8 Matching Results

Search Results

Advanced search parameters have been applied.

Measurement of the E1 strength function of {sup 11}Be

Description: The authors have investigated the E1 strength function of {sup 11}Be by Coulomb excitation and measurement of the subsequent projectile photon decay. The photons were measured in a wall of BaF{sub 2} detectors. The authors have used the virtual photon method to extract the photoabsorption cross section and hence the dipole strength function. They compare the findings with sum rule predictions. This is a first example of techniques they will extend to heavier mass nuclei.
Date: November 1, 1998
Creator: Varner, R.L.; Gan, N. & Beene, J.R.
Partner: UNT Libraries Government Documents Department

Reactions of halo states: Coulomb excitations

Description: Coulomb dissociation is a relatively clean probe of the structures of one- and two-nucleon halo nuclei. This is illustrated by the breakup of {sup 11}Be, {sup 8}B and {sup 11}Li and is discussed in terms of first order perturbation theory. First-order dipole transitions usually dominate the Coulomb dissociation but quadrupole transitions are not insignificant for a proton halo (e.g. {sup 8}B). Higher-order processes can also distort the observables, such as the momentum distributions of the fragments and the excitation energy spectrum.
Date: September 1, 1997
Creator: Esbensen, H.
Partner: UNT Libraries Government Documents Department

Momentum distributions in breakup reactions

Description: Measurements of the breakup reactions: {sup 11}Be {yields} {sup 10}Be+n and{sup 8} {yields} {sup 7}Be+p are analyzed in a single-particle description. The signature of various structure properties associated with the valence nucleon axe discussed, as well as the significance of the different reaction mechanisms, namely Coulomb dissociation, stripping and nuclear induced diffraction.
Date: February 1, 1996
Creator: Esbensen, H.
Partner: UNT Libraries Government Documents Department

Use of gamma rays from the decay of 13.8-sec {sup 11}Be to calibrate a germanium gamma ray detector for measurements up to 8 MeV

Description: Gamma rays from the {beta}{sup {minus}} decay of 13.8-sec {sup 11}Be can be used for Ge photon detector efficiency calibration at energies > 2--3 MeV that are not accessible using more conventional gamma-ray sources. {sup 11}Be is generated by the {sup 11}B(n,p){sup 11}Be reaction using a boron oxide sample and 14-MeV neutrons from a neutron generator. The short-lived activity is carried to the detector using a pneumatic transport system. This paper describes the experimental method used and provides an example of a Ge detector efficiency calibration curve augmented by this technique.
Date: June 1, 1997
Creator: Ikeda, Y.; Maekawa, F.; Uno, Y.; Kasugai, Y.; Kawade, K. & Smith, D.
Partner: UNT Libraries Government Documents Department

ENDF/B-VI nuclear data evaluations for fusion applications

Description: The next release of the ENDF/B data library planned for 1989 contains improved data evaluations of interest to the fusion neutronics community. New data formats permit inclusion of energy-angle correlated particle emission spectra and recoil nucleus energy spectra. Enhanced formats for covariance information have been developed. Many new isotopic evaluations will lead to improved energy conservation and kerma factor calculations. Improved nuclear model calculations will provide reliable particle emission data where experimental information is sparse. Improved Bayssian fitting codes will provide more accurate evaluations for data rich reactions such as Li(n,nt)..cap alpha... All of the most important fusion material evaluations contain these new features. 32 refs., 8 figs.
Date: January 1, 1988
Creator: Dunford, C.L.; Larson, D.C. & Young, P.G.
Partner: UNT Libraries Government Documents Department

First forbidden beta decay in light nuclei

Description: Beta decay matrix elements for the operators sigma dot del and sigma dot r are calculated for eight J/sup +/ ..-->.. J/sup -/ or J/sup -/ ..-->.. J/sup +/ beta transitions. Results using harmonic oscillator wave functions differ markedly from those using more realistic Woods-Saxon wave functions. A substantial contribution to the sigma dot del matrix elements from pion exchange currents is required to reproduce the experimental beta decay rates. 15 references.
Date: January 1, 1984
Creator: Millener, D.J. & Warburton, E.K.
Partner: UNT Libraries Government Documents Department