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The difference in decay rate for 7Be in Ta and 7Be in Li was measured and found to be (6.43 ± 0.76) x 10-4wk-1, making the relative difference in decay rate ∆λ/λ= (0.71 ± 0.09)%. The probability of decay by electron capture is proportional to the density of electrons at the 7Be nucleus; therefore, 7Be nuclei in different chemical environments may decay at measurably different rates. Most previous measurements for different chemical combinations of 7Be have found ∆λ/λto be on the order of 10-4to 10-3. A quasi-differential counting method was used in the current experiment wherein two samples are alternately placed in front of a high-purity germanium detector (HPGe) and the number of counts recorded. A plot of the ratio of counting rates vs. time yielded a straight-line whose slope was proportional to ∆λ.The proportionality constant was determined from the intercept of this plot.

Scattering cross sections for fast neutrons were investigated for low-lying levels of 159Tb by a Ge detector with a NaI(Tl) Compton suppression annulus in conjunction with the pulsed-beam time-of-flight technique. Thirty-eight transitions from 27 levels were observed and differential gamma-ray production cross sections for the 159Tb(n, n, nʹϒ) reaction were measured at 125° for incident neutron energies from 400 to 1000 keV. Level cross sections were also inferred. Neutron scattering cross sections for the states at 241, 348, 363.5, 535 and 580.7 keV are compared to the ENDF/B-VI, JEF-2, and JENDL-3 evaluations.