Neutron Total Cross-Section Measurements of ⁹Be, ^10,11B, and ^12,13C from 1.0 to 14 MeV Using the ⁹Be(d,n)¹⁰B Reaction as a “White” Neutron Source

High-resolution and high-accuracy total cross sections of ⁹Be, ^10,11B, and ^12,13C have been measured from 1.0 to 14 MeV. The Los Alamos Scientific Laboratory Tandem Accelerator was used to produce a “white” source of neutrons by stopping a pulsed beam of 15-MeV deuterons in a thick beryllium target. The neutron energy resolution (full-width at half-maximum) achieved in kiloelectron volts is given by 1.4E(MeV)^3/2, and the accuracy of the neutron energy scale in kiloelectron volts is given by ±E(MeV) [0.00744E(MeV) + 0.01592]^1/2. The statistical uncertainties in the transmission vary from 0.5 to 2%, and the systematic error in the transmission is estimated to ±1.7%. The cross sections are compared with those in the ENDF/BIV library where appropriate. The high statistical accuracy of the ¹¹B data, for example, has revealed fine structure at high excitation energy (around 9 MeV), which correlates with the structure observed in charged particle measurements on the same compound nucleus. There are also indications of additional structures that have not been seen previously in the ¹²B compound nucleus at this excitation energy.