Simulation of Cosmic Ray Interactions with Materials
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
A representative group of target materials were simulated and irradiated within the physics framework of two Monte Carlo particle transport codes to determine the general effects of energetic space radiation on common solid materials. The target materials consisted of low-density polyethylene, polyethylene-based composite filled with glass particles, and solid slabs of beryllium, aluminum, and tungsten metals. The simulated composites were irradiated by solar protons within the MCNPX software to determine the secondary gamma and neutron radiation generated in and transmitted through potential lightweight shielding materials. The pure polyethylene and elemental targets were bombarded by protons and 12C nuclei within FLUKA to determine the extent of charged meson production, energy deposition, and generation of stable or unstable nuclear fragments within the target. The polyethylene-based composites of this work enable a maximum of 8% weight reductions, so have potential value as lightweight shielding materials, but any incorporated elements with Z significantly larger than one cause detrimental neutron and gamma radiation to be produced by the incident proton events. Charged meson production peaks at a density of about 10-4 per incident primary at the center of the particle beam, and a maximum of roughly 10-4 GeV/cm3 of energy is deposited in all targets per primary proton. The polyethyelene targets appear to backscatter significant particle radiation, and also yield only 6 unstable fragments within, compared to 11 stable fragments. Unstable fragments decay by electron capture, which does not result in a significant dose from the emitted neutrinos. The effects of other radiation-matter interactions such as scattering events and Bremsstrahlung are also discussed.
Advisory committee members: Alexis Clare, Doreen Edwards, William Carlson.Dissertation completed in partial fulfillment of the requirements for the degree of Doctorate of Philosophy in Glass Science at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University