Cross section measurement for the ~(10)B(n,t2α) three-body reaction at 4.0, 4.5, and 5.0 MeV. II. Experimental setup and results

摘要

Cross sections of the ~(10)B(n,t2α) three-body reaction were measured at E_n= 4.0, 4.5, and 5.0 MeV using a twin gridded ionization chamber and a thin-film ~(10)B sample. The present paper is the second part of the work. A digital data-acquisition system was developed for the gridded ionization chamber based on the waveform digitizer. A thin-film ~(10)B sample was designed and prepared. The number of ~(10)B atoms in the sample was determined by the relative method using the thermal neutron induced ~(10)B(n_(th),α)~7Li and 6Li(n_(th),t)~4He reactions with a ~6LiF sample as the reference. The measurement of the ~(10)B(n,t2α) reaction was performed at the 4.5 MV Van de Graaff accelerator of Peking University. In the measurement, the double-coincidence technique was used, which involves the forward-backward and the grid-anode coincidence. In the data processing, the effective event area in the forward two-dimensional spectrum and the time window in the drift-time spectrum were employed to reject the background events. Cross sections of the ~(10)B(n,t2α) and ~(10)B(n,α)7Li reactions were obtained. The present results are compared with the data of existing measurements and evaluations.