Schottky-like phase transition in the fission of atomic nuclei: U235

Results: We have found anomalies of the thermodynamic functions of the ensemble of fragments of fission of 235U in the temperature range when the shape of the yields of fragment fission changes from asymmetric to symmetric. In particular, the peaklike form of the heat capacity C(T ) indicates a Schottky-like phase transition. We also point out the experimental possibility of observing such a phase transition within the nuclear temperature range of 1–2 MeV. Conclusions: This article shows that a new Schottky-like phase transition can be observed under nuclear fission. It differs from known phase-type transformations under nuclear fission, which have been intensively investigated lately and may be due to fundamental factors such as loss of statistical nonequivalence or the identity of nucleons in different fission fragments.