Particles Of Various Energies Research Articles

Efficient and fast detection of alpha particles using CR-39 detector

The CR-39 track detector was used to create alpha particle tracks using molten hydrated barium hydroxide (MBH). In this experiment, seventeen CR-39 plates with a thickness of 250 μm were used. For determining the bulk etch rate, the rate of the change of track dimeter of fission fragments has been used. The detectors were etched at the suitable etching conditions of MBH, and the track diameters were measured using two suitable image analysis software (Infinity Analyzer and ImageJ). A standard micrometer slit was used to calibrate the images in the field of view of the microscope. The results of this investigation demonstrated that MBH provides significant etching characteristics in addition to shorter etching times and higher etching efficiency for the registration and detection of charged particles of various energies. This work has numerous uses, ranging from plastic nuclear track filters and environmental applications to alpha spectroscopy and neutron detection. Results of sample irradiation, track diameter analysis, sensitivity analysis, and etching efficiency analysis are covered in detail.

Characterization of Charging Lithium Niobate and Lithium Tantalate Ferroelectrics Under Irradiation With Defocused Electron and Ion Beams

This article presents the experimental characteristics of charging lithium niobate and lithium tantalate ferroelectrics under irradiation with wide electron and ion beams. Electron irradiation has carried out in the scanning electron microscope (SEM) over the range of primary electron energies from 0.2 to 10 keV. Ion irradiation has performed using Ar <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathbf {+}}$ </tex-math></inline-formula> ions with the energy of 6 keV. The density of particle beams is of the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{\mathbf {-6}} \text {A} \cdot \text {cm}^{\mathbf {-2}}$ </tex-math></inline-formula> . Calculations of the charges and fields in the frameworks of the proposed models of four-layer charge distributions under electron irradiation and three-layer distribution under ion irradiation were discussed. Anomalies in the emission characteristics under bombardment with particles of various energies are found. The charging efficiency factor for ion irradiation is almost an order of magnitude of the irradiation dose higher than in the case of electron irradiation. In turn, smaller irradiation doses are required for charging customary dielectrics than for charging ferroelectrics. A possible explanation of these differences is proposed.

Quantitative theory of channeling particle diffusion in transverse energy in the presence of nuclear scattering and direct evaluation of dechanneling length

A refined equation for channeling particle diffusion in transverse energy taking into consideration large-angle scattering by nuclei is suggested. This equation is reduced to the Sturm–Liouville problem, allowing one to reveal both the origin and the limitations of the dechanneling length notion. The values of the latter are evaluated for both positively and negatively charged particles of various energies. New features of the dechanneling dynamics of positively charged particles are also revealed. First, it is demonstrated that the dechanneling length notion is completely inapplicable for their nuclear dechanneling process. Second, the effective electron dechanneling length of positively charged particle varies more than twice converging to a constant asymptotic value only at the depth exceeding the latter.

Local weighting of nanometric track structure properties in macroscopic voxel geometries for particle beam treatment planning

The research project BioQuaRT within the European Metrology Research Programme aimed at correlating ion track structure characteristics with the biological effects of radiation and developed measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigated methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Here we make use of parameterizations that link the energy of the projectile to the ionization pattern of the track using nanodosimetric ionization cluster size distributions. They were defined with data generated by simulations of ion tracks in liquid water using the Geant4 Monte Carlo toolkit with the Geant4-DNA processes. For the clinical situation with a mixed radiation field, where particles of various energies hit a cell from several directions, we have to find macroscopic relevant mean values. They can be determined by appropriate local weighting functions for the identified parameterization. We show that a stopping power weighted mean value of the mentioned track structure properties can describe the overall track structure in a cell exposed to a mixed radiation field. The parameterization, together with the presented stopping power weighting approach, show how nanometric track structure properties could be integrated into treatment planning systems without the need to perform time consuming simulations on the nanometer level for each individual patient.

In situ deuterium observation in deuterium-implanted tungsten

In order to evaluate the tritium inventory in plasma-facing tungsten components of a fusion reactor, deuterium depth profiles in tungsten were observed in situ using nuclear reaction analysis (NRA) under continuous implantation of 3keV D ions. Measurements were conducted at temperatures of 384, 473, 573 and 673K. Recombination coefficients and rate constants for the surface recombination process were estimated from the observed deuterium concentration. It is indicated that the measured surface recombination rate constant is applied in a case wherein tungsten is exposed to hydrogen particles of various energies from a fusion plasma. The measured recombination coefficient was identical to that found by a different technique in a previous work. Deuterium in trap sites was found to contribute to deuterium retention in the samples as well as to deuterium in solution sites. The deuterium retention was low in the 384K sample, in which trap sites had not appeared. Deuterium retention was very low in the 673K sample, where most deuterium atoms were detrapped and desorbed. At an intermediate temperature of 473K, the retention showed a maximum value due to a large occupancy of deuterium over many trap sites. The dependence of the retention on deuterium fluence was explained assuming that trap sites were produced by implantation.

Charged particles on the Earth–Jupiter–Europa spacecraft trajectory

Charged particle fluxes on the trajectory of future Russian space research mission to Jupiter and its satellite Europa are investigated. The existing experimental data and models of Jupiter’s main magnetic field and radiation belts are summarized. Preliminary results of computations of energetic particle fluxes and radiation doses for each stage of the flight are given. Special attention is paid to estimation of radiation conditions in Europa’s orbit and on its surface; influence of the satellite on spatial distribution of the fluxes of charged particles of various energies is studied.

Study of the charge sharing in silicon pixel detector by means of heavy ionizing particles interacting with a Medipix2 device

The charge sharing effect has been investigated in a 300 μm thick silicon pixel detector bump-bonded to a Medipix2 readout chip and exposed to heavy ionizing particles of various energies, namely protons and alpha-particles. The lateral spread of the charge carriers from the interaction of a heavy ionizing particle in the silicon detector causes a sharing of the charge among adjacent pixels, giving a signal in clusters of multiple pixels of the Medipix2 device. A model of charge sharing, including the plasma effect on top of diffusion and drift processes has been compared to the measured lateral spread of the charge for bias voltage values beyond the full depletion voltage. Results of the measurements of the cluster size as a function of the energy and incidence angle of incoming heavy ionizing particles are also reported and compared with the model.

Physics validation of detector simulation tools for LHC

Extensive studies aimed at validating the physics processes built into the detector simulation tools Geant4 and Fluka are in progress within all Large Hardon Collider (LHC) experiments, within the collaborations developing these tools, and within the LHC Computing Grid (LCG) Simulation Physics Validation Project, which has become the primary forum for these activities. This work includes detailed comparisons with test beam data, as well as benchmark studies of simple geometries and materials with single incident particles of various energies for which experimental data is available. We give an overview of these validation activities with emphasis on the latest results.

Determining charged particle energy losses with the aid of transmutation isotopes

A new method is proposed for determining the energy losses of charged particles in solids, which is based on the comparison of profiles of the transmutation isotopes measured in the samples irradiated by particles of various energies.

The Biological Effectiveness of Radon-Progeny Alpha Particles. V. Comparison of Oncogenic Transformation by Accelerator-Produced Monoenergetic Alpha Particles and by Polyenergetic Alpha Particles from Radon Progeny

Generation of estimates of risk caused by exposure to radon in the home, either from miner data or from A-bomb data, requires several scaling factors such as for dose, dose rate and radiation quality, and possible synergisms. Such scaling factors are best developed from laboratory-based studies. Two possible sources of alpha particles for such studies are (1) a polyenergetic spectrum, generated directly by radon and its progeny, or (2) a series of monoenergetic alpha particles. We compare here the results of oncogenic transformation from studies using both systems. At the Columbia University Radiological Research Accelerator Facility (RARAF), C3H 10T1/2 cells were irradiated with alpha particles of various energies, with defined LETs from 70 to 200 keV/mum. At Pacific Northwest Laboratory, cells from the same stock were exposed to alpha particles from radon gas and its progeny, which were in equilibrium with the culture medium. There was good agreement between the results of oncogenic transformation experiments using the two different exposure systems. Apart from the experimental transformation frequencies themselves, such a comparison requires (1) reliable dosimetry at both facilities and (2) estimated LET distributions for the polyenergetic alpha-particle irradiator. Thus this good agreement gives some confirmation to the technique which is used to fold together oncogenic transformation rates from monoenergetic alpha particles to yield a predicted rate for a spectrum of alpha particles.

Theory of fast ion transport during sawtooth crashes in tokamaks

An approach is suggested for the description of fast ion transport in tokamaks during sawtooth crashes, which takes into account the orbital motion of the particles and the temporal evolution of the magnetic configuration. The approach is based on a kinetic equation for the distribution function of fast ions derived using different scales with characteristic times of the sawtooth crash and of the fast ion motion. The evolution of the magnetic configuration in the process of the crash is assumed to be known, and its analytical description is suggested for the case of the Kadomtsev type of crash. The derived kinetic equation is analysed for both trapped and circulating particles, and conclusions are drawn concerning redistribution of particles of various energies and pitch angles during crashes. The physical nature of fast ion transport induced by the sawtooth crash is elucidated

Fission fragment angular distribution in alpha-particle-induced fission of actinide elements

Using Lexan polycarbonate plastic as the fission fragment track detectors, the fragment angular distributions have been measured in the cases of fission of232Th and238U induced by alpha particles of various energies ranging from 40 to 70MeV obtained from the 88″ variable energy cyclotron at Calcutta. The center-of-mass angular distributions have been calculated and fitted by a series of Legendre polynomials. TheW(10°)/W(90°) ratios (defined as anisotropy) were measured at several energies for both the targets. These data are utilized in calculation of the energy dependence ofK 0 2 , the standard deviation of the distribution in the angular momentum projection on the nuclear symmetry axis at the saddle point. Values of Γ f /Γ η , i.e. the ratio of the fission width to neutron emission width have been determined for232Th and238U nuclei. The integral cross-section for alpha induced fission in each target was determined by numerical integration of the respective center-of-mass angular differential cross-sections. The results were compared with similar data available in the literature which served to resolve some of the discrepancies observed in earlier measurements. The results were also compared with theoretical cross-sections.

Precise determination of critical features in radiohalo-type coloration of biotite

HIGH precision techniques of photomicrography and densitometry are here used to investigate the coloration of artificially α-irradiated biotite. A computer simulated spherical radiation pattern is found to produce coloration peaks, contrary to the negative results of earlier investigators. A clearer understanding of the relationship between the usually defined α ranges and ‘coloration ranges’ is obtained as well as the elucidation of several other features of radiohaloes. In spite of more than a half a century of investigation, the parameters of α-induced radiation damage in biotite are still only crudely known. The principal parameter, the ‘range’ of the α particle, has been studied primarily by means of the uranium radiohalo and its close relatives (ref. 1; see also, refs 2 and 5). The coloration rings of these haloes lend themselves to direct, though somewhat inexact, measurements of the ranges of α particles of various energies. Early investigators also made use of measured α ranges in air and then converted these to ranges in biotite. Recently, Gentry2,3 has made a substantial number of direct ‘range’ measurements in biotite and other minerals by bombardment with accelerator-produced α particles.

Gas phenomena in spark chambers

The spark chamber is used to study the following gas phenomena: drift of single electrons under the influence of an electric field, deexcitation of metastable rare-gas atoms in collisions with molecules, and ionization by high-energy particles of various energies. The method determines the average number of electrons from the spark efficiency and is capable of showing that a large fraction of the primary ionization is due to metastable atoms.

Annealing of Defects Formed in Germanium After Irradiations with Particles of Various Energies

Isochronal annealing of the defect induced in germanium by electrons of 10, 5 or 1.5 MeV or fast neutrons was studied. For the case of crystals irradiated with 10 MeV or 5 MeV electrons, an annealing stage was observed in the range 180 K–240 K. The stage was observed in all specimens doped with antimony, arsenic or phosphorus after irradiation with 10 MeV electrons, but it was not observed for crystals irradiated with 1.5 MeV electrons. These behaviours were discussed and it was concluded that the defect which anneals in the stage is considered to be a stable vacancy-interstitial pair. Considering from the fact that the annealing in the range 260 K–480 K was independent of irradiating energies, the induced defects by 10 MeV electron irradiation are of the same kind as those induced by 1.5 MeV electron irradiation except for the stable vacancy-interstitial pair which anneals near 200 K.

Ion beam sputtering - the effect of incident ion energy on atomic mixing in subsurface layers

Abstract Secondary ion mass spectrometric methods were used to study the effect of incident ion energy on atomic mixing in subsurface layers. A Ta2O5 film containing a 50 A 3lP-rich layer 230 A below the surface was depth profiled for phosphorus using normal incidence 160 primary particles of various energies (1.75 to 18.5 keV). A pronounced energy effect was observed in the widths of 31P profiles generated by >4 keV 16O. For 18.5 keV 16O, the observed profile contained two distinct components-the 31P-rich layer and the 31P recoil distribution. This later condition, prevails when the peak of the incident ion damage distribution occurs at a depth which equal or exceeds the distance from the surface to the 31P-rich layer. The desirable primary ion beam energy for characterizing the true elemental distribution is dictated by the shape and location of the layer to be profited. In most instances, a low energy beam is preferred.

A theoretical analysis of extensive air showers. III. Muon showers at large zenith angles

For Pt. II see abstr. A15896 of 1968. A theoretical analysis has been made of the muon component of extensive air showers incident at large angles to the vertical. Using the model described previously, calculations have been made of the expected numbers of muons reaching ground level as a function of threshold energy and zenith angle for primary particles of various energies. The data have been combined with alternative primary spectra of cosmic rays, with and without an enhanced contribution from heavy nuclei, to give the expected muon density spectra. It is found that the density spectrum is sensitive to the distribution of transverse momentum among the parents of the muons and to a lesser extent to the mass composition of the primaries. There is thus the possibility of deriving information about the mean transverse momentum, and perhaps setting limits on the mass composition, from a comparison with experiment.

Determination of the mean multiplicity of particles produced in a nuclear interaction using the method of the inverse problem

The possibility of the determination of the mean multiplicity of secondaries, n(E), with the aid of the cascade characteristics has been studied using the nuclear cascade with one-type particles as an example. For the simple model of interaction with the inelasticity coefficient k = 1 the energy spectra of particles in the showers produced by the particles of various energies have been calculated. The function n(E) has been restored in the higher-energy range on the assumption that the calculated spectra are known from the "experiment," and the function n(E) at low energies has been measured within good accuracy. Estimates of the accuracy of the cascade data necessary for determining n(E) within the given accuracy are presented.

Propagation of energetic particles through interplanetary space according to the data of 11-yr cosmic ray variations

The size of the region occupied by the solar wind and the transport scattering path of the particles of various energies are determined and the change in the spectrum of magnetic inhomogeneities in the wind with changing the solar activity is studied on tne basis of investigation of the 11-yr variations of the cosmic rays of relatively high energies taking account of the lag of the change in the conditions in the interplanetary space with respect to the processes on the Sun. The solar wind properties are also found for the period of solar minimum. The residual modulation for the particles of various energies at solar minimum is determined and the true cosmic ray intensity beyond the region of the solar wind is evaluated. Analysis of the expected variations in the ranges of various energies for the protons, α-particles and electrons of the galactic cosmic rays is also carried out. The spectrum of the cosmic ray rigidities beyond the modulation region outside the solar system is determined. It has been shown that an essential part of the ‘bend’ of the spectrum is due to modulation in the interplanetary space. Other possible causes of the ‘bend’ are also discussed. The expected gradient of the cosmic ray intensity in the interplanetary space is evaluated as a function of Z and particle rigidity. The results obtained on the gradient are in agreement with the data from ‘Mariner 2’. The change in the electromagnetic conditions in the interplanetary space with decrease in solar activity is evaluated according to the data of the stratospheric measurements in July, 1963 and of ‘IMP-1’ measurements.

Solar wind properties obtained from the study of the 11-year cosmic-ray cycle: 1

On the basis of investigations of the 11-year cosmic-ray cycle, the dimensions of the region filled with the solar wind, the scattering transport paths of particles of various energies, and the change in spectrum of magnetic inhomogeneities with respect to solar activity are studied. Using comparatively high-energy cosmic rays and taking account of the time lag of interplanetary space conditions relative to processes on the sun, these properties of the solar wind and others, such as the true cosmic-ray intensity beyond the region filled with the solar wind, are evaluated.