Project 1: 

Electronic factors for electric monopole transitions 

in atomic nuclei

Contact: Tibor Kibedi, Nuclear Physics, RSPhysSE, ANU, x52093,

Tibor.Kibedi@anu.edu.au

Single-photon nuclear transitions between states with zero spin and the

same parity (0+ or 0-) are forbidden by the law of conservation of

angular momentum. These types of transitions are the so called electric

monopole (E0) transitions.  The cause of the E0 transitions is the

Coulomb interaction between the nucleons and the electrons of the atomic

shell or the Dirac background. The most probable processes are the

emission of internal-conversion electrons or electron-positron pairs.

The E0 transition probability can be expressed as a product of the

monopole strengths and an electronic factor. While the monopole

strengths depend on nuclear properties, the electronic factor depends

only on the atomic properties.

The project is aiming to calculate the electronic factors for both

processes involving internal-conversion electrons and electron-positron

pairs. The theoretical background of the calculations, based on Dirac`s

relativistic electron theory is relatively well understood. The project

would involve the development of a computer code (in C or FORTRAN) and

to carry out calculations for a wide range of elements and transition

energies.