Status report to the DOE Nuclear Data Committee. [Research at ORNL]

Abstract

The report was mostly generated through a review of abstracts of work completed to the point of being subjected to some form of publication in the open literature, formal ORNL reports, ORNL technical memoranda, progress reports, or presentation at technical conferences. As much as possible we have reproduced the complete abstract of the original publication with only minor editing. In a few cases progress reports were written specifically •for this publication. The editors have selected the materials to be included in this report on the basis of perceived interests of DOE Nuclear Data Committee members and cannot claim completeness. A. CROSS SECTION MEASUREMENTS 1. Gamma-Ray Production Data a. The Na(n,xy} Reaction Cross Section for Incident Neutron Energies Between 0.2 and 20.0 MeV* (D. C. Larson and G. L. Morgan) Differential cross sections for the neutron-induced gammaray production from sodium have been measured for incident neutron energies between 0.2 and 20.0 MeV. The Oak Ridge Electron Linear Acceleratrir (ORELA) was used to provide the neutrons and a Nai spectrometer to detect the gamma rays at 125°. The data presented are the double differential cross section, d 2 cr/d~dE, for gamma-ray energies between 0.35 and 10.6 MeV for coarse intervals in incident neutron energy. The integrated yield of gamma rays of energies greater than 350 keV with higher resolution in the neutron energy is also presented. Finally, the excitation function for the 440-keV gamma ray is given for incident neutron energies between 400 keV and 20 MeV. The experimental results are compared with the Evaluated Nuclear Data Files (ENDF). b. Absolute Measurement of Cross Section** D. K. McConnell) 0.478-MeV and J. W. Measurements were performed using a Ge(Li) detector at 125° to a neutron beam whose energy ranged from 0.5 to 5.0 MeV. The neutron flux was measured using a proton recoil detector based on polyethylene foils and a silicon surface barrier detector.• The cross sections are accurate to a relative error of about •6% and an absolute uncertainty of about 8%. This isotropic gamma.-ray has potential as a secondary standard for inelastic scattering (n,n•y) cross sections.