Cross Section Standards for Neutron-induced Gamma-ray Production in the MeV Energy Range
Cross Section Standards for Neutron-induced Gamma-ray Production in the MeV Energy Range

Author:

Publisher:

Published: 2004

Total Pages: 5

ISBN-13:

DOWNLOAD EBOOK

Gamma-ray cross section standards for neutron-induced reactions are important in enabling the accurate determination of absolute cross sections from relative measurements of gamma-ray production. In our work we observed a need for improvement in these standards. In particular there are large discrepancies between evaluations of the {sup nat}Fe(n, n1'[gamma]) cross section for the 847-keV gamma ray. We have performed (1) absolute cross section measurements, (2) measurements relative to the {sup nat}Cr(n, n1'[gamma]) 1434-keV gamma ray, and (3) comparisons using measured total and elastic scattering cross sections to refine our knowledge of the Fe cross section and the closely linked inelastic channel cross section for Fe. Calculation of integral tests of the cross section libraries may indicate that adjustment of the angular distributions of the neutron elastic and inelastic scattering may be needed.

High-resolution Neutron-induced [gamma]-ray Production Cross Sections for Oxygen and Beryllium for Neutron Energies from 4 to 200 MeV.
High-resolution Neutron-induced [gamma]-ray Production Cross Sections for Oxygen and Beryllium for Neutron Energies from 4 to 200 MeV.

Author:

Publisher:

Published: 2001

Total Pages: 4

ISBN-13:

DOWNLOAD EBOOK

Measurements of discrete gamma-ray spectra from neutron-induced reactions on a Be0 sample have been performed using the broad-spectrum neutron spallation source of the WNR facility at LANSCE. Incident neutron energies were determined by the time-of-flight technique. Two high-purity Ge detectors were used to detect gamma rays in the energy range from 0.150 to 9.0 MeV. Spectra were measured at seven angles. Absolute gamma-ray production cross sections were delermined from the measured neutron fluence and detector efficiencies. A new evaluation of the reaction cross sections has been performed based on this data. GNASH model calculations were performed for 20

Gamma-ray Production Cross Sections in Multiple Channels for Neutron Induced Reaction on 48Ti for En
Gamma-ray Production Cross Sections in Multiple Channels for Neutron Induced Reaction on 48Ti for En

Author:

Publisher:

Published: 2006

Total Pages: 26

ISBN-13:

DOWNLOAD EBOOK

Prompt [gamma]-ray production cross sections were measured on a 48Ti sample for incident neutron energies from 1 MeV to 200 MeV. Partial [gamma]-ray cross sections for transitions in 45−48Ti, 45−48Sc, and 43−45Ca were determined. The observation of about 130 transitions from 11 different isotopes in the present work provides a demanding test of reaction model calculations, and is the first study in this mass region to extract partial [gamma]-ray cross sections for many different reaction channels over a wide range of incident neutron energies. The neutrons were produced by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction [gamma] rays were detected with the large-scale Compton-suppressed GErmanium Array for Neutron Induced Excitations (GEANIE). Event neutron energies were determined by the time-of-flight technique. The [gamma]-ray excitation functions were converted to partial [gamma]-ray cross sections and then compared with model calculations using the enhanced GNASH reaction code. Compound nuclear, pre-equilibrium emission and direct reaction mechanisms are included. Overall the model calculations of the partial [gamma]-ray cross sections are in good agreement with measured values.

Re-measurement of the Neutron-induced Gamma-ray Production Cross Sections for Iron in the Energy Range 850 KeV Less Than Or Equal to E/sub N/ Less Than Or Equal to 20. 0 MeV. [Tables].
Re-measurement of the Neutron-induced Gamma-ray Production Cross Sections for Iron in the Energy Range 850 KeV Less Than Or Equal to E/sub N/ Less Than Or Equal to 20. 0 MeV. [Tables].

Author:

Publisher:

Published: 1976

Total Pages:

ISBN-13:

DOWNLOAD EBOOK

Values of the gamma-ray production cross sections for neutron interactions with iron as reported by previous investigators have differed by as much as a factor of 1.5 or more at neutron energies greater than about 5 MeV. Because of this discrepancy, the measurements were repeated at ORNL using the ORELA as a pulsed source of neutrons with energies between 850 keV and 20 MeV. The data were obtained using a NaI(Tl) gamma-ray spectrometer oriented at an angle of 125° to the incident neutron beam. The sample was positioned in the beam at a distance of 47.35 meters from the neutron source. The resulting data, presented as differential cross sections (d2sigma/d.cap omega.dE) for gamma rays between 0.7 and 10.5 MeV, show good agreement with some previously published data, but are significantly different from previous ORNL measurements for neutron energies greater than 5 MeV.