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Abstract: We demonstrate the equivalence of a generalized Fermi breakup model, in which densities of excited states are taken into account, to the microcanonical statistical multifragmentation model used to describe the disintegration of highly excited fragments of nuclear reactions. We argue that such a model better fulfills the hypothesis of statistical equilibrium than the Fermi breakup model generally used to describe statistical disintegration of light mass nuclei. [Copyright &y& Elsevier]

We study the standard 1 S 0 and the quasideuteron 3 S 1–3 D 1 pairing fields in asymmetric nuclear matter, using a Bonn meson-exchange interaction in a Dirac-Hartree-Fock-Bogoliubov approximation. We obtain a quasideuteron field very similar to those found in nonrelativistic calculations at densities below saturation, both in symmetric and asymmetric nuclear matter. This field has the properties of a Bose-Einstein condensate at low densities and those of a BCS condensate at high densities. The quasideuteron pairing field in asymmetric nuclear matter is stable only when accompanied by standard 1 S 0 neutron-neutron and proton-proton pairing fields. [Copyright &y& Elsevier]

We study the standard 1 S 0 and the quasideuteron 3 S 1−3 D 1 pairing fields in asymmetric nuclear matter, using a Bonn meson-exchange interaction in a Dirac-Hartree-Fock-Bogoliubov approximation. As in earlier calculations, the standard pairing fields fall to zero at densities below saturation, due to relativistic effects. We obtain a quasideuteron field very similar to those found in nonrelativistic calculations at densities below saturation, both in symmetric and asymmetric nuclear matter. This field has the properties of a Bose-Einstein condensate at low densities and those of a BCS condensate at high densities. The quasideuteron pairing field in asymmetric nuclear matter is stable only when accompanied by standard 1 S 0 neutron-neutron and proton-proton pairing fields that are different from the fields obtained when the quasideuteron field is zero. The coupled pairing field configuration is the nuclear matter ground state. [Copyright &y& Elsevier]

Abstract: We discuss the effects of medium polarization on nuclear pairing in the context of the relativistic Hartree–Fock–Bogoliubov (HFB) approximation in the model. The medium polarization effects on the scalar and vector meson masses, and on the pairing gap are shown for several values of the coupling constants scaled by a parameter x. We find that the medium polarization increases the magnitude of the pairing gap at low density while the vacuum polarization decreases its magnitude at higher density. [Copyright &y& Elsevier]

Abstract: EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, proton, any ion (including heavy-ions) or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions (∽ keV) and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nucleus ones. Direct reactions are described by a generalized optical model (ECIS03) or by the simplified coupled-channels approach (CCFUS). The pre-equilibrium mechanism can be treated by a deformation dependent multi-step direct (ORION + TRISTAN) model, by a NVWY multi-step compound one or by either a pre-equilibrium exciton model with cluster emission (PCROSS) or by another with full angular momentum coupling (DEGAS). Finally, the compound nucleus decay is described by the full featured Hauser-Feshbach model with γ-cascade and width-fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. The fission probability is derived in the WKB approximation within the optical model of fission. Several options for nuclear level densities include the EMPIRE-specific approach, which accounts for the effects of the dynamic deformation of a fast rotating nucleus, the classical Gilbert-Cameron approach and pre-calculated tables obtained with a microscopic model based on HFB single-particle level schemes with collective enhancement. A comprehensive library of input parameters covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, moments of inertia and γ-ray strength functions. The results can be converted into ENDF-6 formatted files using the accompanying code EMPEND and completed with neutron resonances extracted from the existing evaluations. The package contains the full EXFOR (CSISRS) library of experimental reaction data that are automatically retrieved during the calculations. Publication quality graphs can be obtained using the powerful and flexible plotting package ZVView. The graphic user interface, written in Tcl/Tk, provides for easy operation of the system. This paper describes the capabilities of the code, outlines physical models and indicates parameter libraries used by EMPIRE to predict reaction cross sections and spectra, mainly for nucleon-induced reactions. Selected applications of EMPIRE are discussed, the most important being an extensive use of the code in evaluations of neutron reactions for the new US library ENDF/B-VII.0. Future extensions of the system are outlined, including neutron resonance module as well as capabilities of generating covariances, using both KALMAN and Monte-Carlo methods, that are still being advanced and refined. [Copyright &y& Elsevier]

Evaluated cross sections of beam-monitor reactions are expected to become the de-facto standard for cross-section measurements that are performed over a very broad energy range in accelerators in order to produce particular radionuclides for industrial and medical applications. The requirements for such data need to be addressed in a timely manner, and therefore an IAEA coordinated research project was launched in December 2012 to establish or improve the nuclear data required to characterise charged-particle monitor reactions. An international team was assembled to recommend more accurate cross-section data over a wide range of targets and projectiles, undertaken in conjunction with a limited number of measurements and more extensive evaluations of the decay data of specific radionuclides. Least-square evaluations of monitor-reaction cross sections including uncertainty quantification have been undertaken for charged-particle beams of protons, deuterons, 3 He- and 4 He-particles. Recommended beam monitor reaction data with their uncertainties are available at the IAEA-NDS medical portal www-nds.iaea.org/medical/monitor_reactions.html . [ABSTRACT FROM AUTHOR]

Abstract: The ground-state structure of the near-drip-line nucleus 23O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections for electromagnetic excitation of 23O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including γ rays. The analysis of the deduced dipole-transition probability into the continuum infers a ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin , resolving earlier conflicting experimental findings. Final-state interaction is of significant influence, an effective reduced scattering length for low-energy neutron scattering could be derived from the data. [Copyright &y& Elsevier]