No description available.

Note:

It is important that accurate estimates of crew exposure to radiation are obtained for future long - term space missions. To predict the radiation environment, a few space radiation transport codes exist, all of which use basic nuclear cross section information for transport of radiation through materials. Little theoretical and experimental work has been conducted on reactions induced by the electromagnetic (EM) force, especially with regard to di?erential cross sections. Therefore, radiation transport codes have typically neglected to incorporate EM nuclear collision cross sections. EM cross sections for single nucleon removal have been included in some radiation codes, but better values can be obtained by using an energy dependent branching ratio. Most previous theoretical and experimental work has been devoted to total cross sections. Therefore, the energy dependent branching ratios presented can be extensively compared to past theory and experiment. Such comparisons indicate that using energy dependent branching ratios yield better estimates of total cross sections. Differential cross sections for electromagnetic dissociation in nuclear collisions are calculated for the first time. In order to be useful for three - dimensional transport codes, these cross sections have been calculated in both the projectile and lab frames. The formulas for these cross sections are such that they can be immediately used in space radiation transport codes. Only a limited amount of data exists, but the comparison between theory and experiment is good.

No description available.

No description available.

No description available.

A Dissertation Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the degree of Master of Science. Johannesburg March 1975

Thesis (M.S.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 44-48). Online version available on the World Wide Web.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 123-130). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR45983

The present study combines modern jet reconstruction algorithms and particle identification (PID) techniques in order to study the enhancement of proton/pion ratio at mid transverse momentum ([mathematical symbols] 1.5 - 4.0 GeV/c) observed in central Au + Au collisions at [mathematical symbols] = 200 GeV. The ratio enhancement is thought to be caused by recombination processes and/or parton fragmentation modification of jets in relativistic heavy ion collisions. The fragmentation modification hypothesis is tested in this analysis by reconstructing and selecting energetic jets presumably biased to fragment outside of the medium created in Au + Au collisions and comparing their particle composition to the recoiling (medium-traversing) jets. The bias assumption is confirmed by comparing jets in central collisions, where the effect of proton/pion enhancement is present, with peripheral ones where no medium effects are expected. The selected jets are reconstructed by using the anti-k[subscript T] algorithm from the modern FASTJET package. The PID in the p[subscript T] region of interest is possible by combining measurements of the particles' energy deposition and velocity from the Time Projection Chamber and the recently installed (2009-2010) Time of Flight detectors at STAR. The acceptance of these detectors, [eta] < 1.0 and full azimuth, make them extraordinary tools for correlation studies. These features allow for the measurement of relative azimuth ([phi] [subscript jet] - [phi] [subscript pion,proton]) distributions by using the selected jet axis in order to disentangle the uncorrelated background present in the high multiplicity heavy ion collisions. The proton/pion ratios in two different centrality bins and p[subscript T] = 1.2 - 3.0 GeV/c are presented for biased (vacuum fragmenting) jets and their recoiling counterparts / text