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Manuscript Title: HIJING 1.0: a Monte Carlo program for parton and particle production in high energy hadronic and nuclear collisions.
Authors: M. Gyulassy, X.-N. Wang
Program title: HIJING 1.0
Catalogue identifier: ACVR_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 83(1994)307
Programming language: Fortran.
Computer: SPARCstation ELC.
Operating system: SUNOS 4.1.1.
RAM: 90K words
Word size: 32
Keywords: Particle physics, Elementary, Event simulation, Relativistic heavy ion Collisions, Quark-gluon plasma, Partons, Hadrons, Nuclei, Jets, Minijets, Particle production, Parton shadowing, Jet quenching.
Classification: 11.2.

Nature of problem:
In high-energy hadron and nuclear interactions, multiple minijet production becomes more and more important. Especially in relativistic heavy-ion collisions, minijets are expected to dominate transverse energy production in the central rapidity region. Particle production and correlation due to minijets must be investigated in order to recognize new physics of quark-gluon plasma formation. Due to the complication of soft interactions, minijet production can only be incorporated in a pQCD inspired model. The parameters in this model have to be tested first against the wide range of data in pp collisions. When extrapolating to heavy-ion collisions, nuclear effects such as parton shadowing and final state interactions have to be considered.

Solution method:
Based on a pQCD-inspired model, multiple minijet production is combined together with Lund-type model for soft interactions. Within this model, triggering on parge PT jet production automatically biases toward enhanced minijet production. Binary approximation and Glauber geometry for multiple interaction are used to simulate pA and AA collisions. A parametrized parton distribution function inside a nucleus is used to take into account parton shadowing. Jet quenching is modeled by an assumed energy loss dE/dz of partons traversing the produced dense matter. A simplest color configuration is assumed for the multiple jet system and Lund jet fragmentation model is used for the hadronization.

The program is only valid for collisions with c.m. energy (sqrt(s)) above $ GeV/n. For central Pb+Pb collisions, some arrays have to be extended above sqrt(s)=10 TeV/n.

Unusual features:
The random number generator used in the program is a VAX VMS system subroutine RAN(NSEED). When compiled on a SPARCstation, -xl flag should be used. This function is not protable. Therefore, one should supply a random number generator to replace this function whenever a problem is encountered.

Running time:
The running time largely depends on the energy and the type of collisions. For example (not including initialization):
 pp                sqrt(s)=200 GeV   ~ 700 events/min.                   
 pp                sqrt(s)=1.8 TeV   ~ 250 events/min.                   
 Au + Au(central)  sqrt(s)=200 GeV/n ~ 1 event/min.                      
 Pb + Pb(central)  sqrt(s)=6.4 TeV/n ~ 1 event/10 min.