摘要:

The present status of the phenomenological neutron optical potential is briefly reviewed, with particular attention to the dependence on the nuclear asymmetry. It is shown that the conventional parametrization is inadequate and some possible improvements are discussed. These improvements are of two types: firstly a more flexible global parametrization and secondly some ways of incorporating data relating to each particular nucleus. Two ways of doing this are proposed, using the RMS matter radius to improve the real potential and the nuclear level density to improve the imaginary potential.

ISSN:0094-243X    

DOI:10.1063/1.34990

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Elastic scattering of neutrons, protons and antiprotons from complex nuclei is microscopically analysed with Bru¨ckner’s reaction matrix as effective interaction. This interaction is generated with the Paris (NN) and (NN¯) potentials as fundamental input and it houses medium effects such as density and energy dependencies. Here we address ourselves to energies between 25 and 100 MeV and discuss the relevant aspects for the three different projectiles. Properties of the effective interaction play thereby a central role.

ISSN:0094-243X    

DOI:10.1063/1.34987

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Microscopic calculations of the second order imaginary optical potential are presented for neutron and proton scattering from spherical target nuclei using random phase approximation transition densities for intermediate excited states. Both inelastic and charge‐exchange intermediate states are considered. The contribution of the deuteron channel to the absorption is estimated. The sensitivity of the surface absorption on details of the nuclear structure wave functions is discussed. Calculations are presented for the isoscalar term W0of the optical potential, the isovector term W1(Lane‐term), and the Coulomb correction term &Dgr;WC. Elastic scattering cross sections are calculated from the microscopic nonlocal potentials and are compared to cross sections which were obtained from the equivalent local potentials. The validity of the local approximation to the nonlocal potential is investigated. The differences and similarities between the nuclear matter approach and the nuclear structure approach to the calculation of the imaginary potential are discussed. The nuclear structure approach is also applied to the calculation of the imaginary inelastic form factor used in inelastic scattering. First results are presented for the48Ca(p,n)48Sc(O+,Ex=6.8 MeV) reaction at an incident energy of 25 MeV.

ISSN:0094-243X    

DOI:10.1063/1.34995

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The mass operator for nuclear matter calculations is studied in the BHF approximation. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.34978

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Analyzing power Ay(&thgr;) and cross section measurements have been obtained from 10 to 17 MeV for 20 isotopes ranging from6Li to208Pb. These combined data sets provide a unique data base for nuclear model development. The experimental method for the Ay(&thgr;) measurements and comparisons to coupled‐channels and spherical optical model calculations are given.

ISSN:0094-243X    

DOI:10.1063/1.34981

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The most complete set of differential cross sections &sgr;(&thgr;) and vector analyzing power Ay(&thgr;) for neutron scattering from28Si and32S over the 8 to 40 MeV energy range has been collected and evaluated. These data have been successfully described with the spherical optical model (SOM) and with phenomenological coupled‐channels (CC) calculations. For the case of28Si, various calculations were performed to determine the sensitivity of the data and calculations to the sign of the potential deformation parameters &bgr;2and &bgr;4. Comparisons of the present analyses to the corresponding analyses of proton‐scattering data have yielded interesting results concerning the magnitudes of the Coulomb corrections to the OM potentials for28Si and32S.

ISSN:0094-243X    

DOI:10.1063/1.34982

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Significant progress has been made over the past several years in developing energy‐ and density‐dependent effective interactions and optical potentials based on free nucleon‐nucleon potentials. This leads to the hope that the nucleon‐scattering reaction mechanism may be well enough known to probe details of nuclear spectroscopy (i.e., transition densities) more accurately than with purely phenomenological approaches. Of particular interest to this conference is the possibility of separating neutron and proton transition densities by comparing proton and neutron scattering, which can be done reliably only if the isovector parts of the effective interaction are well known. This paper attempts to assess the accuracy of presently available interactions through comparisons with elastic and inelastic scattering over a wide mass range, and also with the (p,n) isobaric‐analog reaction. Particular emphasis has been placed on the isovector parts of the interaction and on Coulomb corrections by comparing proton and neutron scattering on the same targets. In a number of cases, precise neutron data have been measured to facilitate these comparisons.

ISSN:0094-243X    

DOI:10.1063/1.34983

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Proton charge exchange reactions and inelastic scattering are studied on6Li and12C targets. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.35006

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

There is increasing evidence that relativistic effects play an important role in the description of nuclear structure and reactions. The development of a relativistic impulse approximation (RIA) and its success at intermediate energies is a case in point. Although the RIA cannot be used to describe proton scattering at low energies it successfully describes recent p¯–12C data at 46.8 MeV. We discuss a phenomenological nuclear optical model approach based on the Dirac equation containing large cancelling Lorentz scalar and Lorentz vector potentials. The model is used to describe proton and neutron scattering at low energy (T<100 MeV) from various targets. Systematic features of the phenomenology and its relationship to relativistic mean field theory (RMFT) calculations are given.

ISSN:0094-243X    

DOI:10.1063/1.35007

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The Wronskian of the Dirac equation is considered for nucleon‐40Ca scattering. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.35008

出版商:AIP    

年代:1985

数据来源: AIP