Fast-neutron induced pre-equilibrium reactions on 55Mn and 63,65Cu at energies up to 40 MeV

Abstract

Excitation functions were measured for the 55 Mn(n,2n) 54 Mn, 55 Mn(n,α) 52 V, 63 Cu(n,α) 60 Co, 65 Cu(n,2n) 64 Cu, and 65 Cu(n,p) 65 Ni reactions from 13.47 to 14.83 MeV. The experimental cross sections are compared with the results of calculations including all activation channels for the stable isotopes of Mn and Cu, for neutron incident energies up to 50 MeV. Within the energy range up to 20 MeV the model calculations are most sensitive to the parameters related to nuclei in the early stages of the reaction, while the model assumptions are better established by analysis of the data in the energy range 20-40 MeV. While the present analysis has taken advantage of both a new set of accurate measured cross sections around 14 MeV and the larger data basis fortunately available between 20 and 40 MeV for the Mn and Cu isotopes, the need of additional measurements below as well as above 40 MeV is pointed out.

Complementary optical-potential analysis of -particle elastic scattering and induced reactions at low energies

“…The odd proton-numbers of the target and the compound and residual nuclei, with larger nuclear level densities, make the statistical-model calculations more reliable. The appropriateness of the last comment is also proved by the agreement of the calculated and experimental cross sections, although the same consistent parameter set [30,31] has been involved for all four target nuclei.…”

“…For the rest of statistical-model parameters we have used consistent sets established by analyzing various independent experimental data for all stable isotopes of V, Mn, Co, Ni, Cu [29,30,31], Mo [32], and Pd, Sn and Te [33], which finally allow us to focus on the uncertainties of the α-particle OMP. While a suitable description of the (α, n) reaction cross sections was found for lighter target nuclei with A≤54, a major overestimation of (α, γ) reaction cross sections resulted for 62,64 Ni, 63 Cu, 96,98 Ru, 106 Cd and 112,118 Sn.…”

“…They were carried out similarly to the previous analysis of (n, α) reaction cross section for A ∼90 [10,75], except the investigated OMP was now related to α-particles in the incident channel. For the rest of statistical-model parameters we have used consistent sets established by analyzing various independent experimental data for all stable isotopes of V, Mn, Co, Ni, Cu [29,30,31], Mo [32], and Pd, Sn and Te [33]. While a suitable description of the (α, n) reaction cross sections was found for lighter target nuclei with A≤54 (Fig.…”

“…The simultaneous description of these data is most important for the validation of α-particle OMP below the Coulomb barrier, especially within the energy ranges where the (α, γ) and subsequently (α, n) reactions stand for nearly the whole range of the α-particle interaction. On the other hand, the assumption [14,15] concerning the similar overestimation of the (α, γ) cross sections and underestimation of the (α, p) cross sections, caused not only by the α-potential, led us to an additional investigation in this respect [33]. Thus, we analyzed the neutron total cross sections for the Cd, Sn and Te isotopes and the neutron energies up to 30 MeV, as well as the neutron capture on the same target nuclei for the neutron energies up to 3 MeV.…”

“…4, starting with the accurate total-reaction cross sections of Vonach et al [28] and including the open questions recently noted for 63 Cu [20] and A ∼100 nuclei [14,15,21,22]. As a matter of fact, in order to calculate the reaction cross section we have used a consistent parameter set established by analyzing various independent exper-imental data for all stable isotopes of V, Mn, Co, Ni, Cu [29,30,31], Mo [32], Pd, Sn and Te [33]. Thus, it became possible to focus on the uncertainties of the α-particle OMP parameters and their improvement.…”