Determination of the 6Li(n,t)4 He Standard Cross Section

Abstract

The neutron total and differential neutron elastic scattering cross sections of 6Li were measured at the Van de Graaff with monoenergetic neutron beam and time-of-flight techniques in the neutron energy range from 80 keV to 3.0 MeV, yielding the angle integrated 6Li(n,t)4He cross section from 80 keV to 500 keV with an accuracy ranging from 2.5% to 6.5%. Angular distributions of the tritons with respect to the incident neutron beam direction were measured with the pulsed white spectrum neutron source GELINA in the neutron energy range from 10 eV to 330 keV. Both experiments were combined to give the absolute differential 6Li (n,t)4He cross section in the debated region of the resonance. A comparison of recent cross section shape measurements in the resonance region, which were normalized at low neutron energies to the 6Li(n,t)4 He cross section itself, shows good agreement with the present cross section measurements for which the absolute scale does not depend from other experiments. A further comparison of the present differential (n,t) cross section for zero and 180 degrees shows excellent agreement with the same quantity determined by Brown et al. from the measurement of the zero degree laboratory 6Li yield of the inverse reaction 3H(4He,6Li)n, which was normalized relative to the 3H-4He elastic scattering cross sections.