High Energy Cosmic Ray Particles Research Articles

The Charged Particle Detection System of the SRD Module onboard the China Space Station

The radiation field environment outside the Earth varies greatly with space location and the cycle of solar activity, and the radiation environment near the space station’s orbit is much more complex than that on the Earth’s surface. Various high-energy cosmic ray particles and secondary particles produced by them and the bulkhead of the space station greatly impact the health of astronauts and the working conditions of instruments. Each aircraft is always equipped with some dedicated radiation monitoring instruments to assess the exposure risk for astronauts, and to analyze the causes of instrument failures. The Space Radiation Detector Module (SRDM) is working in the China Space Station (CSS) to measure the radiation environment inside, including two parts: the Charged Particle Detection System (CPDS) and the Neutron Detection System (NDS). The CPDS, which is the main content of this paper, contains a detector unit, that consists of three silicon detectors a BGO calorimeter, and the corresponding readout electronics unit of the detector unit. Ground test results show that the detection system can detect various charged particles from hydrogen to nitrogen ions with an energy resolution of less than 15%. The actual measurement results for a period in orbit show that the main types of charged particles in the cabin are protons and α particles, with measured energies ranging from 0.8 to 265.2 MeV for protons and from 1.0 to 61.6 MeV/A for α particles(where A is the mass number), and linear energy density (LET) range mainly from 1.0 to 612.4 keV/μm. The radiation environment data measured in CSS can provide an important reference value for the exposure risk, life science experiments, and the status of instruments on board.

Has telescope array discovered electroweak monopole?

We propose the ultra high energy cosmic ray recently detected by Telescope Array to be the electroweak monopole, and present theoretical arguments which support this. This strongly motivates the necessity for the “cosmic” MoEDAL experiment which could back up our proposal. To confirm this we propose Telescope Array to measure the magnetic charge of the ultra high energy cosmic ray particles with SQUID.

Differentiating signal from artefacts in cosmic ray detection: Applying Siamese spiking neural networks to CREDO experimental data

The Cosmic Ray Extremely Distributed Observatory (CREDO) is an international research consortium aimed at observing high energy cosmic ray particles. The associated Android/iOS application enables the registration of muons with smartphone devices. The ubiquity of the CREDO infrastructure entails virtually no control over the detectors’ working conditions. In order to tag artefacts appearing in the CREDO database, we propose a Siamese spiking neural network (SNN) model, trained by optimizing Earth Mover’s Distance (EMD) between spike train outputs of the SNN. We first test the feasibility of our approach by training models on MNIST images converted into the spiking domain with novel conversion schemes. Then, on a binary classification problem of signal/artefact discrimination on CREDO images our model has achieved a class-balanced accuracy of 96.35%, close to the existing non-spiking solutions. Notably, the model has shown adaptability to input data properties in terms of the spiking network activity sparsity and prediction latency.

Mitigating the effects of particle background on the Athena Wide Field Imager

The Wide Field Imager (WFI) flying on Athena will usher in the next era of studying the hot and energetic Universe. Among Athena’s ambitious science programs are observations of faint, diffuse sources limited by statistical and systematic uncertainty in the background produced by high-energy cosmic ray particles. These particles produce easily identified “cosmic-ray tracks” along with less easily identified signals produced by secondary photons or x-rays generated by particle interactions with the instrument. Such secondaries produce identical signals to the x-rays focused by the optics and cannot be filtered without also eliminating these precious photons. As part of a larger effort to estimate the level of unrejected background and mitigate its effects, we here present results from a study of background-reduction techniques that exploit the spatial correlation between cosmic-ray particle tracks and secondary events. We use Geant4 simulations to generate a realistic particle background signal, sort this into simulated WFI frames, and process those frames in a similar way to the expected flight and ground software to produce a realistic WFI observation containing only particle background. The technique under study, self-anti-coincidence (SAC), then selectively filters regions of the detector around particle tracks, turning the WFI into its own anti-coincidence detector. We show that SAC is effective at improving the systematic uncertainty for observations of faint, diffuse sources, but at the cost of statistical uncertainty due to a reduction in signal. If sufficient pixel pulse-height information is telemetered to the ground for each frame, then this technique can be applied selectively based on the science goals, providing flexibility without affecting the data quality for other science. The results presented here are relevant for any future silicon-based pixelated x-ray imaging detector and could allow the WFI and similar instruments to probe to truly faint x-ray surface brightness.

Spectra and composition of ultrahigh-energy cosmic rays and the measurement of the proton-air cross section

The shape of the longitudinal development of the showers generated in the atmosphere by very high energy cosmic ray particles encodes information about the mass composition of the flux, and about the properties of hadronic interactions that control the shower development. Studies of the energy dependence of the average and width of the depth of maximum distribution of showers with $E \gtrsim 10^{17.3}$ eV measured by the Pierre Auger Observatory, suggest, on the basis of a comparison with current models, that the composition of the cosmic ray flux undergoes a very important evolution, first becoming lighter and then rapidly heavier. These conclusions, if confirmed, would have profound and very surprising implications for our understanding of the high energy astrophysical sources. Studies of the shape of the depth of maximum distribution in the same energy range have been used by Auger and by the Telescope Array Collaboration to measure the interaction length of protons in air, a quantity that allows to estimate the $pp$ cross sections for values of $\sqrt{s}$ well above the LHC range. In this paper we argue that it is desirable to combine the studies of the cosmic ray composition with those aimed at the measurement of the $p$--air cross section. The latter allow to obtain estimates for the fraction of protons in the flux that can be of great help in decoding the composition and its energy dependence. Studies that consider multiple parameters to characterize the depth of maximum distributions also offer the possibility to perform more sensitive tests of the validity of the models used to describe high energy showers.

Estimating the Lateral Distribution of High Energy Cosmic Ray Particles by Depending on Nishimura-Kamata-Greisen Function

The calculation of charged particles density in Extensive Air Showers (EAS) that reach the earth’s surface is described through estimating the lateral distribution function (LDF) at very high energies of different primary particles. The simulation of LDF is performed through the simulator of air shower which is called AIR-shower Extended Simulations (AIRES) system (2.8.4a version). The LDF simulation is performed for different charged particles like the muons, electron-positron pair production and all charged particles as well as gamma rays at very high energies (1016, 1018 and 1019) eV. The influence of the primary energies, primary particles (such as the proton and the iron nuclei) and the zenith angle (θ) on the charged particles LDF that generated in the EAS has been taken into the account. The calculation of charged particles LDF is fulfilled using “Nishimura-Kamata-Greisen” (NKG) function. The LDF using NKG function is compared with that simulated using AIRES system and gave a good agreement at high energies for (electron and positron) secondary particles, which were initiated by the primary proton.

Determination of Zenith Angle Dependence of Incoherent Cosmic Ray Muon Flux Using Smartphones of the CREDO Project

The Cosmic-Ray Extremely Distributed Observatory (CREDO) was established to detect and study ultra high-energy cosmic ray particles. In addition to making use of traditional methods for finding rare and extended cosmic ray events such as professional-grade Extensive Air Shower (EAS) arrays, as well as educational ‘class-room’ detectors, CREDO also makes use of cameras in smartphones as particle detectors. Beyond the primary scientific goal of the CREDO project, to detect Cosmic Ray Ensembles, is the equally important educational goal of the project. To use smartphones for EAS detection, it is necessary to demonstrate that they are capable of effectively registering relativistic charged particles. In this article, we show that the events recorded in the CREDO project database are indeed tracing incoherent cosmic ray muons. The specific observed distribution of zenith angle of charged particle direction corresponds to that expected for muons. It is difficult, if not impossible, to imagine different mechanisms leading to such a distribution, and we believe it clearly demonstrates the suitability of smartphone-based detectors in supporting the more traditional cosmic ray detectors.

Mechanism of cosmic ray high-energy particles charging test mass

The testing mass is the core sensor for measuring the spatial gravitational waves. The high-energy cosmic ray particles penetrating the outer structure of the spacecraft result in the electrical charges on the testing mass. The Coulomb force produced by the charges on the surrounding conducting surface and the Lorentz force generated by the motion through the interplanetary magnetic field will exert a serious influence on the geodesic motion of the testing mass. In this paper are investigated the process and mechanism of charging the testing mass by high-energy particles from different cosmic rays through using the Monte Carlo simulation method. It is concluded that the charging rate gradually increases with the decrease of cut-off energy under the same energy spectrum. The positive charging rate (elementary charges per second) in the years of minimum solar activity is predicted to be 39.5 +e/s, and the protons account for approximately 83.16% of the total quantity of galactic cosmic rays. The positive charging rate of the testing mass during the years of maximum solar activity is about 12.5 +e/s, and the charging rate of the testing mass of the worst solar energetic particle event in 1989 is about 120700 +e/s. The charging rate of the components of the galactic cosmic ray depends on the deposition of primary particles of each component in the testing mass during the years of minimum solar activity, with primary particles accounting for 73% of the total charging rate. The charging contribution of protons in years of minimum solar activity is mainly in an energy range of 0.1–1 GeV, accounting for about 65%. The research results can be used to assess the charging patterns of test quality on-orbit charges and provide a basis for designing the charge management and on-orbit work.

The first CREDO registration of extensive air shower

The Cosmic-Ray Extremely Distributed Observatory (CREDO) is the project to search and study ultra high-energy cosmic ray particles from deep space producing simultaneous extensive air showers over the entire exposed surface of the Earth. The concept of the CREDO infrastructure assumes absorbing all kinds of cosmic ray data from any apparatus all over the world, including professional instruments, educational detectors and arrays, and popular devices such as smartphones. We discuss here the usefulness and possibilities of using the last one and present the educational CREDO-Maze mini array comprised of four CosmicWatch detectors. This simple and affordable apparatus is shown to be able to register the extensive air showers and can be used to study cosmic rays much more effectively than the simple two-detector CosmicWatch muon telescope station. The further development direction is indicated.

Optimizing Cherenkov Photons Generation and Propagation in CORSIKA for CTA Monte–Carlo Simulations

CORSIKA (COsmic Ray SImulations for KAscade) is a program for detailed simulation of extensive air showers initiated by high energy cosmic ray particles in the atmosphere, and is used today by almost all the major instruments that aim at measuring primary and secondary cosmic rays on the ground. The Cherenkov telescope array (CTA), currently under construction, is the next-generation instrument in the field of very-high-energy gamma-ray astronomy. Detailed CORSIKA Monte Carlo simulations will be regularly performed in parallel to CTA operations to estimate the instrument response functions, necessary to extract the physical properties of the cosmic sources from the measurements during data analysis. The estimated CPU time associated with these simulations is very high, of the order of 200 million HS06 hours per year. Code optimization becomes a necessity towards fast productions and limited costs. We propose in this paper multiple code transformations that aim to facilitate automatic vectorization done by the compiler, ensuring minimal external libraries requirement and high hardware portability.

Wormhole as a possible accelerator of high-energy cosmic-ray particles

We present the simplest topological classification of wormholes and demonstrate that in open Friedmann models the genus nge 1 wormholes are stable and do not require the presence of exotic forms of matter, or any modification of general relativity. We show that such wormholes may also possess magnetic fields. It is found that when the wormhole gets into a galaxy or a surrounding region, it works as an accelerator of charged particles. If the income of the energy from radiation is small, such a wormhole works simply as a generator of synchrotron radiation. Estimates show that the threshold energy of such an accelerator may vary from sufficiently modest energies of the order of a few Gev, up to enormous energies of the Planckian order and even higher, depending on wormhole parameters.

Relationship between time series cosmic ray data and aerosol optical properties: 1999–2015

High energy cosmic ray (CR) particles are capable of ionizing the Earth's atmosphere, which lead to changes in the atmospheric properties that affect its physical and chemical characteristics. One of the most important results of the interactions between the CR particles and the atmospheric molecules is the formation of aerosol and its subsequent condensation processes. In this study, the relationship between the time series of the aerosol optical properties; namely the aerosol optical depth (AOD) and Angstrom exponent (α), and the CR muons and neutrons was investigated and established. AOD and α monthly mean data were obtained from the AERONET site located in central Saudi Arabia (24.91° N, 46.41° E, 760 m), for the period of 1999–2015 and the corresponding CR data from Oulu neutron monitor were used for these investigations. Cosmic ray data for the period of 2002–2012 obtained from KACST muon detector were also used in this study. Correlation analyses between the time series of CR data (measured by NM and muon detector) and the aerosol optical properties were carried out and showed significant correlations between these variables. While AOD was positively correlated with the CR data, α showed the opposite.Power spectral analyses using Fast Fourier transform (FFT) were applied on the monthly mean time series of the considered variables to search for possible common periodicities between them. The results showed that there is similarity in position of at least one local peak in PSD (near 1.6–1.7 years) in α and in CR. The correlation and power spectral analyses indicate possible mutual relation between variations of aerosols observed at a particular site and CR intensity observed on the ground.

The Origin of the Most Energetic Galactic Cosmic Rays: Supernova Explosions into Massive Star Plasma Winds

We propose that the high energy Cosmic Ray particles up to the upturn commonly called the ankle, from around the spectral turn-down commonly called the knee, mostly come from Blue Supergiant star explosions. At the upturn, i.e., the ankle, Cosmic Rays probably switch to another source class, most likely extragalactic sources. To show this we recently compiled a set of Radio Supernova data where we compute the magnetic field, shock speed and shock radius. This list included both Blue and Red Supergiant star explosions; both data show the same magnetic field strength for these two classes of stars despite very different wind densities and velocities. Using particle acceleration theory at shocks, those numbers can be transformed into characteristic ankle and knee energies. Without adjusting any free parameters both of these observed energies are directly indicated by the supernova data. In the next step in the argument, we use the Supernova Remnant data of the starburst galaxy M82. We apply this analysis to Blue Supergiant star explosions: The shock will race to their outer edge with a magnetic field that is observed to follow over several orders of magnitude B ( r ) × r ∼ c o n s t . , with in fact the same magnetic field strength for such stellar explosions in our Galaxy, and other galaxies including M82. The speed is observed to be ∼0.1 c out to about 10 16 cm radius in the plasma wind. The Supernova shock can run through the entire magnetic plasma wind region at full speed all the way out to the wind-shell, which is of order parsec scale in M82. We compare and identify the Cosmic Ray spectrum in other galaxies, in the starburst galaxy M82 and in our Galaxy with each other; we suggest how Blue Supergiant star explosions can provide the Cosmic Ray particles across the knee and up to the ankle energy range. The data from the ISS-CREAM (Cosmic Ray Energetics and Mass Experiment at the International Space Station) mission will test this cosmic ray concept which is reasonably well grounded in two independent radio supernova data sets. The next step in developing our understanding will be to obtain future more accurate Cosmic Ray data near to the knee, and to use unstable isotopes of Cosmic Ray nuclei at high energy to probe the “piston” driving the explosion. We plan to incorporate these data with the physics of the budding black hole which is probably forming in each of these stars.

Revisiting the cosmic-ray induced Venusian ionization with the Atmospheric Radiation Interaction Simulator (AtRIS)

Context.Cosmic ray bombardment represents a major source of ionization in planetary atmospheres. The higher the energy of the primary cosmic ray particles, the deeper they can penetrate into the atmosphere. In addition, incident high energy cosmic ray particles induce extensive secondary particle cascades (“air showers”) that can contain up to several billion secondary particles per incoming primary particle. To quantify cosmic ray-induced effects on planetary atmospheres it is therefore important to accurately model the entire secondary particle cascade. This is particularly important in thick planetary atmospheres where the secondary particle cascades can develop extensively before being absorbed by the surface.Aims.Inside the Venusian atmosphere, cosmic rays are the dominant driver for the ionization below an altitude of ~100 km. In this work we revisit the numerical modeling of the galactic and solar cosmic-ray induced atmospheric ionization for cosmic ray ions from Hydrogen (Z= 1) to Nickel (Z= 28) and investigate the influence of strong solar energetic particle events inside the Venusian atmosphere.Methods.The Atmospheric Radiation Interaction Simulator (AtRIS), a newly developed simulation code to model the interaction of the near-(exo)planet particle and radiation field with the (exo)planetary atmosphere, was used to revisit the modeling of the altitude-dependent Venusian atmospheric ionization. Thereby, spherical geometry, the newest version of Geant4 (10.5) as well as the newest Geant4-based hadronic and electromagnetic interaction models were utilized.Results.Based on our new model approach we show that previous studies may have underestimated the galactic cosmic ray-induced atmospheric ion pair production by, amongst others, underestimating the influence of galactic cosmic ray protons above 1 TeV/nuc. Furthermore, we study the influence of 71 exceptionally strong solar particle events that were measured as Ground Level Enhancements at the Earth’s surface, and show a detailed analysis of the impact of such strong events on the Venusian ionization.

Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance

The DArk Matter Particle Explorer (DAMPE) is a space-borne apparatus for detecting the high-energy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector (PSD) is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident high-energy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction. A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%.

On distortion of the background radiation spectrum by wormholes: kinematic Sunyaev-Zel’dovich effect

The problem of scattering of the background radiation on relic cosmological wormholes is considered. It is shown that static wormholes do not perturb the spectrum at all. The presence of peculiar velocities of wormholes results in a distortion of the CMB spectrum which is analogous to the kinematic Sunyaev-Zel'dovich effect. In the first order in $v/c$ the distortion of CMB cannot be separated from from the Compton scattering on electrons. In next orders the scattering on wormholes exhibits some difference from the Compton scattering. High-energy cosmic-ray particles spectrum does not change the form by KSZ, but undergoes a common Doppler shift. Such features may give a new tool to detect the presence of relic wormholes in our Universe.

IceCube can constrain the intrinsic charm of the proton

The discovery of extraterrestrial neutrinos in the $\sim$ 30 TeV -- PeV energy range by IceCube provides new constraints on high energy astrophysics. An important background to the signal are the prompt neutrinos which originate from the decay of charm hadrons produced by high energy cosmic-ray particles interacting in the Earth's atmosphere. It is conventional to use the calculations of charm hadroproduction using gluon splitting $g \to c \bar c$ alone. However, QCD predicts an additional "intrinsic" component of the heavy quark distribution which arises from diagrams where heavy quarks are multiply connected to the proton's valence quarks. We estimate the prompt neutrino spectrum due to intrinsic charm. We find that the atmospheric prompt neutrino flux from intrinsic charm is comparable to those calculated using QCD computations not including intrinsic charm, once we normalize the intrinsic charm differential cross sections to the ISR and the LEBC-MPS collaboration data. In future, IceCube will constrain the intrinsic charm content of the proton and will contribute to one of the major questions in high energy physics phenomenology.

European annual cosmic-ray dose: estimation of population exposure

ABSTRACTThe earth is continually bombarded by high-energy cosmic ray particles, and the worldwide average exposure to cosmic rays represents about 13% of the total annual effective dose received by the population. Therefore, assessment of cosmic ray exposure at the ground level is of great interest to better understand population exposure to ionizing radiation. This paper presents and describes the European Annual Cosmic-Ray Dose Map at 1 km resolution (Main Map). The Main Map displays the annual effective dose that a person may receive from cosmic rays at the ground level, which ranges from 301 to 3955 μSv. Moreover, thanks to the availability of population data, the annual cosmic-ray collective dose has been evaluated and population-weighted average annual effective dose (per capita) due to cosmic ray has been estimated for each European country considered in this study. The accuracy of the present study has been confirmed by comparing our results with those obtained using other models.

Observing particle clusters with energies above tens of GeV in a flux of cosmic rays by means of neutron monitors

Neutron monitors at the Baksan, Moscow, Apatity, and Barentsburg stations are equipped with a unique high-speed registration system that registers the arrival of a pulse with an error of about 1 μs. Analysis of data obtained using the neutron monitors reveals the presence of isolated particle clusters in the flux of high-energy (above tens of GeV) cosmic ray particles. The clusters are known as transients. The neutron monitors detect brief surges of density in the high-energy particle flux. Each surge lasts 20–40 s. The flux density inside the transients is about twice the average level. The transients are isolated by dips that are brief 200–300% drops in the particle flux density, observed in front of and behind each one. It is assumed that a transient is a brief local surge in particle flux density during cosmic ray diffusion and scattering in the interplanetary magnetic field.

The high energy cosmic ray particle spectra measurements with the PAMELA calorimeter

Up until now there has been limited, contradictive data on the high energy range of the cosmic ray electron-positron, proton and helium spectra. Due to the limitations of the use of a magnetic spectrometer, over 8 years experimental data was processed using information from a sampling electro-magnetic calorimeter, a neutron detector and scintillator detectors. The use of these devices allowed us to successfully obtain the high energy cosmic ray particle spectra measurements. The results of this study clarify previous findings and greaten our understanding of the origin of cosmic rays.