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Manuscript Title: LUCIFER: a Monte Carlo for high-p(transverse) photoproduction.
Authors: G. Ingelman, A. Weigend
Program title: LUCIFER VERSION 2.2
Catalogue identifier: AAXH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 46(1987)241
Programming language: Fortran.
Computer: IBM 3084Q.
Operating system: MVS XA.
RAM: 680K words
Word size: 32
Keywords: Particle physics, Photo-nucleon Photo-gluon fusion, Prompt photons, Monte carlo simulation, Event simulation, Elementary, Collisions, High-p(transverse) Particles, Higher twist, Hadronization, Prompt mesons, Low-p(transverse) vdm.
Classification: 11.2.

Subprograms used:
Cat Id Title Reference
AAFP_v1_0 JETSET 6.2 CPC 39(1986)347
AAFP_v2_0 JETSET 6.3 CPC 43(1987)367

Nature of problem:
Low-p(transverse) interactions of high energy photons with nuclear targets are described by the vector meson dominance model (VDM) in which the photon appears as a virtual vector meson (rho0 dominantly) which interacts strongly with the nucleon. High-p(transverse) interactions, on the other hand, occur through the point-like interaction of the photon with a constituent quark in the nucleon. This latter process is particularly interesting as a clean probe of quark dynamics within QED and QCD.

Solution method:
For high p(transverse) interactions, perturbatively calculated matrix elements for the QED and QCD Compton processes, the photon-gluon fusion process and prompt meson production through the higher twist mechanism are used. Low-p(transverse) events are treated as p rho-nucleon interactions using a simple VDM approach. The Lund string model is used for the fragmentation of colour charged partons into final state hadrons such that complete events are simulated which facilitates easy comparison with any experimental observable.

Restrictions:
For each subprocess, only the leading order matrix elements are used, but some higher order correction effects (K-factors) can be reduced by an optimal scale choice.

Unusual features:
A random number generator and the ordinary gamma function are required.

Running time:
The time needed to generate one event is 0.02 to 0.03 seconds depending on energy and p(transverse) scale.