arXiv subjects

R. E. Prael

Publications and source records attributed to R. E. Prael.

At least 19 recordsLinked to original sources

arXiv2012

Current status of MCNP6 as a simulation tool useful for space and accelerator applications

For the past several years, a major effort has been undertaken at Los Alamos National Laboratory (LANL) to develop the transport code MCNP6, the latest LANL Monte-Carlo transport code representing a merger and improvement of MCNP5 and MCNPX. We emphasize a description of the latest developments of MCNP6 at higher energies to improve its reliability in calculating rare-isotope production, high-energy cumulative particle production, and a gamut of reactions important for space-radiation shielding, cosmic-ray propagation, and accelerator applications. We present several examples of validation and verification of MCNP6 compared to a wide variety of intermediate- and high-energy experimental data on reactions induced by photons, mesons, nucleons, and nuclei at energies from tens of MeV to about 1 TeV/nucleon, and compare to results from other modern simulation tools.

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arXiv2008

CEM03.03 and LAQGSM03.03 Event Generators for the MCNP6, MCNPX, and MARS15 Transport Codes

A description of the IntraNuclear Cascade (INC), preequilibrium, evaporation, fission, coalescence, and Fermi breakup models used by the latest versions of our CEM03.03 and LAQGSM03.03 event generators is presented, with a focus on our most recent developments of these models. The recently developed "S" and "G" versions of our codes, that consider multifragmentation of nuclei formed after the preequilibrium stage of reactions when their excitation energy is above 2A MeV using the Statistical Multifragmentation Model (SMM) code by Botvina et al. ("S" stands for SMM) and the fission-like binary-decay model GEMINI by Charity ("G" stands for GEMINI), respectively, are briefly described as well. Examples of benchmarking our models against a large variety of experimental data on particle-particle, particle-nucleus, and nucleus-nucleus reactions are presented. Open questions on reaction mechanisms and future necessary work are outlined.

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arXiv2007

LAQGSM03.03 Upgrade and its Validation

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.

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arXiv2005

Merging the CEM2k and LAQGSM Codes with GEMINI

An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions contained in the code CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) are merged with the well-known sequential-binary-decay model GEMINI by Charity. We present some results on proton-induced fragmentation, fission-product yields and on particle spectra predicted by these extended versions of CEM2k and LAQGSM. We show that merging CEM2k and LAQGSM with GEMINI allows us to describe many fission and fragmentation reactions in addition to the spallation and evaporation reactions which are already described well by these codes. Nevertheless, the current version of GEMINI we use does not provide a completely satisfactory description of some complex-particle spectra, fragment emission, and spallation yields for some reactions, and is not yet a universal tool for applications. Our results show that GEMINI contains a powerful model to describe evaporation/fission/fragmentation reactions and often provides better results when compared to other models, especially for emission of heavy fragments from reactions on medium-heavy nuclei (where most other models simply fail), but it must be further extended and improved in order to properly describe arbitrary reactions.

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arXiv2005

Extension of the CEM2k and LAQGSM Codes to Describe Photo-Nuclear Reactions

The improved Cascade-Exciton Model (CEM) code CEM2k+GEM2 and the Los Alamos version of the Quark-Gluon String Model code LAQGSM are extended to describe photonuclear reactions. First, we incorporate into CEM2k+GEM2 new evaluations of elementary cross sections based on the latest experimental data and also make several improvements in the description of the de-excitation of nuclei remaining after the cascade stage of reactions induced by arbitrary projectiles. Next, for photonuclear reactions we include in CEM2k+GEM2 a normalization to evaluated experimental absorption cross sections based on the recent systematics by Kossov. Then, we extend our high-energy code LAQGSM by adding the photonuclear mode which was ignored in all its previous versions, and add to it the photonuclear part from our improved CEM2k+GEM2. In this work we present a short description of the photonuclear mode as incorporated into our codes, show several illustrative results, and point out some unresolved problems.

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arXiv2005

Improved Intranuclear Cascade Models for the Codes CEM2k and LAQGSM

An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions implemented in the codes CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) has been developed recently at LANL to describe reactions induced by particles and nuclei at energies up to hundreds of GeV/nucleon for a number of applications. We present several improvements to the intranuclear cascade models used in CEM2k and LAQGSM developed recently to better describe the physics of nuclear reactions. First, we incorporate the photonuclear mode from CEM2k into LAQGSM to allow it to describe photonuclear reactions, not previously modeled there. Then, we develop new approximations to describe more accurately experimental elementary energy and angular distributions of secondary particles from hadron-hadron and photon-hadron interactions using available data and approximations published by other authors. Finally, to consider reactions involving very highly excited nuclei (E* > 2-3 MeV/A), we have incorporated into CEM2k and LAQGSM the Statistical Multifragmentation Model (SMM), as a possible reaction mechanism occurring after the preequilibrium stage. A number of other refinements to our codes developed recently are also listed.

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arXiv2004

Analysis of the JINR p(660 MeV) + 129I, 237Np, and 241Am Measurements with Eleven Different Models

We have analyzed the recent JINR measurements on nuclide production cross sections from interaction of 660 MeV proton beams with radioactive targets of enriched 129I (85% 129I and 15% 127I), 237Np, and 241Am with eleven different models, realized in eight transport codes and event-generators: LAHET (Bertini, ISABEL, INCL+ABLA, and INCL+RAL options), CASCADE, CEM95, CEM2k, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI, and CEM2k+GEMINI. We found out that all these models have problems in a correct description of many of these cross sections, though some of these models describe very well most of the recent measurements done at GSI using inverse kinematics, as well as many other reactions. None of the tested here models is able to reproduce well all the JINR data and all of them should be further improved. Development of a better universal evaporation/fission model should be of a highest priority. We conclude that it is impossible to make a correct choice between fission and fragmentation reaction mechanisms analyzing only measurements on product cross sections; addressing this question would require analysis of two- or multi-particle correlation measurements.

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arXiv2004

Analysis of the GSI A+p and A+A Spallation, Fission, and Fragmentation Measurements with the LANL CEM2k and LAQGSM codes

The CEM2k and LAQGSM codes have been recently developed at Los Alamos National Laboratory to simulate nuclear reactions induced by particles and nuclei for a number of applications. We have benchmarked our codes against most available measured data at projectile energies from 10 MeV/A to 800 GeV/A and have compared our results with predictions of other current models used by the nuclear community. Here, we present a brief description of our codes and show illustrative results obtained with CEM2k and LAQGSM for A+p and A+A spallation, fission, and fragmentation reactions measured recently at GSI compared with predictions by other models. Further necessary work is outlined.

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arXiv2004

Study of Proton Induced Reactions in a Radioactive 129-I Target at Ep=660 MeV

Two NaI (85% 129-I and 15% 127-I) targets were exposed to a beam of 660-MeV protons. Cross sections for formation of 76 residual nuclei were obtained by the induced activity method. The results are compared with other experimental data on 127-I and theoretical calculations by eleven models contained in the codes LAHET3 (using the Bertini+Dresner, ISABEL+Dresner, INCL+Dresner, and INCL+ABLA options), CASCADE, CEM95, CEM2K, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI, and CEM2k+GEMINI. Most of the models describe spallation products with masses close to the target reasonably well while the reliability of the codes differs greatly in the deep spallation and fission/fragmentation regions. The difficulties in describing products with A=40-80 by all of the codes tested here except for CEM2k+GEMINI and LAQGSM+GEMINI is related to the neglect of fission (and fragmentation) processes for targets as light as 129-I.

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arXiv2004

Nuclide Production in 197Au, 208Pb, and natU Irradiated with 0.8-1 GeV Protons: Comparison with other Experiments and with Theoretical Predictions

The ITEP proton synchrotron U10 was used to irradiate isotopically-enriched 208Pb and natU thin targets with 1.0 GeV protons and 197Au thin targets with 0.8 GeV protons. More than 400 cross sections of the nuclides produced were measured using the direct spectrometry method with a high-resolution Ge detector. The measured cross sections are compared with similar data obtained at GSI for kinematically inverse reactions of 1 GeV/nucleon 208Pb, 1 GeV/nucleon 238U, and 0.8 GeV/nucleon 197Au interacting with a hydrogen target and with the ZSR data on natPb and 197Au irradiated with 1 and 0.8 GeV protons, respectively. Our results are on average ~ 10 to 20% higher than the GSI data. The measured data are analyzed with the LANL codes CEM2k+GEM2 and LAQGSM+GEM2 and with the INCL intranuclear cascade code from Liege merged with the GSI evaporation/fission code ABLA.

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arXiv2004

High-Energy Threshold Reaction Rates on 0.8 GeV Proton-Irradiated Thick W and W-Na Targets

Threshold activation reaction rates in 12C, 19F, 27Al, 59Co, 63Cu, 65Cu, 64Zn, 93Nb, 115In, 169Tm, 181Ta, 197Au, and 209Bi experimental samples placed along the axis inside and outside the 0.8 GeV proton-irradiated 92-cm thick W-Na and 4-cm thick W targets where measured at the ITEP proton synchrotron. 158 reactions of up to +AH4-0.5 GeV thresholds have been measured in 123 activation samples for W-Na target, and 157 reactions in 36 activation samples for W target. The reaction rates were determined using the gamma-spectrometry method. In total, more than 1000 values of activation reactions were determined in the experiments. In both cases the measured reaction rates were compared with the LAHET code simulated rates and using several nuclear databases for the respective excitation functions, namely, ENDF/B6 for cross section of neutrons at energies below 20 MeV and MENDL2 together with MENDL2P for cross sections of protons and neutrons of 20 to 100 MeV energies. A general satisfactory agreement between simulated and experimental data has been found.

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arXiv2003

Analysis of Intermediate-Energy Nucleus-Nucleus Spallation, Fission, and Fragmentation Reactions with the LAQGSM code

The LAQGSM code has been recently developed at Los Alamos National Laboratory to simulate nuclear reactions for proton radiography applications. We have benchmarked our code against most available measured data both for proton-nucleus and nucleus-nucleus interactions at incident energies from 10 MeV to 800 GeV and have compared our results with predictions of other current models used by the nuclear community. Here, we present a brief description of our code and show illustrative results obtained with LAQGSM for neutron spectra measured recently by Nakamura's groups for reactions induced by light and medium nuclei on targets from C to Pb at several incident energies from 95 to 600 MeV/nucleon and with the recent GSI measurements of spallation, fission, and fragmentation yields from A+p and A+A reactions at incident energies near and below 1 GeV/nucleon. Further necessary work is outlined.

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arXiv2003

Cross Sections for Nuclide Production in 1 GeV Proton-Irradiated 208Pb and 0.8 GeV Proton-Irradiated 197Au

Measured at ITEP (Moscow) cross sections for nuclide production in 1.0 GeV proton-irradiated 208Pb and 0.8 GeV proton-irradiated 197Au targets are presented. The cross sections were measured by direct gamma-spectrometry with a high-resolution Ge detector. The measured cross sections are compared with experimental data of GSI (inverse kinematics, 1 GeV/nucleon 208Pb and 0.8 GeV/nucleon 197Au interacting with a liquid hydrogen target, and the ZSR data (direct kinematics, 1.0 and 0.8 GeV protons on nat-Pb and 197Au, respectively). All experimental data are compared with each other and with results by the Los Alamos codes CEM2k+GEM2, LAQGSM+GEM2, and LAHET (INLC option: Cugnon's INC + Schmidt's evaporation and fission models).

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arXiv2003

Threshold Activation Reaction and Absorption Dose Rates Inside and on the Surface of a Thick W-Na Target Irradiated with 0.8-GeV Proton

Results of measured threshold activation reaction rates in 12C, 19F, 27Al, 59Co, 63Cu, 65Cu, 64Zn, 93Nb, 115In, 169Tm, 181Ta, 197Au, and 209Bi experimental samples placed both along the axis inside and outside a 0.8 GeV proton-irradiated thick W-Na target are presented. Absorption dose rates outside the target are presented as well. The target was irradiated by the proton beam from the ITEP U10 accelerator. The measured reaction rates were compared with the LAHET code simulated rates and using several nuclear databases for the respective excitation functions, namely, ENDF/B6 for cross section of neutrons at energies below 20 MeV and MENDL2 together with MENDL2P for cross section of protons and neutrons of 20 to 100 MeV energies.

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arXiv2003

Nuclide Production Cross Sections for 59Co and nat-Cu Irradiated with 0.2 and 2.6 GeV Protons and 0.2 GeV/Nucleon Carbon Ions

Results of experimental cross sections for residual nuclide production in interactions of 200 MeV/A 12C ions and 0.2 and 2.6 GeV protons with nat-Cu, 59Co, and 27Al targets are presented. The residual products are measured at ITEP (Moscow) by gamma-spectrometry with a detector of 1.8 keV resolution in the 1332 keV 60Co gamma-line. The measured data are compared with predictions by the LANL (Los Alamos) code LAQGSM+GEM2 and JINR (Dubna) code CASCADE.

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arXiv2002

CEM2k and LAQGSM as Event Generators for Space-Radiation-Shielding and Cosmic-Ray-Propagation Applications

The CEM2k and LAQGSM codes have been recently developed at Los Alamos National Laboratory to simulate nuclear reactions for a number of applications. We have benchmarked our codes against most available measured data at incident particle energies from 10 MeV to 800 GeV and have compared our results with predictions of other current models used by the nuclear community. Here, we present a brief description of our codes and show illustrative results to show that CEM2k and LAQGSM can be used as reliable event generators for space-radiation-shielding, cosmic-ray-propagation, and other astrophysical applications. Finally, we show the use of our calculated cross sections together with experimental data from our LANL T-16 compilation to produce evaluated files which we use in the GALPROP model of galactic particle propagation to better constrain the size of the CR halo.

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arXiv2000

Cross sections for nuclide production in 1 GeV proton-irradiated 208-Pb

114 cross sections for nuclide production in a 1.0 GeV proton-irradiated thin 208Pb target have been measured by the direct gamma spectrometry method using a high-resolution Ge detector. The gamma spectra were processed by the GENIE-2000 code. The ITEP-developed SIGMA code was used together with the PCNUDAT nuclear decay database to identify the gamma lines and to determine the cross sections. The 27Al(p,x)22Na reaction was used to monitor the proton flux. Results of a feasibility study of the auxiliary 27Al(p,x)24Na and 27Al(p,x)7Be monitor reactions in the 0.07-2.6 GeV proton-energy range are presented as well. Most of the experimental data have been analyzed by the LAHET (with ISABEL and Bertini options), CEM95, CEM2k, INUCL, CASCADE, CASCADE/INPE, and YIELDX codes that simulate hadron-nucleus interactions.

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arXiv1999

Experimental and Computer Simulation Study of Radioactivity of Materials Irradiated by Intermediate Energy Protons

The results of measurements and computer simulations of radioactivities and dose rates as functions of decay time are presented for Pb-nat and Bi-209 irradiated by 1.5-GeV protons, Co-59, Cu-63, and Cu-65 irradiated by 0.13- and 1.2-GeV protons, and Th-232 and U-nat irradiated by 0.1- and 0.8-GeV protons. The activities and dose rates are measured by direct high-precision gamma spectrometry. The irradiations were made using external beams extracted from the ITEP U-10 proton synchrotron. Simulations made using the LCS and CINDER'90 code systems are compared with measurements.

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