D(e.e'p)Coincidence Measurement at Threshold Region

点击翻译按钮获取中文摘要

Coincidence measurements will be made for the d (e.e'p) reaction at low relative n-p energy and high four-momentum transfer. In the experiment, a liquid-deuterium target is irradiated with a high-energy continuous electron beam from the pulse-stretcher under construction at MIT-Bates laboratory. Cross sections will be measured as a function of proton angle in order to determine the non-interference o_Lo_T and interference o_<LT> cross sections.Study of the deuteron, the most simple nucleus which consists of one proton and one neutron. occupies a special position to understand nuclear structure and reactions. Recently, degrees of freedom beyond nucleons particularly draw the attension of physisits. The contribution of meson-exchange currents was clearly observed at the break-up threshold of the deuteron in single-arm electron scattering about 10 years ago. Coincidence experiments, however, have never been made in the region. Several calculations shows the sigma_<LT> interference cross section is sensitive to relativistic effects there.A pulse stretcher has been constructed in MIT-Bates laboratory. Our proposal has been accepted as one of experiments using continuous beams from the stretcher ring. The construction was completed at the end of the last year, and it is under commissioning now.Our experiment is made in the region where the cross section is small. It needs carefull preparation of equipments. we chose, therefore, an experiment at the quasi-elastic scattering region as the first experiment to contribute, that has been proposed by several gropes in USA.This experiment is capable with a pulsed beam available now. It uses a polarized electron beam, and an extra term can be obtained to extract a spetial term that depends on the spin of the electron. In the experiment, protons are detected out of the scatterig plane using four spectrometers in addition to a coincided electron. The experiment will be made in the spring of 1996.