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

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Published: 2004

Total Pages: 5

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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.

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Published: 2001

Total Pages: 4

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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


Inelastic Cross Sections from Gamma-ray Measurements

Inelastic Cross Sections from Gamma-ray Measurements

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Published: 2010

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Measurements of gamma rays following neutron induced reactions have been studied with the Germanium Array for Neutron-induced Excitations (GEANIE) at the Los Alamos Neutron Science Center (LANSCE) for many years. Gamma-ray excitation functions and coincidence studies provide insight into nuclear reaction mechanisms as well as expanding our knowledge of energy levels and gamma-rays. Samples studied with Ge detectors at LANSCE range from Be to Pu. Fe, Cr and Ti have been considered for use as reference cross sections. An overview of the measurements and efforts to create a reliable neutron-induced gamma-ray reference cross section will be presented.


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

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Published: 2006

Total Pages: 26

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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.


Gamma-Ray Production Cross Sections for Iron and Aluminum

Gamma-Ray Production Cross Sections for Iron and Aluminum

Author: Victor J. Orphan

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Published: 1971

Total Pages: 182

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The Linac time-of-flight technique has been used to measure the differential gamma-ray production cross sections for neutron interactions with natural Fe and Al in the neutron energy range 0.9 to 17 MeV. Ring-shaped scattering samples were placed at the terminus of a 51-meter neutron flight path at the Gulf Radiation Technology Linac facility. The gamma rays from (n, x gamma) reactions were detected with an 80-cc Ge(Li) detector placed on the centerline of the flight path so as to observe gamma rays emitted from the samples at an angle of about 125 degrees with respect to the incident neutron beam. This angle minimized the effect of gamma-ray anisotropy on the determination of the angle-integrated cross section. (Author).