Effective nucleon mass and the nuclear caloric curve

Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region could be sensitive to the nuclear mass evolution of the effective nucleon mass.

Figure 1

Temperature as a function of excitation energy for mass $A=100\text{−}140$. The data points (inverted triangles) are from Ref. [3]. The dotted curve is the Fermi-gas relation. The dot-dot-dashed curve is from Ref. [6]. The dot-dashed curve is from Ref. [2]. The solid and the dashed curves are from Eqs. (5) and (7), respectively.

Figure 2

(a) Effective nucleon mass ratio, (b) density, and (c) $K_{\mathrm{eff}}$, as a function of excitation energy. The different curves in (a) and (c) correspond to the different mass ranges.

Figure 3

Temperature as a function of excitation energy for various mass ranges. The data points (inverted triangles) are from Ref. [3]. The solid curves are obtained from Eq. (5). The dashed curve is the Fermi-gas relation.

Figure 4

Same as Fig. 3, but showing the results of Eq. (7).

Figure 5

Comparison between the caloric curves obtained from Eq. (5) for three different mass ranges.