Energy Spectra Of Particles Research Articles

Investigation of the reaction d + d → 2He + 2 n at the deuteron energy of 15 MeV

An experimental setup for studying the reaction d + d → 2He + 2 n is described, and the first preliminary results of measurements at a deuteron energy of 15 MeV are presented. The experiment was aimed at determining the energies of quasibound singlet states of two-nucleon systems (nn and pp), these energies being important features of nucleon–nucleon (NN) interaction. The measurements in question were performed at a deuteron beamfrom the U-120 cyclotron of the Skobeltsyn Institute ofNuclear Physics (Moscow State University). Two protons and one of the neutrons fromthe breakup of the dineutron system were detected in the experiment. A simulation of the reaction in question and preliminary experimental results reveal the possibility of determining the energy of quasibound singlet states on the basis of the form of the energy spectra of particles originating from their breakup.

Particle acceleration and radiation friction effects in the filamentation instability of pair plasmas

The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. After an exponential growth of both the magnetic field and the current density, a nonlinear quasi-stationary phase sets up characterized by filaments of opposite currents. During the nonlinear stage, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.

Energy spectra of low-energy solar iron particles measured in the orbit of the international space station in the period 2002–2004

The energy spectrum of iron is measured over the range of 30–150 MeV/nucleon using the PLATAN-M chamber consisting of solid-state track detectors mounted on the external surface of the International Space Station (ISS) in the period 2002–2004. The spectra of solar and galactic cosmic rays (SCRs and GCRs) are compared to the data from the SIS instrument on board the ACE spacecraft, transformed to the ISS orbit. Compared to the SIS data, the energy resolution of the PLATAN-M spectrum is twice better and the spread of experimental points is 50% lower.

Calibration of particle detectors for secondary cosmic rays using gamma-ray beams from thunderclouds

After observation of hundreds of Thunderstorm Ground Enhancements (TGEs) we measure energy spectra of particles originated in clouds and directed towards Earth. We use these “beams” for calibration of cosmic ray detectors located beneath the clouds at an altitude of 3200m at Mount Aragats in Armenia. The calibrations of particle detectors with fluxes of TGE gamma rays are in good agreement with simulation results and allow estimation of the energy thresholds and efficiencies of numerous particle detectors used for studying galactic and solar cosmic rays.

Estimating of Cherenkov Radiation in Extensive Air Showers Using CORSIKA Code for Tunka133 EAS Cherenkov Array

The simulation of Cherenkov light Lateral distribution function (LDF) in Extensive Air Showers (EAS) initiated primary particles such as primary calcium, argon, proton iron nuclei, neutron and nitrogen have been performed using CORSIKA program for conditions and configurations of Tunka133 EAS Cherenkov array. The simulation was fulfilled at the high energy range 1014-1016eV for four different zenith angles 0o, 10o, 15oand 30o. The results of the simulated Cherenkov light LDF are compared with the measurements of Tunka133 EAS array for the same particles and energy range mentioned above. This comparison may give the good ability to reconstruct the energy spectrum and mass composition of the primary cosmic ray particles in EAS. The main feature of the given approach consists of the possibility to make a library of Cherenkov light LDF samples which could be utilized for analysis of real events which can be detected with different EAS arrays and reconstruction of the primary cosmic rays energy spectrum and mass composition of EAS particles.

Cosmic rays in astrospheres

Cosmic rays passing through large astrospheres can be efficiently cooled inside these "cavities" in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front of the astrospherical bow shocks. We study the cosmic ray flux in and around lambda Cephei as an example for an astrosphere. The large-scale plasma flow is modeled hydrodynamically with radiative cooling. We studied the cosmic ray flux in a stellar wind cavity using a transport model based on stochastic differential equations. The required parameters, most importantly, the elements of the diffusion tensor, are based on the heliospheric parameters. The magnetic field required for the diffusion coefficients is calculated kinematically. We discuss the transport in an astrospheric scenario with varying parameters for the transport coefficients. We show that large stellar wind cavities can act as sinks for the galactic cosmic ray flux and thus can give rise to small-scale anisotropies in the direction to the observer. Small-scale cosmic ray anisotropies can naturally be explained by the modulation of cosmic ray spectra in huge stellar wind cavities.

Muon-Induced Soft Errors in SRAM Circuits in the Terrestrial Environment

Muon-induced soft errors are an increasing concern with technology scaling. However, the impact of terrestrial muons to the failure rate of circuits is unclear as methodologies have not yet been developed to extrapolate from accelerated measurements to the terrestrial environment. We introduce a new method to estimate muon-induced soft error rates (SERs) in SRAM devices by equating the muon energy spectrum with an alpha particle energy spectrum with an equivalent LET. Using this method, we estimate that, in the terrestrial environment, a muon-induced SER is smaller than that from packaging-related alpha particle and cosmic ray neutron components. FinFET SRAM devices will show a much reduced muon SER compared with planar transistors due to the minimization of charge collection associated with the fin geometry.

Neutron Production Cross-Section and Geant4 Calculations of the Structural Fusion Material 59Co for (α,xn) and (γ,xn) Reactions

Recent advances in technology and computer sciences give us simplicity to investigate phenomena of nuclear physics. Scientists have improved various nuclear reaction codes such as Talys, Alice/ASH, Cem95, Empire, Geant4 and Fluka. These programs give us chance to calculate crucial quantity like reaction cross-section, energy spectrum of out-going particles, stopping power and penetrating distances in target material. The stopping power of alpha in 59Co material is acquired as it has helpful applications of shielding and choosing the proper thickness of the target. Evaluation of the reaction cross-section data is very important to various applications such as improvement structural material, reactor design and radioisotopes production. In this study, we calculated the neutron production cross-sections of 59Co using TALYS 1.6 and EMPIRE 3.1 codes for different level density models. Penetrating distances and stopping powers have been calculated for the alpha particles taking into consideration all possible reactions in 59Co using GEANT4 simulation program. The obtained (α,xn) and (γ,xn) reactions (x = 1, 2, 3) cross-section values have been compared with the each other and against the experimental nuclear reaction data existing in EXFOR database.

Alpha spectroscopy for in-situ liquid radioisotope measurements

Using calculation and SRIM simulations of alpha particle energy spectroscopy, we show that the initial energies and concentrations of alpha-emitting radioisotopes can be measured in-situ in a liquid environment. We quantify the effect on the alpha spectrum of reducing the thickness of the liquid source in front of the alpha particle detector as well as adding a cover material onto the alpha particle detector surface. In all cases, initial energies and concentrations are recoverable from the alpha particle energy spectra. By reducing the thickness of the liquid source, the contribution to the spectrum for low count rate, low energy radioisotopes can be revealed. However, adding a cover on the detector obscures the contributions of these radioisotopes.

Analysis of the conditions underlying the formation of emitted atomic ion fluxes in the nonlinear collision-cascade mode of the sputtering of metals

The ionbeam sputtering of metals carried out in the nonlinear collisioncascade mode, where the excitation level (average energy per atom) in the thermalpeak volume exceeds the critical ambient tempera� ture, initiates quasithermal atom and atomic ion emissi ons. The energy spectrum of atomic particles is sub� stantially shifted toward the lowenergy region and do es not correspond to a Maxwellian distribution. Correct description of quasithermal ion emission requires firs t of all knowledge of the conditions under which a sput� tered particle flux is formed. The conditions leading to the formation of an atomic ion flux are analyzed for the case where metals are sputtered in the nonlinear collisioncascade mode.

Constraints of hadronic interaction models from the cosmic muon observations

A simple method of the vertical muon energy spectrum simulations has been suggested. These calculations have been carried out in terms of various models of hadronic interactions. The most energetic π ± -mesons and K ± -mesons produced in hadron interactions contribute mainly to this energy spectrum of muons due to the very steep energy spectrum of the primary particles. So, some constraints on the hadronic interaction models may be set from a comparison of calculated results with cosmic data on the vertical muon energy spectrum. This comparison showed that the most energetic secondary particles production is too high in the case of the QGSJET II-04 model and rather low in the case of the QGSJET II-03 model. These conclusion have been supported by the LHC data. The longitudinal development of extensive air showers (EAS), in particular, the depth Xmax of its maximum, is determined by the rate of fragmentation of energy E0 of the primary particle. This rate depends on the interaction cross sections of shower particles, and on the energy spectra of secondary particles are generated in interactions. Obviously, if the probability of particle production with energies close to the energy of the incident particle is high then the development of the cascade slows down. Conversely, in the case of rapid fragmentation of the incident energy cascades develop rather rapidly. The depth Xmax of shower maximum in many studies is the main parameter for determining the composition of primary cosmic radiation (PCR) at ultra-high energies. It should also be noted that in the case of the slow rate of development cascade and hence large values of depth Xmax the lateral distribution of the shower particles at the observation level becomes narrower. Therefore, the values of signals in the surface and underground detectors located at large distances from the shower core are decreased. It must be taken into account when determining the density of muons at large distances from the shower core and the composition of the PCR found from the muon lateral distribution. Studies of the composition and characteristics of the energy spectrum of the PCR are important components of theories of the origin of cosmic rays at ultra-high energies. Interpretation of experimental data on the depth of the shower maximum Xmax and the observed fraction of muons at a fixed distance from the shower core are carried out in terms of different hadronic

Status and perspectives of fragmentation beams at LNS with CHIMERA detector

Relatively large yields of various exotic beams produced through in-flight fragmentation are available at LNS. Using the CHIMERA detector, we performed various experiments to study elastic and inelastic scattering, transfer, break-up, and reaction dynamics with targets from proton and deuteron to carbon and heavier. For reactions with relatively light systems we used the kinematical coincidence method to extract high resolution angular distributions of binary reactions from the measured light particle energy spectra. We also used the CsI detectors of CHIMERA to detect gamma rays emitted in the reactions. Some of most recent results are presented together with future perspectives with the coupling of CHIMERA with FARCOS array.

Direct Interband Light Absorption in Conical Quantum Dot

In the framework of the adiabatic approximation, the energy states of electron as well as the direct light absorption are investigated in conical quantum dot. Analytical expressions for particle energy spectrum are obtained. The dependence of the absorption edge on geometrical parameters of conical quantum dot is obtained. Selection rules are revealed for transitions between levels with different quantum numbers. In particular, it is shown that for the radial quantum number transitions are allowed between the levels with the same quantum numbers, and any transitions between different levels are allowed for the principal quantum number.

Kinetic effects in the transverse filamentation instability of pair plasmas

The evolution of the filamentation instability produced by two counter-streaming pair plasmas is studied with particle-in-cell (PIC) simulations in both one (1D) and two (2D) spatial dimensions. Radiation friction effects on particles are taken into account. During the nonlinear stage of the instability, a strong broadening of the particle energy spectrum occurs accompanied by the formation of a peak at twice their initial energy. A simple theory of the peak formation is presented. The presence of radiative losses does not change the dynamics of the instability but affects the structure of the particle spectra.

Exciton states and interband absorption of cylindrical quantum dot with Morse confining potential

In this paper the exciton and electron sates in cylindrical quantum dot with Morse potential made of GaAs are studied. For the regime of strong size quantization, energy spectrum with the parabolic approximation case are compared. For strong and weak size quantization regimes analytic expressions for the particle energy spectrum, absorption coefficient and dependencies of effective threshold frequencies of absorption on the geometrical parameters quantum dot are obtained. For the intermediate size quantization regime the problem solved in the framework of variation method. The selection rules corresponding to different transitions between quantum levels are found. The size dispersion distribution of growing quantum dots by the radius and height by two experimentally realizing distribution functions have been taken into account. Distribution functions of Gauss, Lifshits-Slezov have been considered.

Interpretation of cosmic ray spectrum above the knee measured by the Tunka-133 array

A probable interpretation of the fine structure of all particle energy spectrum between the knee and the ankle (the sharp first knee at 3–4 PeV, the spectrum hardening at 20–30 PeV, the second knee at 200–300 PeV) as well as a <ln⁡A> (E) dependence measured recently by the Tunka-133 experiment, is presented. We show that these features are compatible with the combined model where cosmic rays around the knee are produced by the group of dedicated sources and the extragalactic light component appears in the energy region of 1016–1017 eV and reaches about 50% of all particles around (2–3)×1017 eV.

NON-THERMAL ELECTRON ACCELERATION IN LOW MACH NUMBER COLLISIONLESS SHOCKS. I. PARTICLE ENERGY SPECTRA AND ACCELERATION MECHANISM

Electron acceleration to non-thermal energies in low Mach number (M<5) shocks is revealed by radio and X-ray observations of galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Diffusive shock acceleration, also known as first-order Fermi acceleration, cannot be directly invoked to explain the acceleration of electrons. Rather, an additional mechanism is required to pre-accelerate the electrons from thermal to supra-thermal energies, so they can then participate in the Fermi process. In this work, we use two- and three-dimensional particle-in-cell plasma simulations to study electron acceleration in low Mach number shocks. We focus on the particle energy spectra and the acceleration mechanism in a reference run with M=3 and a quasi-perpendicular pre-shock magnetic field. We find that about 15 percent of the electrons can be efficiently accelerated, forming a non-thermal power-law tail in the energy spectrum with a slope of p~2.4. Initially, thermal electrons are energized at the shock front via shock drift acceleration. The accelerated electrons are then reflected back upstream, where their interaction with the incoming flow generates magnetic waves. In turn, the waves scatter the electrons propagating upstream back toward the shock, for further energization via shock drift acceleration. In summary, the self-generated waves allow for repeated cycles of shock drift acceleration, similarly to a sustained Fermi-like process. This mechanism offers a natural solution to the conflict between the bright radio synchrotron emission observed from the outskirts of galaxy clusters and the low electron acceleration efficiency usually expected in low Mach number shocks.

Extension of Cherenkov Light LDF Parametrization for Tunka and Yakutsk EAS Arrays

The Cherenkov light Lateral Distribution Function (LDF) from particles initiated Extensive Air Showers (EAS) with ultrahigh energies (E > 1016 eV) was simulated using CORSIKA program for configuration of Tunka and Yakutsk EAS arrays for different primary particles (p, Fe and O2) and different zenith angles. By depending on the Breit–Wigner function, a parametrization of the Cherenkov light LDF was reconstructed on the basis of this simulation as a function of the primary energy. The comparison of the approximated Cherenkov light LDF with that measured on Tunka and Yakutsk EAS arrays gives the possibility of identification of energy spectrum and mass composition of particles initiating EAS about the knee region of the cosmic ray spectrum. The extrapolation of approximated Cherenkov light LDF for energies 20, 30 and 50 PeV was obtained for different primary particles and different zenith angles.

Analysis on High-Energy Physical Problems in Monte Carlo Simulation

This paper analyzes the data got in two Monte Carlo simulations, namely, extensive air shower simulation and detector simulation. Then, based on the data from experimental arrays, some physical problems have been analyzed and illustrated. Those problems include the distribution of energy spectrum of secondary particles, the distribution of zenith angle, of azimuths, of background noises, and that of strip pattern, as well as the atmospheric absorption.

Time Discreteness &amp;amp; Wave Function Aliasing

The conditions of arising and some effects of physical phenomenon that may be found in the process of observing high energy particles are considered in this work. This phenomenon is consequence of time discreteness. When the repetition frequency of a particle discrete state proves to be commensurable with its own frequency (energy), the aliasing effect of its wave function may take place. The wave function aliasing limits the particle energy spectrum giving rise to the uninvestigated abnormal modes of movement. In view of the fact the discreteness of particle states at a time is a prerequisite for aliasing, the effect under consideration, in case of its experimental verification, may serve a proof of this discreteness.