abstract

The investigation of thermodynamic properties of nuclei as a function of excitation energy is one of the challenges in nuclear physics. In this work, we have, for the first time, extracted the entropy, entropy excess, nuclear temperature, and heat capacity of the \(^{138,139}\)La nuclei as a function of excitation energy from their experimental nuclear-level densities. We observed that the odd–odd \(^{138}\)La has a higher entropy due to the additional unpaired neutron. In particular, it has an average entropy excess of 2.3 \(\pm \) 0.5 \(k_\mathrm {B}\), which corresponds to the 10 times higher nuclear-level density due to the last unpaired neutron in \(^{138}\)La. The nuclear temperature and heat capacity show evidence for the sequential breaking of Cooper nucleon pairs and as a result, we observed approximately constant temperatures of 0.7 \(\pm \) 0.3 and 0.8 \(\pm \) 0.2 MeV in the quasi-continuum of \(^{138}\)La and \(^{139}\)La, respectively.

abstract

Unlike biodosimetry of sparsely ionizing photons (X and \(\gamma \) rays), radiobiology and biodosimetry of densely ionizing (characterized by high linear energy transfer) heavy ions are still relatively poorly developed domains of science, despite a growing role of hadron beams in cancer therapy and an increasing frequency of exposure of humans to cosmic radiation. The most radiosensitive cell structure is the DNA which is responsible for storing genetic information. Interaction of radiation with the DNA leads to the formation of different types of DNA damage, the most severe of which are DNA double-strand breaks (DSBs). Damage to the DNA activates repair processes and their performance may be significantly reduced or stopped if the resulting damage is densely localized (clustered) on the distances of the order of nanometers. Erratic DNA repair leads to changes in the DNA structure causing rearrangements of the genome (chromosome aberrations), possibly resulting in subsequent cell death or induction of cancer. Relating models of chromosome geometry and their spatial position in the nucleus to a characteristic pattern of energy deposition in the biological target by incident radiation (track structure) allows us to predict the frequency and distribution of DSBs, displacement of formed fragments, and probability of translocation of genetic material between pairs of chromosomes. In this work, we analyze results of the biophysical modeling of chromosome packing in the cell nucleus and confront them with cytogenetic experimental data evidenced by the former in vitro studies. In the quest for understanding effects of interphase chromosome geometry on the induction and frequency of chromosome aberrations, we have evaluated two models of the DNA polymer packing within the cell nucleus and validated the predicted exchange of genome with experimental findings.

abstract

The QCD effective charge extracted from the experimental data is used to construct the vector interaction of a Dirac relativistic model for the charmonium spectrum. The process required to fit the spectrum is discussed and the relationship with a previous study of the vector interaction is analyzed.