Intranuclear Cascade Model Research Articles

Measurement of aluminum activation cross section and gas production cross section for 0.4 and 3-GeV protons

To estimate the lifetime and the radiation dose of the proton beam window used in the spallation neutron source at J-PARC, it is necessary to understand the accuracy of the production cross section of 3-GeV protons. To obtain data on aluminum, the reaction cross section of aluminum was measured at the entrance of the beam dump placed in the 3-GeV proton synchrotron. Owing to the use of well-calibrated current transformers and a well-collimated beam, the present data has good accuracy. After irradiation, the cross sections of Al(p,x)7 Be, Al(p,x)22 Na-22 and Al(p,x)24 Na were obtained by gamma-ray spectroscopy using a Ge detector. It was found that the evaluated data of JENDL/HE-2007 agree well with the current experimental data, whereas intra-nuclear cascade models (Bertini, INCL-4.6, and JAM) with the GEM statistical decay model underestimate by about 30% in general. Moreover, gas production, such as T and He, and the cross sections were measured for carbon, which was utilized as the muon production target in J-PARC. The experiment was performed with 3-GeV proton having beam power of 0.5 MW, and the gasses emitted in the process were observed using a quadrupole mass spectrometer in the vacuum line for beam transport to the mercury target. It was found that the JENDL/HE-2007 data agree well with the present experimental data.

Validation of PHITS Spallation Models from the Perspective of the Shielding Design of Transmutation Experimental Facility

The impact of different spallation models implemented in the particle transport code PHITS on the shielding design of Transmutation Experimental Facility is investigated. For 400-MeV proton incident on a lead-bismuth eutectic target, an effective dose rate at the end of a thick radiation shield (3-m-thick iron and 3-m-thick concrete) calculated by the Liege intranuclear cascade (INC) model version 4.6 (INCL4.6) coupled with the GEMcode (INCL4.6/GEM) yields about twice as high as the Bertini INC model (Bertini/GEM). A comparison with experimental data for 500-MeV proton incident on a thick lead target suggest that the prediction accuracy of INCL4.6/GEM would be better than that of Bertini/GEM. In contrast, it is found that the dose rates in beam ducts in front of targets calculated by the INCL4.6/GEMare lower than those by the Bertini/GEM. Since both models underestimate the experimental results for neutron-production doubledifferential cross sections at 180◦ for 140-MeV proton incident on carbon, iron, and gold targets, it is concluded that it is necessary to allow a margin for uncertainty caused by the spallation models, which is a factor of two, in estimating the dose rate induced by neutron streaming through a beam duct.

Monte carlo simulations of the n_TOF lead spallation target with the Geant4 toolkit: A benchmark study

Monte Carlo (MC) simulations are an essential tool to determine fundamental features of a neutron beam, such as the neutron flux or the γ-ray background, that sometimes can not be measured or at least not in every position or energy range. Until recently, the most widely used MC codes in this field had been MCNPX and FLUKA. However, the Geant4 toolkit has also become a competitive code for the transport of neutrons after the development of the native Geant4 format for neutron data libraries, G4NDL. In this context, we present the Geant4 simulations of the neutron spallation target of the n_TOF facility at CERN, done with version 10.1.1 of the toolkit. The first goal was the validation of the intra-nuclear cascade models implemented in the code using, as benchmark, the characteristics of the neutron beam measured at the first experimental area (EAR1), especially the neutron flux and energy distribution, and the time distribution of neutrons of equal kinetic energy, the so-called Resolution Function. The second goal was the development of a Monte Carlo tool aimed to provide useful calculations for both the analysis and planning of the upcoming measurements at the new experimental area (EAR2) of the facility.

Dependence of neutron rate production with accelerator beam profile and energy range in an ADS-TRIGA RC1 reactor

Abstract Lead, mercury, tantalum and tungsten were used as target material for calculation of spallation processes in an ADS-TRIGA RC1 reactor. The results show that tungsten has the highest neutron production rate. Therefore it was selected as target material for further calculations. The sensitivity of neutron parameters of the ADS reactor core relative to a change of beam profile and proton energy was determined. The core assembly and parameters of the TRIGA RC1 demonstration facility were used for the calculation model. By changing the proton energy from 115 to 1 400 MeV by using the intra-nuclear cascade model of Bertini (INC-Bertini), the quantity of the relative difference in % for energy gain (G) and spallation neutron yield (Yn/p), increases to 289.99 % and 5199.15 % respectively. These changes also reduce the amount of relative difference for the proton beam current (Ip) and accelerator power (Pacc), 99.81 % and 81.28 % respectively. In addition, the use of a Gaussian distribution instead of a uniform distribution in the accelerator beam profile increases the quantity of relative difference for energy gain (G), net neutron multiplication (M) and spallation neutron yield (Yn/p), up to 4.93 %, 4.9 % and 5.55 % respectively.

Systematic measurement of double-differential neutron production cross sections for deuteron-induced reactions at an incident energy of 102 MeV

Double-differential neutron production cross sections (DDXs) for deuteron-induced reactions on Li, Be, C, Al, Cu, and Nb at 102MeV were measured at forward angles ≤25° by means of a time of flight (TOF) method with NE213 liquid organic scintillators at the Research Center of Nuclear Physics (RCNP), Osaka University. The experimental DDXs and energy-integrated cross sections were compared with TENDL-2015 data and Particle and Heavy Ion Transport code System (PHITS) calculation using a combination of the KUROTAMA model, the Liege Intra-Nuclear Cascade model, and the generalized evaporation model. The PHITS calculation showed better agreement with the experimental results than TENDL-2015 for all target nuclei, although the shape of the broad peak around 50MeV was not satisfactorily reproduced by the PHITS calculation.

Comparison of Physics Model for 600 MeV Protons and 290 MeV·n<sup>-1</sup> Oxygen Ions on Carbon in MCNPX

Background: With the increase in the number of particle accelerator facilities under either operation or construction, the accurate calculation using Monte Carlo codes become more important in the shielding design and radiation safety evaluation of accelerator facilities. Materials and Methods: The calculations with different physics models were applied in both of cases: using only physics model and using the mix and match method of MCNPX code. The issued conditions were the interactions of 600 MeV proton and 290 MeV·n-1 oxygen with a carbon target. Both of cross-section libraries, JENDL High Energy File 2007 (JENDL/HE-2007) and LA150, were tested in this calculation. In the case of oxygen ion interactions, the calculation results using LAQGSM physics model and JENDL/ HE-2007 library were compared with D. Satoh’s experimental data. Other Monte Carlo calculations using PHITS and FLUKA codes were also carried out for further benchmarking study. Results and Discussion: It was clearly found that the physics models, especially intra-nuclear cascade model, gave a great effect to determine proton-induced secondary neutron spectrum in MCNPX code. The variety of physics models related to heavy ion interactions did not make big difference on the secondary particle productions. Conclusion: The variations of secondary neutron spectra and particle transports depending on various physics models in MCNPX code were studied and the result of this study can be used for the shielding design and radiation safety evaluation.

Cross sections of proton- and neutron-induced reactions by the Liège intranuclear cascade model

The purpose of the paper is mainly to test the validity of the Liege intranuclear cascade (INCL) model in calculating the cross sections of proton-induced reactions for cosmogenic nuclei using the newly compiled database of proton cross sections. The model calculations of He-3 display the rising tendency of cross sections with the increase of energy, in accordance with the experimental data. Meanwhile, the differences between the theoretical results and experimental data of production cross sections (Be-10 and Al-26) are generally within a factor of 3, meaning that the INCL model works quite well for the proton-induced reactions. Based on the good agreement, we predict the production cross sections of Al-26 from reactions n + Al-27, n + Si-28, and n + Ca-40 and those of Be-10 from reactions n + O-16 and n + Si-28. The results also show a good agreement with a posteriori excitation functions.

Ranking and validation of the spallation models for description of intermediate mass fragment emission from p + Ag collisions at 480 MeV incident proton beam energy

Double-differential cross-sections $d^{2}\sigma/d\Omega dE$ for isotopically identified intermediate mass fragments ( 6Li up to 27Mg from nuclear reactions induced by 480 MeV protons impinging on a silver target were analyzed in the frame of a two-step model. The first step of the reaction was described by the intranuclear cascade model INCL4.6 and the second one by four different models (ABLA07,GEM2, GEMINI++, and SMM). The experimental spectra reveal the presence of low-energy, isotropic as well as high-energy, forward-peaked contributions. The INCL4.6 model offers a possibility to describe the latter contribution for light intermediate mass fragments by coalescence of the emitted nucleons. The qualitative agreement of the model predictions with the data was observed but the high-energy tails of the spectra were significantly overestimated. The shape of the isotropic part of the spectra was reproduced by all four models. The GEM2 model strongly underestimated the value of the cross-sections for heavier IMF whereas the SMM and ABLA07 models generally overestimated the data. The best quantitative description of the data was offered by GEMINI++, however, a discrepancy between the data and the model cross-sections still remained for almost all reaction products, especially at forward angles. It indicates that non-equilibrium processes are present which cannot be reproduced by the applied models. The goodness of the data description was judged quantitatively using two statistical deviation factors, the H-factor and the M-factor, as a tool for ranking and validation of the theoretical models.

Processes involving few degrees of freedom in the frame of Intranuclear Cascade approaches

This article focuses on spallation reactions, i.e. interactions of energetic nucleons, basically with a kinetic energy in the 100MeV to a few GeV range, with a target nucleus. These processes are described rather successfully by the so-called Intranuclear Cascade (INC) plus evaporation models. They can be viewed as a first stage of nucleon-nucleon collisions, ejecting fast particles, followed by evaporation of slow particles from the target remnant. These cascade + evaporation models have, now, globally reached a high level of predictive power, owing in particular to successive research programs. The present work, which is an outcome of one of these programs, the recent European Union ANDES research program, deals with a set of reactions (or observable quantities), which can be due to a single collision, such as the one-nucleon removal reactions or the quasi-elastic elastic process. A survey of the experimental data is presented, which allows to clearly point out that, often, the INC models are unsatisfactory for the description of these peculiar events, whereas they are rather successful for the rest of the experimental data. This paradoxical situation is tentatively related to quasi-particle effects which are neglected in INC models.

Impact of PHITS spallation models on the neutronics design of an accelerator-driven system

ABSTRACTThe impact of different spallation models and parametrisation of nucleon–nucleus interactions in the particle transport code PHITS on the nuclear characteristics of an accelerator-driven system (ADS) is investigated. Cut-off neutrons below 20 MeV calculated using the default option of the current spallation model (i.e. Liège intranuclear cascade (INC) model version 4.6, INCL4.6) are found to be 14% less than those calculated by the old spallation model (i.e. Bertini INC model). This decrease increases the proton beam current that drives the 800-MW thermal power and impacts various ADS parameters, including material damage, nuclear heating of the proton beam windowand the inventory of spallation products. To validate these options based on the ADS neutronics design, we conduct benchmark calculations of the total and non-elastic cross sections, thick target neutron yields and activation reaction rate distributions. The results suggest that Pearlstein–Niita systematics, which is a default option of the nucleon–nucleus interaction parametrisation, would be the best option and that Bertini INC is better suited for cut-off neutrons than INCL4.6. However, because of the difficulty in making a definite conclusion on the spallation models, we conclude that relatively large uncertainty in the cut-off neutrons, which is the difference between the two spallation models (i.e. 14%), should be considered.

Extended Intranuclear Cascade model for pickup reactions induced by 50-MeV-range protons

The intranuclear cascade model was investigated to explain (p, dx ) and (p, ax ) reactions at incident energies of around 50 MeV. Since these reactions are governed mainly by the direct pickup process, the model was expanded to include exclusive pickup processes leading to hole-state-excitations. The energy of the outgoing clusters is determined with single-particle energies of transferred nucleons, the reaction Q -value, and the recoil of the residual nucleus. The rescattering of the produced cluster inside the nucleus is treated within the intranuclear cascade model. The emission angle is given by the sum of momentum vectors of transferred nucleons in addition to the deflection at the nuclear surface, which was introduced to explain angular distributions of elastic scattering. Double differential cross sections of reactions were calculated and compared with experimental data. The proposed model showed a high predictive power over the wide range of emission energies and angles. The treatment ofthe cluster transport inside the nucleus was also verified.

Angular distribution of evaporated protons from 50-MeV-range proton-nucleus reactions

The angular distribution of compound reactions at bombarding energies lower than 10 MeV is known to be 90˚ symmetry. At the higher incident energies, 50-MeV range, the quantization axis tilts from the beam axis due to the particle emission in the cascade or the pre- equilibrium process. Therefore, it is necessary to know the tilted quantization axis for the angular distribution calculation of the evaporated protons from (p, p'x) reactions. In the present work, we applied the intranuclear cascade (INC) model to determine the tilted quantization axis by a classical vector analysis. The proton evaporation was calculated by the generalized evaporation model (GEM). By fitting calculations to experimental angular distributions, we deduced the angular momentum transfer from the equilibrium state.

Development of an intranuclear-cascade code CBIM applicable to the nuclear reaction with incident particle energy above 45 MeV

The Monte Carlo intra-nuclear cascade program CBIM has been developed for describing spallation reactions involving protons, neutrons and pions on complex nuclei. In order to describe cascade process, several simplifications and assumptions are made in the following:firstly, neither reaction, nor reflection, nor refraction, nor ionization will be taken into account before the incident particle enters into the target nucleus; secondly, target nucleus is regarded as being spherical and the atom number should be greater than 2; thirdly, the knocked nucleon is determined by cross section sampling; finally, in the center-of-mass frame, the scattering angle is sampled based on differential cross section distribution. The basis physics model is based on the above assumptions and Bertini intra-nuclear cascade model; meanwhile, nucleon-nucleon angle differential distributions of INCL in the center-of-mass frame are introduced to overcome the shortage of Bertini model. The interactions between nucleon and nucleon or between nucleon and pion, such as elastic scattering, pion production and charge exchange, are included in the code. In the particles collision, the nucleon density changes with the target nucleus radius; and the interaction cross sections refer to 22 kinds of experimental cross sections in Bertini model. The intra-nuclear cascades induced by 45-3500 MeV neutron, proton or pion below 2500 MeV can be simulated by this code. Finally, comparisons between experimental reaction cross section over the energy range 60-378 MeV, and some simulation results by MCNPX, GEANT4 and PHITS over the energy range 65-3000 MeV show that they are in reasonable agreement with the CBIM results over the broad energy range considered.

The production of residual radionuclides by a 250 MeV proton beam

Radionuclide production was studied by bombarding Cu, W and Pb targets with a 250 MeV proton beam. The data were obtained by using the off-line γ-spectroscopy method. Six nuclides in Cu, 28 nuclides in W and 34 nuclides in Pb targets were identified and their cross sections were determined. The measured results were compared to other experiments with isotopic Cu and W targets. Corresponding simulations using the MCNPX transport code were also performed to compare the measurements. In the simulations, eight different models or combinations of intranuclear cascade and de-excitation models were introduced. The comparison indicated that most cross sections were fairly reliably predicted for nuclides in the spallation mass region, but differ greatly for nuclides in the medium and fission mass regions.

The Geant4 Bertini Cascade

One of the medium energy hadron–nucleus interaction models in the Geant4 simulation toolkit is based partly on the Bertini intranuclear cascade model. Since its initial appearance in the toolkit, this model has been largely re-written in order to extend its physics capabilities and to reduce its memory footprint. Physics improvements include extensions in applicable energy range and incident particle types, and improved hadron–nucleon cross-sections and angular distributions. Interfaces have also been developed which allow the model to be coupled with other Geant4 models at lower and higher energies. The inevitable speed reductions due to enhanced physics have been mitigated by memory and CPU efficiency improvements. Details of these improvements, along with selected comparisons of the model to data, are discussed.

Antideuteron sensitivity for the GAPS experiment

The General Antiparticle Spectrometer (GAPS) is a novel approach for indirect dark matter searches that exploits cosmic antiparticles, especially antideuterons. The GAPS antideuteron measurement utilizes distinctive detection methods using atomic X-rays and charged particles from the decay of exotic atoms as well as the timing and stopping range of the incoming particle, which together provide excellent antideuteron identification. Prior to the future balloon experiment, an accelerator test and a prototype flight were successfully conducted in 2005 and 2012 respectively, in order to verify the GAPS detection concept. This paper describes how the sensitivity of GAPS to antideuterons was estimated using a Monte Carlo simulation along with the atomic cascade model and the Intra-Nuclear Cascade model. The sensitivity for the GAPS antideuteron search obtained using this method is 2.0 ×10−6[m−2s−1sr−1(GeV/n)−1] for the proposed long duration balloon program (LDB, 35 days × 3 flights), indicating that GAPS has a strong potential to probe a wide variety of dark matter annihilation and decay models through antideuteron measurements. GAPS is proposed to fly from Antarctica in the austral summer of 2019–2020.

Calculation and analysis of cross-sections for p+184W reactions up to 200 MeV**Supported by National Basic Research Program of China, Technology Research of Accelerator Driven Sub-critical System for Nuclear Waste Transmutation (2007CB209903) and Strategic Priority Research Program of Chinese Academy of Sciences, Thorium Molten Salt Reactor Nuclear Energy System (XDA02010100)

A set of optimal proton optical potential parameters for p+ 184W reactions are obtained at incident proton energy up to 250 MeV. Based on these parameters, the reaction cross-sections, elastic scattering angular distributions, energy spectra and double differential cross sections of proton-induced reactions on 184W are calculated and analyzed by using theoretical models which integrate the optical model, distorted Born wave approximation theory, intra-nuclear cascade model, exciton model, Hauser-Feshbach theory and evaporation model. The calculated results are compared with existing experimental data and good agreement is achieved.

Disintegration of 12C nuclei by 700–1500 MeV photons

Disintegration of 12C nuclei by tagged photons of 700–1500 MeV energy at the GRAAL facility has been studied by means of the LAGRANγE detector with a wide angular acceptance. The energy and momentum distributions of produced neutrons and protons as well as their multiplicity distributions were measured and compared with corresponding distributions calculated with the RELDIS model based on the intranuclear cascade and Fermi break-up models. It was found that eight fragments are created on average once per about 100 disintegration events, while a complete fragmentation of 12C into 12 nucleons is observed typically only once per 2000 events. Measured multiplicity distributions of produced fragments are well described by the model. The measured total photoabsorption cross section on 12C in the same energy range is also reported.

PHITS Simulation of Quasi-Monoenergetic Neutron Sources from 7Li(p,n) Reactions

Abstract We developed a new method that is a combination of the intranuclear cascade model and the distorted wave Born approximation (DWBA) calculation, and implemented into the particle and heavy ion transport code system (PHITS). The new method was applied to estimate the neutron spectra in reactions induced by protons incident on the 7Li target at incident energies of 150, 246, and 389 MeV. The results obtained by PHITS using the new method reproduced observed sharp peaks in the neutron spectrum as a result of taking into account the transitions to discrete nuclear states by DWBA.

Improving the description of proton-induced one-nucleon removal in intranuclear-cascade models

It is a well-established fact that intranuclear-cascade models generally overestimate the cross sections for one-proton removal from heavy, stable nuclei by a high-energy proton beam, but they yield reasonable predictions for one-neutron removal from the same nuclei and for one-nucleon removal from light targets. We use simple shell-model calculations to investigate the reasons for this deficiency. We find that a refined description of the neutron skin and of the energy density in the nuclear surface is crucial for the aforementioned observables, and that neither ingredient is sufficient if taken separately. As a by-product, the predictions for removal of several nucleons are also improved by the refined treatment.