Intranuclear Cascade Model Research Articles

Measurement of thick target neutron yield at 180°for a mercury target induced by 3-GeV protons

A thick target neutron yield (TTNY) for a mercury target at an angle of 180°from the incident beam direction was measured with the time-of-flight method using a 3-GeV proton beam at the Japan Proton Accelerator Research Complex (J-PARC). Comparison of the experimental results with a Monte Carlo particle transport simulation by the Particle and Heavy Ion Transport code System (PHITS) shows that the default spallation model of PHITS, the Liège intranuclear cascade model version 4.6 coupled with the generalized evaporation model (INCL4.6/GEM) reproduces the measured TTNY fairly well, whereas apparent overestimation is observed for the former default model, the Bertini intranuclear cascade model coupled with GEM (Bertini/GEM). These trends are consistent with the experimental results of neutron-induced reaction rates obtained using indium and niobium activation foils.

Two effects in nucleon-induced nonelastic cross sections based on the intranuclear cascade model

Proton- and neutron-induced nonelastic cross sections for $^{12}\mathrm{C}, ^{27}\mathrm{Al}, ^{56}\mathrm{Fe}$, and $^{208}\mathrm{Pb}$ are investigated in the low-energy region from 100 MeV down to nearly 0 MeV based on a framework of the extended intranuclear cascade (INC) model. It is shown that the present INC model can reproduce the experimental data both for the proton- and for the neutron-induced nonelastic cross sections of a wide range of targets in a systematic way and that the crucial point is to include the suppressed transition probability of the excited particles due to the discrete level constraint. On the basis of the reliability of the INC calculation, we analyze two effects of the discrete level constraint and Coulomb repulsion separately for the proton and for the neutron injection cases, and we elucidate the domain of the target mass and the incident energy where two effects play important roles.

Direct pickup and knockout processes in inclusive (p,αx) reactions from 42 to 300 MeV

Inclusive $(p,\ensuremath{\alpha}x)$ reactions from 42 to 300 MeV are investigated to quantitatively understand the roles of direct pickup and knockout processes. These two processes as well as indirect pickup are incorporated into the intranuclear cascade model. Calculations followed by the evaporation model successfully explain the double-differential cross-section spectra in terms of both shape and magnitude. Direct pickup occupies the low excitation energies of the spectra, and knockout appears between the direct pickup and evaporation regions. The contribution of knockout is negligible below 100 MeV, increases to be comparable with that of direct pickup at 160 MeV, and is dominant above 200 MeV. Indirect pickup shows an important contribution at 300 MeV. The direct pickup and knockout processes show decreasing trends of incident-energy dependence, common to targets ranging from $^{12}\mathrm{C}$ to $^{209}\mathrm{Bi}$. However, the decrease of direct pickup is much faster than that for knockout.

Measurement of thick target neutron yields from 7 MeV/u [formula omitted] incidence on 209Bi

Thick target neutron yields produced by 7 MeV/u α incidence on a 209Bi target were measured at emission angles of 0°, 45°, and 90° using EJ301 liquid scintillators and the time-of-flight method. The experimental thick target yields were compared with those calculated using the Liège IntraNuclear-Cascade (INCL) and the JAERI Quantum Molecular Dynamics (JQMD) models followed by the Generalized Evaporation Model (GEM) implemented in PHITS. The INCL model successfully reproduced the neutron energy distribution. In contrast, the JQMD model could not reproduce the distribution, even for the reactions induced by low energy composite particles.

Theoretical calculation and evaluation of n + 237,241,243,245Pu reactions

Plutonium isotopes are important fuel or radioactive waste loaded to accelerator driven systems and some Generation-IV reactors, so accurate nuclear data of neutron induced reactions on them for the incident energy up to 150 MeV are required for the design of these facilities. The nuclear data on n + 237,241,243,245Pu reactions below 150 MeV are consistently calculated and evaluated by using the optical model, distorted wave Born approximation theory, Hauser-Feshbach theory with width fluctuation correction, fission model, evaporation model, exciton model and the intranuclear cascade model. In the meanwhile, new experimental data are taken into account. Our new evaluated data are compared with the presently existing experimental data and the evaluated data from ENDF/B-VIII, JENDL-4.0/HE and TENDL. In addition, the variation tendency of reaction cross sections related to the target mass numbers is obtained.

Strangeness production in the new version of the Liège intranuclear cascade model

The capabilities of the new version of the Li\`ege Intra-Nuclear Cascade model (INCL++6) are presented in detail. This new version INCL is able to handle strange particles, such as kaons and the $\Lambda$ particle, and the associated reactions and also allows extending nucleon-nucleon collisions up to about $15-20$ GeV incident energy. Compared to the previous version, new observables can be studied, e.g., kaon, hyperon, and hypernuclei production cross sections (with the use of a suitable de-excitation code) as well as aspects of kaon-induced spallation reactions. The main purpose of this paper is to present the specific ingredients of the new INCL version and its new features, notably the new variance reduction scheme. We also compare for some illustrative strangeness production cases calculated using this version of INCL with experimental data.

Theoretical calculation and evaluation of neutron inducedreactions on Pu isotopes

The nuclear data on n+239,240,242,244Pu reactions for the incident energy up to 200 MeV are consistently calculated and evaluated in order to meet the design requirements of Generation-IV reactors and accelerator driven systems. The optical model, the distorted wave Born approximation theory, the Hauser-Feshbach theory, the fission model, the evaporation model, the exciton model and the intranuclear cascade model are used in the calculation, and new experimental data are taken into account. Our data are compared with experimental data and the evaluated data from JENDL-4/HE and TENDL. In addition, the variation tendency of reaction cross sections related to the target mass numbers is obtained, which is very important for the prediction of nuclear data on neutron-actinides reactions because the experimental data are lacking.

Double-differential cross section measurement with low threshold detector for proton production induced by several tens of MeV protons

We have developed a low threshold detector consisting of Bragg curve counter (BCC), two siliconsurface barrier detectors (SSDs) and BGO scintillator to obtain experimental double-differential cross section (DDX) data for low energy proton production. Since the BCC offers advantage of self particle identification capability and a few μm-thick entrance window, protons produced by nuclear reactions down to 1 MeV have been identified. The capability of the detector is demonstrated in measurements using 70-MeV protons. Measured spectra are compared with calculation results of intra-nuclear cascade (INC) plus evaporation models and nuclear data library.

The High-Energy Intra-Nuclear Cascade Liège-based Residual (HEIR) nuclear data library

It is standard practice for nuclear data files to include tabulated data for distinct reaction channels for incident energies up to 20-30 MeV. Above these energies, the assumptions implicit in the definition of individual channels break down and event generators are typically used within codes that simulate nuclear observables in applications. These offer robust simulation of the physics but increase the computational burden. So-called ‘high-energy’ nuclear data files have been produced, but the well-known libraries are more than a decade old and rely upon models developed many years before their release. This presentation describes a modern library with a high level of production automation that offers regular updates as the models it is based upon are improved. The most recent versions of the intra-nuclear cascade and de-excitation models available within Geant4 were used to generate tabulated data of residual nuclide production. For the first released library, the INCL++5.3 and ABLA version within Geant4 v10.3 were used to calculate over 1012 incident protons over 2095 target isotopes with incident energies up to 1 GeV. These were collated into tabulated data in the international-standard ENDF-6 format. The resulting files were provided as group-wise files and were distributed as HEIR-0.1 with the FISPACT-II version 4.0 release. A second library, HEIR-0.2, has been generated using the new INCL++6.0 and C++ translation of the ABLA07 model available within Geant4 v10.4. Simulations were performed using incident protons, neutrons, deuterons and π±. An improved agreement is observed in the comparison to experimental data not only between the two versions, but against the other well-known high-energy nuclear data files and models available within Geant4. This benchmark includes mass and isotopic distributions, as well as incident-energy dependent cumulative and independent cross sections from the EXFOR database.

Low-energy-threshold detector for measuring proton spectra at several tens of MeV using Bragg curve spectroscopy

We have developed a low-energy-threshold detector comprising a Bragg curve counter (BCC), two silicon-surface barrier detectors, and a bismuth germanate scintillator to obtain experimental double-differential cross section (DDX) data on (p,p′x) reactions for incident energies of several tens of MeV. The BCC can identify particles by itself and can do so for protons down to 1 MeV. The developed detector is used to measure the DDXs of (p,p′x) reactions for incident proton energies of 40 and 70 MeV at 15–150°. The minimum energy in the DDX data is 1.3 MeV, which gives spectra of emitted particles in the whole energy range. The resultant DDXs are compared with results calculated using intranuclear cascade plus evaporation models. Below 10 MeV, the calculation results agree reasonably with measured data for the natC(p,p′x), 27Al (p,p′x), and natCu(p,p′x) reactions, but they disagree regarding energy and angular dependence for the 197Au(p,p′x) reaction.

Extension of the intranuclear cascade model to neutron-induced nonelastic cross sections in the low-energy region

Two features, a slow slope and a sharp drop, in neutron induced total nonelastic cross-sections are analyzed within the framework of an intra-nuclear cascade (INC) model. First, to reproduce the slow slope from 100MeV to 10 MeV, the original INC is generalized in two points; a method to construct the ground state of the target nucleus, and a method of taking the effective two body cross-sections between two nucleons. Secondly, to analyze the origin of the sharp drop from 10MeV to nearly 1 MeV, the INC is extended to include quantum effects which are originated from the existence of the discrete states in the nuclear potential. It is shown that this extension leads to the sharp drops in the very low energy below around 10MeV. It is concluded that the INC model can be extended to explain the sharp drops in addition to the slow slope in neutron induced nonelastic cross-sections in the energy region from 100MeV down to 1 MeV.

Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb, and Te projectiles beyond the N = 82 shell closure

Inclusive one- and multi-nucleon removal cross sections have been measured for several Sn, Sb and Te isotopes just beyond the N=82 neutron shell closure. The beams were produced in the projectile fission of a 238U beam at the Radioactive Isotope Beam Factory at RIKEN. The experimental cross sections are compared to predictions from the most recent version of the Liege intranuclear cascade model. Although the overall agreement is good, severe discrepancies are observed for the cases of one- and two-neutron removal from 134Sn and 135Sb projectiles and one-proton knockout from all measured N=84 isotones. These discrepancies, as well as the relevance of quasi-elastic reaction channels to the one-neutron removal cross sections, are discussed. In addition, the measured inclusive one-proton knockout cross section for the semi-magic 134Sn projectile is compared to eikonal direct reaction theory calculations to assess if the suppression factors to these calculated cross sections, deduced from data on reactions of lighter projectile nuclei, are also applicable to heavy nuclei.

Microscopic description of proton-induced spallation reactions with the constrained molecular dynamics (CoMD) model

We studied the complete dynamics of the proton-induced spallation process with the microscopic framework of the constrained molecular dynamics (CoMD) model. We performed calculations of proton-induced spallation reactions on 181Ta, 208Pb, and 238U targets with the CoMD model and compared the results with a standard two-step approach based on an intranuclear cascade model followed by a statistical deexcitation model. The calculations were also compared with recent experimental data from the literature. Our calculations showed agreement with some aspects of the experimental data and suggest further improvements in the models. We point out that this CoMD study represents the first complete dynamical description of spallation reactions with a microscopic N-body approach and may lead to advancements in the physics-based modeling of the spallation process.

Using world π± -nucleus scattering data to constrain an intranuclear cascade model

The NEUT intranuclear cascade model is described and fit to a large body of \pipm--nucleus scattering data. Methods are developed to deal with deficiencies in the available historical data, and robust uncertainty estimates are produced. The results are compared to a variety of simulation packages, and the data itself. This work provides a method for tuning Final State Interaction models, which are of particular interest to neutrino experiments that operate in the few-GeV energy region, and provides results which can be used directly by the T2K and Super-Kamiokande collaborations, for whom NEUT is the primary simulation package.

The mechanism of cumulative proton production in the collision of 12C and 9Be nuclei at the energies of 0.6, 0.95 and 2 GeV/nucleon

The collision of carbon nuclei with beryllium nuclei was simulated in the framework of Liège Intranuclear-Cascade model at the initial kinetic energies of the carbon nuclei 0.6, 0.95, 2.0 GeV/nucleon. The invariant cross sections of inclusive proton production at an angle of 3.5° are obtained. It is shown that the dependence of experimental invariant cross sections of proton production on the cumulative variable x in the range 0.9 < x < 2.4 can be explained on the basis of Fermi motion of nucleons in the nuclei, multiple scattering processes and delta resonance formation. A comparison was made with results obtained within the framework of the quark cluster model and experimental data.

Unified description of the fission probability for highly excited nuclei

ABSTRACT We present a new model to describe the fission probability of the high-energy fission model, as deduced from the intra-nuclear cascade calculation with the Intra-Nuclear Cascade model of Liége (INCL) version 4.6 and Prokofiev’s phenomenological systematics of the proton-induced fission cross-sections. This model is implemented in the de-excitation model of the generalized evaporation model (GEM), and applied to Monte Carlo spallation reaction simulation using the Particle and Heavy Ion Transport code System (PHITS). Comparing with experimental data for subactinide nuclei shows that this model can provide a unified prediction of the proton-, neutron-, and deuteron-induced fission cross-sections with markedly improved accuracy. The calculated fission fragments tend to shift to higher mass numbers. To account for the isotopic distributions of fission fragments within the framework of a coupled INCL/GEM, modification of INCL would be required, especially for description of the highly excited states of residual nuclei.

Cumulative Protons in Collisions between Carbon and Beryllium Nuclei at Energies of 0.60, 0.95, and 2.0 GeV/nucleon

Collisions between carbon and beryllium nuclei at initial kinetic energies of carbon nuclei of 0.6, 0.95, and 2.0 GeV/nucleon have been simulated within the Liege intranuclear cascade model. Invariant proton production cross sections at an angle of 3.5° have been determined. It has been shown that the dependence of experimental invariant proton production cross sections on the cumulative variable can be explained in terms of Fermi processes of motion of nucleons in a nucleus, multiple scattering, and production of delta resonances. Results of simulation have been compared to experimental data and results obtained within the quark cluster model.

Parametrization of cross sections for elementary hadronic collisions involving strange particles

The production of strange particles (kaons, hyperons) and hypernuclei in light charged particle induced reactions in the energy range of a few GeV (2-15 GeV) has become a topic of active research in several facilities (e.g., HypHI and PANDA at GSI and/or FAIR (Germany), JLab (USA), and JPARC (Japan)). This energy range represents the low-energy limit of the string models (degree of freedom: quark and gluon) or the high-energy limit of the so-called spallation models (degree of freedom: hadrons). A well known spallation model is INCL, the Li\`ege intranuclear cascade model (combined with a de-excitation model to complete the reaction). INCL, known to give good results up to 2-3 GeV, was recently upgraded by the implementation of multiple pion emission to extend the energy range of applicability up to roughly 15 GeV. The next step, to account also for strange particle production, both for refining the high energy domain and making it usable when strangeness appears, requires the following main ingredients: i) the relevant elementary cross sections (production, scattering, and absorption) and ii) the characteristics of the associated final states. Some of those ingredients are already known and, sometimes, are already used in models of the same type (e.g., Bertini, GiBUU), but this paper aims at reviewing the situation by compiling, updating, and comparing the necessary elementary information which are independent of the model used.

Constraining the Λ -nucleus potential within the Liège intranuclear cascade model

The new version of the Li\`ege intranuclear-cascade model (INCL), recently extended to the production of strange particles and hypernuclei, is used to investigate the $\mathrm{\ensuremath{\Lambda}}$-nucleus potential in a broad range of nuclear masses from Si to Pb. The combination of the INCL calculation results with experimental cross sections of $\mathrm{\ensuremath{\Lambda}}$ hypernuclei, obtained from (${\ensuremath{\pi}}^{+},{K}^{+}$) reaction studies, allows us to constrain the $\mathrm{\ensuremath{\Lambda}}$-nucleus potential depth with an accuracy of about 0.9 MeV. Our results show that the potential depth increases with the mass number ($A$) from 28 MeV in the region of medium-mass hypernuclei up to a maximum of 39.6 MeV in the region of heavy hypernuclei around $A=208$. This deviation could be related to the nucleon-isospin dependence of the three-body $\mathrm{\ensuremath{\Lambda}}$-nucleon-nucleon force in asymmetry matter whose contribution is more relevant in hyperneutron matter due to a strong contribution from $\mathrm{\ensuremath{\Lambda}}nn$ interactions.

Characterization of a mixed high-energy spallation neutron–proton field using monoisotopic activation detectors

We used monoisotopic Co, Au, and Bi threshold activation detectors to characterize the high-energy (>5 MeV) portion of a mixed spallation neutron–proton (n/p) field. The field was produced by irradiating the natural uranium target–blanket subcritical assembly Quinta with 660-MeV protons from Phasotron accelerator at the Joint Institute for Nuclear Research (JINR) in Dubna. Experimental yields of the (n,x) and (p,x) reactions were compared to the calculated reaction rates, which represent the convolution of particle flux and reaction cross section. The flux was simulated using the radiation transport code MCNPX 2.7.0, and the cross sections were extracted from the following three sources: the intranuclear cascade model INCL4.2, the phenomenological spherical optical model from TALYS-1.8, and the evaluated nuclear data file TENDL-2015. We show that, in most cases, the evaluated data provide a closer agreement with the experimental data in comparison with INCL4.2 model, which is an integral part of MCNPX. Our results bring a contribution to those fields of physics research that utilize computer prediction of neutron generation in the energy range of tens to hundreds MeV, such as the medical radioisotope production, radiation shielding of spallation neutron sources, and nuclear transmutation in accelerator-driven systems.