Possible Improvements to MCNP6 and its CEM/LAQGSM Event-Generators

Mashnik, S. G.

doi:10.2172/1207753

Cited by 3 publications

(4 citation statements)

References 29 publications

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“…The nuclear physics implemented in GALPROP is impressive: a nuclear reaction network from 64 Ni downward; nuclear decays, mostly β, from the Nuclear Data Sheets; total p(p, x) and A(p, x) inelastic cross sections adapted from Ref. [10]; total A( 4 He, x) inelastic cross sections from fits to data; A(p, x)B spallation cross sections from LANL-T16, CEM2k and LAQGSM [11], Silberberg-Tsao's YIELDX2000 [12] and/or Webber et al [13], with special fits to data for production of 2,3 H, 3 He, Li, Be, B, Al, Cl, Sc, Ti, V, Mn; A( 4 He, x)B spallation cross sections from Ref. [14].…”

Section: Cosmic Ray Backgroundsmentioning

confidence: 99%

Wanted! Nuclear Data for Dark Matter Astrophysics

Gondolo

2014

Nuclear Data Sheets

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Astronomical observations from small galaxies to the largest scales in the universe can be consistently explained by the simple idea of dark matter. The nature of dark matter is however still unknown. Empirically it cannot be any of the known particles, and many theories postulate it as a new elementary particle. Searches for dark matter particles are under way: production at high-energy accelerators, direct detection through dark matter-nucleus scattering, indirect detection through cosmic rays, gamma rays, or effects on stars. Particle dark matter searches rely on observing an excess of events above background, and a lot of controversies have arisen over the origin of observed excesses. With the new high-quality cosmic ray measurements from the AMS-02 experiment, the major uncertainty in modeling cosmic ray fluxes is in the nuclear physics cross sections for spallation and fragmentation of cosmic rays off interstellar hydrogen and helium. The understanding of direct detection backgrounds is limited by poor knowledge of cosmic ray activation in detector materials, with order of magnitude differences between simulation codes. A scarcity of data on nucleon spin densities blurs the connection between dark matter theory and experiments. What is needed, ideally, are more and better measurements of spallation cross sections relevant to cosmic rays and cosmogenic activation, and data on the nucleon spin densities in nuclei.

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Section: Cosmic Ray Backgroundsmentioning

confidence: 99%

Wanted! Nuclear Data for Dark Matter Astrophysics

Gondolo

2014

Nuclear Data Sheets

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“…Figure 4: Comparison of experimental data by Green et al [13] (circles) for the production of 6 Li at an angle of 60 • from the reaction 480 MeV p + nat Ag, with results by standard CEM03.03 (dot-dashed line) from CEM03.03F without coalescence expansion (solid line) and CEM03.03F with coalescence expansion (dashed line) (see details in [5,19]).…”

Section: Introduction and Theoretical Backgroundmentioning

confidence: 96%

“…As of today, neither the "S" nor the "G" versions of CEM and LAQGSM have been implemented in MCNP6. We plan to incorporate them in our event generators used by MCNP6 after we tune several parameters in SMM and GEMINI, that are essential in chosing the excitation energy (or temperature) of nuclei when reaction mechanisms change from "usual evaporation", to binary decays described by GEMINI, and/or to multifragmentation simulated with SMM (see details in [19]). Figure 6: Measured cross sections for 48 Ca fragmentation on 9 Be at 140 MeV/nucleon [15] compared with LAQGSM03.03 predictions (see details in [9]).…”

Section: Introduction and Theoretical Backgroundmentioning

confidence: 99%

MCNP6 simulation of light and medium nuclei fragmentation at intermediate energies

Mashnik

Kerby

2016

EPJ Web of Conferences

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Fragmentation reactions induced on light and medium nuclei by protons and light nuclei of energies around 1 GeV/nucleon and below are studied with the Los Alamos transport code MCNP6 and with its CEM03.03 and LAQGSM03.03 event generators. CEM and LAQGSM assume that intermediate-energy fragmentation reactions on light nuclei occur generally in two stages. The first stage is the intranuclear cascade (INC), followed by the second, Fermi breakup disintegration of light excited residual nuclei produced after the INC. CEM and LAQGSM account also for coalescence of light fragments (complex particles) up to 4 He from energetic nucleons emitted during INC. We investigate the validity and performance of MCNP6, CEM, and LAQGSM in simulating fragmentation reactions at intermediate energies and discuss possible ways of further improving these codes.

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“…Evaporation continues until the overall excitation energy is below that required for particle emission, at which point the remaining energy is released through isotropic secondary gamma radiation. (Mashnik 2008). Physics models are used in MCNP6 whenever cross-sections are unavailable from the cross-section library; the user must specify which library to use for each material composition in the simulation.…”

Section: Introductionmentioning

confidence: 99%

Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS

Griffin

Yeom

Mille

et al. 2022

Biomed. Phys. Eng. Express

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Monte Carlo (MC) methods are considered the gold-standard approach to dose estimation for normal tissues outside the treatment field (out-of-field) in proton therapy. However, the physics of secondary particle production from high-energy protons are uncertain, particularly for secondary neutrons, due to challenges in performing accurate measurements. Instead, various physics models have been developed over the years to reenact these high-energy interactions based on theory. It should thus be acknowledged that MC users must currently accept some unknown uncertainties in out-of-field dose estimates. In the present study, we compared three MC codes (MCNP6, PHITS, and TOPAS) and their available physics models to investigate the variation in out-of-field normal tissue dosimetry for pencil beam scanning proton therapy patients. Total yield and double-differential (energy and angle) production of two major secondary particles, neutrons and gammas, were determined through irradiation of a water phantom at six proton energies (80, 90, 100, 110, 150, and 200 MeV). Out-of-field normal tissue doses were estimated for intracranial irradiations of 1-, 5-, and 15-year-old patients using whole-body computational phantoms. Notably, the total dose estimates for each out-of-field organ varied by approximately 25% across the three codes, independent of its distance from the treatment volume. Dose discrepancies amongst the codes were linked to the utilized physics model, which impacts the characteristics of the secondary radiation field. Using developer-recommended physics, TOPAS produced both the highest neutron and gamma doses to all out-of-field organs from all examined conditions; this was linked to its highest yields of secondary particles and second hardest energy spectra. Subsequent results when using other physics models found reduced yields and energies, resulting in lower dose estimates. Neutron dose estimates were the most impacted by physics model choice, and thus the variation in out-of-field dose estimates may be even larger than 25% when considering biological effectiveness.

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Possible Improvements to MCNP6 and its CEM/LAQGSM Event-Generators

Cited by 3 publications

References 29 publications

Wanted! Nuclear Data for Dark Matter Astrophysics

Wanted! Nuclear Data for Dark Matter Astrophysics

MCNP6 simulation of light and medium nuclei fragmentation at intermediate energies

Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS

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