Decoherence of collective motion in warm nuclei


Decoherence of collective motion in warm nuclei

Frauendorf, S.; Petrache, C.; Schwengner, R.; Wimmer, K.

Collective states in cold nuclei are represented by a wave function that assigns coherent phases to the participating nucleons. The degree of coherence decreases with excitation energy above the yrast line because of coupling to the increasingly dense background of quasiparticle excitations. The consequences of decoherence are discussed, starting with the well studied case of rotational damping. In addition to superdeformed bands, a highly excited oblate band is presented a new example of screening from rotational damping. Suppression of pair correlation leads to incoherent thermal M1 radiation, which appears as an exponential spike (LEMAR) at zero energy in the gamma strength function of spherical nuclei. In deformed nuclei a Scissors Resonance appears and LEMAR changes to damped magnetic rotation, which is interpreted as partial restoration of coherence.

Keywords: Collective motion in atomic nuclei; quantal coherence; collective bands; rotational damping; magnetic rotation; thermal M1 radiation; Scissors resonance

Permalink: https://www.hzdr.de/publications/Publ-29423
Publ.-Id: 29423