Energy Distributions Of Secondary Particles Research Articles

NDPlot - A plotting tool for nuclear data

NDPlot is an efficient plotting tool for nuclear data. It is not only a plotting tool, but also an integrated application system. The first beta version of NDPlot was released in October 2018. The current version is 0.94 beta. NDPlot can plot experimental and evaluated data of reaction cross sections, angular distributions of secondary particles, energy distributions of secondary particles and product energy-angle distributions etc. It also provides data processing functions such as curve summation capability to meet user’s requirements.

Probing the Cluster Structure of a Light Nucleus with d 9Be Scattering

It is proposed that deuteron quasi-free scattering on separate clusters of the 9Be nucleus be used to estimate the contributions from different cluster configurations (8Be + n, α + α + n, α + 5He) to the structure of 9Be. These scattering processes are modeled kinematically. It is shown there are isolated regions in the angular and energy distributions of secondary particles that correspond to certain configurations of the clusters in 9Be are identified. The modeling results show the obtained data on the energies and angles of emission of two secondary particles (d + n and d + α) allow us to identify the contributions from different reaction channels and draw conclusions regarding the cluster structure of the 9Be nucleus. The results from this analysis are employed in the inclusive exclusive experimental investigations of the 9Be cluster structure using the deuteron beam at Moscow State University’s Skobeltsyn Institute of Nuclear Physics.

Reactive ion beam sputtering of Ti: Influence of process parameters on angular and energy distribution of sputtered and backscattered particles

This work focuses on the angular and energy distribution of secondary particles during the ion beam sputtering of a Ti target in a reactive oxygen atmosphere. The influence of ion species, ion energy, and scattering geometry (ion incidence angle and polar emission angle) was investigated systematically. Ion energies of 0.5, 1.0, and 1.5 keV and an ion current of roughly 10 mA were used to sputter deposit TiO2 films from a pure Ti target at an operating pressure of 5.0 × 10−5 and 6.5 × 10−5 mbar and an oxygen partial pressure of 1.0 × 10−5 and 2.5 × 10−5 mbar for sputtering with Ar and Xe ions, respectively. The angular distribution of the flux of sputtered Ti particles was determined by measuring the thickness of TiO2 films. The flux of sputtered Ti particles is described by the superposition of an isotropic and anisotropic part. The isotropic part increases when increasing ion energy, decreasing the incidence angle, or changing the sputtering gas from Xe to Ar. An energy-selective mass spectrometer was used to measure the mass and energy distribution of secondary ions. Several species of sputtered particles were detected, e.g., Ti, TiO, TiO2, Ti2, O, and O2 ions. The most prevalent species are Ti, TiO, and O ions. The energy distribution of the sputtered Ti and TiO ions shows a maximum at an energy between 10 and 30 eV followed by a high-energetic tail proportional to exp(−n·E). Decreasing the scattering angle leads to a decrease in the slope of the high-energetic tail, i.e., it extends to higher energies. The backscattered primary ions (Ar and Xe) and the sputtered atomic O ions show a maximum between 5 and 20 eV, which is followed by a sudden signal drop. For scattering angles less than 90°, additional peaks at higher energy can appear in the energy distribution of Ar, Xe, and O ions. These peaks are related to direct scattering and sputtering events. The experimental results are compared with calculations based on a simple elastic two-particle-interaction theory and with simulations carried out using the Monte Carlo code SDTrimSP.

Ion beam sputtering of Ti: Influence of process parameters on angular and energy distribution of sputtered and backscattered particles

In the present study, the influence of ion energy and geometrical parameters onto the angular and energy distribution of secondary particles for sputtering a Ti target with Ar ions is investigated. The angular distribution of the particle flux of the sputtered Ti atoms was determined by the collection method, i.e. by growing Ti films and measuring their thickness. The formal description of the particle flux can be realized by dividing it into an isotropic and an anisotropic part. The experimental data show that increasing the ion energy or decreasing the ion incidence angle lead to an increase of the isotropic part, which is in good agreement with basic sputtering theory. The energy distribution of the secondary ions was measured using an energy-selective mass spectrometer. The energy distribution of the sputtered target ions shows a maximum at an energy between 10eV and 20eV followed by a decay proportional to E−n, which is in principle in accordance with Thompson’s theory, followed by a high energetic tail. When the sum of incidence angle and emission angle is increased, the high-energetic tail expands to higher energies and an additional peak due to direct sputtering events may occur. In the case of backscattered primary Ar ions, a maximum at an energy between 5eV and 10eV appears and, depending on the scattering geometry, an additional broad peak at a higher energy due to direct scattering events is observed. The center energy of the additional structure shifts systematically to higher energies with decreasing scattering angle or increasing ion energy. The experimental results are compared to calculations based on simple elastic two-particle-interaction theory and to simulations done with the Monte Carlo code SDTrimSP. Both confirm in principle the experimental findings.

Energy Distribution of Secondary Particles in Ion Beam Deposition Process of Ag: Experiment, Calculation and Simulation

AbstractIon beam sputter deposition allows tailoring the properties of the film‐forming, secondary particles (sputtered target particles and backscattered primary particles) and, hence, thin film properties by changing ion beam (ion energy, ion species) and geometrical parameters (ion incidence angle, polar emission angle). In particular, the energy distribution of secondary particles and their influence on the ion beam deposition process of Ag was studied in dependence on process parameters. Energy‐selective mass spectrometry was used to measure the energy distribution of sputtered and backscattered ions. The energy distribution of the sputtered particles shows, in accordance with theory, a maximum at low energy and an E–2 decay for energies above the maximum. If the sum of incidence angle and polar emission angle is larger than 90°, additional contributions due to direct sputtering events occur. The energy distribution of the backscattered primary particles can show contributions by scattering at target particles and at implanted primary particles. The occurrence of these contributions depends again strongly on the scattering geometry but also on the primary ion species. The energy of directly sputtered and backscattered particles was calculated using equations based on simple two‐particle‐interaction whereas the energy distribution was simulated using the well‐known Monte Carlo code TRIM.SP. In principal, the calculation and simulation data agree well with the experimental findings. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Influence of the patient size on secondary doses delivered in light ion beams

*Secondary radiation exposure of patients in light ion therapy is of concern due to possible normal tissue damage and risk of induction of secondary cancers. Neutrons, protons and heavier ions are generated by nuclear inelastic interactions of primary ions both in the beam line and in the patient. The patient is exposed to a complex radiation field and secondary doses can be deposited in normal tissues both close to and relatively far from the treated volume. The energy distribution of secondary particles and secondary doses delivered to different organs were studied by the MC code SHIELD-HIT10 using the anthropomorphic phantoms representing a 10-year-old child (CHILD-HIT) and an adult male (ADAM-HIT). Brain tumor irradiations were simulated with approximated scanned beams of 1 H, 7 Li and 12 C ions. The influence of patient size on the secondary dose distributions were studied using the same target definition and irradiation geometry with a lateral beam. For the scanned beams, the secondary organ absorbed doses normalized per absorbed dose to the treated volume (brain tumor) were in the range 1 nGy/Gy - 0.1 mGy/Gy and the absorbed doses in the CHILD-HIT phantom were higher than in ADAM-HIT by up to a factor of 5, depending on organ.

Distributions of secondary particles in proton and carbon-ion therapy: a comparison between GATE/Geant4 and FLUKA Monte Carlo codes

Monte Carlo simulations play a crucial role for in-vivo treatment monitoring based on PET and prompt gamma imaging in proton and carbon-ion therapies. The accuracy of the nuclear fragmentation models implemented in these codes might affect the quality of the treatment verification. In this paper, we investigate the nuclear models implemented in GATE/Geant4 and FLUKA by comparing the angular and energy distributions of secondary particles exiting a homogeneous target of PMMA. Comparison results were restricted to fragmentation of 16O and 12C. Despite the very simple target and set-up, substantial discrepancies were observed between the two codes. For instance, the number of high energy (>1 MeV) prompt gammas exiting the target was about twice as large with GATE/Geant4 than with FLUKA both for proton and carbon ion beams. Such differences were not observed for the predicted annihilation photon production yields, for which ratios of 1.09 and 1.20 were obtained between GATE and FLUKA for the proton beam and the carbon ion beam, respectively. For neutrons and protons, discrepancies from 14% (exiting protons–carbon ion beam) to 57% (exiting neutrons–proton beam) have been identified in production yields as well as in the energy spectra for neutrons.

Systematic investigations of low energy Ar ion beam sputtering of Si and Ag

Ion beam sputter deposition (IBD) delivers some intrinsic features influencing the growing film properties, because ion properties and geometrical process conditions generate different energy and spatial distributions of the sputtered and scattered particles. Even though IBD has been used for decades, the full capabilities are not investigated systematically and specifically used yet. Therefore, a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the generated secondary particles and backscattered ions and the deposited films needs to be done.A vacuum deposition chamber has been set up which allows ion beam sputtering of different targets under variation of geometrical parameters (ion incidence angle, position of substrates and analytics in respect to the target) and of ion beam parameters (ion species, ion energy) to perform a systematic and comprehensive analysis of the correlation between the properties of the ion beam, the properties of the sputtered and scattered particles, and the properties of the deposited films. A set of samples was prepared and characterized with respect to selected film properties, such as thickness and surface topography. The experiments indicate a systematic influence of the deposition parameters on the film properties as hypothesized before. Because of this influence, the energy distribution of secondary particles was measured using an energy-selective mass spectrometer. Among others, experiments revealed a high-energetic maximum for backscattered primary ions, which shifts with increasing emission angle to higher energies. Experimental data are compared with Monte Carlo simulations done with the well-known Transport and Range of Ions in Matter, Sputtering version (TRIM.SP) code [J.P. Biersack, W. Eckstein, Appl. Phys. A: Mater. Sci. Process. 34 (1984) 73]. The thicknesses of the films are in good agreement with those calculated from simulated particle fluxes. For the positions of the high-energetic maxima in the energy distribution of the backscattered primary ions, a deviation between simulated and measured data was found, most likely originating in a higher energy loss under experimental conditions than considered in the simulation.

Features of the energy distribution of secondary particles upon the ion bombardment of graphite

The secondary emission of carbon atoms from the (0001) plane of graphite nanocrystallites bombarded with argon ions with energies of 1 and 10 keV and the incidence angle α = 45° is investigated. The unusual oscillating energy distributions of secondary C+ ions with main maxima E max in the range of 40–60 eV and peaks corresponding to the energies E 1 ≈ 20, 30, 70, 80, and 100 eV have been revealed. The C+ ion yield decreases, the energy spectrum increases, and the maximum E max shifts to larger energies E 1 with increasing emission angle (with respect to the normal to the surface). The secondary-ion emission from the (0001) face of graphite is numerically simulated with allowance for the charge exchange of secondary ions to obtain a qualitative explanation of the observed results.

Shielding Experiments by the JASMIN Collaboration at Fermilab (II) - Radioactivity Measurement Induced by Secondary Particles from the Anti-proton Production Target

The JASMIN Collaboration has performed an experiment to conduct measurements of nuclear reaction rates around the anti-proton production (Pbar) target at the Fermi National Accelerator Laboratory (FNAL). At the Pbar target station, the target, consisting an Inconel 600 cylinder, was irradiated by a 120 GeV/c proton beam from the FNAL Main Injector. The beam intensity was 3.6 x 10{sub 12} protons per second. Samples of Al, Nb, Cu, and Au were placed near the target to investigate the spatial and energy distribution of secondary particles emitted from it. After irradiation, the induced activities of the samples were measured by studying their gamma ray spectra using HPGe detectors. The production rates of 30 nuclides induced in Al, Nb, Cu, Au samples were obtained. These rates increase for samples placed in a forward (small angle) position relative to the target. The angular dependence of these reaction rates becomes larger for increasing threshold energy. These experimental results are compared with Monte Carlo calculations. The calculated results generally agree with the experimental results to within a factor of 2 to 3.

Evaluation of solar proton spectra using balloon cosmic ray observations and Monte Carlo simulation results

We have developed a method to evaluate the spectrum of solar energetic protons at the top of the Earth’s atmosphere from the measurements of our balloon cosmic ray experiment. By using the Monte Carlo PLANETOCOSMICS code based on Geant4 we compute the interaction of solar protons [10 MeV–10 GeV] with the Earth’s atmosphere. We obtain the angular and energy distributions of secondary particles (p, e −, e +, photons, muons) at different atmospheric levels as a function of primary proton spectra. By comparing the calculated depth dependence of the particle flux with the data obtained by our balloon experiment we can deduce the parameters of the solar proton spectrum that best fit the observations. In this paper we discuss our solar proton spectrum estimation method, and present results of its application to selected solar proton events from 2001 to 2005.

SU-FF-T-341: Energy Distributions of Proton Interactions in MCNPX and GEANT4 Codes Using a Slab Target

Purpose: Nuclear interactions for proton radiation therapy can be simulated by different Monet Carlo codes. In this study, the energy distributions of secondary particles generated from proton nuclear interactions by GEANT4 and MCNPX are compared. Method and Materials: Proton ranges were first calculated for proton energies from 70 to 250 MeV using these two codes respectively. A 1-cm thick water (or brass) slab was placed in the vacuum as a target of nuclear interaction. A point-like proton source was emitted in a single direction perpendicularly to the slab. The detector on the other side of the slab recorded the energy distributions of particles generated in nuclear interactions including neutrons, protons, alpha particles. The simulations were repeated for both slab materials at different energies between 100 MeV and 250 MeV. Results and Discussions: We first compared the calculated ranges with the proton CSDA data from NIST. GEANT4 always gives shorter ranges than the CSDA, while MCNPX only does so for energies higher than 100 MeV. We next studied the energy distribution of the particles generated in nuclear interactions. The proton distributions are quite similar for 150 MeV incident energy case. MCNPX predicts neutrons with, on average, higher energies that GEANT4. As for alphas, the statistical uncertainties are too high (∼30%) and the results are qualitative rather than quantitative. Conclusion: The results suggest that these two codes are in good agreement for proton distribution, although discrepancies in the average neutron energies are observed due to the different physical models.

Secondary neutral and ionized particle measurements under MeV-energy ion bombardment

We have measured both secondary neutral and ionized particles from an InSb target under 3.0MeV Si ion bombardment. Measurements of both ions and neutrals have not been carried out so far in the MeV-energy range. The mass spectra and axial emission energy distributions of secondary particles were investigated. Secondary ions were measured with a linear- and a reflective-type time-of-flight technique, whereas secondary neutral particles were photo-ionized by a UV pulsed laser (ArF: 193nm) and measured with a reflective-type time-of-flight technique. Different results were obtained for neutral particles in comparison with ionized particles. The mean energy of neutral Sb atoms was much lower than that of neutral In atoms, whereas the mean energies of secondary In and Sb ions were nearly equal.

Multiple Meson Production in Nucleon-Nucleon Interactions at Energies around 200 GeV

The interactions considered as collisions between nucleons with the primary energies of the order of 100 GeV are analyzed. i) The average values of P T , , are obtained for individual showers. A shower whose value of is exceptionally small, i.e. 0.11 GeV/c, is found. ii) The energy distribution of secondary particles has the form of inverse square distribution, except for the lowest energy interval ( E * / m π c 2 <1.5). The average value of energy has a tendency to increase slowly with increasing primary energy, though it is nearly constant up to 200 GeV. iii) The individual angular distribution of secondary particles in the center-of-mass system seems to differ from event to event, but the overall distribution can be expressed in the form F (cos θ * )=1+ k cos 2 θ * , k =5.2±2.0.

On some interaction characteristics of very high-energy particles and their interpretation from the view point of the hydrodymical yheory of multiple particles production

S>Landau, using the idea stated by Fermi, employed relativistic hydrodynamics in describing very high energy particle collision. The first attempts to compare the conclusions of hydrodynamical theory with experimental data on the multiplicity and angular and energy distributions of secondary particles already showed that the hydrodynamical theory satisfactorily described many multiple process characteristics. By comparison of the theory with experimental data taken from the analysis of showers recorded in photographic emulsion, a number of essential additional assurnptions were made. These assumptions caused a certain obscurity of the conclusions. For example, it was assumed that the collision of nucleons with heavy nuclei took place in the coordinate system in which notion of substance was symmetrical. Extensive shower analysis carried out on the assumption that the nuclear interaction cross section is independent of energy shows that the formal part of the hydrodynamical theory is incomplete. (A.C.)