Improvements of microscopic transport models stimulated by spallation data for incident energies from 113 to MeV Umm Al-Qura University and King Abdul-Aziz city for science and Technology, Saudi Arabia. * CERN Khaled Abdel-Waged, Nuha Felemban, and V.V. Uzhinskii*

UrQMD Contents Comparison of the (INC, BUU, QMD) transport models with Spallation data. Improvements in the dynamical contents of the UrQMD model are presented Confrontation of the UrQMD calculations with the spallation data in the energy range from 113 to MeV

Figure 1: Schematic view of the spallation and intranuclear cascade processes.

Microscopic transport models used for the description of spallation process. Microscopic transport models used for the description of spallation process. Static (time independent) Mean Field Models: Static (time independent) Mean Field Models: Intranuclear Cascade (INC) Intranuclear Cascade (INC) Dynamical Mean Field models: Dynamical Mean Field models: Boltzmann Uehling Uehlenbek (BUU) Boltzmann Uehling Uehlenbek (BUU) (Time dependent average of the nucleon density: over ( ) “test” particles are used in Simulation) (Time dependent average of the nucleon density: over ( ) “test” particles are used in Simulation) Quantum Molecular Dynamics (QMD) Quantum Molecular Dynamics (QMD) (Time dependent sum of 2 and 3-nucleon interaction densities of all (projectile and target) nucleons) (Time dependent sum of 2 and 3-nucleon interaction densities of all (projectile and target) nucleons)

The second “de-excitation” stage of the interaction is described by: Evaporation model Evaporation model Generalized Evaporation model Generalized Evaporation model Statistical Multifragmentation model Statistical Multifragmentation model

Spallation Data SATURNE (2002): SATURNE (2002): p+Al, Fe, Zr, W, Pb and Th at 1.2 GeV p+Al, Fe, Zr, W, Pb and Th at 1.2 GeV p+Fe and Pb at 0.8 and 1.6 GeV p+Fe and Pb at 0.8 and 1.6 GeV PISA Collaboration (2007): PISA Collaboration (2007): (p +Au at 1.2, 1.9 and 2.5 GeV) (p +Au at 1.2, 1.9 and 2.5 GeV) HARP collaboration (2009) HARP collaboration (2009) (Various targets at 3, 5, 8, 12 and15 GeV/c) (Various targets at 3, 5, 8, 12 and15 GeV/c)

Fig.2 Different INC models versus data of p(800 MeV)+ Pb (left) and Fe (right) Phys. Rev. C 65, (2002)

Fig.3 Different INC models versus data of p(1600 MeV)+ Pb (left) and Fe (right) Phys. Rev. C 65, (2002)

Fig.4 J. Cugnon Phys. Rev. C 66, (2002) Modified Cascade versus data

Fig.6 JQMD, Phys. Rev. C 52, 2620 (1995); Phys. Rev. C79, (2009). JAERI QMD model versus data

Fig.7 PISA Phys. Rev. C 76, (2007) Giessen BUU versus data of p(2.5 GeV)+Au

UrQMD model Prog. Part. Nucl. Phys. 41, (1998)

UrQMD model Mean field potential (similar to QMD) applied to nucleons at E< 5 GeV. Collision term is similar to RQMD. Resonances are produced at < 5 GeV for baryon- baryon and 3 GeV for meson-meson and meson- baryon reactions: 55 baryon and 32 meson states can be created with masses up to 2.25 GeV. Color strings are formed and they decay into hadrons according to the Lund string model. All of these hadrons can propagate and re-interact in phase space.

Standard UrQMD versus data Fig.8 Khaled Abdel-Waged Phys.Rev.C 67,064610(2003)

Main improvements of UrQMD code A clusterization procedure followed by an afterburner. 1 Medium modified angular distributions for Reactions. 2 Introduction of a proper initial ground state. 3

Fig.9 The angular distributions of neutrons evaluated at different laboratory energies for (left panels) and (right panels). (a) and (b) are the results calculated by the free Cugnon parametrizations, while (c) and (d) are those calculated by medium parameterizations.

Fig.10 Kh. Abdel-Waged Phys. Rev. C 70, (2004)

Fig.11 Time evolution of (left panel) binding energy and (right panel) root mean square radius of the ground state of studied interactions computed by ImUrQMD (solid circles). The lines are the best fit to the results.

Fig.12 The root mean square radii for the ground state of selected nuclei from to as calculated by ImUrQMD. The experimental data are the Bethe-Weizsacker values.

Fig.13 Kh. Abdel-Waged,Phys. Rev. C 74, (2006)

Fig.14 Kh. Abdel-Waged, J. of Phys. G 34, 883 (2007)

Fig.15 Kh. Abdel-Waged et al.,,Phys. Rev. C 81, (2010)

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Fig.17 UrQMD calculations with frictional cooling

Fig.18 Improved UrQMD calculations in potential mode

HARP-CDP data comparisons (3-15 GeV/c) UrQMD calculations in cascade mode

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Fig.28 HARP-CDP, CERN-PH- EP/

1 A clusterization algorithm at the end of the fast stage of the cascade process. UrQMD is a powerful tool for investigating spallation data in the incident energy range from 113 to MeV. However, several features should be taken into account before comparison with spallation data. These features are: CONCLUSIONS An afterburner mechanism. 2 The UrQMD should be run in the potential mode for E< =3000 GeV. 3 4 UrQMD Medium modification of the angular distributions of the scattered nucleons. 5 The UrQMD (in cascade mode) calculations show the same trend as the HARP-CDP data for the inclusive cross sections of proton-production by protons beam in the energy range GeV