Abstract
The primary goal of this work was to initiate the use of BaF2 arrays for detection of high energy photon emission from nuclear reactions. A beam from the Texas A&M University K-500 Superconducting Cyclotron, and a variety of detectors for hard photons, neutrons, charged particles, and fission fragments were used to study the reaction 160 + 238 U at a projectile energy of 50 MeV/u. Inverse slope values of the photon spectra were extracted for inclusive data and data of higher multiplicities at angles of 90' and 135'. Two 19-element barium fluoride (BaF2) arrays, an array of liquid scintillation fast neutron detectors and plastic scintillation charged-particle veto detectors, together with a silicon-cesium iodide (Si-CsI) telescope and a silicon fission fragment detector allowed the possibility of impact parameter selection through neutron and charged particle multiplicities. The associated multiplicity distributions of photon and fast neutron triggers were compared at 30' and 90' angles. The hardware and electronics layout of the experimental set up are described. Fundamental properties of the various detectors are explained and typical spectra are shown as examples for each detector system. The data acquisition and data compression is described in Chap. III, and followed by the calibration methods used for the BaF2 and Nal(TI) detectors. A description of a dynamic pedestal (zero level) correction mechanism, is followed by a description of several cosmic ray background reduction methods, including the highly effective centrality condition. A summary is given to compare the various methods. After a description of the other types of detectors used in the experiment, an example is given how the final photon spectra were produced. In Chap. IV the measured results are presented and compared to those in the literature. The last chapter provides the conclusions of this work.
Jabs, Harry (1997). High energy photon emission. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -J32.