Howard A. Shugart

Atomic Physics 5

Reviews of the current state of research in atomic physics are presented. Experimental work on such topics as search for parity violation, spectroscopy and collision processes of fast, highly-stripped heavy ions, exotic atoms, high Rydberg states, laser spectroscopy, photoelectron spectroscopy, and others is described. Twenty-seven papers were prepared for the data base. (GHT)

Evidence against correlations between nuclear decay rates and Earth-Sun distance

We have reexamined our previously published data to search for evidence of correlations between the rates for the alpha, beta-minus, beta-plus, and electron capture decays of 22Na, 44Ti, 108Agm, 121Snm, 133Ba, and 241Am and the Earth?Sun distance. We find no evidence for such correlations and set limits on the possible amplitudes of such correlations substantially smaller than those observed in previous experiments.

Half-lives of 101 Rh g and 108 Ag m

Using long-term gamma-ray spectroscopy with high resolution germanium detectors and a ratio method, the half-lives of 101Rhg and 108Agm have been determined to be 4.07 ± 0.05 years and 448 ± 27 years, respectively. These results are compared with previously reported values.

Measurement of cross sections for {alpha}-induced reactions on {sup 197}Au and thick-target yields for the ({alpha},{gamma}) process on {sup 64}Zn and {sup 63}Cu

We have measured the cross sections for the {sup 197}Au({alpha},{gamma}){sup 201}Tl and {sup 197}Au({alpha},2n){sup 199}Tl reactions in the 17.9- to 23.9-MeV energy range, and {sup 197}Au({alpha},n){sup 200}Tl reaction in the 13.4- to 23.9-MeV energy range using an activation technique. Thick-target yields for the {sup 64}Zn({alpha},{gamma}){sup 68}Ge (7- to 14-MeV) and {sup 63}Cu({alpha},{gamma}){sup 67}Ga (7-MeV) reactions were measured. For all measurements, natural elements were bombarded with He{sup +} beams from the 88 In. Cyclotron at the Lawrence Berkeley National Laboratory (LBNL). Irradiated samples were counted using a {gamma}-spectrometry system at LBNLs Low Background Facility. Measured {sup 197}Au({alpha},{gamma}){sup 201}Tl cross sections were compared with the NON-SMOKER theoretical values. The thick-target yields for the {sup 64}Zn({alpha},{gamma}){sup 68}Ge and {sup 63}Cu({alpha},{gamma}){sup 67}Ga reactions are also compared with the theoretical yield, calculated numerically using the energy dependent NON-SMOKER cross section data. In both cases, measured values are found to follow a trend of overlapping the predicted value near the alpha nucleus barrier height and fall below with a slowly widening difference between them in the sub-barrier energy points.

Measurement of Cross Sections for the 63Cu(α,γ)67Ga Reaction from 5.9–8.7 Mev

We have measured cross sections for the 63Cu(alpha,gamma)67Ga reaction in the 5.9-8.7 MeV energy range using an activation technique. Natural Cu foils were bombarded with alpha beams from the 88 Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Activated foils were counted using gamma spectrometry system at LBNLs Low Background Facility. The 63Cu(alpha,gamma)67Ga cross-sections were determined and compared with the latest NON-SMOKER theoretical values. Experimental cross sections were found to be in agreement with theoretical values.

DIRECT MEASUREMENTS OF SPINS OF RADIOACTIVE NUCLEI

This article contains a brief review of the principal optical and radio-frequency spectroscopic methods for determining spins of ground and long-lived-nuclear states. Some of the advantages and disadvantages of these techniques for radioactive isotope investigations are explained. A survey of the required sample sizes has been made to indicate the relative sensitivities of the various methods.