Composition Of Primary Cosmic Rays Research Articles

Highlights of the results from the GRAPES-3 experiment

The GRAPES-3 experiment is a unique, extensive air shower experiment consisting of 400 scintillator detectors spread over 25000 m^22 and a 560 m^22 muon telescope. The experiment located at Ooty, India, has been collecting data for the past two decades. The unique capabilities of GRAPES-3 have allowed the study of cosmic rays over energies from a few TeV to tens of PeV and beyond. The measurement of the directional flux of muons (E_\muμ≥1 GeV) by the large muon telescope permits an excellent gamma-hadron separation, which then becomes a powerful tool in the study of multi-TeV gamma-ray sources and the composition of primary cosmic rays. However, the high precision measurements also enable studies of transient atmospheric and interplanetary phenomena such as those produced by thunderstorms and geomagnetic storms. This paper presents some exciting new and recent results, including updates on various ongoing analyses.

A GEANT4 based simulation framework for the large area muon telescope of the GRAPES-3 experiment

The GRAPES-3 experiment located in Ooty, India, samples the electron and muon components in extensive air showers using an array of plastic scintillator detectors and a muon telescope (G3MT) consisting of proportional counters to study the composition of primary cosmic rays (PCRs) as well as γ-ray sources in the TeV–PeV energy range. The G3MT is designed with an appropriate mass absorber to shield the electromagnetic and hadronic components in the shower and to detect muons above 1 GeV×sec(θ) energy, incident from a zenith angle θ. We developed a simulation framework based on the GEANT4 toolkit to evaluate the response of shower particles such as muons, γ-rays, electrons and hadrons in the G3MT. We discuss the geometric modeling of the G3MT using GEANT4 starting with the proportional counter. We estimated the punch-through contribution of hadrons in the G3MT. We compare the simulated muon multiplicity distributions with the observed ones assuming PCR composition from a four population supernova remnant acceleration model namely H4a.

SPHERE-3 Project for Studying the Composition of Primary Cosmic Rays in the Energy Range Between 1 and 1000 PeV

SPHERE-3 Project for Studying the Composition of Primary Cosmic Rays in the Energy Range Between 1 and 1000 PeV

Search for solar atmospheric neutrinos with the ANTARES neutrino telescope

Solar Atmospheric Neutrinos (SAνs) are produced by the interaction of cosmic rays with the solar medium. The detection of SAνs would provide useful information on the composition of primary cosmic rays as well as the solar density. These neutrinos represent an irreducible source of background for indirect searches for dark matter towards the Sun and the measurement of their flux would allow for a better assessment of the uncertainties related to these searches. In this paper we report on the analysis performed, based on an unbinned likelihood maximisation, to search for SAνs with the ANTARES neutrino telescope. After analysing the data collected over 11 years, no evidence for a solar atmospheric neutrino signal has been found. An upper limit at 90% confidence level on the flux of solar atmospheric neutrinos has been obtained, equal to 7×10-11 [ TeV-1 cm-2 s-1] at E ν = 1 TeV for the reference cosmic ray model assumed.

A Monte Carlo study to check muon numbers in hadronic interaction models observed by the Tibet hybrid experiment (YAC-II + Tibet-III + MD)

The interpretation of the EAS data relies on the employment of hadronic interaction models, which are subject to theoretical and experimental uncertainties that may hamper composition studies of cosmic rays. To check the reliability of such models at the energies relevant for EAS studies, the predictions of the models can be compared with data from air shower observatories. In this regard, the study of the number of muons becomes extremely useful, since they are sensitive to the hadronic interactions that occur in the early phases of the EAS development. In the paper, we propose a Monte Carlo study to test the number of muons in hadronic interaction models by the hybrid experiment (YAC-II + Tibet-III + MD). For an air-shower event, the Tibet air-shower array (Tibet-III) provides the arrival direction and the air-shower size which are interrelated to primary energy, the Yangbajing Air shower Core detector (YAC-II) array measures the high energy electromagnetic particles in the very forward region so as to obtain the characteristic parameters of air-shower cores, at the same time, the underground MDs record the number of high-energy muons above 1 GeV. Since we can select proton events with high accuracy by YAC-II almost independently of the hadronic interaction models, the accompanying number of muons induced by proton events can be fed out. With the unique settle of YAC-II, our results show that the description of muon numbers in different hadronic interaction models can be well systematics-checked to avoid the ambiguity of the primary cosmic-ray mass composition around the knee energy region by the Tibet hybrid experiment (YAC-II + Tibet-III + MD).

Particle physics in cosmic rays

The Pierre Auger Observatory is the world’s largest detector of ultra-high energy cosmic rays (UHECRs). It uses an array of fluorescence telescopes and particle detectors at the ground to obtain detailed measurements of the energy spectrum, mass composition and arrival directions of primary cosmic rays (above the energy of [Formula: see text] eV) with accuracy not attainable until now. Observations of extensive air showers performed by the Pierre Auger Observatory can also be used to probe hadronic interactions at high energy, in a kinematic and energy region not accessible by man-made accelerators. Indeed, exploiting Auger data, we reach center-of-mass energies up to 400 TeV, i.e. more than 30 times of those attainable at the Large Hadron Collider (LHC), and explore interactions in the very forward region of phase space on targets of atomic mass of 14. In addition, a precise measurement of the muon component of air showers at the ground is more sensitive to the details of the hadronic interactions along many steps of the cascade development, such as the multiplicity of the secondaries and the fraction of electromagnetic component with respect to the total signal. On the other hand, the intrinsic muon fluctuations mostly depend on the first interaction. In this paper, we overview the new Auger studies exploring the connection between the dynamics of the air shower and the multi-particle production, and how this knowledge can be translated into constraints of the high-energy hadronic models as well as direct measurements, complementary to, and beyond the reach of, accelerator experiments.

Dynamic range extension of the Tibet underground muon detectors for measurements up to the knee energy region with 3-inch photomultipliers

Aiming to study the primary cosmic-ray mass composition up to the knee energy region with the Tibet underground water-Cherenkov muon-detector array (MD), we propose to extend the dynamic range of each MD detector with an 8-inch PMT (Beijing Hamamatsu CR365) and a 3-inch PMT (HZC XP72B22). We carried out a series of tests on the candidate 3-inch XP72B22 PMT to examine whether it can meet our requirements. The measurement results showed that the XP72B22 has a wide dynamic range of 3 orders of magnitude and a linear response up to ∼105 photoelectrons (PEs) at the supply voltage of 700 V. Combined with previous test results of the CR365, these two types of PMT can achieve an equivalent dynamic range from 30 to 106 PEs. As a result, an MD cell is able to detect cosmic rays around the knee energies by adding the CR365 and the XP72B22.

Calibration of the underground muon detector of the Pierre Auger Observatory

To obtain direct measurements of the muon content of extensive air showers with energy above 1016.5 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m2-modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m2 close to the intersection of the shower axis with the ground to much less than one per m2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years.

Depth of the Maximum of Extensive Air Showers (EASes) and the Mean Mass Composition of Primary Cosmic Rays in the 1015–1018 eV Range of Energies, According to Data from the TUNKA-133 and TAIGA-HiSCORE Arrays for Detecting EAS Cherenkov Light in the Tunkinsk Valley

Depth of the Maximum of Extensive Air Showers (EASes) and the Mean Mass Composition of Primary Cosmic Rays in the 1015–1018 eV Range of Energies, According to Data from the TUNKA-133 and TAIGA-HiSCORE Arrays for Detecting EAS Cherenkov Light in the Tunkinsk Valley

An Ultra-High Time Resolution Cosmic-Ray Detection Mode for the Murchison Widefield Array

The radio-wavelength detection of extensive air showers (EASs) initiated by cosmic-ray interactions in the Earth’s atmosphere is a promising technique for investigating the origin of these particles and the physics of their interactions. The Low-frequency Array (LOFAR) and the Owens Valley Long Wavelength Array (OVRO-LWA) have both demonstrated that the dense cores of low-frequency radio telescope arrays yield detailed information on the radiation ground pattern, which can be used to reconstruct key EAS properties and infer the primary cosmic-ray composition. Here, we demonstrate a new observation mode of the Murchison Widefield Array (MWA), tailored to the observation of the sub-microsecond coherent bursts of radiation produced by EAS. We first show how an aggregate 30.72[Formula: see text]MHz bandwidth ([Formula: see text][Formula: see text]kHz frequency channels) recorded at 0.1[Formula: see text]ms resolution with the MWA’s voltage capture system (VCS) can be synthesized back to the full bandwidth Nyquist resolution of 16.3[Formula: see text]ns. This process, which involves “inverting” two sets of polyphase filterbanks, retains 90.5% of the signal-to-noise of a cosmic-ray signal. We then demonstrate the timing and positional accuracy of this mode by resolving the location of a calibrator pulse to within 5[Formula: see text]m. Finally, preliminary observations show that the rate of nanosecond radio-frequency interference (RFI) events is 0.1[Formula: see text]Hz, much lower than that found at the sites of other radio telescopes that study cosmic rays. We conclude that the identification of cosmic rays at the MWA, and hence with the low-frequency component of the Square Kilometre Array, is feasible with minimal loss of efficiency due to RFI.

Muon–Electron Pulse Shape Discrimination for Water Cherenkov Detectors Based on FPGA/SoC

The distinction of secondary particles in extensive air showers, specifically muons and electrons, is one of the requirements to perform a good measurement of the composition of primary cosmic rays. We describe two methods for pulse shape detection and discrimination of muons and electrons implemented on FPGA. One uses an artificial neural network (ANN) algorithm; the other exploits a correlation approach based on finite impulse response (FIR) filters. The novel hls4ml package is used to build the ANN inference model. Both methods were implemented and tested on Xilinx FPGA System on Chip (SoC) devices: ZU9EG Zynq UltraScale+ and ZC7Z020 Zynq. The data set used for the analysis was captured with a data acquisition system on an experimental site based on a water Cherenkov detector. A comparison of the accuracy of the detection, resources utilization and power consumption of both methods is presented. The results show an overall accuracy on particle discrimination of 96.62% for the ANN and 92.50% for the FIR-based correlation, with execution times of 848 ns and 752 ns, respectively.

Intensity of muon bundles according to the NEVOD-DECOR cosmic ray experiment

Data of NEVOD-DECOR experiment on investigations of inclined cosmic ray muon bundles for a long time period (May 2012 – May 2020) are presented. Their comparison with the results of calculations based on simulations of extensive air shower hadron and muon components is carried out. The analysis showed that the observed intensity of muon bundles at primary particle energies of about 1018 eV and higher can be compatible with the expectation only under the assumption of an extremely heavy mass composition of cosmic rays. On the contrary, measurements of the depth of the shower maximum in the atmosphere in the experiments using air fluorescence technique, favour a light mass composition of primary cosmic rays at these energies.

Possibilities of the Tunka-Grande and TAIGA-Muon scintillation arrays with the TAIGA-HiSCORE Cherenkov array joint operation in the research of cosmic and gamma rays

The Tunka-Grande scintillation array is part of the TAIGA Gamma Observatory. It is intended for investigation of energy spectrum and mass composition of primary cosmic rays in the energy range 10 PeV–10 EeV and the search for diffuse cosmic gamma rays. The TAIGA-HiSCORE Cherenkov array aims at observing gamma-rays with the energy from 1 TeV. TAIGA-Muon low-threshold scintillation detector array is a network of surface and underground detectors for registration charge particles of EAS. Currently, 3 clusters have been deployed. The first cluster is running in test mode. It is planed that in the future the total area of the TAIGA-Muon will be about 2000 sq. m. and it will search astrophysical gamma-rays in the energy range from 100 TeV together with the Tunka-Grande scintillation array and the Cherenkov experiments of the TAIGA Gamma Observatory. To evaluate the possibility of join operation Tunka-Grande, TAIGA-Muon and TAIGA-HiSCORE, a simulation was performed using the CORSIKA and Geant4 software packages. The status of model-based studies is presented and assessed the prospects for joint operation of the arrays.

Investigation of the energy spectrum and chemical composition of primary cosmic rays in 1–100 PeV energy range with a UAV-borne detector

A new project is developed with the implementation of a relatively new method of studying primary cosmic rays—the detection of reflected from the snow surface optical Vavilov-Cherenkov radiation from extensive air showers. The aim of the new project is to study the cosmic ray mass composition in the energy range of 1–100 PeV. Silicon photomultipliers are planned to be used as the main photosensitive element of the detector and an unmanned aerial vehicle is going to be used to lift the measuring equipment over the snow surface.

Testing cosmic ray composition models with very large-volume neutrino telescopes

The composition in terms of nuclear species of the primary cosmic ray flux is largely uncertain in the knee region and above, where only indirect measurements are available. The predicted fluxes of high-energy leptons from cosmic ray air showers are influenced by this uncertainty. Different models have been proposed. Similarly, these uncertainties affect the measurement of lepton fluxes in very large-volume neutrino telescopes. Uncertainties in the cosmic ray interaction processes, mainly deriving from the limited amount of experimental data covering the particle physics at play, could also produce similar differences in the observable lepton fluxes and are affected as well by large uncertainties. In this paper we analyse how considering different models for the primary cosmic ray composition affects the expected rates in the current generation of very large-volume neutrino telescopes (ANTARES and IceCube). This is tested comparing two possible models of cosmic ray composition, but the same procedure can be expanded to different possible combinations of cosmic ray abundances. We observe that a certain degree of discrimination between composition fits can be already achieved with the current IceCube data sample, even though in a model-dependent way. The expected improvements in the energy reconstruction achievable with the next-generation neutrino telescopes is be expected to make these instruments more sensitive to the differences between models.

Journey through the birth, growth and maturity of X-ray astronomy

In this biographical account, I recall my scientific journey that began in 1961 when I joined as a Physics Trainee in the BARC Training School and after one year course was admitted in TIFR as a Research Associate. During 1962–1967, I worked on determination of the He3/He4 ratio in cosmic rays using a gas Cerenkov counter and also used a scintillation + solid Cerenkov detector to measure flux of protons and helium nuclei in primary cosmic rays. I also developed a large area scintillation-Cerenkov detector with a spark chamber between them for measuring charge composition of primary cosmic rays. I joined the X-ray astronomy programme in 1967 initiated by Prof. B. V. Sreekantan and played a leading role in developing a balloon borne hard X-ray instrument for studying time variability and energy spectra of cosmic X-ray sources. We carried out a series of balloon experiments and studied temporal intensity variation and energy spectra of X-ray objects like Sco X-1, Cyg X-1, etc. Results on rapid intensity changes and spectra appeared in a series of publications based on which I obtained a Ph.D. degree in 1972. Immediately afterwards, I joined Prof. Gordon Garmire at Caltech as a Research Fellow (a post-doctoral position) to work with him on the low energy component of HEAO A-2 experiment. The instrument was developed and successfully realised. Working on this satellite experiment was a thrilling experience which exposed me to the technical complexities of space instruments. The HEAO-1 satellite was launched in 1978. During 1978–1979, Guenter Riegler and I, working at JPL, reported detection of intense soft X-rays from several classes of extragalactic and Galactic objects like new BL Lacs, a new AM Her binary, coronal X-rays from active stars, etc. After returning to TIFR, I developed a rocket experiment with K. P. Singh to map the spatial and spectral distribution of the Soft Diffuse X-ray Background. At the same time, I also designed 15 cm deep Xenon filled Proportional Counters (XPCs) of ∼ 2500 cm2 area for balloon experiments which were done during 1983–1990 and produced new results on several X-ray binaries. During this period I also developed a proportional counter (PC) based satellite instrument and submitted a proposal jointly with the astronomy group at the Indian Space Research Organization (ISRO) for an Indian X-ray Astronomy Experiment (IXAE). After success of the Polar Satellite Launch Vehicle (PSLV), the IXAE instrument was included on the top deck of the IRS-P3 satellite that was launched in March 1996. Despite the severe limitation of a polar orbit, the IXAE observed a good number of X-ray binaries and produced interesting results, with the most notable being quasi-regular bursts from a new transient, GRS 1915+105, which turned out to be an enigmatic black hole source. Following success of the IXAE, a proposal for an ambitious multiwavelength astronomy satellite, named ASTROSAT, with broad spectral coverage in the optical, NUV, FUV, soft X-ray and hard X-ray by a suite of instruments, was submitted to ISRO and finally approved by the Govt. of India in 2004. Over the next 10 years, the development and fabrication of the five ASTROSAT instruments were accomplished and a PSLV launch on Sept. 28, 2015 placed ASTROSAT in a 650 km circular orbit with 6 degree inclination. The ASTROSAT instruments have been performing well for ∼ 4 years and have observed more than 500 cosmic sources. Results from ASTROSAT have appeared in a large number of journal publications. Successful realization and performance of ASTROSAT marks culmination of my research career. I formally retired as a Senior Professor from TIFR on 2006 April 30 on attaining the age of superannuation. However by agreement with TIFR, ISRO designated me ‘ISRO Chair Professor’, which was later renamed as ISRO Satish Dhawan Professor, and asked me to continue to lead ASTROSAT as PI. At the end of my tenure as ISRO Professor on 2011 April 30, I relinquished the PI position. I am at present affiliated with the MU-DAE Centre of Excellence for Basic Sciences, Mumbai University Campus at Mumbai as an Emeritus Professor.

Predictors of myocardial functional recovery following successful reperfusion of acute ST elevation myocardial infarction

We present the main results of the Extensive Air Shower Cherenkov array Tunka-25. They cover the energy spectrum from 8 · 1014 to 1017 eV and mass composition of primary cosmic rays in the energy range of 3·1015 − 3 · 1016 eV. A new lateral distribution function (LDF) of Air Shower Cherenkov light and a new method to analyze the maximum depth distribution of the shower have been developed. Both have been successfully applied in the data analysis of Tunka-25. We also discuss methods of time and amplitude calibration of the array, providing an accurate determination of the primary energy and the steepness of the LDF.

Studying the Mass Composition of Cosmic Rays with Energies of 1015–1017 eV in the PRISMA Project

The mass composition of primary cosmic rays remains an unresolved problem of physics in the region of energies above the knee. Results from different experiments are contradictory in assessments of the mean mass number and its variation as the primary energy grows. The PRISMA project is designed to study the energy spectrum and mass composition of cosmic rays at energies of 1015–1017 eV. The project is based on a detector capable of simultaneously detecting the electromagnetic and hadron components of a shower. The results are presented from measurements with the PRISMA-YBJ prototype located at 4300 m a.s.l., made over 3.5 years of operation. A new way of estimating the average mass composition from the electron/neutron ratio is tested.

Determination of cosmic-ray primary mass on an event-by-event basis using radio detection

We present a new methodology to discriminate between light and heavy ultra-high energy cosmic-ray primaries on an event-by-event basis using information from the radio detection of extensive air showers at MHz frequencies. Similarly to other methods to determine primary cosmic ray composition, the one presented here is based on comparisons between detected radio signals and Monte Carlo simulations for multiple primary cosmic ray compositions. Unlike other methods that first reconstruct the depth of maximum shower development Xmax to relate it to the nature of the primaries, we instead infer the cosmic-ray composition directly. The method is most effective in the case of inclined showers that arrive at large zenith angles with respect to the vertical to the ground, where methods based on the determination of Xmax lose accuracy. We show that a discrimination efficiency between 65% and 80% can be reached for zenith angles θ ≳ 60∘, even when typical uncertainties in radio detection are taken into account, including shower energy uncertainty. Our methodology could in principle be applied in large and sparse radio arrays, designed with the large radio footprint of inclined showers in mind, to significantly increase the statistics of ultra-high energy cosmic-ray composition studies.

On the efficiency of the evaluation of the primary cosmic ray composition using lateral distributions of air shower electromagnetic component

New analysis of lateral distributions (LD) of electrons, muons and charged particles in extensive air showers generated by 1015 − 1019 eV cosmic rays has been made with respect to the scaling formalism for LD and air shower universality paradigm. It is found that lateral distributions of electrons and muons, when considered separately, are well described by one-parametric scaling functions, while for the charged particles mixture distributions the scaling description is not accurate in radial distance range where electrons and muons give a comparable contribution to the local particle densities. The use of scaling formalism enables enhancing the electron/muon separation capabilities and, when combined with theoretically motivated air shower universality concept, provides robust mass composition estimates. The proposed approach could be implemented for the present and future (multi-) hybrid air shower observations, especially in realizing the potential of Auger and Telescope Array observatories upgrades, as well as for re-analysis and cross-calibration of the data collected from different air shower arrays in a broad primary energy range.