The cross-section of the 10B(n,α)7Li reaction measured in the MeV energy range

The excitation function of the 10B(n,α)7Li reaction was measured between 1.5 and 5.6 MeV within the frame of the IAEA Coordinated Research Project (CRP) on “Improvement of the Standard Cross Sections for Light Elements”. An ionisation chamber and signal digitisation were used for the spectrometry of the reaction products, which were forwards emitted by bombarding a thin boron target with neutrons produced at the IRMM Van de Graaff accelerator. The neutron flux was determined by measuring the backwards emitted fission fragments from a 238U sample mounted in a back-to-back geometry relative to the boron target. The highlight of this study was the discovery of the kinematic effect of particle leaking, which is very important for the accurate determination of the number of the boron reaction events. The experiment is described and the results are discussed and compared with evaluations and experimental data of other groups.