Abstract
Neutron induced reactions on the radioactive nuclei 7Be represent a unique tool for study of the 8Be nuclear structure in the high-energy region. The interactions of thermal neutrons with 7Be is dominated by the strong 7Be(nth,p)7Li reactions. While 8Be in the ground state disintegrates rapidly into two α particles, the alpha decay from the 2− neutron capture state is prohibited because of the parity violation. The study of the 7Be(nth,α)4He reaction (with two 9496 keV α particles) is then a unique tool to study parity violation in strong interactions. The test was carried out on the collimated thermal neutron beam at NPI Rez using the large angle coincidence spectroscopy. The 7Be nuclei were prepared at the ISOLDE facility by implantation of the 60 keV 7Be ions into 5μm Al foil. The results showed that the ratio of the cross sections is σ(p1)/σ(p0) = (1.58 ± 0.06) x 10-2, and in the coincidence measurement simultaneous emission of two 8775 keV α particles is observed. This reaction channel corresponds to a two-stage process comprising transition from the neutron capture state (18991 keV) to an intermediate state by emission of γ photon that is followed by the decay into two alphas. The intermediate state in the highly excited 8Be nuclei is the level at 17640 keV (1+), which is in contrast to the previous reported data. In the experiment no α particles with the energy 9495 keV were observed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
