V. Lakshminarayana

The radioactive decay of Ag111

Abstract The radioactive decay of Ag111 is studied employing a 4π sum peak coincidence spectrometer. It is observed that the beta decay of Ag111 leads to an excited state at 610 keV, in addition to the previously reported levels at 340 and 247 keV. The beta branch feeding the 610 keV level is estimated to be 0.5±0.05%. The relative intensities of gamma transitions involved are measured. The decay scheme of Ag111 incorporating the results of the present investigations is presented.

The radioactive decay of cadmium-115m

Abstract The radioactive decay of cadmium-115m is studied with an electronic summing scintillation spectrometer. New gamma-components with energies 165±5, 270±5, 300±5, 650±10, 910±10, 1125±10, 1420±15 and 1560±15 keV are observed. These have been fitted into a comprehensive level scheme by introducing three new levels at 650 keV, 1125 keV and 1560 keV. Possible spin and parity assignments are made based on energy and intensity considerations.

Elastic scattering of 145 keV gamma rays

The differential elastic scattering cross sections of 145 keV gamma rays in Pb, Ta, Sn and Zr have been measured at angles ranging from 45 degrees and 115 degrees using a high-resolution lithium-drifted germanium detector. The experimental cross sections are compared with the available theoretical data. The present experimental results are in agreement with the theoretical results of Johnston et al. (1976) calculated using S-matrix theory of quantum electrodynamics. For medium- and low-Z elements the present experimental values are in agreement with the theoretical values compiled by Hubbell et al. (1975). At 45 degrees the experimental results for all elements are in agreement with the values calculated using Moileres expression. The experimental results are in good agreement with the theoretical values of Smend et al. (1973) at all angles in high- and low-Z elements.

ELASTIC SCATTERING OF 1.12 Mev GAMMA RAYS

Total elastic scattering cross-sections of 1.12 MeV gamma rays in elements Pb, Pt, Ta and Sn are determined with a collimator geometry and a 2 Cur Sc46 source for scattering angles 20°, 30°, 45°, 60° and 90°. The present experimental results are compared with the theoretical computations employing the form-factor formalism of Bethe and the exact formalism of Brown et al. The experimental values of elastic scattering cross-sections in Sn show satisfactory agreement with the form-factor values for scattering angles 20°, 30° and 45°, while deviations occur for scattering angles 60° and 90°. The present values of elastic scattering cross-sections for Pb, Pt and Ta at scattering angles 20°, 30°, 45° and 90° are in conformity with the exact calculations.

The lifetime of the 75 keV level of Dy161

Abstract The lifetime of the 75 keV level of Dy 161 was measured with a time-to-amplitude converter and found to have a half-life of 2.95±0.15 ns. A retardation factor of 115 for the 49 keV M1 transition, and a retardation factor of 10 4 for the 75 keV E1 transition are observed. In a comparison of the experimental transition probabilities with Nilssons estimates, the retardation factors are found to be 6.8 and 7.6 for the 49 and 75 keV transitions, respectively.