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Manuscript Title: SOS: sequential or simultaneous nuclear multifragmentation.
Authors: J.A. Lopez, J. Randrup
Program title: SOS
Catalogue identifier: ACHA_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 70(1992)92
Programming language: Fortran.
Computer: VAX 11/780.
Operating system: VMS.
RAM: 46K words
Word size: 32
Peripherals: disc.
Keywords: Nuclear physics, Preequilibrium decay, Nuclear collisions, Statistically generated Multifragment events, Sequential and Prompt nuclear decays.
Classification: 17.12.

Nature of problem:
In nucleus-nucleus collisions with beam energies between a few tens and a few hundreds of MeV per nucleon, intermediate-mass fragments are produced by yet poorly understood reaction mechanisms. A possible way to identify the breakup mechanism is by analyzing the kinematical correlations between the produced fragments. Sequential binary splits and simultaneous multifragmentation provide two instructive opposite extremes.

Solution method:
Assuming that the reaction forms a transient compound system, we simulate its decay in two different ways: 1) first by a sequence of binary decays, 2) and then by a prompt breakup into the same fragments, in both cases followed by further particle evaporation. With regard to mass partition, total energy, and fragment excitation energy, the code thus produces identical multifragment channels using these two modes of disassembly, but the two mechanisms lead to different momenta for the individual fragments.

The code is intended for excitation energies of the order of a few MeV per nucleon.

Running time:
Average CPU time for the decay of a source of A=111 at 610 MeV of excitation energy is 4.5 seconds per event on a VAX 11/780.