Partial Fragmentation Cross Sections Research Articles

Current status of the “Hybrid Kurotama model” for total reaction cross sections

To be able to calculate the nucleon+nucleus and nucleus+nucleus total reaction cross sections with precision is of great importance for studies of fundamental nuclear properties, e.g., the nuclear structure. This is also very important for particle and heavy ion transport calculations since in all particle and heavy ion transport codes, the probability function according to which a projectile particle will collide within a certain distance in a matter depends on the total reaction cross sections. This will also scale the calculated partial fragmentation cross sections. It is therefore crucial that accurate total reaction cross section models are used in the transport calculations. In this paper, a new general purpose total reaction cross section model/subroutine called “Hybrid Kurotama” is presented. The model has been tested against available p+He, p+nucleus, and nucleus+nucleus total reaction cross sections and an overall better agreement has been found than for earlier published models. This model is therefore very suitable to be used in any deterministic or Monte Carlo particle and heavy ion transport code.

Comparative study of depth dose-distributions and partial fragmentation cross sections of 56Fe ions on polyethylene using GEANT4

The depth dose-distributions and partial fragmentation cross sections for 56Fe ions on a polyethylene medium are estimated using Geant4: a Monte Carlo simulation toolkit. The models employed in the present work are the Binary Cascade, Abrasion-Ablation and Quantum Molecular Dynamics. The multifragmentation models, such as statistical multifragmentation and Fermi break-up models are used in combination with the other models to define the nuclear interactions more precisely. The partial fragmentation cross sections are calculated on the basis of charge scored in the detector. The simulated results are validated by comparing with the experimental data.

A comparison of total reaction cross section models used in particle and heavy ion transport codes

Understanding the interactions and propagations of high energy protons and heavy ions are essential when trying to estimate the biological effects of Galactic Cosmic Rays (GCR) and Solar Particle Events (SPE) on personnel in space. To be able to calculate the shielding properties of different materials and radiation risks, particle and heavy ion transport codes are needed. In all particle and heavy ion transport codes, the probability function that a projectile particle will collide within a certain distance x in the matter depends on the total reaction cross sections, and the calculated partial fragmentation cross sections scale with the total reaction cross sections. It is therefore crucial that accurate total reaction cross section models are used in the transport calculations. In this paper, different models for calculating nucleon–nucleus and nucleus–nucleus total reaction cross sections are compared with each other and with measurements. The uncertainties in the calculations with the different models are discussed, as well as their overall performances with respect to the available experimental data. Finally, a new compilation of experimental data is briefly presented.

Fragmentation of 370MeV/n 20Ne and 470MeV/n 24Mg in light targets

Total charge-changing cross sections and cross sections for the production of projectile-like fragments were determined for fragmentation reactions induced by 370 MeV/n Ne-20 ions in water and lucite, and 490 MeV/n Mg-24 ions in polyethylene, carbon and aluminum targets sandwiched with CR-39 plastic nuclear track detectors. An automated microscope system and a track-to-track matching algorithm were used to count and recognize the primary and secondary particles. The measured cross sections were then compared with published cross sections and predictions of different models. Two models and the three-dimensional Monte Carlo Particle Heavy Ion Transport Code System (PHITS) were used to calculate total charge-changing cross sections. Both models agreed within a few percent for the system Mg-24 + CH2, however a deviation up to 20% was observed for the systems Ne-20 + H2O and C5H8O2, when using one of the models. For all the studied systems, PHITS systematically underestimated the total charge-changing cross section. It was also found that the partial fragmentation cross sections for Mg-24 + CH2 measured in present and earlier works deviated up to 20% for Z = 6-11. Measured cross sections for the production of fragments (Z = 4-9) for Ne-20 + H2O and C5H8O2 were compared with predictions of three different semi-empirical models and JQMD which is used in the PHITS code. The calculated cross sections differed from the measured data by 10-90% depending on which fragment and charge was studied, and which model was used. (C) 2010 Elsevier Ltd. All rights reserved.

Fragmentation cross sections of Fe 26+, Si 14+ and C 6+ ions of 0.3–10 [formula omitted] on polyethylene, CR39 and aluminum targets

We present new measurements of the total and partial fragmentation cross sections in the energy range 0.3–10 A GeV of 56Fe, 28Si and 12C beams on polyethylene, CR39 and aluminum targets. The exposures were made at Brookhaven National Laboratory (BNL), USA, and Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. The CR39 nuclear track detectors were used to identify the incident and survived beams and their fragments. The total fragmentation cross sections for all targets are almost energy independent while they depend on the target mass. The measured partial fragmentation cross sections are also discussed.

Recent developments and benchmarking of the PHITS code

Many new options have recently been included in PHITS, e.g., to calculate LET distributions of particles in matter or energy-deposition distributions event by event and correlations between energy depositions in different regions. This makes it possible to calculate the effects of particle radiation on biological and non-biological materials, e.g., risk for single event upsets in electronic devices. As a part of an extensive ongoing benchmarking of PHITS, we have compared calculated partial projectile fragmentation cross sections with accelerator-based measurements from the reactions of 200–1000 MeV/n 4He, 12C, 14N, 16O, 20Ne, 28Si, 40Ar, and 56Fe on polyethylene, carbon, aluminum, copper, tin and lead, with different thicknesses, using different total reaction cross section models in PHITS. We have compared simulated and measured Bragg and attenuation curves of 200 MeV/n 12C in water, and neutron energy spectra, at different angles, from 100 to 400 MeV/n 12C stopped in water. Bragg curves for 110, 140, 170, 190 and 225 MeV/n 3He in water have been studied, as well as gamma-ray dose decay curves of activated Cu target bombarded by 400 and 800 MeV/n 40Ar. When using the default total reaction cross section model developed by Tripathi et al. (1996,1997 and 1999) [Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections, Nucl. Instr. Methods B117, 347, 1996; Tripathi, R.K., Wilson, J.W., Cucinotta, F.A. Accurate universal parameterization of absorption cross sections II – neutron absorption cross sections. Nucl. Instr. Methods B129, 11, 1997 ; Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections III – light systems. Nucl. Instr. Methods B155, 349, 1999.] the partial fragmentation cross sections appear to be systematically slightly underestimated by a factor which is independent on the fragment species within the same data set, and so do the simulated neutron energy spectra from selected heavy ion reactions; especially in the forward direction. The simulated attenuation and Bragg curves, however, show good agreement with measured ones. These observations stimulate further benchmarking to confirm the accuracy of the code and gives directions on possible improvements to be applied to the code in the near future.

ELECTROMAGNETIC DISSOCIATION IN ULTRARELATIVISTIC HEAVY ION REACTIONS

Over the last years ultrarelativistic heavy ion beams with energies from 14.5 GeV/nucleon up to 200 GeV/nucleon were accelerated at the Brookhaven and CERN accelerators. We measured total charge changing cross sections and partial fragmentation cross sections for 16 O , 28 Si and 32 S projectiles breaking up into fragments with charges ZF≥6. The measured contributions of electromagnetic dissociation (ED) to the total charges changing cross sections are in agreement with theoretical calculations. By application of factorization rules it is possible to separate measured partial cross sections into a pure nuclear component and into a component caused by ED. The ED component shows a significant contribution from fragmentation events with ΔZ>2 which can be explained by interactions of energetic photons with generation and decay of nucleon resonances in the projectile.