Fast Decision in Favor of the Slow Fission Process

Authors :: A. Letourneau
C.-M. Herbach
J. Galin
V. Tishchenko
Frank Goldenbaum
D. Hilscher
W. U. Schröder
U. Jahnke
Grand Accélérateur National d'Ions Lourds (GANIL)
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Source :: Physical Review Letters, Physical Review Letters, 2005, 95, pp.162701. ⟨10.1103/PhysRevLett.95.162701⟩, Physical review letters 95, 162701 (2005). doi:10.1103/PhysRevLett.95.162701
Publication Year :: 2005
Publisher :: American Physical Society (APS), 2005.
Abstract: The fission probability P{sub f} of highly excited targetlike nuclei produced in reactions of 2.5 GeV protons on Au, Bi, and U was studied as a function of excitation energy E* whereby E* is deduced eventwise from the multiplicity of evaporated light particles. At the highest E* of 1000 MeV P{sub f} amounts to {approx_equal}30% with all 3 target nuclei irrespective of the initial fissility. Statistical-model calculations satisfactorily reproduce the observed evolution of P{sub f} with E* - provided that no extra transient delay is introduced. Fission thus is decided upon very fast and early in the long deexcitation chain towards scission which comprises as much as {approx_equal}80% of all evaporated alpha particles.