-normalizing, thin-film waterfall target enabled a systematically rigorous measurement. Five-fold differential cross-section data for the removal of protons from the 1p-shell have been obtained for 0<p{sub miss}<350 MeV/c. Six-fold differential cross-section data for 0<E{sub miss}<120 MeV were obtained for 0<p{sub miss}<340 MeV/c. These results have been used to extract the A{sub LT} asymmetry and the R{sub L}, R{sub T}, R{sub LT}, and R{sub L+TT} effective response functions over a large range of E{sub miss} and p{sub miss}. Detailed comparisons of the 1p-shell data with Relativistic Distorted-Wave Impulse Approximation (RDWIA), Relativistic Optical-Model Eikonal Approximation (ROMEA), and Relativistic Multiple-Scattering Glauber Approximation (RMSGA) calculations indicate that two-body currents stemming from meson-exchange currents (MEC) and isobar currents (IC) are not needed to explain the data at this Q{sup 2}. Further, dynamical relativistic effects are strongly indicated by the observed structure in A{sub LT} at p{sub miss}{approx_equal}300 MeV/c. For 25<E{sub miss}<50 MeV and p{sub miss}{approx_equal}50 MeV/c, proton knockout from the 1s{sub 1/2}-state dominates, and ROMEA calculations do an excellent job of explaining the data. However, as p{sub miss} increases, the single-particle behavior of the reaction is increasingly hidden by more complicated processes, and for 280<p{sub miss}<340 MeV/c, ROMEA calculations together with two-body currents stemming from MEC and IC account for the shape and transverse nature of the data, but only about half the magnitude of the measured cross section. For 50<E{sub miss}<120 MeV and 145<p{sub miss}<340 MeV/c (e,e{sup '}pN) calculations which include the contributions of central and tensor correlations (two-nucleon correlations) together with MEC and IC (two-nucleon currents) account for only about half of the measured cross section. The kinematic consistency of the 1p-shell normalization factors extracted from these data with respect to all available {sup 16}O(e,e{sup '}p) data is also examined in detail. Finally, the Q{sup 2}-dependence of the normalization factors is discussed.
- OSTI ID:
- 20695527
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 70, Issue 3; Other Information: DOI: 10.1103/PhysRevC.70.034606; (c) 2004 American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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ASYMMETRY
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CEBAF ACCELERATOR
COMPARATIVE EVALUATIONS
CORRELATIONS
DIFFERENTIAL CROSS SECTIONS
DISTORTED WAVE THEORY
EIKONAL APPROXIMATION
ELECTRON REACTIONS
ELECTRONS
GEV RANGE
IMPULSE APPROXIMATION
KNOCK-OUT REACTIONS
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