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Manuscript Title: LUCIAE 3.0: A new version of a computer program for Firecracker Model and rescattering in relativistic heavy-ion collisions.
Authors: A. Tai, B.-H. Sa
Program title: LUCIAE version 3
Catalogue identifier: ADBS_v2_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 116(1999)353
Programming language: Fortran.
Computer: HP Model 715/100.
Operating system: HP-UX 10.20.
RAM: 90K words
Word size: 32
Keywords: Particle physics, Elementary, Phase space, Relativistic nucleus Nucleus collisions, Monte carlo, Collective effects, Colour rope, Effective string tension, Rescattering.
Classification: 11.2.

Nature of problem:
The experiments of relativistic pA and AA collisions reveal that high energy heavy-ion collisions have some features which can not be understood by the simple superposition of independent nucleon-nucleon collisions. They indicate clearly that the collective effects are important in the relativistic pA and AA collisions. Formation of a QGP is often suggested to be a candidate to account for some of these collective effects. Could we understand those new features in pA and AA collisions by conventional physics (on which LUCIAE is based)? What is the limit of a model to explain the experimental data without the formation of QGP within a reasonable margin of flexibility of the model? The Monte-Carlo generator, LUCIAE is built in an attempt to answer these questions.

Solution method:
When many strings or colour dipoles are formed in relativistic pA and AA collisions, it is natural to ask if there is some interaction among those strings close by so that both the emission of gluonic bremsstrahlung as well as the fragmentation properties can be affected by the large common energy density of the string cluster (Colour Rope). The Firecracker Model is developed to study such a collective effect. Moreover, many hadrons are produced in a small space-time volume through fragmentation of these strings, which implies that they will interact with each other and with the surrounding cold spectator matter. The rescattering effect on the distributions of the final state hadrons is also included in LUCIAE program.

Summary of revisions:
  1. The initialization of hadrons in the space-time is modified.
  2. Much more inelastic channels and their reverse reactions have been included in the rescattering sector.
  3. The annihilation of pbar and Alphabar in nuclear matter is taken into account.
  4. The effect of firecracker gluons on the fragmentation of a string has been included.
  5. The sizes of arrays have been enlarged. The values of a few parameters are adjusted and a few bugs are fixed.

At very high energies (sqrt(s) in the TeV range), especially for collisions of massive nuclei, certain arrays need to be expanded to accommodate the large number of particles produced.

Running time:
Depends on the type of collision and energy. Three examples of central collisions (b=0) running on a HP Station:
 32S + 32S       plab = 200 A GeV/c:  ~0.6 minutes/event                 
 207Pb + 207Pb   plab = 158 A GeV/c:  ~9 minutes/event                   
 197Au + 197Au   sqrt(s) = 200 GeV:   ~80 minutes/event