Recent experimental studies of the total photonuclear cross-sections between 30 and 140 MeV

Abstract

Recent experimental data concerning the total photonuclear cross-section from 30 to 140 MeV have recently been obtained at the ALS linac of Saclay by means of quasi-monochromatic photons produced by in-flight annihilation of positrons. This total photonuclear cross-section was obtained in the case of heavy nuclei as the sum of all the measured cross-sections for the partial photoneutron decay channels. The integrated cross-section, integrated up to 140 MeV, shows an enhancement factorK≈0.76 above the classicalE1 sum rule. This largeK value is well explained by the effect of the tensor force and the tensor correlations. The dependence of σ(γ, tot;Eγ) upon the energyEγ agrees well with the new quasi-deuteron models.