Kinetic energy and fragment mass distributions for Pu 240 (s.f.), <mml:mi mathvariant="normal…
1981; American Institute of Physics; Volume: 23; Issue: 5 Linguagem: Inglês
10.1103/physrevc.23.2104
ISSN1538-4497
AutoresHubert Thierens, A. De Clercq, E. Jacobs, D. De Frenne, P. D’hondt, P. De Gelder, A.J. Deruytter,
Tópico(s)Rare-earth and actinide compounds
ResumoEnergy correlation measurements were performed for $^{240}\mathrm{Pu}$(s.f.), $^{239}\mathrm{Pu}({n}_{\mathrm{th}},f)$, and the photofission of $^{240}\mathrm{Pu}$ with 12-, 15-, 20-, and 30-MeV bremsstrahlung. The photofission cross section for $^{240}\mathrm{Pu}$ was determined up to 30 MeV, which permitted the calculation of the average excitation energy $〈{E}_{\mathrm{exc}}〉$ of the compound nucleus. The average total kinetic energy $〈{E}_{k}〉$ of the fragments for $^{240}\mathrm{Pu}$(s.f.) was found to be 1.2\ifmmode\pm\else\textpm\fi{}0.5 MeV higher than for $^{239}\mathrm{Pu}({n}_{\mathrm{th}},f)$. A decrease of $〈{E}_{k}〉$, with $〈{E}_{\mathrm{exc}}〉$, $\frac{d〈{E}_{k}〉}{d〈{E}_{\mathrm{exc}}〉}=\ensuremath{-}0.37\ifmmode\pm\else\textpm\fi{}0.08$, is observed in the photofission of $^{240}\mathrm{Pu}$. Fragment shell effects are present in the kinetic energy and mass distributions for $^{240}\mathrm{Pu}$(s.f.). Changes in the measured distributions with increasing excitation energy of the compound nucleus $^{240}\mathrm{Pu}$ are discussed in the framework of the scission point model of Wilkins et al.RADIOACTIVITY Fission $^{240}\mathrm{Pu}$(s.f.). NUCLEAR REACTIONS Fission $^{239}\mathrm{Pu}({n}_{\mathrm{th}},f)$, $^{240}\mathrm{Pu}(\ensuremath{\gamma},f)$, ${E}_{{\ensuremath{\gamma}}_{max}}=12, 15, 20, 30$ MeV; measured: photofission yields, fragment energies ${E}_{1}$, ${E}_{2}$; deduced: $\ensuremath{\sigma}(\ensuremath{\gamma},f)$, $\frac{N(\ensuremath{\mu},{E}_{k})}{〈{E}_{\mathrm{exc}}({E}_{e})〉}$.
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