Manifestation of transient effects in fission induced by relativistic heavy ion collisions
Mar, 2004
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Abstract:
We examine the manifestation of transient effects in fission by analysing experimental data where fission is induced by peripheral heavy-ion collisions at relativistic energies. Available total nuclear fission cross sections of 238U at 1 A GeV on gold and uranium targets are compared with a nuclear-reaction code, where transient effects in fission are modelled using different approximations to the numerical time-dependent fission-decay width: a new analytical description based on the solution of the Fokker-Planck equation and two widely used but less realistic descriptions, a step function and an exponential-like function. The experimental data are only reproduced when transient effects are considered. The deduced value of the dissipation strength depends strongly on the approximation applied for the time-dependent fission-decay width and is estimated to be of the order of 2x10**21 s**(-1). A careful analysis sheds severe doubts on the use of the exponential-like in-growth function largely used in the past. Finally, we discuss which should be the characteristics of experimental observables to be most sensitive to transient effects in fission- 24.10.-i
- 24.75.+i
- 25.75.-q
- Nuclear fission
- Transient effects
- Dynamical nuclear deexcitation code
- Time-dependent fission-decay width
- Relativistic nucleus–nucleus collisions
- Comparison with experimental total nuclear fission cross sections
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