Thesis (M.S.)--University of Michigan, 1958.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1989. / Cover title. Includes bibliographical references (p. 245-251).

The efficiency of NaI(T1) scintillation counters for the detection of gamma rays is discussed and experimentally determined. Experimental efficiencies, based upon the number of counts above a bias equal to one-half the gamma ray energy and a solid angle defined to the crystal effective centre, for a three-inch-diameter by three-inch long (3 x 3) crystal are given for gamma ray energies of 0.51, 1.275 and 6.14 MeV. Gamma ray spectra at 1.275 and 6.14 MeV are extrapolated to zero energy in order to compare theoretical efficiencies, based upon the integrated primary absorption, with the experimental results. These results show that, with experience, one can expect accuracy to better than 5% at these energies. Tables are given of the theoretical efficiency for 3x3, 2¾ x 4½ and 5x4 crystals for several gamma ray energies and source-to-counter distances of from 0.1 cm to 1 m. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 53-54). Also available on the World Wide Web.

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The efficiency of a 4" x 5" Nal(Tl) scintillation counter for detecting gamma-rays has been measured by a number of experimental techniques, and the results compared with the efficiencies predicted from total absorption cross sections. The experimental techniques involve coincidence measurements of the cascade gamma-rays from a Co-60 source (1.173 MeV and 1.333 MeV), and from the reaction B¹¹(pγγ)C¹² (4.43 MeV and 11.68 MeV). The Co-60 measurements also lead to knowledge of the absolute strength of the sources. For both cascades it was necessary to know the angular correlations between the radiations; for the reaction B¹¹ (pγγ)C¹² a separate investigation of this correlation was made using a 180 KeV accelerator. Computer programs were written to analyze the experimental data, and to calculate the theoretical efficiency estimates, taking into account the collimator and shield geometry. The results of this work define the efficiency of the scintillation counters to better than 5% for a number of gamma-ray energies and a specific geometry. On the other hand, the efficiencies based on the total number of counts in the observed spectra were 20 percent to 40 percent higher than the theoretical efficiencies. The departures from theory depend on the gamma-ray energy and the geometry of the shielding and collimators in such a way that it is not possible to provide a simple basis for relating theoretical efficiencies to the experimental data. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 112-120).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 143-157).