Photoexcitation mechanisms and photofission cross section for Bi by 100–300 MeV quasi-monochromatic photons

Mass and energy dependence of pion-induced fission

“…The (6) 95 (14) 330 (40) 483 (128) rise in Ps for Sn from stopped to energetic re-is much steeper than that provided by the high excitation model. Photofission probabilities of Bi over a wide range of photon energies and inferred excitations E showed a saturation at higher energies, with Py ceasing to rise as naively expected [28]. Detailed statistical calculations confirm that such a saturation is predicted through an intranuclear cascade calculation [29].…”

“…This presentation has been used for photofission probabilities [28] and for other beams [24]. Our data are plotted in this fashion in Fig.…”

“…4 are plotted against the reciprocal of the square root of the total pion energy, kinetic, rest mass, and Coulomb. Bismuth photofission data of Guaraldo [-28] are shown by crosses, using the photon energy for E. The solid lines for the photofission data show the effect suggested in [28]. These are traced as parallel dashed curves for comparison to the pion data for Bi and Sn…”

Photofission of209Bi,232Th and238U in the quasi-deuteron energy region

“…The validity of (20) for nuclei like Th and U needs further verification. Also for Bi the applicability of (20) is questionable [12,19].…”

“…High energy photofission of heavy nuclei (Z2/A > 30) up to and above the pion threshold by quasi-monochromatic photons has been extensively discussed in recent reports of the Catania-Frascati-Moscow collaboration [12,13]. They have found, that, defining the ratio ofphotofission to photoabsorption cross section Pj= crj (e,)/.aus (E,), * Dottorato di ricerca in Fisica, Universitfi consorziate di Cagliari e Torino, Italy…”