A Deuterated Neutron Detector Array for the Study of Nuclear Reactions with Stable and Rare Isotope Beams.

Abstract

Deuterated liquid scintillation detectors have shown promising results as neutron spectrometers for nuclear science and other applications. Unlike normal hydrogen-based scintillators, they can provide neutron spectroscopic information without time-of-flight (ToF), allowing for close proximity to the neutron source for good angular coverage and absolute detector efficiency. Likewise DC-beams can then be used with higher intensity than a typical pulsed beam, resulting in a significant advantage. Neutron spectra can be extracted directly from the measured light-response spectra with higher energy resolution than short-path neutron ToF.

In this thesis, the development, extensive evaluation, and full characterization of an array of such detectors (The University of Michigan Deuterated Scintillator Array: UM-DSA) is discussed. Digital Pulse-Shape Discrimination (DPSD) using fast waveform digitizers (1-2 GS/s) is employed to permit not only separation of neutron and gamma events but also various recoils from nuclear reactions within the scintillator with subsequent improvements in the neutron spectra extracted. A series of (d,n), (3He,n), and (α,n) experiments performed at the University of Notre Dame Nuclear Structure Laboratory illustrate the advantage of these detectors for nuclear reaction measurements, including those using exotic beams. Differential cross section measurements and extracted spectroscopic factors over a range of nuclei using the spectrum unfolding technique show good agreement with published results using neutron ToF which demonstrates the capability of these detectors for nuclear physics measurements.