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The fission cross section of 232 Th has been measured at fast neutron energies, using a setup based on Micromegas detectors. The experiment was performed at the 5.5 MV Van de Graaff Tandem accelerator in the neutron beam facility of the National Centre for Scientific Research "Demokritos". The quasi-monoenergetic neutron beams were produced via the 3 H(p,n), 2 H(d,n) and 3 H(d,n) reactions, while the 238 U(n,f) and 235 U(n,f) reactions were used as references, in order to acquire cross-section data points in the energy range 2–18 MeV. The characterization of the actinide samples was performed via α -spectroscopy with a Silicon Surface Barrier (SSB) detector, while Monte Carlo simulations with the FLUKA code were used to achieve the deconvolution of the 232 Th α peak from the α background of its daughter nuclei present in the spectrum. Special attention was given to the study of the parasitic neutrons present in the experimental area, produced via charged particle reactions induced by the particle beam and from neutron scattering. Details on the data analysis and results are presented. [ABSTRACT FROM AUTHOR]

Several cross-section measurements of neutron-induced reactions on Ge found in literature, are performed utilizing natGe targets. The production of the same residual nucleus as the measured one might occur as a result of the unavoidable presence of neighboring isotopes in the same target, acting as a contamination. Corrections must be made based on theoretical calculations and models in order to resolve this problem. The accuracy and limits of a methodology for these "theoretical corrections" are investigated in this work using isotopically enriched targets, which can produce very accurate results without the need for such corrections. Experimental cross-section measurements have been made for the 76Ge(n,2n)75Ge, 72Ge(n, α)69mZn and 72Ge(n,p)72Ga reactions, via the activation technique, with the 27Al(n, α)24Na reaction used as reference, employing both a natGe and isotopically enriched Ge targets. The 3H(d,n)4He (D–T) reaction was used for producing the quasi-monoenergetic neutron beam in the 5.5 MV Tandem Accelerator Laboratory of the National Centre for Scientific Research "Demokritos" in Athens, Greece, at an incident deuteron beam energy of 2.9 MeV. Using HPGe detectors, γ -ray spectroscopy was applied to determine the induced γ -ray activity of the residual nuclei. • Cross section measurements with natural Ge targets need to be corrected for contaminations from neighboring isotopes • A methodology is proposed for the correction of the contribution from parasitic channels • The accuracy and limits of the methodology are investigated with two sets of measurements • Enriched and natural Ge targets were employed for cross-section measurements via the activation technique [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: 10.1140/epja/s10050-021-00590-w [ABSTRACT FROM AUTHOR]

The cross section of the 193Ir(n, 2n)192Ir reaction has been determined by means of the activation technique, relative to the 27Al (n, α ) and 197Au(n, 2n) reference reactions cross sections, at neutron beam energies ranging from 10 to 21 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" via the 2H(d, n) and 3H(d, n) reactions. The induced γ -ray activity of the irradiated target and reference foils was measured with high resolution HPGe detectors. In order to correct for the contribution of the 191Ir(n, γ )192Ir reaction, which is open to low energy parasitic neutrons, a recently developed analysis method was implemented and it is presented in great detail. Furthermore, cross section theoretical calculations were carried out using the EMPIRE and TALYS codes over a wide energy range. [ABSTRACT FROM AUTHOR]

The cross sections of the 191 Ir (n, 2 n) 190 Ir and 191 Ir (n, 3 n) 189 Ir reactions have been determined by means of the activation technique, relative to the 27 Al (n, a) 24 Na reaction, at neutron beam energies higher than 15 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" by implementing the 3 H (d, n) 4 He reaction. The induced γ -ray activity of the irradiated target and reference foils was measured with high resolution, high purity germanium (HPGe) detectors. The cross section for the high-spin isomeric state (11 -) of the 190 Ir nucleus was determined along with the sum of the ground (4 -), the first (1 -), and the second (11 -) isomeric states. Moreover, the cross section for the production of the ground state of the residual nucleus of (n, 3 n) reaction, 189 Ir, was also estimated. Additionally, cross section theoretical calculations were carried out using the empire 3.2.2 and talys 1.8 codes, in which the input parameters were chosen in such a way as to simultaneously reproduce several experimental reaction channel cross sections in a satisfactory way, namely the (n, 2 n), (n, 3 n), (n, p), (n, a), and (n, total) ones. Similar combination of theoretical model parameters had also been successfully used in the case of the neighboring 197 Au nucleus, and this constitutes an encouraging confirmation of how accurately the theoretical models can reproduce the experimental results in this mass region. [ABSTRACT FROM AUTHOR]