E08-008: Exclusive study of deuteron electrodisintegration near threshold

Abstract

The study of threshold electrodisintegration of and elastic scattering on the only stable two nucleon system, the deuteron, can reveal specific aspects of the N-N interaction. The simplicity of electrodisintegration along with the simplicity of the deuteron makes this study most appropriate for revealing these interactions. By using an incident beam of polarized electrons and by measuring the polarization of the recoiling proton, the ratio of the electric (GE) and magnetic (GM) form factors for \(d\left( {\vec e,e'\vec p} \right)\) (and \(p\left( {\vec e,e'\vec p} \right)\)) reactions may be extracted. This experiment was conducted in Hall A at Jefferson Lab in Newport News, Virginia using a beam of polarized electrons provided by the CEBAF Accelerator incident on a liquid deuterium (and hydrogen) target. The scattered electron and the recoiling (polarized) proton were detected using the High Resolution Spectrometers of Hall A. To determine the polarization of the recoil proton, an analyzing material was placed perpendicular to the protons trajectory through the spectrometer, in front of a set of straw chambers. Due to the spin-orbit interactions involved in the scattering of the proton from the analyzer material, asymmetries seen in the distribution of events detected by these straw chambers reveal the polarization of the recoil proton. By tracking the spin procession of the polarized protons from the straw chambers back to the target, the transferred and induced polarization of the proton may be determined. The (double-spin) asymmetries observed in the straw chambers will first be studied for the well-known elastic \(p\left( {\vec e,e'\vec p} \right)\) process and compared to the asymmetries for \(d\left( {\vec e,e'\vec p} \right)n\left( {x_B = 1} \right)\). The analysis will then be repeated to determine how these asymmetries change with increasing xB (to the kinematic limit for deuteron electrodisintegration).