Nucleon direct-semidirect radiative capture with Skyrme-Hartree-Fock-BCS bound states

Abstract

The nucleon direct-semidirect (DSD) capture cross sections are obtained by calculating a transition amplitude to the Hartree-Fock-BCS bound states. The radial matrix elements in the DSD amplitudes are calculated from the radial part of the single-particle wave functions. For deformed nuclei the single-particle states are expanded in the cylindrical harmonic-oscillator basis and then projected on the spherical harmonic-oscillator basis. The pairing correlations are treated in the BCS approach and the calculated spectroscopic factors are in fairly good agreement with experimental data in the even tin isotopes from 116 Sn to 124 Sn. The resulting DSD cross sections for the neutron capture by 208 Pb and 238 U are found to be in good agreement with the available experimental data. The calculations are also performed for the neutron capture on 122 Sn and 132 Sn isotopes that are important for the r-process in astrophysics.

Microscopic models for direct inelastic scattering and direct preequilibrium emission: nucleon induced reactions

“…We present differential cross sections calculated for 208 Pb, 116 Sn, 90 Zr, 40,48 Ca and 16 O. Comparisons with experimental data are shown in Fig.1(a,b) 1 excitation where our predictions do not exactly match the data.…”

“…We depict in Fig.1(c) the same comparison extended to the first 3 − excitation in the other doubly-closed-shell nuclei 16 O and 40,48 Ca as well as neutron or proton closedshell nuclei 90 Zr and 116 Sn, respectively. The overall agreement between calculations and data is still very good.…”

“…state |kΩ k . More details can be found in [16]. Finally, for our preequilibrium calculations, we adopt the following approximation for physical states…”

Advances in nuclear reaction calculations by incorporating information from nuclear mean-field theories

“…So far there are two models in CoH 3 that utilize the mean-field calculation outputs. As mentioned before, the single-particle wave-functions of FRDM and HF-BCS can be used in the DSD model [2]. In addition, the singleparticle state density parameter g in the pre-equilibrium model can be estimated by Strutinsky's method in FRDM, as it is given by smoothed variation in the single-particle energies [24].…”

“…Although pre-calculated model inputs are available in a computer readable format [1], we still envision that combining nuclear structure models with the nuclear reaction calculations will be very attractive for further development of nuclear reaction codes. An example is the mean-field model calculation for the neutron direct/semi-direct (DSD) capture model developed at Los Alamos [2], where the Hartree-Fock (HF) BCS theory is used for calculating bound-neutron wave-functions as well as the particle occupation probabilities in a deformed nucleus. Recently this technique was extended to the Finite-Range Droplet Model (FRDM) [3] and the model was unified with the statistical Hauser-Feshbach code CoH 3 at Los Alamos National Laboratory (LANL) [4].…”