Total Charge-changing Cross Sections Research Articles

Total and partial charge changing cross-sections of 300 A MeV Fe26+ ion beam in different target media

In the present study, the total and partial charge changing cross-sections of 300 A MeV Fe26+ ion beam in CR39 and in combined medium of Al and CR39 were measured. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments using an automated image analyzing system. The total charge changing cross-section as calculated is (1220 ± 132) mb in CR39 target and (1472 ± 170) mb in combined target of Al and CR39. The total charge changing cross-section was fitted to the Bradt-Peters geometrical cross-section and compared with earlier results. For calculating the partial charge changing cross-sections for ΔZ = -1, −2, −3,….…,–23, the number of events corresponding to each fragment were determined from multiple Gaussian fitting of the diameter distributions within ±2σ confidence levels and the number of incident and survived beam ions were counted within ±3σ confidence levels. Some beam contaminated events were observed and presented.

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.

Image sorting of nuclear reactions recorded on CR-39 nuclear track detector using deep learning

Deep learning has been utilized to trace nuclear reactions in the CR-39 nuclear track detector. Etch pit images on front and back surfaces of the CR-39 detector were obtained sequentially by moving the objective lens of a microscope, and merged to one image. This image merging makes it possible to combine information on the displacement of the position of the etch pits produced by single particle traversals through a CR-39 layer in a single image, thereby making it easier to recognize corresponding nuclear fragmentation reactions. Object detection based on deep learning has been applied to the merged image to identify nuclear fragmentation events for measurement of the total charge changing cross-section based on the number of incident particles (Nin) and the number of particles that passed through target without any nuclear reaction (Nout). We verified the accuracy (correct answer rate) of algorithms for extracting the two patterns of etch pit in merged images which corresponds to Nin and Nout using the learning curves expressed as a function of the number of trainings. Accuracy of Nin and Nout were found to be 97.3 ± 4.0% and 98.0 ± 4.0%, respectively. These results show that the object detection algorithm based on the deep learning can be a strong tool for CR-39 etch pit analysis.

Applicability of composite materials for space radiation shielding of spacecraft

Energetic ion beam experiments with major space radiation elements, 1H, 4He, 16O, 28Si and 56Fe, have been conducted to investigate the radiation shielding properties of composite materials. These materials are expected to be used for parts and fixtures of space vehicles due to both their mechanical strength and their space radiation shielding capabilities. Low Z materials containing hydrogen are effective for shielding protons and heavy ions due to their high stopping power and large fragmentation cross section per unit mass. The stopping power of the composite materials used in this work is intermediate between that of aluminum and polyethylene, which are typical structural and shielding materials used in space. The total charge-changing cross sections per unit mass, σUM, of the composite materials are 1.3–1.8 times larger than that of aluminum. By replacing conventional aluminum used for spacecraft with commercially available composite (carbon fiber / polyether ether ketone), it is expected that the shielding effect is increased by ∼17%. The utilization of composite materials will help mitigate the space radiation hazard on future deep space missions.

Fragmentation of carbon on elemental targets at 290AMeV

The total charge-changing cross-sections and the partial cross-sections for projectile fragments (PFs) production for the fragmentation of 12C on C, Al, Cu, Pb and CH2 targets at the highest energy of 290[Formula: see text]A[Formula: see text]MeV were studied. It was found that the total charge-changing reaction cross-sections and the partial reaction cross-sections of PFs production were independent of the beam energy, and increased with increase of mass of target for the same beam energy. The total charge-changing reaction cross-section was the same as the prediction of Bradt–Peters semi-empirical formula, PHITS and NUCFRG2 simulation models. The partial cross-section of PFs production increased with the increase of the mass of target, and it was the same as the prediction of NUCFRG2 models. The mean scattering angle of projectile particle was smaller than the average emission angle of PF, and the width of scattering angle distribution of projectile particle was smaller than that of emission angle distribution of PFs. The mean emission angle of PFs does not obviously depend on the target mass and beam energy in our studied beam energy regions.

Contribution of the projectile neutrons to the total charge-changing cross sections

We focus on the formulae currently used to calculate the total charge-changing cross sections (σcc), these formulae assume that the contribution of the projectile neutrons to the total charge-changing cross sections is small. We show that the dependence of the charge-changing cross sections on the projectile neutrons is strong as its dependence on the projectile protons. We estimate the contribution of the projectile neutrons to the total charge-changing cross sections to be about 40%, so neglecting the projectile neutron density in calculating σcc may not be adequate. Furthermore, we propose an empirical formula to evaluate the total charge-changing cross sections.

Projectile Fragmentation of 16O and 32S beams from Dubna LHE Synchrophasotron

We investigate the charge changing collisions for 16O and 32S beams, using the experimental method of Solid State Nuclear Track Detectors (SSNTD). Sample reading was performed by an automatic measurement system. We determined the total charge changing cross sections and the partial cross sections for the production of fragments of cherge 9<Z<14.

High-precision angular measurement of 12C ion interaction using a new imaging method with a CR-39 detector in the energy range below 100 MeV/nucleon

In this study, we show that angular measurement of nuclear tracks produced in heavy ion interactions can be made with high precision using a CR-39 solid-state nuclear track detector. For this purpose, we have increased the position resolution of nuclear track (etch pit) analysis and the precission of thickness measurement of the CR-39 detector. The position resolution of the heavy ion track was verified to be 0.02 μm by the dedicated image analysis software package PitFit. The precision of the thickness measurement of the CR-39 detector was increased to 0.6 μm by our new both sides imaging method of the CR-39 detector using the autofocus system of the microscope. As a consequence, the angular distributions of projectiles and fragments can be realized with a precision of 1.4 × 10−2 degrees (2.5 × 10−4 radian). As a demonstration, we applied the angular measurement technique to the diagnosis of heavy ion beam and the small Coulomb scattering angle measurement of interactions of 12C + Al in energies below 100 MeV/nucleon. By this new imaging technique, event-by-event interaction of the projectiles in the CR-39 detector can be measured rapidly and can be applied to the measurement of the total charge-changing cross section, the decay mode, and the branching ratios of the projectile with higher angular precision.

The total charge-changing cross sections and the partial cross sections of 56Fe fragmentation on Al, C and CH2 targets

The total charge-changing cross sections and the partial cross sections of 56Fe fragmentation on polyethylene, carbon and aluminum targets at the highest energy of 496 A MeV are investigated using CR-39 plastic nuclear track detector. The total charge-changing cross-section for hydrogen target is calculated based on the results of polyethylene and carbon targets. It is found that the total charge-changing cross sections for fragmentation of 56Fe on hydrogen, carbon and aluminum targets are independent on the beam energy in our studied energies, and are consistent with the predictions of Bradt–Peter semi-empirical formula, Nilsen parameterized formula, NUCFRG2 and QMSFRG theoretical simulation codes. The partial cross sections for projectile fragment production are independent on beam energy in our studied energies for each targets and do not show a significant even-odd effect.

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.

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.

Fragmentation cross section of 800 A · MeV silicon ions on polyethylene target

The total charge-changing cross sections and the partial cross sections of projectile fragment production of the fragmentation of silicon ions on polyethylene target at 800 A · MeV are measured using CR-39 plastic nuclear track detector. The total charge-changing cross sections of silicon ions on polyethylene targets at 800 A · MeV is 761 ± 24 mb, which agree well with the prediction of Bradt-Peters semi-empirical formula using parameter r0 = 1.31fm and b = 0.94 within experimental errors. The obvious even-odd effect is observed for the partial cross sections in present investigation.

Fragmentation cross sections of 788A MeV 28Si on carbon and polyethylene targets

The total charge-changing cross sections and the partial cross sections of silicon ions on carbon and polyethylene targets are studied at 788 A MeV by using CR-39 plastic nuclear track detectors. The results are compared with other experimental and theoretical results. The obvious even-odd effect for partial cross sections is observed.

Fragmentation Cross Section of 800 A MeV Silicon Ions on Carbon Target

The total charge changing cross sections and the partial cross sections of projectile fragment production of the fragmentation of silicon ions on carbon target at 800 A MeV are measured using CR-39 plastic nuclear track detector. The total charge changing cross section agrees well with other experimental results at different energies and the prediction of theoretical models. The partial cross sections are consistent with other results at close energy. The obvious even-odd effect is observed in present investigation.

Total Charge Changing Cross-Sections of 300 MeV/A Fe26+ Ion Beam in Different Target Media

Total charge changing cross-sections of 300 MeV/A Fe26+ ion beam in Al and combined media of CH2, CR39 and Al were calculated by CR39 track etch detectors using an image analysing system; DM6000M optical microscope attached with a personal computer installed with Leica QWin Plus software. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments. Exposed CR39 detectors were etched in 6N NaOH solution + 1% ethyl alcohol at 70 ˚C to visualize the tracks produced by primary ion beam and its fragmentations under optical microscope. The temperature was kept constant throughout the etching within ± 0.1˚C. The present work shows better response of the CR39 track etch detector up to an improved threshold Z/β ∼ 4.6. The cone-diameter distributions were fitted by multiple Gaussians using ROOT software analysis toolkit. The numbers of incident and survived ions were determined within 99.7% confidence levels. The calculated values of total charge changing cross-section were (1663 ± 236) mb in Al target, (1219 ± 29) mb in combined target CH2+CR39+Al and (1020 ± 121) mb in combined target CH2+CR39.

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

Response of CR39 detector to 5 A GeV Si14+ ions and measurement of total charge changing cross-section

In the present work, response of CR39 track etch detector was obtained by cone-height measurement technique. CR39 track etch detector was used to identify the incident charged particles and their fragments by the measurements of cone-height of tracks using an optical microscope DM6000 M and automated image analyzer system installed with Leica QWin Plus software. The CR39 detector was calibrated and the response points were fitted with a linear relation and all the points are within the limits of the experimental errors. The charge resolution of the detector was calculated to be 0.2e. The response function is obtained and fitted with a linear relation which is good throughout Z/β=6.1–14.1. The experimental value of the total charge changing cross-section of 5A GeV Si14+ ion beam in polyethylene and CR39 combined target is σtot=(734±128)mb. The total charge changing cross-section is compared with the experimental results of others based on cone base-area measurement technique and also fitted by the Bradt–Peters geometrical cross-section.

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.

Measurement of total and partial charge changing and charge pick-up cross-sections for 300A MeV Fe26+ beam in Al with a new system of analysis

In the present study, total and partial charge changing cross-sections of 300AMeV Fe26+ ion beam in aluminum target were measured by a new system of analysis installed with the Leica QWin Plus software. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments. The CR39 detectors just before and just after the target were calibrated and found to have the same charge response and the charge resolution, which were 0.19e and 0.20e, respectively. The response points were fitted with a polynomial of degree one and all the points are within the limits of experimental errors. The value of total charge changing cross-section was calculated to be σtot=(1663±236)mb. To determine the partial charge changing cross-sections for ΔZ=−23,−22,…,−1, number of events corresponding to each fragment were determined from multiple Gaussian fitting of diameter distributions within 95.5% confidence levels and the numbers of incident and survived beam ions were counted within 99.7% confidence levels. Charge pick-up cross-section for ΔZ=+1 was calculated and is (92±6)mb.

Calibration of CR39 detectors with new system for Fe26+ ion beam and measurement of total charge changing cross-section in Al target

Abstract In the present study, CR39 track etch detector was calibrated with a new system and the total charge changing cross-section of 300 A MeV Fe 26+ ion beam in aluminum target was measured. The CR39 nuclear track detectors were used to identify the incident charged particles and their fragments using an optical microscope DM6000 M and automated image analyzer system installed with Leica QWin Plus software. The CR39 detectors before and after the target were calibrated and found to have the same charge response; the charge resolution in both of the detectors were 0.19e and 0.20e, respectively. The calibration points were fitted with a polynomial of degree one and all the points are within the limits of the experimental errors. The response functions were also obtained and fitted with a polynomial of degree three which are quite good throughout Z / β = 4.6 to 41.4. The value of the total charge changing cross-section is σ tot = (1663 ± 236) mb. The total charge changing cross-section was compared with the experimental results of others and also fitted by the Bradt-Peters geometrical cross-section.