K. Kumagai

Advanced focal plane detector with improved particle identification

Abstract A focal plane detector for a magnetic spectrograph was developed, which consists of two position counters, two energy-loss counters, and large-area silicon detectors. The energy, energy-loss and time-of-flight signals from this detector system depend on the particle incident angle into the counter and the position on the focal plane. Corrections to the angle and position dependence have improved the resolutions of these signals significantly and given unambiguous particle identification for studying reactions which have very small yields under intense backgrounds. The incident angle into the focal plane detector is found to be very useful to determine the scattering angle of reaction products.

Determination of the sub-threshold contribution in the 13C(α,n)16O reaction for the neutrons of s-process

Abstract A large enhancement of the 13 C(α,n) 16 O reaction cross section at low energy limit due to the sub-threshold state in 17 O has been predicted, explaining the neutron source of s-process nucleosynthesis. By the 13 C( 6 Li,d) 17 O transfer reaction, we had deduced the resonance strength of the state. Contrary to the predictions, the sub-threshold state was found to have very small contribution to the astrophysical S factor.