Cross sections of the 20 Ne( n , α ) 17 O reaction in the 8.9 –11.5 MeV neutron energy region

Abstract

Abstract

Abstract State-resolved cross sections for the 20 Ne( n , α i ) 17 O ( i =0,1,2,3) reactions were measured in the 8.9 –11.5 MeV neutron energy region (11 energy points) at the HI-13 tandem accelerator of the China Institute of Atomic Energy (CIAE). The present measurements extend the data of the α 0 , α 1 , α 2 , and α 3 channels from 9.6 MeV to 11.5 MeV, where previous measurements reported only the summed ( α 0 + α 1 ) cross sections. A twin gridded ionization chamber (GIC) filled with a neon-based gas mixture was used as the charged-particle detection, with the neon gas serving as an active sample. Corrections for detector efficiency, background interference, and neutron-field non-uniformity were performed by combining experimental measurements and detailed Monte Carlo simulations. From 9.6 to 11.5 MeV, the measured 20 Ne( n , α 0 ) 17 O and 20 Ne( n , α 1 ) 17 O cross sections decrease as neutron energy increases, and are generally consistent with those in JENDL-5. The 20 Ne( n , α 2 ) 17 O cross sections are generally above those in JENDL-5, whereas the 20 Ne( n , α 3 ) 17 O cross sections are below those in JENDL-5. In detail, the measured excitation functions exhibit noticeable fluctuations that are not included in JENDL-5. The TALYS-2.2 calculations can describe the measured α 0 , α 1 and α 2 cross sections reasonably, whereas the calculated α 3 cross sections are generally higher than the measured α3 cross sections. The present data provide new state-resolved constraints for modeling the 20 Ne( n , α ) 17 O reaction and improving nuclear data evaluation.