Spectrum-Integrated Helium Generation Cross Sections for exp 6 Li and exp 10 B in the sigma and Fission Cavity Standard Neutron Fields

摘要

The spectrum-integrated helium generation cross sections for exp 6 Li and exp 10 B have been determined for the Sigma Sigma and Fission Cavity standard neutron fields of the BR1 reactor at the CEN/SCK Laboratories, Mol, Belgium. The cross sections were obtained from helium concentrations measured in numerous small crystalline samples of natural boron, enriched exp 10 B, and enriched exp 6 LiF by precise high-sensitivity mass spectrometry. The measured helium concentrations have been corrected for such factors as neutron self-shielding, flux depression, and flux gradients. The determined cross sections are compared with values calculated from the ENDF/B-V cross section file using theoretical and evaluated spectra for the two facilities. The results of these comparisons are similar to those previously obtained for exp 6 Li and exp 10 B in BIG-10 and CFRMF, and indicate discrepancies between the measured and calculated cross sections. Obtaining acceptable consistency will require changes to the neutron spectrum in Sigma Sigma and to one or both isotope cross sections. (ERA citation 07:050241)