V. A. Narasimha Murty

External bremsstrahlung spectra excited by 32P and 35S beta rays in different elements

The spectra shapes of the external bremsstrahlung produced by 32P and 35S beta rays when they are completely absorbed in different elements such as carbon, aluminium, copper, silver, tin and lead are experimentally measured with a multichannel NaI(Tl) scintillation spectrometer along with a standard geometrical arrangement. After making all the necessary corrections, the final distributions are compared with the modified Bethe-Heitler theory. The experimental results are in excess over theory for high Z elements and this experimental excess over theory is found to increase with increasing nuclear mass and photon energy.

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.

Inner Bremsstrahlung Following the 169Er Beta Decay

The spectral distribution of the Internal Bremsstrahlung from the forbidden beta decay of 169 Er was measured from 50 to 290 keV with a NaI(Tl) scintillation spectrometer with a standard geometrical arrangement. The experimental results agree fairly well in the middle photon energy region i.e., from 70 to 210 keV with the KUB theory and at high as well as at low photon energies, the Nilsson theory is found to explain the observed excess over KUB theory.

Internal bremsstrahlung spectral shapes of 45Ca and 3aS

The internal bremsstrahlung spectra emitted in the beta decays of 45Ca and 35S were measured using a multichannel NaI(Tl) scintillation spectrometer with a standard geometrical arrangement. After making all the necessary corrections, the experimental results were compared with theory.