Interactions Of Primary Cosmic Rays Research Articles

Light Antinuclei from the Laboratory to the Cosmos

The antiproton was experimentally discovered at the Bevatron, Berkeley, in 1955, earning Segré and Chamberlain the 1959 Nobel Prize in Physics. After that, light antinuclei, bound states of antiprotons and antineutrons, have been observed in high-energy interactions in the laboratory from antideuteron to antihelium-4 [1]. In nature, antinuclei are extremely rare objects to be found. The search for antinuclei in space has received considerable attention in recent years, following the suggestion that cosmic antinuclei might be produced in the annihilation or decay of dark matter (DM) particles [2]. Alternatively, “secondary” antinuclei could be produced in ordinary high-energy interactions of primary cosmic rays with the interstellar matter in our galaxy. A precise assessment of the background constituted by secondary antinuclei is pivotal for these searches and for the interpretation of the results. The spectrum of antiprotons observed in cosmic rays is consistent with the hypothesis of secondary production. No evidence of primary antiprotons, antihelium, and antideuterons has been found in the cosmic radiation so far. It is clear that the study of the formation of composite antimatter objects cannot but rely on samples of antimatter produced in the laboratory. Comprehensive measurements of different nuclear (and hypernuclear1) species are necessary to meaningfully constrain formation models and require large data samples to be inspected, as the production of nuclear clusters becomes rarer with increasing mass number. Additional fundamental constraints to the production models are obtained from systematic studies of different particle sources, from ­proton–proton (pp) to heavy-ion collisions, where the size of the system can be experimentally controlled based on the number of particles (multiplicity) produced in the collision.

Cosmic ray neutron spectrometry and dosimetry at High Altitude Research Laboratory, Gulmarg, Kashmir, India

Cosmic ray neutrons are produced by the interaction of primary cosmic rays with the air molecules present in the atmosphere. At the ground level, these secondary neutrons are one of the important contributors of natural cosmic ray radiation background dose. With two major peaks around 1 MeV and 100 MeV, the neutron energies can extend up to 10 GeV. At the ground level, considerable presence of thermal neutrons can also be observed due to collisions and moderation of fast neutrons with the soil and other surrounding materials. A study on the evaluation of cosmic ray neutron spectra, and the resulting ambient dose equivalents was carried out at High Altitude Research Laboratory, Gulmarg, India (altitude 2650 m, N34.0484°, E74.3805°) considering the enhanced contribution of cosmic ray background in the region. Extended energy Bonner Sphere Spectrometer (BSS) was used for the continuous measurement of cosmic ray neutrons during the period of October 2018 to June 2019. Neutron spectra and ambient dose equivalents were unfolded from the BSS counts with the Monte Carlo generated response matrix and the FRUIT unfolding code. Along with Bonner sphere spectrometer, Tissue Equivalent Proportional Counter (TEPC) was also used for a limited period for independent measurement of cosmic ray dose equivalents and Linear Energy Transfer (LET) distribution. For comparison, neutron spectra and dose equivalent rates were also calculated using Monte Carlo code FLUKA and EXPACS software program. The ambient dose equivalent rates were found to vary in the range of 24–34 nSv. h−1 during the entire observation period of 9 months. No considerable seasonal variations were observed during the course of the study. Dose equivalent rates, estimated by the TEPC were slightly higher than the neutron dose equivalent rates measured by BSS. Experimentally measured values match reasonably well with theoretically simulated results.

Particle identification and analysis in the SciCRT using machine learning tools

Machine learning is a powerful tool used in many different areas, from image processing to space navigation and high-energy physics. In this paper we present a configuration of different artificial intelligent tools aimed at the extraction of features from data registered in the SciBar Cosmic Ray Telescope (SciCRT).The SciCRT is an array of plastic scintillator bars that work nearly independently as particle detectors. When a particle crosses inside the telescope, scintillation photons are emitted by the plastics. The intensity of photons is directly proportional to the energy deposited in each bar. Taking advantage of the construction of the telescope, the small transverse area of the scintillator bars, it is possible to do particle tracking and analysis.The main purpose of SciCRT is the detection of solar neutrons originated in the violent phenomena taking place at the surface of the Sun. Nonetheless, the SciCRT is capable of detecting different kinds of secondary particles produced by the interactions of primary cosmic rays with the atmospheric nuclei. For this reason, the task of signal classification is essential.Our final goal will be the classification of detected cosmic ray particles, as well as, the unfolding of the neutron energy spectrum and the estimation of the angular distribution. To achieve this our methodology relies of pattern recognition, artificial neural networks, k-means clustering and k-Nearest Neighbors. In addition, our paper presents a Monte Carlo simulation of the SciCRT for the training and evaluation of the machine learning algorithms.

The North-West University’s High Altitude Radiation Monitor programme

Since the discovery of cosmic radiation by Victor Hess in 1912, when he reported a significant increase in radiation as altitude increases, concerns about radiation effects on human bodies and equipment have grown over the years. The secondary and tertiary particles which result from the interaction of primary cosmic rays with atmospheric particles and commercial aircraft components, are the primary cause of the radiation dose deposited in human bodies and in electronic equipment (avionics) during aircraft flights. At an altitude of about 10 km (or higher) above sea level, the dose received by frequent flyers, and especially flight crew, is a serious concern. Also of concern is the possible failure of sensitive equipment on board commercial aircrafts as a result of flying through this mixed radiation field. Monitoring radiation in the atmosphere is therefore very important. Here we report on the first measurements by the High Altitude Radiation Monitor (HARM) detector during a commercial flight from Johannesburg (O.R. Tambo International Airport) to Windhoek (Hosea Kutako International Airport). As part of a public awareness activity, the HARM detector was placed on a high-altitude balloon, and these measurements are also shown here. Model calculations (estimations) of radiation levels for the commercial aircraft flight are shown and the results are used to interpret our measurements.
 Significance:
 
 Measurements of the Regener–Pfotzer maximum in South Africa and dosimetric measurements on board a commercial flight are presented.
 These radiation measurements are compared to model calculations which can be used to predict the radiation dose during commercial flights.
 This study also aims to raise public awareness about the atmospheric radiation environment from ground level to the Regener–Pfotzer peak at high altitude.

Rigidity dependences of the main characteristics of Forbush decreases

Forbush decrease is an effect in the cosmic rays physics which manifests itself as a sudden depression of the intensity of cosmic rays. Active phase of Forbush decrease lasts for several days and is often accompanied by a geomagnetic storm. The reason for such sudden depressions originates from the Sun, and is connected with a phenomenon of solar physics known as coronal mass ejections. Nowadays Forbush decreases are mostly studied by ground based detectors such as neutron monitors and muon hodoscopes. These detectors are characterized by small statistical fluctuations but register secondary cosmic rays which are created in interactions of primary cosmic rays with Earth atmosphere. This work is based on the data obtained by the satellite experiment PAMELA. The main characteristics of Forbush decreases are calculated for a fluxes of cosmic rays protons in the rigidity range 0.8 – 9 GV.

Detectors for antideuteron search in cosmic rays: current status and new ideas

The observation of sub-GeV antideuteron in the cosmic ray flux could be a very strong signature of dark matter (DM) annihilation in our galaxy. The predicted antideuteron flux resulting from secondary interactions of primary cosmic rays with the Inter-Stellar medium is expected to be very low and in particular is kinematically suppressed at low energy (sub-GeV). Well motivated theories beyond the Standard Model contain viable dark matter candidates, which could lead to a significant enhancement of the antideuteron flux due to annihilation or decay of dark matter particles. This flux contribution is believed to be relatively large at low energies, where the secondary background is suppressed, which leads to an high interest in the development of new detection techniques for low energy antideuteron. Current search of antideuteron in cosmic rays are based on the well established technique of magnetic spectrometry (BESS-Polar II and AMS-02 experiments). With the aim to explore kinetic energy regions below 0.2 GeV/n, i.e. below the lower threshold of current and past magnetic spectrometers, some new detection techniques, involving stopping antideuterons captured to form exotic atoms, have been developed. The GAPS experiment, based on the detection of characteristics X-rays, and the ADHD concept, based on the metastable states in Helium target, will be described. In particular the performances of an high pressure (200 bar) Helium scintillator prototype, capable of fast timing and good spatial and energy resolution will be shown. As a result of the preliminary test phase of this prototype in the INFN-TIFPA laboratory, the perspectives of this detection technique for antiproton rejection and its sensitivity to the Dark Matter search in the antideuteron annihilation channel will be described.

Search for Delayed and Advanced Particles in the Interaction of Ultrahigh-Energy Cosmic Rays with the Earth’s Atmosphere in the Flow of EAS Muons at the MSU EAS Setup

The results obtained by studying temporal distributions of particles of energy in excess of 5 GeV in extensive air showers (EAS) of energy above $$10^{15}$$ eV at distances shorter than 200 m from the EAS axis with the aim of searches in data from the MSU EAS setup for delayed and advanced new particles that could arise in the interactions of primary cosmic rays in the Earth’s atmosphere are presented. These investigations were performed with the aid of an unshielded ground-based detector and an underground detector shielded by a ground layer 20 m.w.e. thick. It is shown that delayed particles having a delay time between 100 and 300 ns and an exponentially descending temporal distribution with an exponent of 120 ns exhibit a higher ionizing ability than relativistic muons. The flow of such particles is attenuated by the ground layer between the unshielded and shielded detectors by a factor of about 30. Particles moving ahead of the EAS disk were not detected in the present study. Properties of delayed particles are discussed. Special features of calibrations and auxiliary tests confirming data from the present measurements are analyzed.

Search for Albedo Tritium with PAMELA Experiment

Particles of albedo radiation are the particles born in interactions of primary cosmic rays penetrating inside Earth’s atmosphere and magnetosphere and the atmosphere nuclei. These interactions result in so-called particle showers and the detection of these showers is the essence of work for ground-based cosmic-ray detectors such as neutron monitors, muon hodoscopes and EAS arrays. Some products of these interactions undergoing by scattering and having the curve paths in geomagnetic field propagate upwards to the boundary of Earth’s magnetosphere. These particles are called albedo particles. The principle of their identification is simple. They are registered in geomagnetic zones where the penetration of low-energy galactic or solar cosmic rays is restricted due to Earth’s magnetic field. The results of measurements of albedo protons, deuterons, electrons and positrons has been already published by PAMELA collaboration. In this work the first approach to search for the albedo tritium nuclei with energies above 100 MeV/nucleon is described.

Interpretation of the excess of antiparticles within a modified paradigm of galactic cosmic rays

We argue that the anomalously high fluxes of positrons and antiprotons found in cosmic rays (CR) can be satisfactorily explained by introducing two additional elements to the current "standard" paradigm of Galactic CRs. First, we propose that the antiparticles are effectively produced in interactions of primary CRs with the surrounding gas not only in the interstellar medium (ISM) but also inside the accelerators. Secondly, we postulate the existence of two source populations injecting CRs into the ISM with different, (1) soft (close to $FI \propto E^{-2.3}$) and (2) hard ($FII \propto E^{-1.8}$ or harder), energy distributions. Assuming that CRs in the 2nd population of accelerators accumulate "grammage" of the order of $1 \ \rm g/cm^2$ before their leakage into ISM, we can explain the energy distributions and absolute fluxes of both positrons and antiprotons, as well as the fluxes of secondary nuclei of the (Li,Be,B) group. The superposition of contributions of two source populations also explains the reported hardening of the spectra of CR protons and nuclei above 200 GV. The 2nd source population accelerating CRs with a rate at the level below 10 percent of the power of the 1st source population, can be responsible for the highest energy protons and nuclei of Galactic CRs up to the "knee" around $10^{15} \ \rm eV$.

Modeling of rigidity dependent CORSIKA simulations for GRAPES-3

The GRAPES-3 muon telescope located in Ooty, India records 4x10^9 muons daily. These muons are produced by interaction of primary cosmic rays (PCRs) in the atmosphere. The high statistics of muons enables GRAPES-3 to make precise measurement of various sun-induced phenomenon including coronal mass ejections (CME), Forbush decreases, geomagnetic storms (GMS) and atmosphere acceleration during the overhead passage of thunderclouds. However, the understanding and interpretation of observed data requires Monte Carlo (MC) simulation of PCRs and subsequent development of showers in the atmosphere. CORSIKA is a standard MC simulation code widely used for this purpose. However, these simulations are time consuming as large number of interactions and decays need to be taken into account at various stages of shower development from top of the atmosphere down to ground level. Therefore, computing resources become an important consideration particularly when billion of PCRs need to be simulated to match the high statistical accuracy of the data. During the GRAPES-3 simulations, it was observed that over 60% of simulated events don't really reach the Earth's atmosphere. The geomagnetic field (GMF) creates a threshold to PCRs called cutoff rigidity Rc, a direction dependent parameter below which PCRs can't reach the Earth's atmosphere. However, in CORSIKA there is no provision to set a direction dependent threshold. We have devised an efficient method that has taken into account of this Rc dependence. A reduction by a factor ~3 in simulation time and ~2 in output data size was achieved for GRAPES-3 simulations. This has been incorporated in CORSIKA version v75600 onwards. Detailed implementation of this along the potential benefits are discussed in this work.

Deuteron and antideuteron production simulation in cosmic-ray interactions

The study of the cosmic-ray deuteron and antideuteron flux receives an increasing interest in current astrophysics investigations. For both cases an important contribution is expected from the nuclear interactions of primary cosmic rays with intergalactic matter. In this work, deuteron and antideuteron production from 20 to 2.6$\times$10$^{7}$ GeV beam energy in p+p and p+A collisions were simulated using EPOS-LHC and Geant4's FTFP-BERT Monte Carlo models by adding an event-by-event coalescence model afterburner. These estimates depend on a single parameter ($p_0$) obtained from a fit to the data. The $p_0$ for deuterons in this wide energy range was evaluated for the first time. It was found that $p_0$ for antideuterons is not a constant at all energies as previous works suggested and as a consequence the antideuteron production cross section can be at least 20 times smaller in the low collision energy region, than earlier estimations.

Equatorial secondary cosmic ray observatory to study space weather and terrestrial events

Recently, equatorial secondary cosmic ray observatory has been established at Equatorial Geophysical Research Laboratory (EGRL), Tirunelveli, (Geographic Coordinates: 8.71°N, 77.76°E), to study secondary cosmic rays (SCR) produced due to the interaction of primary cosmic rays with the Earth’s atmosphere. EGRL is a regional center of Indian Institute of Geomagnetism (IIG), located near the equator in the Southern part of India. Two NaI(Tl) scintillation detectors are installed inside the temperature controlled environment. One detector is cylindrical in shape of size 7.62 cm × 7.62 cm and another one is rectangular cuboid of 10.16 cm × 10.16 cm × 40.64 cm size. Besides NaI(Tl) detectors, various other research facilities such as the Geomagnetic observatory, Medium Frequency Radar System, Digital Ionosonde, All-sky airglow imager, Atmospheric electricity laboratory to measure the near-Earth atmospheric electric fields are also available at EGRL. With the accessibility of multi- instrument facilities, the objective is set to understand the relationship between SCR and various atmospheric and ionospheric processes, during space weather and terrestrial events.For gamma-ray spectroscopy, it is important to test the performance of the NaI(Tl) scintillation detectors and to calibrate the gamma-ray spectrum in terms of energy. The present article describes the details of the experimental setup installed near the equator to study cosmic rays, along with the performance testing and calibration of the detectors under various conditions. A systematic shift in the gain is observed with varying temperature of the detector system. It is found that the detector’s response to the variations in the temperature is not just linear or non-linear type, but it depends on the history of the variation, indicating temperature hysteresis effects on NaI detector and PMT system. This signifies the importance of isothermal environment while studying SCR flux using NaI(Tl) detectors, especially for the experiments conducted during daytime such as solar eclipses etc.

Interpretation of the cosmic ray positron and antiproton fluxes

The spectral shape of cosmic ray positrons and antiprotons has been accurately measured in the broad kinetic energy range 1-350 GeV. In the higher part of this range (E > 30 GeV) the e+ and pbar are both well described by power laws with spectral indices gamma[e+] = 2.77 +-0.02 and gamma[pbar] = 2.78 +- 0.04 that are approximately equal to each other and to the spectral index of protons. In the same energy range the positron/antiproton flux ratio has the approximately constant value 2.04+-0.04, that is consistent with being equal to the ratio e_/pbar calculated for the conventional mechanism of production, where the antiparticles are created as secondaries in the inelastic interactions of primary cosmic rays with interstellar gas. The positron/antiproton ratio at lower energy is significantly higher (reaching the approximate value e+/pbar = 100 for E around 1 GeV), but in the entire energy range 1-350 GeV, the flux ratio is consistent with being equal to ratio of the production rates in the conventional mechanism, as the production of low energy antiprotons is kinematically suppressed in collisions with a target at rest. These results strongly suggest that cosmic ray positrons and antiprotons have a common origin as secondaries in hadronic interactions. This conclusion has broad implications for the astrophysics of cosmic rays in the Galaxy.

FLUKA Monte Carlo assessment of the terrestrial muon flux at low energies and comparison against experimental measurements

In recent years, there has been an increasing interest in the assessment and modelling of Galactic Cosmic Rays (GCR) particularly regarding the evaluation of the radiation effects on airline crew and passengers, interplanetary missions and on-board microelectronics. In the latter field, today the problem is not just limited to Single Event Effects (SEE) as used in avionics, but is more and more observed at ground level. Galactic cosmic muons, coming from the interaction of primary cosmic rays in the Earth's atmosphere, represent the most numerous species at ground level. In this work, we used the Monte Carlo code FLUKA to assess the atmospheric and terrestrial neutron and muon differential fluxes at various altitudes and specific examples such as the geographic coordinates corresponding to New York City and Vancouver. In this context, particle energy spectra were compared with references available in literature, calculation results obtained by both the QARM and EXPACS codes, as well as recently performed measurements. In addition, the zenith angular distribution, at ground level, was assessed for both neutrons and muons and compared with available references. Differential particle fluxes assessed for Vancouver were used as a primary source to simulate a muon detector currently taking data at TRIUMF to evaluate the passing and stopping terrestrial muon rate under different conditions. Finally, simulations were compared with the experimental measurements made at TRIUMF. Results show an excellent agreement between the FLUKA simulations and both references and the experimental measurements made at TRIUMF.

Salient features, response and operation of Lead-Free Gulmarg Neutron Monitor

Lead-Free Gulmarg Neutron Monitor (LFGNM) provides continuous ground level intensity measurements of atmospheric secondary neutrons produced in interactions of primary cosmic rays with the Earth׳s constituent atmosphere. We report the LFGNM detector salient features and simulation of its energy response for 10−11MeV to 104MeV energy incident neutrons using the FLUKA Monte Carlo package. An empirical calibration of the LFGNM detector carried out with a Pu–Be neutron source for maximising its few MeV neutron counting sensitivity is also presented. As an illustration of its functionality a single representative transient solar modulation event recorded by LFGNM depicting Forbush decrease in integrated neutron data for which the geospace consequences are well known is also presented. Performance of LFGNM under actual observation conditions for effectively responding to transient solar modulation is seen to compare well with other world-wide conventional neutron monitors.

Search of predictors of geoeffective heliospheric events by means of muon hodoscope URAGAN

The flux of charged primary cosmic rays (PCR) is modulated by changes of interplanetary magnetic field which depend on various heliospheric processes. After interaction of PCR with nuclei of atoms of the Earth's atmosphere, these modulations are transferred to a flux of secondary muons. Muon hodoscope URAGAN allows to trace changes not only of intensity of the muon flux, but also its angular distribution in a wide range of zenith angles (0-80°). Some results of searching of predictors of geoeffective heliospheric events by means of muon hodoscope URAGAN are presented.

Numerical calculations of cosmic ray cascade in the Earth's atmosphere using different particle interaction models

The interaction of primary cosmic rays with the Earth's atmosphere is investigated using the simulation toolkit GEANT4. Two reference lists of physical processes - QGSP_BIC_HP and FTFP_BERT_HP - are used in the simulations of cosmic ray cascade in the atmosphere. The cosmic ray neutron fluxes are calculated for mean level of solar activity, high geomagnetic latitudes and sea level. The calculated fluxes are compared with the published results of other analogous simulations and with experimental data.

A new look at the cosmic ray positron fraction

Context. The positron fraction in cosmic rays has recently been measured with improved accuracy up to 500 GeV, and it was found to be a steadily increasing function of energy above ~10 GeV. This behaviour contrasts with standard astrophysical mechanisms, in which positrons are secondary particles, produced in the interactions of primary cosmic rays during their propagation in the interstellar medium. The observed anomaly in the positron fraction triggered a lot of excitement, as it could be interpreted as an indirect signature of the presence of dark matter species in the Galaxy, the so-called weakly interacting massive particles (WIMPs). Alternatively, it could be produced by nearby sources, such as pulsars.

Cosmic ray modulation studies with Lead-Free Gulmarg Neutron Monitor

A lead-free neutron monitor operating at High Altitude Research Laboratory (HARL), Gulmarg optimized for detecting 2.45MeV neutron bursts produced during the atmospheric lightning discharges is also concurrently used for studying background neutron component present in the atmosphere. These background neutrons are produced due to the interaction of primary cosmic rays with the atmospheric constituents. In order to study and extract the information about the yield of the neutron production during transient atmospheric lightning discharges, the system is continuously operated to monitor and record the cosmic ray produced background secondary neutrons in the atmosphere. The data analysis of the background neutrons recorded by Lead-Free Gulmarg Neutron Monitor (LFGNM) has convincingly established that the modulation effects due to solar activity phenomena compare very well with those monitored by the worldwide IGY or NM64 type neutron monitors which have optimum energy response relatively towards the higher energy regime of the cosmic rays. The data has revealed various types of modulation phenomena like diurnal variation, Forbush decrease etc. during its entire operational period. However, a new kind of a periodic/seasonal variation pattern is also revealed in the data from September 2007 to September 2012, which is seen to be significantly consistent with the data recorded by Emilio Segre observatory, Israel (ESOI) Neutron Monitor. Interestingly, both these neutron monitors have comparable latitude and altitude. However, the same type of consistency is not observed in the data recorded by the other conventional neutron monitors operating across the globe.

Measurement of the atmospheric ν μ energy spectrum from 100 GeV to 200 TeV with the ANTARES telescope

Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In this paper, a measurement of the atmospheric \nu_\mu + \bar{\nu}_\mu energy spectrum in the energy range 0.1 - 200 TeV is presented, using data collected by the ANTARES underwater neutrino telescope from 2008 to 2011. Overall, the measured flux is ~25% higher than predicted by the conventional neutrino flux, and compatible with the measurements reported in ice. The flux is compatible with a single power-law dependence with spectral index \gamma_{meas}=3.58\pm 0.12. With the present statistics the contribution of prompt neutrinos cannot be established.