Fission of doubly even actinide nuclei induced by direct reactions

TLDR

The authors measured fission probability distributions for a range of doubly even actinide nuclei using ($t,pf$), ($t,\alpha f$), ($t,t' f$), ($p,p' f$), ($^3$He,df), and ($^3$He,$\alpha f$) reactions at 15–24 MeV and analyzed the data with a statistical model of resonant penetration of a double‑humped fission barrier. Subbarrier vibrational resonances were observed in $^{234}$Th, $^{236,238,240}$U, $^{242}$Pu, and $^{250}$Cm, and the study extracted the heights and curvatures of the two fission‑barrier peaks for Th, U, Pu, and Cm isotopes, comparing them with theoretical predictions.

Abstract

Fission probability distributions have been measured by ($t,pf$), ($t,\ensuremath{\alpha}f$), ($t,{t}^{\ensuremath{'}}f$), ($p,{p}^{\ensuremath{'}}f$), ($^{3}\mathrm{He},df$), and ($^{3}\mathrm{He},\ensuremath{\alpha}f$) reactions with bombarding energies of 15, 16, 20, 22.5, 24, and 24 MeV, respectively. Using targets of $^{230,232}\mathrm{Th}$, $^{231}\mathrm{Pa}$, $^{234,236,238}\mathrm{U}$, $^{237}\mathrm{Np}$, $^{240,242}\mathrm{Pu}$, $^{243}\mathrm{Am}$, and $^{248}\mathrm{Cm}$ the fission decay of $^{230,232,234}\mathrm{Th}$, $^{232,236,238,240}\mathrm{U}$, $^{238,242,244}\mathrm{Pu}$, and $^{244,248,250}\mathrm{Cm}$ was studied. Subbarrier vibrational resonances were observed for $^{234}\mathrm{Th}$, $^{236,238,240}\mathrm{U}$, $^{242}\mathrm{Pu}$, and $^{250}\mathrm{Cm}$. The results are analyzed with a statistical model which involves resonant penetration of the double-humped fission barrier. Estimates of the heights and curvature of the two peaks in the fission barrier are obtained for Th, U, Pu, and Cm isotopes and these values are compared with various theoretical calculations.[NUCLEAR REACTIONS FISSION measured fission probabilities, ${E}^{*}\ensuremath{\le}7.5$ MeV for $^{230,232,234}\mathrm{Th}$, $^{232,236,238,240}\mathrm{U}$, $^{238,242,244}\mathrm{Pu}$, $^{244,248,250}\mathrm{Cm}$ using ($t,pf$), ($t,\ensuremath{\alpha}f$), ($t,{t}^{\ensuremath{'}}f$), ($p,{p}^{\ensuremath{'}}f$), ($^{3}\mathrm{He},df$), ($^{3}\mathrm{He},\ensuremath{\alpha}f$) reactions; deduced heights and curvatures for the double-peaked fission barrier for each case.]