Photoneutron Disintegration Below the Giant Resonance: Beryllium-9 and Carbon-13

Abstract

The photoneutron cross sections of Be d and C 13 have been calculated. A single particle model is used to describe the incident bound and final continuum distorted states. Using reasonable potential well parameters, the calculated Be(y,») cross section near threshold is in agreement with experiment. Cross sections for transitions to both the s\ and d\ final states in C 12 are calculated for y-ray energies below 10 Mev. The calculated cross section is three times as large as the measured value at 6.4 Mev. The thermal neutron capture cross section in C 12 was calculated and the error persisted in magnitude and sign. Origins of the inaccuracies in the model are discussed. Angular distribution and polarization formulas are presented.

Low–energy photodisintegration of 9Be and α+α+n→9Be +γ reactions at astrophysical conditions

“…As in the previous work (e.g. [20]) we confine ourselves to an s-wave relative n 8 Be motion, i.e., with 1/2 + continuum states.…”

“…[22]. In that work a two channel 8 Be+n model of the ground state of 9 Be was introduced to cure the single-particle description [20] of photodisintegration. The 8 Be subsystem was allowed to be in the ground and first excited state, and that led to the reduction factor of 0.5 or 0.6 in the cross section depending on the assumptions.…”