(proton, Gamma) Resonance Strengths in the S-D Shell.

This thesis decribes a program of measurements of (p,(gamma)) resonance strengths in nuclei spanning the s-d shell. The work was prompted by the existence of long -standing serious discrepancies between values reported in the literature. Since some of the discrepancies in the literature involve relative measurements between different nuclei with chemical compound targets containing pairs of nuclei of interest, a system was developed for conducting similar measurements with the added facility for target analysis by Rutherford backscattering. Resonances in the energy range 0.5 - 2.0 MeV in the (p,(gamma)) reactions on ('23)Na, ('26)Mg, ('27)Al, ('30)Si, ('31)P, ('34)S, ('35)Cl, ('37)Cl, ('39)K and ('40)Ca were selected and a series of relative strength measurements was conducted by the thin target technique. In addition, absolute strengths were measured for the E(,p) = 632 and 992 keV resonances in ('27)Al(p,(gamma))('28)Si and the E(,p) = 620 keV resonance in ('30)Si(p,(gamma))('31)P by both the semi-thick and thin target techniques. The target thickness, needed for the latter technique, was determined from Rutherford backscattering. Gamma-ray yield was measured with either a NaI(Tl) or a Ge(Li) detector. The efficiency of the Ge(Li) for detecting radiation from the appropriate resonances was related experimentally to that of the NaI(Tl) and the absolute efficiency of the NaI(Tl) detector was measured experimentally for (gamma)-ray energies from 0.7 to 10.8 MeV. These experimental efficiencies were compared with the results of a calculation based on published (gamma)-ray attenuation coefficients and the measured detector geometry. Absolute strengths were deduced for all of the resonances under investigation by normalizing to the absolute measurements on the ('27)Al(p,(gamma))('28)Si resonances. These strengths, together with published relative measurements between isotopes of the appropriate elements, were used to produce a table of the strengths of selected resonances in 16 s-d shell nuclei. These can now serve as reliable standards for the normalization of all relative measurements on these nuclides. Observations made during this investigation explain the discrepancies in the literature associated with the relative measurements between nuclei, and comparison with the present results made possible an evaluation of the self-consistency of the other techniques used for the absolute (p,(gamma)) strength measurements reported in the literature.