Experimental fissility data from photofission reactions of Th-232, U-238, and U-235 nuclei at 52 MeV have been obtained using monochromatic and polarized photon beams and dielectric fission-track detectors. These data, along with literature data for Np-237, U-235,U-238 Th-232, Bi-209, Pb-208, and Yb-174 nuclei have been analyzed within the framework of a simple two-step model for photofission reactions, i.e., absorption of the incident photon by a neutron-proton pair followed by an evaporation-fission competition mechanism for the excited nucleus. For nuclei in the Ta-Np region the trend of calculated fissilities clearly shows shell effects in the vicinity of Pb-208. In the case of U-238 the effect of photon polarization on fission direction has also been studied, and isotropy was observed in the fragment azimuthal distribution.
Tavares, O., TERRANOVA PERSICHELLI, M.l., Casano, L., D'Angelo, A., Moricciani, D., Schaerf, C., et al. (1991). Fission of complex nuclei induced by 52-MeV monochromatic and polarized photons. PHYSICAL REVIEW. C, NUCLEAR PHYSICS, 44, 1683-1686 [10.1103/PhysRevC.44.1683].
Fission of complex nuclei induced by 52-MeV monochromatic and polarized photons
TERRANOVA PERSICHELLI, MARIA LETIZIA;D'ANGELO, ANNALISA;SCHAERF, CARLO;
1991-01-01
Abstract
Experimental fissility data from photofission reactions of Th-232, U-238, and U-235 nuclei at 52 MeV have been obtained using monochromatic and polarized photon beams and dielectric fission-track detectors. These data, along with literature data for Np-237, U-235,U-238 Th-232, Bi-209, Pb-208, and Yb-174 nuclei have been analyzed within the framework of a simple two-step model for photofission reactions, i.e., absorption of the incident photon by a neutron-proton pair followed by an evaporation-fission competition mechanism for the excited nucleus. For nuclei in the Ta-Np region the trend of calculated fissilities clearly shows shell effects in the vicinity of Pb-208. In the case of U-238 the effect of photon polarization on fission direction has also been studied, and isotropy was observed in the fragment azimuthal distribution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
