D. Mark Manley - US grants

This is a proposal by the Medium-Energy Nuclear Physics Group at Kent State University (KSU) to study Gamow-Teller strength, stretched-state excitations, analyzing powers, and polarization-transfer observables in (p,n) reactions supplemented by (n,p) reactions; to probe the nuclear equation-of-state (EOS) by measuring triple-differential cross sections for neutrons from high-multiplicity collisions of equal-mass nuclei as a function of mass number and bombarding energy, where the azimuthal angle of the reaction plane is determined by measuring the transverse velocities of charged fragments emitted in a collision; and to probe nucleon and nuclear structure via electron-induced reactions. KSU is committed to an experiment to determine the electric form factor of the neutron by using the KSU polarimeter to measure the polarization of the recoil neutron after quasielastic scattering of a longitudinally-polarized electron from an unpolarized neutron in deuterium. Also KSU has submitted letters of intent to CEBAF for experiments on the charge form factor of the neutron, the photoproduction and electroproduction of rho mesons, neutron knockout in the quasielastic (e,e'n) coincidence reaction, and two-nucleon knockout (e,e'2N) reactions. The group is continuing to develop improved instrumentation for the detection of neutrons. Current projects include improved neutron polarimeters and higher efficiency neutron detectors.

This grant provides a state-of-the-art MicroVAX 3500 computer system for use by the Kent State University Intermediate Energy Nuclear Physics faculty and students involved in NSF sponsored research. Essential features of the system include: fast processing time for large scale data replay, line-shape fitting, and analysis codes; large memory; high speed communications; and multi-user environment.

A program of both nuclear structure and fundamental nucleon structure investigations using intermediate energy electrons and protons will be carried out. A major portion of the structure effort will be directed towards the study of stretch state particle-hole excitations in light and medium mass nuclei. These investigations will be carried out at the MIT/Bates linac and at IUCF. Manley will collaborate with others at KSU on a very important experiment to measure the neutron charge form factor. He will also plan fundamental experiments to be carried out on resonance production at CEBAF. Development of neutron detection capability at the MIT/Bates and CEBAF electron accelerators will be carried out in support of Manley's experiments.

A user mode research program will be carried out in nuclear structure studies with electron scattering and charge exchange reactions. This work will be carried out at the Bates linac and at IUCF. Some effort will also be dedicated towards experiment development at CEBAF. Improved understanding of nuclear structure and effective interactions is sought. Data will be compared to theories including large basis shell model calculations. Simulations, detector development, data analysis, interpretation, and other related activities will be carried out at Kent State University.

9409265 Anderson Research will be carried out in nucleon and nuclear structure via electron and proton induced reactions. Polarization transfer in neutron-proton charge exchange reactions will be used to probe the medium effects on the nucleon-nucleon potential. The charge- structure of the neutron will be probed in polarization transfer studies of electron-induced neutron knockout reactions. A high- efficiency neutron polarimeter will be assembled and calibrated for these purposes. The charge exchange reactions will be carried out at the Indiana University Cyclotron Facility, while measurements of the neutron's charge structure will be carried out at the MIT/Bates lab and at CEBAF. Other related experiments will also be carried out at these laboratories. ***

9412175 Manley A program of electromagnetic nuclear physics will be carried out at the MIT/Bates, SLAC, and CEBAF laboratories. Principal focus will be on measurement of the neutron charge form factor. A measurement of the spin structure of the neutron and proton will be carried out at SLAC. In addition, a program of studying nucleon resonances will be initiated at the CEBAF lab. All these measurements will provide important constraints on the quark sub- structure of nucleons. Lastly, a series of nuclear structure measurements at other labs will be brought to completion. ***

This three-year grant will support the research of three faculty members, two post-doctoral fellows, and three graduate students to perform a variety of experiments in medium-energy nuclear physics. Much of the activity of the group is focused around measurements of the neutron polarization. These experiments include studies of the complete set of spin observables in the reaction of polarized protons with a variety of targets at the neutron polarization facility at the Indiana University Cyclotron Facility. These experiments use specialized detectors developed by Kent State to measure normal and sideways polarizations of the neutron simultaneously. Measurements with 2H 3He, and 4He targets would study the nucleon-nucleon interaction part that is mediated by a single pion or rho meson. Other experiments would study the isovector response of the nuclear continuum and the isovector giant dipole resonance. The determination of the electric form factor of the neutron would be obtained from neutron polarization measurements using polarized electron beams at the MIT-Bates Laboratory and the Thomas Jefferson National Accelerator Facility (TJNAF). Other experiments include a search for three-body forces and a search for pion-field effects. This grant would also support experiments with the Crystal Ball at the Brookhaven National Laboratory AGS and the CLAS detector at Hall B at TJNAF in order to study neutral baryon resonances and nucleon resonances, respectively.

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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.