Critical temperature for shape transitions in excited nuclei

The behavior of shell effects with temperature is studied within the framework of the finite-temperature Hartree-Fock-Bogoliubov theory with the Gogny force. Thermal shape fluctuations in the quadrupole degree of freedom are taken into account in the frame of the Landau theory. Numerical results for the superfluid-to-normal and deformed-to-spherical phase transitions are presented for the nucleus ¹⁶⁴Er. We find that the critical temperature for the deformed-spherical shape transition is much lowered when the thermal shape fluctuations are considered.Received: 31 October 2002, Published online: 17 February 2004PACS: 21.60.Jz Hartree-Fock and random-phase approximations - 21.10.Ky Electromagnetic moments - 21.10.Ma Level density