Gheisha





Simulation of Nuclear Effects in High Energy Hadron-Nucleus Collisions

The simulation of particle production in high energy hadron-nucleus collisions is studied in the framework of the GHEISHA code, which was the heart of the old Fortan IV based Gheisha Detector Simulation program (1978 - 1985), then adopted in the Fortran 77 based GEANT3 program (1985 - 1990) and now completetly rewritten in C++ in order to fulfill the requirements of the Object-Oriented GEANT4 simulation tool (1995 - 2000). The intranuclear cascading model for high energy interactions is reviewed. Comparisons with experimental data on multiplicity distributions and cross sections will be shown, for the Fortran code in GEANT3 and as well for the C++ code in GEANT4. The conclusion will be, that GHEISHA is still alive after more than 20 years.

In the GHEISHA code high energy hadron nucleus interactions are simulated by sampling distributions functions of

  • the combined multiplicity w(a,n1,n2,...,ni,...) for all particles i, i = +, -, 0, p, n,..... including the correlations between them;
  • the additive quantum numbers (energy E, charge Q, strangeness S and baryon number B) in the whole phase space region;
  • evaporation and nuclear fission.
A universal function f(b,x/pT,mT) is used for the distribution of the additive quantum numbers, with Feynman variable x, the transverse momentum pT and transverse mass mT. a and b are parameter vectors, which depend on the particle type of the incoming beam and the atomic number A of the target. Any dependence on the beam energy is completely restricted to the multiplicity distribution and the available phase space. The underlying model for establishing the parametrizations is a multi chain model, where the beam particle undergoes multiple collisions with nucleons inside the nucleus; each of these interactions form a fragmenting chain and one recoil nucleon. All produced oarticles are able to reinteract, thus developing an intranuclear cascade. The formation zone concept is taken into account, which means that the produced particles needs some time and thus also some range to hadronize into real particles. It is, however, important to realize that there are numerous tunable parameters introduced in all steps of the GHEISHA simulation. This restricts the use of this code as a generator for understanding the physics of hadron nucleus interactions, since it is not always clear how to relate the parameters to physical quantities. On the other hand a precise simulation of minimum bias events is possible. For the tuning of the parameters a database consisting of results from hadron nucleus scattering experiments and from colarimetric test beam is used.
A few of this comparions between data, GEANT3 and GEANT4 results will be shown on this page. Every plot will be discussed in a short form, for details we refer to the original publication of the experimental data. More of this tests will follow, so it may be a good idea to visit this page again from time to time.

Rapidity and Transverse Momentum Structure
in + and K+ Collisions
with Al and Au Nuclei at 250 GeV/c.
N.M.Agababyan et al., EHS-NA22 Collaboration

Multiparticle production in proton-nucleus collisions
at 360 GeV/c using the European Hybrid Spectrometer
EHS-RCBC Collaboration, J.L.Bailly et al.
Z.Phys.C35,301(1987)

Negative binomials and multiplicity distributions
in 250 GeV/c K+ and + interactions on Al and Au nuclei
EHS-NA22 Collaboration, I.V.Ajinenko et al.
Z.Phys.C46,569(1990)

Transverse momentum distributions of neutral pions
from central and peripheral 16O + Au Collisions at 200 A GeV.
WA80 Collaboration, R. Albrecht et al.
Z.Phys.C47,367(1990)

Inclusive particle production in 400 GeV/c pp-interactions.
M.Aguilar-Benitez et al., CERN-PPE/91-21 (1991)

Inclusive particle production of 0- mesons in p, Kp and p collisions
at energies around 100 GeV.
Omega Photon Collaboration, R.J.Apsimon et al.,
Z.Physik.C52,397(1991)
Angular dependence of high-transverse momentum
inclusive 0- production in p and pp interactions
G.Donaldsen et al., Phys.Lett 73B,375(1978)

Inelastic Hadron Nucleus Interactions at 20 and 37 GeV/c
M.A.Faessler et al., Nuclear Physics B157,1(1979)
The Nuclear Response in High-Energy Hadron-Nucleus Interactions
K.Braune et al., Z.Phys.C13,191(1982)

Dependence of multiplicity and rapidity distributions
on the number of projectile collisions
in 200 GeV/c proton-nucleus interactions
C.D.Marzo et al., Physical Review D29,2476(1984)

Single variable description of inclusive spectra
A.Biallas and L.Stodolsky, Physical Review D13,1199(1976)
Scaling laws for energy inclusive measurements
W.Ochs and L.Stodolsky, Phys.Lett.69B,225(1977)
The energy profile of a proton jet.
H.Fesefeldt, W.Ochs and L.Stodolsky, Phys.Lett.74B,389(1978)
Clustering invariant quantities and Energy Inclusive Measurements
W.Ochs, Physica Scripta 19,127(1979)
Energy and Quantum Number Flow
in K+p and +p interactions at 32 and 70 GeV/c
I.V.Ajinenko et al., Z.Phys.C16,291(1983)
Charge and Energy Flow
in +p, K+p and pp at 250 GeV/c.
I.V.Ajinenko et al., Z.Phys.C43,37(1989)

Cumulative Particle Production in p20Ne Interactions at 300 GeV.
B.S.Yuldashev et al., WISC-EX-90-310(1990)
Production in p20Ne and pN Interactions at 300 GeV.
B.S.Yuldashev et al., WISC-EX-90-309(1990)
Neutral Strange Production in p20Ne and pN Interactions at 300 GeV.
B.S.Yuldashev et al., WISC-EX-90-308(1990)

Characteristics of high energy hadron-nucleus interactions:
protons from the target and their correlations.
W.D.Shephard et al., Talk given at Conference (?).

Production of slow singly charged fragments
in 200 GeV/c hadron nucleus interactions.
R.Albrecht et al., Z.Phys.C57,37(1993).

Study of intranuclear collision effects in interactions
of K+/+ mesons with Al and Au nuclei at 250 GeV/c.
EHS-NA22 Collaboration, N.M.Agababyan et al., Z.Phys.C56,371(1992).

0 and meson production in +p and K+p collisions at 250 GeV/c
EHS-NA22 Collaboration, M.R.Atayan et al., Z.Phys.C54,247(1992).

Meson production in pU, OU and SU interactions at 200 GeV/nucleon.
NA38 Collaboration, M.C.Abreu et al., Z.Phys.C55,365(1992).

Neutral strange particle production in K+ and + collisions
with Al and Au nuclei at 250 GeV/c.
EHS-NA22 Collaboration, F.Botterweck et al., Z.Phys.C55,373(1992).