Nucleon Structure and Nuclear Force Studies at Intermediate Energies

Kent State University, Kent OH

Investigators

Abstract

0072240 Anderson This project is centered around the study of the structure of the nucleon, primarily by the measurement of the electric form factor of the neutron. This group will play a pivotal role in an approved experiment at the Thomas Jefferson National Accelerator Facility (JLab) designed to measure the electric form factor of the neutron as a function of momentum transfer. Because the neutron is overall neutral, the electric form factor is very sensitive to the details of the constituents and their motions. This measurement provides one of the best experimental tests available for any model of the nucleon and is generally considered to be one of the most important measurements to be performed in intermediate-energy nuclear physics. The experiment will be performed by the scattering of longitudinally polarized electrons from a liquid deuterium target and detecting the knock-out neutron in coincidence with the scattered electron. The Kent State group has the responsibility for providing the neutron detector array for this experiment. The array consists of thirty-six separate neutron detectors arranged so as to both detect the neutron and determine its spin. The transfer of the spin from the electron beam to the neutron is directly related to the charge form factor of the neutron. The detector array is called a neutron polarimeter. The Kent State group has used a similar polarimeter in experiments at other accelerator facilities and will have the responsibility for the installation, operation, and maintenance of this detector array for the experiment. This project will be part of the Ph.D. dissertation research of two Kent State graduate students. Support from this award will also enable this group to finish the analysis of experiments performed at the Indiana University Cyclotron Facility to study the spin dependence of the nuclear force, to search for three-body contributions to the nuclear force, and also to analyze measurements of baryon resonances using the Crystal Ball Spectrometer at the Brookhaven AGS accelerator. These measurements were performed with earlier support from the National Science Foundation and are part of the dissertation projects of three Kent State graduate students.