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تسجيل مستخدم جديدReaction cross-section predictions for nucleon induced reactions
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A microscopic calculation of the optical potential for nucleon-nucleus scattering has been performed by explicitly coupling the elastic channel to all the particle-hole (p-h) excitation states in the target and to all relevant pickup channels. These p-h states may be regarded as doorway states through which the flux flows to more complicated configurations, and to long-lived compound nucleus resonances. We calculated the reaction cross sections for the nucleon induced reactions on the targets $^{40,48}$Ca, $^{58}$Ni, $^{90}$Zr and $^{144}$Sm using the QRPA description of target excitations, coupling to all inelastic open channels, and coupling to all transfer channels corresponding to the formation of a deuteron. The results of such calculations were compared to predictions of a well-established optical potential and with experimental data, reaching very good agreement. The inclusion of couplings to pickup channels were an important contribution to the absorption. For the first time, calculations of excitations account for all of the observed reaction cross-sections, at least for incident energies above 10 MeV.
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The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model-space characterized by a $p+n+{rm A}$ three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a
microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels method (CDCC), and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on $^{58}$Ni and $^{208}$Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.
Understanding of inclusive one-nucleon knockout reactions for long-lived fission fragments (LLFPs) is crucial for nuclear transmutation studies. However, the particle and heavy ion transport code system (PHITS) severely overshoots the inclusive one-n
ucleon knockout cross sections sigma_-1N. Therefore development of a reaction model for describing the inclusive one-nucleon knockout processes is necessary. A key is specification of the position and the momentum of a nucleon inside a nucleus to be struck by the incident nucleon. In this paper the semiclassical distorted wave model incorporating the Wigner transform of the one-body nuclear density matrix is applied to the calculation of excitation energy distributions of reaction residues. Decay of a residue is described by introducing a threshold parameter for the minimum excitation energy of it. With reasonable values of the parameter, the measured sigma_-1N for several LLFPs are reproduced by the proposed reaction model. The incident energy dependence of sigma_-1N is found to be governed by that of the nucleon-nucleon cross sections at energies higher than about 75 MeV. At low energies, the nuclear absorption and the Coulomb penetrability also become important. The energy dependence of neutron-induced sigma_-1N is predicted and found to be quite different from that of proton induced one. The proposed reaction model is shown to be promising in discussing the energy dependence of nucleon-induced inclusive one-nucleon knockout processes. The energy dependence of the measured sigma_-1p for 107Pd above 100 MeV is, however, not explained by the present calculation.
The cross sections of the 162Er(a,g,)166Yb and 162Er(a,n)165Yb reactions have been measured for the first time. The radiative alpha capture reaction cross section was measured from Ec.m. = 16.09 down to Ec.m. = 11.21 MeV, close to the astrophysically
relevant region (which lies between 7.8 and 11.48 MeV at 3 GK stellar temperature). The 162Er(a,n)165Yb reaction was studied above the reaction threshold between Ec.m. = 12.19 and 16.09 MeV. The fact that the 162Er(a,g)166Yb cross sections were measured below the (a,n) threshold at first time in this mass region opens the opportunity to study directly the a-widths required for the determination of astrophysical reaction rates. The data clearly show that compound nucleus formation in this reaction proceeds differently than previously predicted.
[Background] Alpha-nucleus optical potentials are basic ingredients of statistical model calculations used in nucleosynthesis simulations. While the nucleon+nucleus optical potential is fairly well known, for the alpha+nucleus optical potential sever
al different parameter sets exist and large deviations, reaching sometimes even an order of magnitude, are found between the cross section predictions calculated using different parameter sets. [Purpose] A measurement of the radiative alpha-capture and the alpha-induced reaction cross sections on the nucleus 115In at low energies allows a stringent test of statistical model predictions. Since experimental data is scarce in this mass region, this measurement can be an important input to test the global applicability of alpha+nucleus optical model potentials and further ingredients of the statistical model. [Methods] The reaction cross sections were measured by means of the activation method. The produced activities were determined by off-line detection of the gamma-rays and characteristic x-rays emitted during the electron capture decay of the produced Sb isotopes. The 115In(alpha,gamma)119Sb and 115In(alpha,n)118Sbm reaction cross sections were measured between Ec.m. = 8.83 MeV - 15.58 MeV, and the 115In(alpha,n)118Sbg reaction was studied between Ec.m. = 11.10 MeV - 15.58 MeV. The theoretical analysis was performed within the statistical model.
Background: The neutron skin thickness $R_{rm skin}^{rm PV}$ of PREX-II is presented in Phys. Rev. Lett. {bf 126}, 172502 (2021). The reaction cross section $sigma_R$ is useful to determine the matter radius $R_m$ and $R_{rm skin}$. For proton scatte
ring, the reaction cross section $sigma_R$ are available for $E_{rm in} > 400$ MeV. Method and results: We determine $R_n^{rm exp}=5.727 pm 0.071$ fm and $R_m^{rm exp}=5.617 pm 0.044$ fm from $R_p^{rm exp}$ = 5.444 fm and $R_{rm skin}^{rm PV}$. The $R_p^{rm GHFB}$ calculated with Gongny-D1S HFB (GHFB) with the angular momentum projection (AMP). agrees with $R_p^{rm exp}$. The neutron density calculated with GHFB+AMP is scaled so as to $R_n^{rm scaling}=5.727$ fm. The Love-Franey $t$-matrix model with the scaled densities reproduces the data on $sigma_R$. Aim: Our aim is to find the $sigma_R$ of proton scattering consistent with $R_{rm skin}^{rm PV}$. Conclusion: The $sigma_R$ of proton scattering consistent with $R_{rm skin}^{rm PV}$ are $sigma_R^{rm exp}$ at $E_{rm in} = 534.1, 549, 806$ MeV.
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