A long-time chopper for direct measurement of 4He(12C,16O)γ reaction cross section

Direct measurement of the 4 He( 12 C, 16 O) γ reaction cross section by detecting 16 O recoils is in progress at Kyushu University tandem laboratory (KUTL). A long-time chopper (LTC) has been developed to reject backgrounds from 16 O recoils which have time (energy) spread. In the measurement of 4 He( 12 C, 16 O) γ cross section at E cm = 2.4 MeV, LTC was found to reduce the backgrounds by about three orders of magnitude.