# Fields of Research

Two photon decay in atoms and ions |

Author: Filippo Fratini | |

The angular and polarization properties of the two emitted photons in order to determine the probability of emission with a certain opening angle (angle between the photons' directions) and a certain relative polarization [1,2]. Two photons resulting from a single decay may show entanglement properties. In collaboration with colleagues from Freiburg University, the polarization analysis was applied to explore the quantum correlations that the two photons possess [3]. More recently, we proposed the study of parity violation in atoms and ions using two-photon transitions. Again, in this analysis, the tool of choice has been the polarization properties of the photons [4]. References[1] A. Surzhykov, A. Volotka, F. Fratini, J. P. Santos, P. Indelicato, G. Plunien, Th. Stöhlker and S. Fritzsche, Phys. Rev. A 81 042510 (2010). [2] F. Fratini and A. Surzhykov, Hyperf. Int. DOI: 10.1007/s10751-011-0303-y (2011). [3] F. Fratini, M.C. Tichy, Th. Jahrsetz, A. Buchleitner, S. Fritzsche and Andrey Surzhykov, Phys. Rev. A 83, 032506 (2011). [4] F. Fratini, S. Trotsenko, S. Tashenov, Th. Stöhlker and Andrey Surzhykov, Phys. Rev. A 83, 052505 (2011). |

Vacancy production via ion-atom collisions |

Author: Sean McConnell |

The creation of vacancies in the electronic shells of heavy atoms and the effects resulting therefrom have been and continue to be of utmost importance in experimental physics involving collision events between atoms and ions. With improvements in experimental techniques, multipole mixing and relativistic effects, not normally resolveable using angle integrated cross sections may be observed should higher bound electrons decay into these newly vacant states. Vacancy production in electronic shells can be achieved using a variety of methods, principally however, via nuclear decay or via ion-atom collision. Our objective is to provide the necessary theoretical calculations to enable accurate interpretation of experimental observations. To date, we have published on the alignment of the vacancy produced in the LIII state of Polonium following alpha decay using first order perturbation theory [1]. We are currently undertaking a replication of this work using exact solutions to a two-centre Dirac equation, cf. [2] References[1] McConnell, S. R.,Artemyev, A. N. & Surzhykov, A., J. Phys. B: At., Mol. Opt. Phys., 2011, 44, 145204 [2] Rumrich, K., Greiner, W., Soff, G., Wietschorke, K. H. & Schluter, P., J. Phys. B: At., Mol. Opt. Phys., 1989, 22, 165-187 |