Distribution Of Secondary Particles Research Articles

Simulating Makrofol as a detector for neutron-induced recoils

The response of solid-state nuclear track detector is extremely dependent on incident angles of neutrons, which determine the angular distribution of secondary particles. In this paper, the authors present a method to investigate the angular response of Makrofol detectors. Using the C++-based Monte-Carlo tool-kit Geant4 in combination with SRIM and our MATLAB codes, we simulated the angular response of Makrofol. The simulations were based on the restricted energy loss model, and the concept of energy threshold and critical angle. Experiments were carried out with (252)Cf neutrons to verify the simulation results.

Microdosimetric evaluation of the neutron field for BNCT at Kyoto University reactor by using the PHITS code

In this study, microdosimetric energy distributions of secondary charged particles from the (10)B(n,α)(7)Li reaction in boron-neutron capture therapy (BNCT) field were calculated using the Particle and Heavy Ion Transport code System (PHITS). The PHITS simulation was performed to reproduce the geometrical set-up of an experiment that measured the microdosimetric energy distributions at the Kyoto University Reactor where two types of tissue-equivalent proportional counters were used, one with A-150 wall alone and another with a 50-ppm-boron-loaded A-150 wall. It was found that the PHITS code is a useful tool for the simulation of the energy deposited in tissue in BNCT based on the comparisons with experimental results.

Coherent radio emission from cosmic ray air showers computed by Monte-Carlo simulation with SElFAS

We present here the first results of SElFAS (Simulation of Electric Field emitted by Air Shower), a new Monte-Carlo simulation of the radio emission by cosmic ray extensive air shower. The simulation is based on the complete geometrical description of secondary electrons and positrons created in air showers generated by protons above 10 PeV. The energy, position and angular distributions of secondary particles are extracted from CORSIKA simulations [1]. The electric field is then computed for each secondary particle during its travel in the atmosphere using the well-known equation of a moving charge which undergoes an acceleration. The total signal emitted by the air shower is per consequent the superposition of all particles contributions and it is computable for any ground position. We present the results obtained for the east–west and north–south polarizations of the total electric field. These polarizations are usually measured by radio detectors such as CODALEMA, LOPES, RAuger and AERA (Auger Engineering Radio Array). The characteristics and the comprehension of the radio emission of cosmic ray extensive air shower are crucial for the development of large radio detectors array.

Microdosimetric investigation of the spectra from YAYOI by use of the Monte Carlo code PHITS

The purpose of this study was to obtain the neutron energy spectrum on the surface of the moderator of the Tokyo University reactor YAYOI and to investigate the origins of peaks observed in the neutron energy spectrum by use of the Monte Carlo Code PHITS for evaluating biological studies. The moderator system was modeled with the use of details from an article that reported a calculation result and a measurement result for a neutron spectrum on the surface of the moderator of the reactor. Our calculation results with PHITS were compared to those obtained with the discrete ordinate code ANISN described in the article. In addition, the changes in the neutron spectrum at the boundaries of materials in the moderator system were examined with PHITS. Also, microdosimetric energy distributions of secondary charged particles from neutron recoil or reaction were calculated by use of PHITS and compared with a microdosimetric experiment. Our calculations of the neutron energy spectrum with PHITS showed good agreement with the results of ANISN in terms of the energy and structure of the peaks. However, the microdosimetric dose distribution spectrum with PHITS showed a remarkable discrepancy with the experimental one. The experimental spectrum could not be explained by PHITS when we used neutron beams of two mono-energies.

Indirect measurement of secondary-particle distributions by an Au activation method at the KEK neutrino target station

Gold activation detectors were placed at nine positions on the inner wall of the KEK neutrino target station, and were exposed to secondary particles during approximately one month of machine operation. After exposure, the production rates of 19 spallation nuclides, which were produced in the Au activation detectors by nuclear reactions with different threshold energies, were determined by γ-ray spectrometry. Thus, it was indicated that the Au activation detector is a novel tool for obtaining the distribution of various secondary particles with high intensity and high energy.

Characterization of Li[Ni[sub 1∕3]Co[sub 1∕3]Mn[sub 1∕3]]O[sub 2] Synthesized Via Salvolatile Coprecipitation for Lithium-Ion Batteries

Spherical Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 cathode material for lithium-ion batteries was prepared by salvolatile coprecipitation. The obtained Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size distribution (PSD), atomic absorption spectroscopy (AAS), and galvanostatic charge-discharge cycling. The XRD pattern of Li[Ni 1/3 CO 1/3 Mn 1/3 ]O 2 revealed a well-ordered hexagonal layered structure with low cation mixing. Spherical secondary particles and spherical primary particles can be identified from SEM observations. Reasonable size distribution of secondary particles was confirmed by PSD measurement. The initial discharge capacity of the Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 cathode was 163.3 mAh g -1 in the voltage range of 2.8-4.3 V at 30°C, and 95.7% of the initial capacity was retained after 30 charge-discharge cycles.

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.

First results of fast one-dimensional hybrid simulation of EAS using conex

A hybrid simulation code is developed that is suited for fast one-dimensional simulations of shower profiles, including fluctuations. It combines the Monte Carlo simulation of high energy interactions with a fast numerical solution of cascade equations for the resulting distributions of secondary particles. Results obtained with this new code, called CONEX, are presented and compared to CORSIKA predictions.

One-parameter cascade model of multiple hadrons production in inelastic hh-processes at high energies

The inhomogeneous cascade-stochastic model of multiple hadrons production in inelastic p ¯ p - and pp-interactions at high energies is proposed. In this model inclusive rapidity distributions of secondary hadrons are used as input data. One-parameter cascade-stochastic multiplicity distribution, where adjustable parameter has sense of the height of Feynman plateau of inclusive rapidity distribution of secondary hadrons in one hadron shower, is obtained. It is shown that all known now experimental data concerning both multiplicity and rapidity distributions of secondary particles in inelastic hh-processes in energy range s = 30 – 1800 GeV , and also the ratio of cumulant moments to factorial moments of the multiplicity distributions in energy range s = 200 – 900 GeV are described with high accuracy by one-parameter cascade-stochastic model of multiple hadrons production. The explicit form of asymptotic of distributions as well-known Polyakov–Dokshitzer's scaling function for quark and gluon jets is obtained by fitting of prognosis multiplicity distributions at energies s = 14 – 30 TeV . A simplified quantitative analysis is presented and the qualitative explanation of behavior features of forward–backward multiplicity correlations is given within the framework of proposed model.

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.

In-Situ Studies of the Oxide Film Properties on BWR Fuel Cladding Materials

Abstract The pre-transition oxides formed on five different types of Zircaloy-2 alloys have been characterized in-situ using electrochemical impedance spectroscopy (EIS) in high-temperature water simulating BWR conditions at 300°C. The contribution of the oxide film properties to the impedance spectra has been distinguished from the contribution of the corrosion reaction by performing additional EIS measurements in a gas atmosphere. To obtain a correlation between the oxide film thickness, the oxide growth rate, and the impedance parameters, the EIS data have been fitted to the transfer functions derived from the Mixed Conduction Model for oxide films. As a result, the oxide growth rate of each alloy has been calculated assuming that the growth rate is proportional to the flux of oxygen vacancies through the film. The values of the oxide film thickness based on the model calculations have proved to be in good agreement with the values measured from the cross-section micrographs of the specimens using scanning electron microscopy (SEM). The measured corrosion properties have been qualitatively correlated to the secondary phase particle distributions of the five fuel cladding materials. However, to establish a quantitative correlation between the corrosion rates and the second phase particle distributions of these alloys, more data on the microstructure of the metal-oxide interface are needed.

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.

Wavelet analysis of angular distributions of secondary particles in high-energy nucleus-nucleus interactions: Irregularity of particle pseudorapidity distributions

Experimental data on interactions of sulfur and oxygen nuclei with photoemulsion nuclei at energies of 200 and 60 GeV/nucleon are analyzed with the help of a continuous wavelet transform. Irregularities in pseudorapidity distributions of narrow groups of the secondary shower particles in these interactions are observed upon application of the second-order derivative of a Gaussian as a wavelet. The irregularities can be interpreted as the existence of preference emission angles of groups of particles. Such an effect is expected during emission of Cherenkov gluons in nucleus-nucleus collisions. Some of the positions of the observed peculiarities on the pseudorapidity axis coincide with those found by Dremin et al. (I. M. Dremin et al., Phys. Lett. B 499, 97 (2001)).

On the emission of fast and slow target fragments from [formula omitted]–AgBr interactions at [formula omitted

Multiplicity distributions of secondary charged particles coming out of 84 Kr –AgBr interaction at 0.95 GeV/ A have been reported. Angular distributions of fast and slow target fragments have also been studied. The sharp forward peak in the angular distribution of knocked out protons has further been analyzed in the light of intermittency and scaled factorial moment.

Energy spectrum and mass composition around the knee by EAS measurements

Primary cosmic ray particles above energies of about 100 TeV are investigated by large-area ground-based detector installations, observing various components of the development of extensive air-showers (EAS). By such an indirect access to the primary cosmic ray spectrum a steepening of the power-law falls off at around 3–5 PeV, known as the knee has been identified. Different experimental techniques are used to deduce mass- and energy-sensitive observables of EAS experiments. The experiments involve measurements of secondary particle distributions at various observation levels and of muons deep underground as well as of observables reconstructed by measuring the air Cherenkov light emitted with the shower development in the atmosphere. Recently methods for analysing multidimensional distributions get favoured since they are able to take into account the correlations between different observables and the influence of large intrinsic fluctuations of the air-shower development. Additionally the use of a larger set of observables provides the possibility of simultaneously testing the consistency of the Monte Carlo models underlying the reconstruction procedures. From a number of experiments the existence of the knee in the primary energy spectrum is confirmed and a tendency of an increasing mean mass above the knee energy is indicated. Recent results show that the knee originates from a decrease of the flux of light primary particles, whereas heavy cosmic ray particles seem to miss a kink in the energy range of 1–10 PeV.

Decoupling of anomalous top-quark-decay vertices in angular distribution of secondary particles

Angular distribution of a secondary particle from top-quark decays is studied in a simple and general manner, paying careful attention to how relevant the top-quark production mechanism is. The conditions that lead to the distribution free from any possible anomalous top-quark-decay interactions are specified. Some approximations adopted in earlier papers are relaxed and their relevance is discussed.

Particle formation in interval III of the emulsion polymerization of styrene with aerosol‐MA as an emulsifier

AbstractParticle nucleation in the seeded emulsion polymerization of styrene in the presence of Aerosol‐MA emulsifier micelles and in the absence of monomer droplets (interval III) was investigated. The seed particles were swollen with different amounts of the styrene monomer before the experiments. A larger number of polymer particles formed in interval III than in the corresponding seeded batch operation in the presence of monomer droplets. The increase in the number of particles could be attributed to the reduced rate of growth of new particles, which retarded the depletion of emulsifier micelles. The number of secondary particles initially increased with the initial polymer weight ratio in the seed particles (wp0) but decreased at a higher range of wp0, after reaching a maximum at wp0 = 0.60, and eventually was reduced to zero. At high values of wp0 (>0.75), polymerization occurred in the seed particles, whereas few or no new particles were formed despite the presence of micelles. The cessation of particle formation at high conversions was ascertained with a semibatch process in which the neat monomer feed was added to the reaction vessel containing the seed particles and emulsifier micelles. For wp0 > 0.85, the emulsifier micelles were disintegrated to stabilize the seed particles with no secondary particle formation. The possible reasons for the cessation of particle formation at high wp0 were examined. The size distribution of secondary particles showed a positive skewness in terms of volume because of the declining rate of growth for particles, together with a low rate of growth for small particles. The distribution breadth of new particles sharpened with increasing wp0. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1652–1663, 2002

Charged-particle multiplicity distributions in different rapidity windows in 800 GeV proton-nucleus interactions

Multiplicity distributions of charged particles produced in interactions of 800 GeV protons with emulsion nuclei in various rapidity windows are presented. The data is also analyzed separately for the forward and the backward hemispheres, for rapidity windows of different widths. It is found that the Negative Binomial Distribution (NBD) describes well the multiplicity distribution of secondary particles in various rapidity windows and also in both the hemispheres. We have compared the NBD parameters, in both the hemispheres, at 200 GeV and 360 GeV, with those at 800 GeV. The behaviour of NBD parameters in rapidity windows of different widths and for different targets has also been studied.

MULTIFRACTAL ANALYSIS OF 1/f FLUCTUATIONS IN SIMULATED EXTENSIVE AIR SHOWERS PRODUCED BY DIFFERENT PRIMARY COSMIC RAY

As was pointed out in some recent papers, the fluctuations in the secondary particle distribution of extensive air showers at observation level exhibit a complex structure which can be interpreted as a white noise plus a 1/f noise. The resulting coloured noise fits very well into the framework of the universal multitractal theory. In this paper we compare the e+ and e- density fluctuations generated by different primary cosmic rays, namely, high energy γ rays, protons, and helium, oxygen and iron nuclei, and the universal multifractal parameters for all these primaries are calculated for several samples. The performed analysis reveals that the Levy index and the mean codimension depend monotonically on the mass of the primary cosmic ray. Some future applications of the multifractal properties of extensive air showers are suggested.

Dosimetric and microdosimetric characteristics of high energy proton beams

High energy (⩾50 MeV) protons can be considered, when their ionization losses stopping power is taken into account, as the radiation with low (<5 keV/ μm) linear energy transfer (LET). However, their energy is already sufficient to create, through the nuclear reactions in irradiated matter, secondary particles with much higher LET. This phenomenon can modify the characteristics of the energy transfer process due to these particles, which should be taken into account when such particles are used for radiobiology studies and/or for radiotherapy. The importance of these secondary particles was studied experimentally by means of the LET spectrometer based on a chemically etched track detector, in which the tracks of primary protons are not revealed. The studies were performed in proton beams available at the Joint Institute of Nuclear Research (JINR) at Dubna, Russia, with protons of primary energies of about 200 MeV and 1 GeV . The microdosimetric distribution of secondary particles mentioned are presented and compared and their contribution to primary proton ionization losses absorbed dose is estimated. This contribution increases relatively with the proton energy, and also changes with the depth of penetrated material. The importance of this phenomenon to some applications is discussed.