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Manuscript Title: A microcanonical model of hot nuclei.
Authors: A.R. DeAngelis, D.H.E. Gross
Program title: MCFRAG
Catalogue identifier: ACNH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 76(1993)113
Programming language: Fortran.
Computer: CONVEX C-240.
Operating system: UNIX.
RAM: 1900K words
Word size: 32
Keywords: Nuclear physics, Nuclear disassembly, Statistical Fragmentation, Heavy ion collisions, Microcanonical, Thermodynamics.
Classification: 17.7.

Nature of problem:
Recently it has been shown experimentally that highly excited nuclei will deexcite by fragmentation into one or more heavy pieces. New detectors enable experimentalists to measure exclusive quantities, including fluctuations and correlations. It is desirable to have models of this process capable of generating a large sample of events covering a wide region of the relevant phase space.

Solution method:
The decay of the excited nucleus can be calculated using statistical models. In our model we explicitly compute the probability (weight) of different decay channels. Using a Metropolis Monte Carlo algorithm we generate millions of theoretical events in proportion to their weights. Energy, mass and charge are exactly conserved in every event.

Our code assumes a statistical distribution, so it is applicable to thermalized systems as well as collections of systems which represent a statistical ensemble. These assumptions are generally valid in an energy range of about 1-20 MeV/nucleon.

Running time:
Approximately 0.35 CPU-seconds per 1000 fragments produced without Coulomb trajectories on a VAX 6000-510, 0.20 CPU-seconds per 1000 fragments on a Convex C-240 (unvectorized).