Partial Charge-changing Cross Sections Research Articles

The total and the partial charge-changing cross sections of 40Ar fragmentation on elemental targets at 500 A MeV

The total and the partial charge-changing cross sections of 40Ar fragmentation on CH2, C, Al, Cu and Pb targets at the highest energy of 495 A MeV were investigated using CR-39 plastic nuclear track detector. The total charge-changing cross-section for hydrogen target was calculated based on the results of polyethylene and carbon targets. It was found that the total charge-changing cross sections for fragmentation of 40Ar on H, C, Al, Cu and Pb targets were independent on the beam energy in our studied energies, and were consistent with the predictions of Bradt-Peters semi-empirical formula. Nilsen semi-empirical formula, NUCFRG2 and PHITS simulation codes given an underestimation of experimental data. The partial cross sections for projectile fragment production were independent on the beam energy in our studied energies for each target and do not show a significant odd-even effect. The partial cross sections for projectile fragment production were also compared with different empirical parametrization formulas, such as different version of Cummings, Nilsen, FRACS and EPAX3. Generally, EPAX3 and FRACS empirical parametrization can give a reasonable estimation of data within 25% relative errors.

Charge-Changing Cross Sections of 736 A MeV 28Si on Carbon Targets**Supported by the National Natural Science Foundation of China under Grant Nos 11075100, 11347198 and 11565001, and the Shanxi Provincial Science Foundation under Grant No 2011011001-2.

The total and partial charge-changing cross sections of 28Si on carbon targets at 736 and 723 A MeV are studied by CR-39 plastic nuclear track detectors using the HSP-1000 microscope system and the PitFit track measurement software. The values of the total charge-changing cross section are and at 736 and 723 A MeV, respectively. The result is compared with the ones obtained by other experimental and theoretical results. The odd–even effect of the partial charge-changing cross section is observed.

Benchmarking GATE/Geant4 for 16O ion beam therapy

Oxygen () ions are a potential alternative to carbon ions in ion beam therapy. Their enhanced linear energy transfer indicates a higher relative biological effectiveness and a reduced oxygen enhancement ratio. Due to the limited availability of ion beams, Monte Carlo (MC) transport codes are important research tools for investigating their potential. The purpose of this study was to validate GATE/Geant4 for ion beam therapy using experimental data from literature. Five hadron physics lists and two electromagnetic options were benchmarked against measured depth dose distributions (DDDs) and charge-changing cross sections. The simulated beam ranges deviated by less than 0.5% for all physics configurations and only a few points exceeded the gamma index criterion (2%/1 mm). However, the simulated partial charge-changing cross sections deviated considerably for some hadron physics configurations. Best agreement with the experimental values was obtained with the quantum molecular dynamics model (QMD), and we therefore suggest using this model in Geant4 to accurately describe the fragmentation of ion beams into lighter fragments ().

Investigations of charge-changing processes for light proton-rich nuclei on carbon and solid-hydrogen targets

We investigated charge-changing processes (total charge-changing cross sections and partial charge-changing cross sections) for light proton-rich nuclei (34–36Ar, 33Cl, 25–28Si) at around 300A MeV on carbon and solid-hydrogen targets. We estimated the nuclear proton point radii of 33Cl and 25,26,27Si from the observed total charge-changing cross sections by using Glauber-model calculations with a phenomenological correction factor. Furthermore, we estimated the proton skin thickness for 33Cl coupled with its previously observed matter radius. From investigations of the partial charge-changing cross sections, clear zigzag pattern was observed for all isotopes. The present studies suggest that the pattern may be common in the proton-rich side, and depends on the odd–even nature of the fragment charge.

Charge-changing cross sections ofNe30,Na32,33with a proton target

The total charge-changing, charge pick-up, and partial charge-changing cross sections of very neutron-rich nuclei (Ne30, Na32,33) with a proton target have been measured at ∼240A MeV for the first time. We introduced the phenomenological correction factor in Glauber-model calculations for the total charge-changing cross sections with the proton target, and applied it to deduce the proton radii of these nuclei. For Ne30 and Na32, the neutron skin thicknesses of the nuclei were deduced by comparing the proton radii with the matter radii deduced from the interaction cross-section measurements. A significant thick neutron-skin has been observed for the nuclei. We also found that the charge pick-up cross sections are much larger than those in the systematics of stable nuclei.Received 30 January 2014Revised 7 March 2014DOI:https://doi.org/10.1103/PhysRevC.89.044602©2014 American Physical Society

Fragmentation cross-section of 600 A MeV Si14+ ions in thick polyethylene target

Total and partial charge-changing cross-sections of 600 A MeV Si14+ ions in a thick polyethylene target were measured by CR39 track etch detectors using an optical microscope DM 6000 M system installed with Leica QWin Plus software. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments using the cone-height distribution method. The charge resolution of CR39 detectors was achieved to be 0.17e in the present condition. The value of the total charge-changing cross-section was calculated to be σ tot = (766±17) mb. To calculate the partial charge-changing cross-sections for ΔZ = −11, −10, ..., −1, , number of events corresponding to each fragment were determined from multiple Gaussian fitting of cone-height distributions within 95.5% confidence level and the number of incident and survived beam ions were counted within 99.7% confidence level. Possible odd-even pattern in the values of the partial charge-changing cross-section is also presented. The measured charge pick-up cross-section for ΔZ = +1 is (7.2 ±1.7) mb.

Systematic study of individual charge-changing cross sections of intermediate-energy secondary beams

Charge-changing interactions of stable and unstable medium-mass nuclides have been systematically investigated at intermediate energies. Secondary beams ranging from Ar to Ge isotopes produced by projectile fragmentation of 56Fe and 70Ge were irradiated onto a carbon target, and their total and partial charge-changing cross sections were precisely measured. A clear odd–even effect found in the partial charge-changing cross sections monotonically varies as a function of the Z/N ratio among the isotopes, and grows toward the neutron-deficient side. The total charge-changing cross sections are sensitive to the Z number of nuclides, and tend to gradually increase toward the neutron-deficient side in some isotopes.

Evaluation of nuclear reaction cross-sections and fragment yields in carbon beams using the SHIELD-HIT Monte Carlo code. Comparison with experiments

In light ion therapy, the knowledge of the spectra of both primary and secondary particles in the target volume is needed in order to accurately describe the treatment. The transport of ions in matter is complex and comprises both atomic and nuclear processes involving primary and secondary ions produced in the cascade of events. One of the critical issues in the simulation of ion transport is the modeling of inelastic nuclear reaction processes, in which projectile nuclei interact with target nuclei and give rise to nuclear fragments. In the Monte Carlo code SHIELD-HIT, inelastic nuclear reactions are described by the Many Stage Dynamical Model (MSDM), which includes models for the different stages of the interaction process. In this work, the capability of SHIELD-HIT to simulate the nuclear fragmentation of carbon ions in tissue-like materials was studied. The value of the parameter κ, which determines the so-called freeze-out volume in the Fermi break-up stage of the nuclear interaction process, was adjusted in order to achieve better agreement with experimental data. In this paper, results are shown both with the default value κ = 1 and the modified value κ = 10 which resulted in the best overall agreement. Comparisons with published experimental data were made in terms of total and partial charge-changing cross-sections generated by the MSDM, as well as integral and differential fragment yields simulated by SHIELD-HIT in intermediate and thick water targets irradiated with a beam of 400 MeV u−1 12C ions. Better agreement with the experimental data was in general obtained with the modified parameter value (κ = 10), both on the level of partial charge-changing cross-sections and fragment yields.

Measurement of the fragmentation of Carbon nuclei used in hadron-therapy

The increasing use of Carbon nuclei in cancer therapy centres is motivated by their potential advantages as a very precise high LET radiation. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighbouring the tumour. We report here a study of the fragmentation with the nuclear emulsion experimental technique. We have designed, built and exposed to a Carbon nuclei beam a chamber made of Lexan plates alternated with nuclear emulsion films. Lexan plates acted as passive material simulating human body tissues while nuclear emulsion films were used as both tracking devices with micrometric accuracy and ionisation detectors. Such a detector allowed the detection of Carbon interactions produced along their path, the identification of the fragments produced and the measurement of their scattering angle. We have measured the Carbon ion survival probability and studied their interactions. We report on the secondary particle multiplicity and the electrical charge distribution. We give results of the scattering angle of final state fragments as well as the range for H and He. Finally we give the total and partial charge-changing cross-sections for Δ z = 1 , 2 , 3 , 4 which are compared with previous results when available. The present work aims at providing data required as input to Monte Carlo simulations of Carbon ion interactions in the human body and ultimately of their therapeutic effectiveness.

Lead Projectile Fragmentation on Aluminum Target: Improved Experimental Results

We investigate 158A GeV 207Pb projectile fragmentation on Al target using CR-39 nuclear track detectors. A stack containing target-detectors assembly was irradiated at SPS-CERN. After chemical etching, detectors were scanned using an optical microscope to collect the data in the form of etched cone heights. From the cone height measurements, total and partial charge changing cross sections of 207Pb projectiles on aluminum target are determined. The results are compared with both relevant published measurements available in the literature and model predictions. Odd-even effect in the formation of the fragments of 158A GeV 207Pb pro-jectiles is observed in a consistent and a clear manner over the observed range of fragments (Z=63-81). This is achieved by using optimized etching and track measurement conditions.

CHARGE AND MASS CHANGING CROSS-SECTIONS OF 158A GeV Pb PROJECTILES ON Al, Cu, Bi, AND Pb TARGETS: FRAGMENTATION PROCESSES

We report here on total and partial charge changing cross-sections of 158A GeV lead projectiles on Al , Cu , Pb and Bi stationary targets using CR-39 detectors. Present results are compared with relevant published results. Deep discussion of nuclear fragmentation processes is provided. Stacks of CR-39 Track Detectors with above-mentioned targets were exposed to 158 A GeV 207 Pb projectiles at the CERN-SPS beam facility at normal incidence with a fluence of about 1500 ions/cm 2. Lengths of etched cones on one face of the CR-39 detectors before and after the target were measured for each stack. These measurements were used for determination of total and partial charge changing cross-sections of 158 A GeV Pb 82+ projectiles on these targets in the charge region 63 < Z < 82. The charge resolution (σZ) achieved in the present experiment is ~0.18e. Mass changing cross-sections are derived from the measured charge changing cross-sections using hyper-geometric relationship. A new method is proposed for separate measurements of electromagnetic and nuclear parts of fragmentation cross-sections using ion channeling and blocking conditions of projectiles in crystalline targets.

Relativistic Energy Pb Projectile Fragmentation with Heavy Target Nuclei

We investigate the fragmentation of 158AGeV 207Pb projectiles with Bi, Pb, Cu and Al targets using CR-39 nuclear track detectors. The exposures were made at SPS-CERN. After the etching, the detectors were scanned using an optical microscope to collect the data of etched cone diameters and lengths. We measured the partial charge-changing cross sections using the data of etched cone lengths. The predicted cross sections are compared to similar measurements reported in literature and their dependences on projectile and target mass are described.

Estimate of the space station shielding thickness at a USLab site using ALTEA measurements and fragmentation cross sections

In this work we presented a method to estimate a local shielding thickness of the International Space Station (USLab), expressed as equivalent of aluminum. The calculation took advantage of total and partial charge-changing cross sections, both measured experimentally and computed theoretically, to obtain the total survival fractions of ions with charge 5 ⩽ Z ⩽ 26 when transversing the space craft hull. The combination of these values with the measured relative abundances outside the space station provided the estimates of the internal relative abundances at several thicknesses. The results have been compared with data measured by ALTEA experiment in the USLab to find the thickness that minimizes the discrepancy between the calculated data and the measurements: the result yielded to an estimate of the shielding thickness at ALTEA site of about 5 cm of aluminum equivalent.

Total Fragmentation Cross Section of 158A GeV Lead Projectiles in Cu Target

Total fragmentation cross section for the reaction 158 A Pb ions + Cu target is measured using the most sensitive track detector CR-39. Measured values are compared with calculations. Exposures of target-detector stack with 158A Pb projectiles are made at CERN-SPS beam facility. Results of calibration of CR-39 detector in a charge region (63 ≤ Z ≤ 83) are also reported, which can be used for high energy particle identification using CR-39 and in determination of partial charge changing cross sections. The charge resolution σz achieved by this technique is about 0.2e. A systematic dependence of total fragmentation cross section on target properties is revealed and the corresponding results are presented.

Examining the fragmentation of 158 A GeV lead ions on copper target: Charge-changing cross sections

A stack of plastic CR-39 Track Detectors were exposed to 158 A GeV 207Pb ions at the CERN-SPS beam facility. The exposure of stack was performed at normal incidence with a fluence of about 1500 ions / cm 2 . The total number of lead ions in each spill was about 7.8 × 10 4 with eight spills on each stack. For the stack with the Cu target, the lengths of etched cones on one face of the CR-39 detectors (before and after the target) were measured. Using these measurements and charge identification methodology in CR-39 track detectors, total and partial charge changing cross sections of 158 A GeV Pb 82 + ions on Cu and CR-39 targets are determined in the charge region 63 ⩽ Z ⩽ 82 . The possibilities of presence and absence of odd–even effect in measured partial charge changing cross sections of 158 A GeV Pb ions for Cu and CR-39 targets are described. The charge resolution ( σ Z ) achieved in the present experiment is ∼ 0.18 e –0.21e. The analysis of discrepancies between our experimental results and other published results for the identical reaction is also presented.

Weak and strong factorization properties in nucleus–nucleus collisions in the energy region 290–2100 [formula omitted

We have collected from the literature partial charge-changing cross sections for projectiles with charge 6 ⩽ Z ⩽ 26 , energy ranging from 290 up to 2100 MeV / nucleon and interacting with several targets, in order to investigate weak and strong factorization properties. The same analysis methods as in our previous work have been applied to the data: we have shown that, except for hydrogen targets, weak and strong factorization properties are valid within 5%, thus confirming the results obtained in the first paper [C. La Tessa, et al., Test of weak and strong factorization in nucleus–nucleus collisions at several hundred MeV / nucleon , Nucl. Phys. A, in press]. Factorization parameters have been calculated and, in particular, target factors have been expressed with ad hoc analytical functions which describe the data trend very well. New expressions for weak and strong factorization properties can then be obtained by substituting the target factors with these functions: this formulation partially isolates the dependence of the partial charge-changing cross sections on the target and projectile mass numbers; moreover, fragment factors are the only parameters left in the formulas thus facilitating the future task of interpolating them with appropriate analytical expressions.

Measurements of total and partial charge-changing cross sections for 200- to 400-MeV/nucleonC12on water and polycarbonate

We have studied charged nuclear fragments produced by 200- to 400-MeV/nucleon carbon ions, interacting with water and polycarbonate, using a newly developed emulsion detector. Total and partial charge-changing cross sections for the production of B, Be, and Li fragments were measured and compared with both previously published measurements and model predictions. This study is of importance for validating and improving carbon-ion therapy treatment planning systems and for estimating the radiological risks for personnel on space missions, because carbon is a significant component of galactic cosmic rays.

Test of weak and strong factorization in nucleus–nucleus collisions at several hundred MeV/nucleon

Projectile total and partial charge-changing cross sections have been measured for argon ions at 400 MeV/nucleon in carbon, aluminum, copper, tin and lead targets; cross sections for hydrogen were also obtained using a polyethylene target. The validity of weak and strong factorization properties has been investigated for partial charge-changing cross sections; measurements obtained for carbon, neon and silicon beams at 290 and 400 MeV/nucleon and iron beam at 400 MeV/nucleon, in carbon, aluminum, copper, tin and lead targets have also been used for the test. Two different analysis methods were applied and both indicated that these properties are valid, without any significant difference between weak and strong factorization. The factorization parameters have then been calculated and analyzed in order to find some systematic behavior useful for modeling purposes.

PHITS – benchmark of partial charge-changing cross sections for intermediate-mass systems

The PHITS (Particle and Heavy Ion Transport System) code is a three-dimensional Monte Carlo code that is able to simulate the transport of nuclei and other particles in complicated geometries and calculate fluxes, doses, energy-deposition distributions and many other observables. Among its many possible fields of application, it can be used e.g. to design and optimise radiation shields for space vessels. However, the reliability of the predictions of the code depends directly on the certified accuracy of the code components, i.e. the models the code uses to estimate the quantities necessary for the transport calculation. As a part of a comprehensive benchmarking program, we have investigated the possibility of using PHITS to calculate partial charge-changing cross sections and we have compared the results with measurements performed by some of us (CZ, LH, JM, SG). The results, although limited, suggest that the current reaction-cross-section models might be inadequate for use in space radioprotection; we therefore claim the need for a thorough benchmarking of the models and for new reaction-cross-section measurements and experimental techniques.

Total charge-changing and partial cross-section measurements in the reaction of [formula omitted]12C with paraffin

We have measured the total and partial charge-changing cross-sections ( Z=5) after the passage of a 110 MeV/ u 12 C beam through an assembly consisting of CR-39 thin detectors and paraffin targets. These experimental cross-sections were compared to the predictions of known models. It was found that the measured total cross-sections agree with the model calculations to within about 8% or even less, while, depending on a model, discrepancies of up to a factor 1.2 higher and up to a factor 2.7 lower values of cross-sections for the production of fragment with Z=5 were observed.