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

Abstract

The photoneutron cross sections of ${\mathrm{Be}}^{9}$ and ${\mathrm{C}}^{13}$ 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 $\mathrm{Be}(\ensuremath{\gamma}, n)$ cross section near threshold is in agreement with experiment. Cross sections for transitions to both the ${s}_{\frac{1}{2}}$ and ${d}_{\frac{3}{2}}$ final states in ${\mathrm{C}}^{12}$ are calculated for $\ensuremath{\gamma}$-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 ${\mathrm{C}}^{12}$ 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.