Haymes, Robert C.2018-12-182018-12-181975Shelton, David Harold. "Azimuthal dependence of the atmospheric gamma-ray background." (1975) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/103970">https://hdl.handle.net/1911/103970</a>.https://hdl.handle.net/1911/103970On May 15, 1973 a balloon borne gamma-ray detector belonging to Rice University was launched from Palestine, Texas. From 19:4 CDT to 21:25 CDT the atmospheric gamma ray background was observed from 56 KeV to 12.4 MeV in energy. The directional detector was pointed at a constant zenith angle of 13.4° and viewed the atmospheric background at all values of azimuth angle. The experiment was carried out at altitudes of roughly 3.5 gm/cm2 residual atmosphere. The detector consisted of a central crystal of Nal(Tl) which was actively collimated by a shield of the same material. The instrument had a beam width of 15° full width half maximum. Results are consistent with an observed sinusoidal perturbation of the average background count rate between 56 KeV and 375 KeV of the form R = B[1 + (.188 ± .33)sin(Az - (12° ± 22°))] where R is the photon count rate, B is the average photon count rate, and Az is the azimuth angle at which the instrument was pointed. No similar behavior was observed at other energies.92 ppengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.ThesisRICE1596reformatted digitalThesis Sp. Sci. 1975 Shelton