M. Van Den Bergh

Quadrupole moments of isomeric states in 212Ra, 213Ra and 214Ra

Abstract The static-quadrupole-interaction frequency of the 8 + isomers in 212 Ra and 214 Ra and of the case17 2 − isomer in 213 Ra has been measured with the level-mixing-spectroscopy (LEMS) method. Measurements have been performed both at low and high target temperatures (10 and 420 K) and on polycrystalline as well as single-crystalline targets. Shell-model calculations have been performed to demonstrate the influence of configuration mixing on the B (E2, 8 + → 6 + ) values and the quadrupole moments of N = 126 isotones.

Quantum interferences in nuclear decay

At nuclear level mixing condition, interferences between different transition amplitudes can occur. In a narrow frequency range, absorption can be hindered while not the emission. This feature offers interesting applications on the design of a graser and of a resonant scatterer for γ-rays.

Measurements of quadrupole interaction frequencies of long-lived isomers with the level mixing spectroscopy (LEMS) method

The level mixing spectroscopy (LEMS) method has proven to be a very useful method to determine the quadrupole interaction frequency of an isomer in a solid host. Especially in the “difficult” cases, e.g. when the isomeric lifetime is very long or its spin is very high, the method yields valuable information which is not accessible with other methods (such as TDPAD). Since the development of the method some years ago, many experiments have been performed on high spin isomers in the lead region. The static quadrupole moment of isomers with lifetimes ranging from 20 ns up to 13 ms andspins up to 65/2ħ have been determined in neutron deficient isotopes of Bi, At, Fr andRa.