Pairing phase transition and thermodynamical quantities in 148,149Sm

Thermal quantities of 46Ti

“…(4), (5) and (6), respectively. For more information on the calculation procedures see our previous publications [2,4,5,12]. The thermodynamic quantities also have been extracted from experimental data on nuclear level density, using Eqs.…”

“…The heat capacity of the system due to the neglect of the small change in λ versus temperature will be [2]: where…”

“…For example the heat capacity finds a sharp peak and discontinuity at critical temperature while experimental results show a smooth S shape behavior at the same temperatures. By applying modified pairing gap [2], we can assume the variation of gap parameter to have temperature dependence of the form of Fermi function after a matching temperature T m that is near critical temperature:…”

“…So the BCS theory alone fails to provide a good approximation of thermal properties. Using the modified nuclear pairing gap proposed in our previous publication [2] results in an S-shaped heat capacity curve with a smooth behavior at critical temperature. The modified pairing gap includes BCS approximation at low temperatures and Fermi type function at higher temperatures.…”

“…Pairing correlations are one of the fundamental properties of nuclei and have a strong influence on the thermal quantities. The BCS model that is based on the Bardeen-Cooper-Schrieffer superconducting theory [1] takes into account pairing correlations by the use of most probable value for the pairing gap parameter [2]. Most probable value of the pairing gap parameter has a sudden decrease at the critical temperature and this leads to a discontinuity of the heat capacity [2].…”