We investigated induction of chromosome aberrations (CA) in human lymphocytes when exposed to 150 MeV and spread out Bragg peak (SOBP) proton beams, and 199 MeV/u carbon beam which are currently widely used for cancer treatment and simultaneously are important components of cosmic radiation. For a comparison, the boron ions of much lower energy 22 MeV/u and a ⁶⁰Co γ rays were used. Dose–effect curves as well as the distributions of CA were studied using Poisson and Neyman type A statistics. Systematics of experimentally determined parameters, their dependence on applied doses and irradiation quality are presented.

Electron emission in the deuteron-deuteron reaction supporting existence of the single-particle threshold resonance in ${}^4\mathrm{He}$ has been observed for the first time. The measured electron energy spectrum and the electron-proton branching ratio agree very well with the assumed electron-positron pair creation decay of the $0^{+}$ resonance state to the ground state and the detailed Monte Carlo simulations of the experimental energy spectrum.

Low-energy nuclear reactions are known to be extremely dependent on the local crystal structure and crystal defects of the deuterated samples. This has a strong influence on both hydrogen diffusion and the effective electron mass. The latter determines the strength of the local electron-screening effect and can change the deuteron–deuteron reaction rates at very low energies by many orders of magnitude. In the present study, zirconium samples were exposed to various conditions and energies of deuteron beams using the unique accelerator system with ultra-high vacuum, installed in the eLBRUS laboratory at the University of Szczecin. Irradiated and virgin samples were investigated by means of the X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS). While the first method delivers information about changes of crystal lattice parameters and possible production of hydrides accompanying the formation of dislocations that are produced during irradiation of the samples, the second one can determine the depth distribution of crystal defects, being especially sensitive to vacancies. The studied Zr samples were also implanted by carbon and oxygen ions in order to simulate the real situation taking place in nuclear reaction experiments and to investigate their influence on the kinetic of produced vacancies. The observed enhancement of the electron-screening effect in the deuteron fusion reaction at very low energies could be explained by formation of a high number of vacancies during the deuteron irradiation of samples. Possible carbon and oxygen impurities can affect this process in various ways by changing the depth distribution of vacancies and their diffusion, but they play only a minor role in the strength of the electron-screening effect.

Breast carcinomas (BC) are among the most frequent cancers in women. Studies on radiosensitivity and ionizing radiation response of BC cells are scarce and mainly focused on intrinsic molecular mechanisms but do not include clinically relevant features as chromosomal rearrangements important for radiotherapy. The main purpose of this study was to compare the ionizing radiation response and efficiency of repair mechanisms of human breast carcinoma cells (Cal 51) and peripheral blood lymphocytes (PBL) for different doses and radiation qualities (⁶⁰Co γ-rays, 150 MeV and spread-out Bragg peak (SOBP) proton beams). The radiation response functions obtained using the conventional metaphase assay and premature chromosome condensation (PCC) technique enabled us to determine the number of chromosomal breaks at different time after irradiation. Both cytogenetic assays used confirmed the higher biological radiosensitivity for proton beams in tumor cells compared to PBL, corresponding to higher values of the linear LQ parameter α. additionally, the ratio of the LQ parameters β/α describing efficiency of the repair mechanisms, obtained for chromosome aberrations, showed higher numbers for PBL than for Cal 51 for all exposures. Similar results were observed for the ratio of PCC breaks determined directly after irradiation to that obtained 12 h later. This parameter (t0/t12) showed faster decrease of the repair efficiency with increasing LET value for Cal 51 cells. This finding supports the use of the proton therapy for breast cancer patients.

The discovery of a new, e + e − reaction channel in deuteron-deuteron (DD) fusion at very low energies might have major implications for understanding primordial and stellar nucleosynthesis, where electron-positron reaction channels are typically not considered. It could also enable research on metal hydride fusion, potentially paving the way for the design and construction of next-generation fusion energy sources. Following the first experimental indications of electron emission, we present here an extensive experimental study confirming emission of high-energy electrons from DD reaction at very low energy. A simultaneous use of Si charged particle detectors of different thicknesses and large-volume NaI(Tl) and HPGe detectors has allowed the determination of the branching ratios between emitted protons, neutrons, and e + e − pairs for deuteron energies down to 5 keV. The high-energy positrons could be unambiguously detected by their bremsstrahlung spectra and annihilation radiation, supported by the eant4 Monte Carlo simulations. The theoretical calculations, based on a destructive interference between the threshold resonance and the known broad resonance in He 4 , agree very well with experimentally observed increase of branching ratios for lowering projectile energies. The partial width of the threshold resonance for the internal e + e − pair creation should be at least 10 times larger than that of the proton channel.

The electron screening effect is responsible for a significant increase in the nuclear reaction rates in metals at very low energies. This is dependent on the local crystal structure of the metallic target and the occurrence of defects or additional elemental impurities in the crystal. Here, we studied the deuteron–deuteron fusion reactions on zirconium targets previously implanted with carbon and oxygen ions. The ²H(d,p)³H reaction yield was measured at two deuteron energies, 8 and 20 keV, in order to determine the strength of the electron screening effect and its dependence on the density of the implanted impurities. We found that carbon implantation strongly reduced the experimentally determined screening energy, while oxygen implantation had the opposite effect. These results are especially important for the application of nuclear fusion in metallic environments at very low energies.