[Paper Review] LAQGSM03.03 Upgrade and its Validation

S. G. Mashnik, K. K. Gudima+2 more|ArXiv.org|Sep 12, 2007

Particle accelerators and beam dynamics34 references16 citations

TL;DR

This paper presents LAQGSM03.03, an upgraded version of the Los Alamos Quark-Gluon String Model event generator for nuclear reaction simulations in MCNPX/6 and MARS15 codes. It improves high-energy reaction modeling by integrating consistent preequilibrium, evaporation, fission, and Fermi breakup models, and successfully validates against diverse experimental data across 140–200 GeV/nucleon, showing strong agreement with measured fragment production cross sections and spectra without parameter tuning.

ABSTRACT

This paper presents part of an internal LANL Progress Report on LAQGSM03.03, an upgrade of the Los Alamos version of the Quark-Gluon String Model event generator for MCNPX/6 and MARS15 transport codes and on its validation and testing against a large variety of recent measurements. We present here an analysis with LAQGSM03.03 of the recent PHENIX mid-rapidity spectra of pi+, pi-, K+, K-, p, and p-bar produced in ultra-relativistic p + p interactions at sqrt(s) = 200 GeV; GSI cross sections for the fragmentation of Pb208 at 1 GeV/nucleon on Be9; fragmentation cross sections of Si28 on H, C, Al, Cu, Sn, and Pb at energies from 290 to 1200 MeV/nucleon measred recently at HIMAC and BNL; recent HIMAC data on B, Be, Li, and He production cross sections from fragmentation of C12 on H, C, Al, Cu, Sn, and Pb at 290 and 400 MeV/nucleon; BNL data on fragmentation cross sections of Fe56 on H, C, Al, Cu, and Pb targets at 1.05 GeV/nucleon; recent pi+ and pi- spectra from 6.4, 12.3, and 17.5 GeV/c p + Be9 from the E910 BNL measurements; and fragmentation cross sections of Ca40, Ca48, Ni58, and Ni64 on Be9 and Ta181 at 140 MeV/nucleon, and of Kr86 at 64 MeV/nucleon on the same targets measured recently at NSCL-MSU and RARF-RIKEN, respectively.

Motivation & Objective

• To enhance the predictive capability of the LAQGSM event generator for nuclear reactions at energies up to 1 TeV/nucleon.
• To resolve inconsistencies in previous versions by unifying preequilibrium, evaporation, fission, and Fermi breakup models with the CEM03.02 framework.
• To eliminate unphysical light unstable nuclei (e.g., 6B, 6Be) produced via asymmetric fission by enforcing immediate Fermi breakup.
• To validate the new model against a broad range of recent experimental data from BNL, GSI, HIMAC, NSCL-MSU, and RARF-RIKEN.
• To demonstrate the model's predictive power without adjustable parameters using only fundamental physics and updated cross sections.

Proposed method

• Uses a three-stage reaction model: Intra-Nuclear Cascade (INC), preequilibrium emission, and evaporation/fission from compound nuclei.
• Employs an improved time-dependent Dubna Intra-Nuclear Cascade Model (DCM) with continuous nuclear density and trawling effect for dynamic density depletion.
• Applies the Quark-Gluon String Model (QGSM) for elementary hadron-hadron and photon-hadron cross sections above 4.5 GeV/nucleon.
• Implements coalescence of nucleons into light ions (d, t, 3He, 4He) via final-state interactions after the INC stage.
• Applies the Generalized Evaporation/Fission Model (GEM2) for heavy compound nuclei (Z ≥ 65), and Fermi breakup for light fragments (A < 13).
• Uses consistent model formulations across low- and high-energy regimes, aligning with CEM03.02 for preequilibrium and evaporation processes.

Experimental results

Research questions

• RQ1 Can LAQGSM03.03 accurately predict fragment production cross sections across a wide energy range without parameter fitting?
• RQ2 How does the removal of unphysical light unstable nuclei (e.g., 6B, 6Be) via Fermi breakup affect model consistency and predictive accuracy?
• RQ3 To what extent does LAQGSM03.03 reproduce detailed experimental data from high-energy p+p, heavy-ion, and light-ion fragmentation reactions?
• RQ4 How does LAQGSM03.03 compare to other models (e.g., EPAX, AA, HIPSE, AMD) in describing complex fragmentation data from 40Ca, 48Ca, 58Ni, 64Ni, and 86Kr beams?
• RQ5 Can the model simultaneously describe particle spectra (e.g., π±) and isotopic cross sections across multiple targets and beam energies?

Key findings

• LAQGSM03.03 successfully reproduces measured fragment production cross sections for 40Ca, 48Ca, 58Ni, 64Ni, and 86Kr on 9Be and 181Ta at 140 MeV/nucleon and 64 MeV/nucleon, respectively, with good agreement across all isotopes.
• For 56Fe at 1.05 GeV/nucleon, the model matches experimental cross sections on H, C, Al, Cu, and Pb targets, with agreement comparable to or better than other models.
• The model accurately predicts inclusive forward π⁺ and π⁻ spectra from 6.4, 12.3, and 17.5 GeV/c protons on 9Be, including unmeasured angles at 90° and 159°.
• LAQGSM03.03 describes PHENIX mid-rapidity spectra of π⁺, π⁻, K⁺, K⁻, p, and p̄ from 200 GeV p+p collisions with good quantitative agreement.
• The model shows superior performance compared to EPAX, AA, HIPSE, and AMD models when tested on the same dataset, particularly in reproducing isotopic cross sections.
• Calculations were performed before receiving experimental values, and results were sent to Dr. Mocko for comparison, confirming the model’s predictive power without tuning.