Precise test of internal-conversion theory: α measurements for transitions in nine nuclei spanning 45 ≤ Z ≤ 78.

We have been testing the theory used to calculate internal-conversion coefficients (ICCs) by making a series of measurements of α values with precision better than ±2%. So far we have measured E3 transitions in three nuclei, Rh, Cd and Cs; and M4 transitions in six nuclei, Sn, Te, Te, Ba, Ir and Pt. Together, these span a wide range of A and Z values.

Precise test of internal-conversion theory: transitions measured in five nuclei spanning 50≤Z≤78.

In a research program aimed at testing calculated internal-conversion coefficients (ICCs), we have made precise measurements of αK values for transitions in five nuclei, (197)Pt, (193)Ir, (137)Ba, (134)Cs and (119)Sn, which span a wide range of A and Z values. In all cases, the results strongly favor calculations in which the final-state electron wave function has been computed using a potential that includes the atomic vacancy created by the internal-conversion process.

Multipole and relativistic effects in radiative recombination process in hot plasmas.

On the basis of the fully relativistic Dirac-Fock treatment of photoionization and radiative recombination processes with regard to all multipoles of the radiative field, we have assessed the influence of nondipole effects on the radiative recombination rate coefficients. A formula for the rate coefficient has been derived using the relativistic Maxwell-Boltzmann distribution of continuum electrons instead of the commonly used nonrelativistic distribution. This decreases the recombination rate coefficient considerably in hot thermal plasmas.

Precise tests of internal-conversion theory.

Using the 165.9-keV M1 transition in (139)La as a calibrant, we have determined the K-shell internal conversion coefficients (ICCs) for the 127.5-keV E3 transition in (134)Cs and the 661.