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# Measurement of interference structure functions in quasielastic proton knockout from carbon-12

Abstract (Summary)
A description of the measurement of quasielastic interference structure functions for the nucleus $\sp{12}$C is presented. Longitudinally polarized electrons with an average polarization of 39 $\pm$ 4% and an initial energy of 660.0 MeV were scattered through 33.4 degrees from a graphite target. The scattered electrons were detected with a large magnetic spectrometer in coincidence with the knockout protons which were detected simultaneously by either of two small magnetic spectrometers placed out of the electron scattering plane. The forward-backward asymmetry A$\sb{91}$ and the beam helicity induced asymmetry A$\sbsp{01}{\prime}$ were measured, and the longitudinal-transverse interference structure functions $f\sb{01}$ and $f\sbsp{01}{\prime}$ were extracted for the $\sp{12}$C p-shell knockout reaction at a missing momentum of 115.0 MeV/c and a Q$\sp2$ of 0.13 (GeV/c)$\sp2$. This experiment was the first attempt in a series of $(\vec e,e\sp{\prime}p)$ experiments using multiple out-of-plane spectrometers to detect hadrons in isolating several interference structure functions simultaneously through precise asymmetry and cross section measurements. The equipment for these measurements was installed from 1995 to 1996 at the Bates Linear Accelerator Center in Middleton, Massachusetts, and this experiment was carried out in September of 1996.
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