Studies of Antineutrinos at Nuclear Reactors and Atomic Final State Effects in Tests of T-Violation

Part I. Nuclear reactors, due to their large flux of low energy electron antineutrinos, are profitable locations for studies of antineutrino induced reactions and possible neutrino oscillations. The calculation of the reactor antineutrino spectrum is presented, together with predictions for weak-interaction experiments performed at nuclear reactors. It is demonstrated that such experiments provide constraints on the parameters describing neutrino oscillations. Part II. Due to interference of atomic processes with nuclear electromagnetic transitions, the emitted radiation acquires a phase shift. The knowledge of accurate values for this phase shift, also called the interference parameter, must be included in the analysis II of time-reversal and Mossbauer absorption experiments. Theoretical expressions for the interference parameter are presented, and calculated values are compared with experiment. Satisfactory agreement is obtained. In particular, an apparent violation of time-reversal invariance in the 129 keV transition of 191Ir is fully explained by these atomic interference effects.