Title

An Improved Knockout-Ablation-Coalescence Model for Prediction of Secondary Neutron and Light-ion Production in Cosmic Ray Interactions

Date of Award

8-2008

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Nuclear Engineering

Major Professor

Lawrence W. Townsend

Committee Members

Laurence F. Miller, Ronald E. Pevey, Thomas Handler

Abstract

An analytical knockout-ablation-coalescence model capable of making quantitative predictions of the neutron and light-ion spectra from high-energy nucleon-nucleus and nucleus-nucleus collisions is being developed for use in space radiation protection studies. The FORTRAN computer code that implements this model is called UBERNSPEC. The knockout or abrasion stage of the model is based on Glauber multiple scattering theory. The ablation part of the model uses the classical evaporation model of Weisskopf-Ewing. In earlier work, the knockout-ablation model was extended to incorporate important coalescence effects into the formalism. Recently, the coalescence model was reformulated in UBERNSPEC and alpha coalescence incorporated. In addition, the ability to predict light ion spectra with the coalescence model was added. Earlier versions of UBERNSPEC were limited to nuclei with mass numbers less than 68. In this work, the UBERNSPEC code has been extended to include heavy charged particles with mass numbers as large as 238. Representative predictions from the code are compared with published measurements of neutron energy and angular production spectra and light ion energy spectra for a variety of collision pairs.

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