Large Air Shower Research Articles

The HiSPARC experiment

The High School Project on Astrophysics Research with Cosmics (HiSPARC) is a large extensive air shower (EAS) array with detection stations throughout the Netherlands, United Kingdom, Denmark and Namibia. HiSPARC is a collaboration of universities, scientific institutes and high schools. The majority of detection stations is hosted by high schools. A HiSPARC station consists of two or four scintillators placed inside roof boxes on top of a building. The measured response of a detector to single incoming muons agrees well with GEANT4 simulations. The response of a station to EASs agrees with simulations as well. A four-scintillator station was integrated in the KASCADE experiment and was used to determine the accuracy of the shower direction reconstruction. Using simulations, the trigger efficiency of a station to detect a shower as function of both distance to the shower core and zenith angle was determined. The HiSPARC experiment is taking data since 2003. The number of stations (∼140 in 2019) still increases. The project demonstrates that its approach is viable for educational purposes and that scientific data can be obtained in a collaboration with high school students and teachers.

Multiple Linsley method for EAS energy determination in LAAS

The observation of the primary energy spectrum in its energy region of 1016 eV to 1019 eV by using compact Extensive Air Shower (EAS) arrays and the time structure of EAS particles which was studied by Linsley (Linsley method) have been carried out by the Large Area Air Shower group. We have estimated the EAS core distance by using only an EAS array and the Linsley method. To improve the determination accuracy of the primary energy, we consider the estimation method of the core distance by using two EAS arrays (multiple Linsley method). We report on the idea of the multiple Linsley method and the comparison of simulation results in various observation modes.

On the origin of the TeV gamma-ray emission from Cygnus X-3

Cygnus X-3 binary system is a famous object studied over the wide range of electromagnetic spectrum. Early detections of ultra-high energy gamma-rays from Cygnus X-3 by Kiel, Havera Park and then by Akeno triggered the construction of several large air shower detectors. Also, Cygnus X-3 has been proposed to be one of the most powerful sources of charged cosmic ray particles in the Galaxy. The results of twenty-year observations of the Cyg X-3 binary at energies 800 GeV - 85 TeV are presented with images, spectra during periods of flaring activity and at low flux periods. The correlation of TeV flux increases with flaring activity at the lower energy range of X-ray and radio emission from the relativistic jets of Cygnus X-3 is found as well as 4.8-hour orbital modulation of TeV γ-ray intensity. Detected modulation of TeV γ-ray emission with orbit and important characteristics of Cyg X-3 such as the high luminosity of the companion star and the close orbit leads to an efficient generation of γ-ray emission through inverse Compton scattering in this object. The different type variability of very high-energy γ-emission and correlation of radiation activity in the wide energy range can provide essential information on the mechanism of particle production up to very high energies.

Prediction of Lightning Inception by Large Ice Particles and Extensive Air Showers.

We derive that lightning can start if the electric field is 15% of the breakdown field, and if elongated ice particles of 6 cm length and 100 free electrons per cm3 are present. This is one particular example set from a parameter range that we discuss as well. Our simulations include the permittivity ε(ω) of ice. 100 free electrons per cm3 exist at 5.5 km altitude in air showers created by cosmic particles of at least 5×10(15) eV. If the electric field zone is 3 m high and 0.2 km2 in the horizontal direction, at least one discharge per minute can be triggered. The size distribution of the ice particles is crucial for our argument; more detailed measurements would be desirable.

Linsley's EAS time structure method for the primary cosmic ray spectrum at LAAS

We have installed a shift register system of ex- tensive air show (EAS) particles in a compact EAS array built on the rooftop of the Faculty of Engineering building in the campus of Okayama University of Science and be- ing operated since April 2006 as part of Large Area Air Shower (LAAS) experiments , in order to register each ar- rival time of EAS particles within 5µs. Detector simulations based on the database obtained from one of the standard cos- mic ray propagation simulator in the atmosphere (AIRES) have also been carried out and the procedures to estimate the primary cosmic ray energy from the Linsley's method have been developed and examined. Applying Linsley's method to the EAS data obtained by our EAS arrays and the simula- tion results, we derived the energy spectrum from 10 16 eV to 10 19.5 eV. Consequently, we obtained the power-law index of 3.2(+0.46 0.8) in the primary energy range of 10 16 eV to 10 18.5 eV, and obtained that a change around 10 18 eV ap- peared if not taking account of the zenith angle distribution of primary cosmic rays. We compared the obtained energy spectrum with other experimental data above 10 16 eV ener- gies, and showed the two components of power-law energy spectra well described our data. We also showed the im- provement of energy resolution by applying the restriction of zenith angle of primary cosmic rays in our simulation re-

THE ARGO-YBJ EXPERIMENT PROGRESSES AND FUTURE EXTENSION

Gamma ray source detection above 30 TeV is an encouraging approach for finding galactic cosmic ray origins. All sky survey for gamma ray sources using wide field of view detector is essential for population accumulation for various types of sources above 100 GeV. To target the goals, the ARGO-YBJ experiment has been established. Significant progresses have been made in the experiment. A large air shower detector array in an area of 1 km2 is proposed to boost the sensitivity. Hybrid detections with multi-techniques will allow a good discrimination between different types of primary particles, including photons and protons, thus enable an energy spectrum measurement for individual species. Fluorescence light detector array will extend the spectrum measurement to 100 PeV and higher where the second knee is located. An energy scale determined by balloon experiments at 10 TeV will be propagated to ultra high energy cosmic ray experiments.

The track imaging Cherenkov experiment

We describe a dedicated cosmic-ray telescope that explores a new method for detecting Cerenkov radiation from high-energy primary cosmic rays and the large particle air shower they induce upon entering the atmosphere. Using a camera comprising 16 multi-anode photomultiplier tubes for a total of 256 pixels, the Track Imaging Cerenkov Experiment (TrICE) resolves substructures in particle air showers with 0.086 degree resolution. Cerenkov radiation is imaged using a novel two-part optical system in which a Fresnel lens provides a wide-field optical trigger and a mirror system collects delayed light with four times the magnification. TrICE records well-resolved cosmic-ray air showers at rates ranging between 0.01-0.1 Hz.

Gamma Rays observation with EAS detectors

Large extensive air shower (EAS) arrays provide complementary technology for observation of very high-energy gamma rays. Whereas their instantaneous sensitivity is currently a factor ∼ 150 less than that of imaging atmospheric Cherenkov telescopes (IACTs), their large field of view (∼ 90 deg; 1.8 sr) and nearly 100% duty cycle makes these observatories particularly suited to conduct all-sky surveys and to detect emission from extended astrophysical sources. Due to the wide field of view coverage of the sky and uninterrupted operation, the EAS technique has also the potential to detect of very high energy (VHE) transient phenomena.

A future project at tibet: the large high altitude air shower observatory (LHAASO)

Gamma ray source detection above 30 TeV is an encouraging approach for finding galactic cosmic ray sources. All sky survey for gamma ray sources using wide field of view detector is essential for population accumulation for various types of sources above 100 GeV. In order to target those goals, a large air shower particle detector array of 1 km2 (the LHAASO project) at 4300 m a.s.l. is proposed. By adding two MagicII-type telescopes in the array as proposed, LHAASO will be enhanced in source morphologic investigation power. The proposed array will be utilized also for energy spectrum measurement for individual cosmic ray species above 30 TeV. By re-configuring the wide field of view telescopes into fluorescence light detector array, the aperture of the detector array can be enlarged to cover an energy region above 100 PeV where the second knee is located. Cosmic ray spectrum and composition will be measured in order to transfer an energy scale to ultra high energy cosmic ray experiments.

Investigation of the S(500) distribution for large air showers detected with the KASCADE-Grande array

Previous EAS investigations have shown that the charged particle density becomes independent of the primary mass at certain distances from the shower core and can be used as an estimator for the primary energy. In the context of the KASCADE-Grande experiment, the particular distance to shower core at which t his effect takes place is around 500 m, hence the study at this particular distance and the notation S(500) for the charged particle density. It has been shown that S(500) maps the primary energy. We present results of further investigations in this direction. An attenuation correction function can be derived from the S(500) attenuation with the EAS angle of incidence, allowing us to build an all event S(500) spectrum. In view of a future conversion of the recorded S(500) spectrum to the primary energy, based on simulations a calibration of the observed S(500) values with the primary energies has been worked out (in the energy range accessible to the KASCADE-Grande array, 10 16 – 10 18 eV ).

The agreement of the Greisen–Zatzepin–Kuzmin prediction with the extensive air shower measurements of giant surface arrays

In very large surface air shower arrays, like AGASA, the primary particle energy has usually been determined via relation to particle densities at 600 m from the shower axis (ρ600). Such a procedure requires a specific treatment for inclined cascades when the maximum of EAS development is close to the array (less than 2–3 radiation lengths above detector). According to the cascade theory and the simulations with the CORSIKA code for primary CR energies above 1019 eV, the exponential function used for ρ600 conversion from inclined to vertical showers is no longer valid. As follows from simulations at energies near to 1020 eV for zenith angles 15–35°, density ρ600 exceeds by about 10% the vertical density, whereas in the previous treatments (using an exponential function) it was usually assumed to be 30% lower. Such treatments generated an artificial increase of the estimated primary cosmic ray energy. The similar behaviour in lateral distributions of muons and photons has an additive contribution to this process. An appropriate algorithm is proposed here to restore the correct primary energy and to amend the previous intensity overestimated for 60–70% of the solid angle inside 45°. We expect that reconstruction of the primary spectrum by the procedure presented here, involving all effects for inclined showers, would eliminate the divergence between measurements at ultra-high energies and confirm the validity of the Greisen–Zatzepin–Kuzmin prediction.

Primary energy spectrum of cosmic rays obtained by arrival time spread of particles in EAS

The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) by using compact arrays. According to J. Linsley, the primary energy of EAS can be estimated from the spread of the arrival times of EAS particles, even with a small array. A shift register system for clocking the arrival times was installed in an array (OUS1) which is located in Okayama University of Science. Analyzing the OUS1 data, we obtained the primary energies of large air showers.

The Neutron ‘Thunder’ Accompanying Large Extensive Air Showers

The bulk of neutrons which appear with long delays in neutron monitors near to the EAS core (‘neutron thunder’) are produced by high energy EAS hadrons hitting the monitors. This conclusion raises an important problem of the interaction of EAS with the ground, the material of the detectors and their environment. Such interactions can give an additional contribution to the signal in the EAS detectors at km distances from the large EAS core a few μs behind the EAS front.

The anisotropy of cosmic ray flux in Large Area Air Shower experiments

The sidereal anisotropy of cosmic rays with energy in the range of 10 14 – 10 15 eV was obtained by using Large Area Air Show (LAAS) experiments which deployed extensive air shower (EAS) arrays in large part of Japan. The first harmonic amplitude and phase in a function of right ascension axis are ( 0.23 ± 0.04 ) × 10 −2 and 0.4 ± 0.7 hour, respectively, and those of the second harmonics are ( 0.06 ± 0.04 ) × 10 −2 and 7.5 ± 2.6 hour, respectively. The first harmonic amplitude are compared with the diffusive mode of cosmic ray propagation, which predicts the dependence of anisotropy amplitudes on primary cosmic ray rigidities. The exponent value of rigidity dependence of diffusion coefficient is estimated as 0.34 ± 0.01 , in good agreement with Kolmogorov type spectrum of turbulence of galactic magnetic filed. Although a sky map in equatorial coordinates indicates excess and deficit regions above the isotropic expectation, their deviations were consistent with statistical ones, and more statistics are required to point the region and the opening angle of them.

Muon components detected by EAS array and Okayama muon telescope experiments

The Okayama muon telescope and the extensive air shower (EAS) array in Large Area Air Shower (LAAS) experiments were used to measure both muon and electron components in EAS events. The average ratio of the number of muon tracks to electron tracks 0.01 ± 0.005 was derived from this analysis, which is consistent with the typical core distance of EAS from the telescope in PeV energies derived from EAS simulation results.

Radio detection of cosmic rays with LOPES (LOPES Collaboration)

Data taken with a radio antenna array in combination with the ground-level air shower experiment KASCADE-Grande at the Forschungszentrum Karlsruhe open up the possibility to measure large extensive air showers with this new technique. The pulse height of the observed radio signals scales with the primary energy of the particles initiating the air shower. The dependence of the radio signal on the angle of the shower axis with respect to the Earth's geomagnetic field and the coherence of the radiation suggest that the radio signal generation is due to the geosynchrotron mechanism.

Energy spectrum of cosmic rays as derived from GPS-synchronized EAS array experiments

Using data from 2.5 years of observations with the Large Area Air Shower (LAAS) experiments in Okayama area, we report the cosmic ray energy spectrum obtained by applying cuts on the number of coincidences of 4 extensive air shower (EAS) arrays, which are synchronized by GPS time stamp system with an accuracy of 1 μ s. The spectral indices in the energy ranges of 10 15 – 10 16 eV and 10 16 – 10 18 eV are obtained and are consistent with assumed ones within statistical errors. The methods to determine the energy spectrum without evaluating the parameters for each individual EAS in each LAAS array, are reported in this paper. The performances of each single array are simulated as well as those of multiple arrays coincident within a several μ s time interval.

Coincidence observations between EAS array and muon spectrometer

The Okayama telescope is a solid iron magnet spectrometer. This telescope enables us to measure the atmospheric muon flux at sea level. A compact extensive air shower (EAS) array which is part of the Large Area Air Shower experiment is also operated, and the telescope is located almost right under this array. From January 2004, we started coincidence observation between the EAS array and the Okayama telescope. Analyzing this coincidence data, we attempt to obtain the momentum spectrum of muons associated with EAS.

Depth development of extensive air showers from muon time distributions

We develop an algorithm that has the potential to relate the depth development of ultra high energy extensive air showers and the time delay for individual muons. The time distributions sampled at different positions at ground level by a large air shower array are converted into distributions of production distances using an approximate relation between production distance, transverse distance and time delay. The method is naturally restricted to inclined showers where muons dominate the signal at ground level but could be extended to vertical showers provided that the detectors used can separate the muon signal from electrons and photons. We explore the accuracy and practical uncertainties involved in the proposed method. For practical purposes only the muons that fall outside the central region of the shower can be used, and we establish cuts in transverse distance. The method is tested using simulated showers by comparing the production distance distributions obtained using the method with the actual distances in the simulated showers. It could be applied in the search for neutrinos to increase the acceptance to highly penetrating particles, as well as for unraveling the relative compositions of protons and heavy nuclei. We also illustrate that the obtained depth distributions have minimum width when both the arrival direction and the core position are well reconstructed.

TeV black hole fragmentation and detectability in extensive air showers

In models with large extra dimensions, particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate nonperturbative gravitational objects. Since cosmic rays have been observed with energies above $10^{8}$ TeV, gravitational effects in the TeV energy range can, in principle, be observed by ultrahigh energy cosmic ray detectors. We consider the interaction of ultrahigh energy neutrinos in the atmosphere and compare extensive air showers from TeV black hole formation and fragmentation with standard model processes. Departures from the standard model predictions arise in the interaction cross sections and in the multiplicity of secondary particles. Large theoretical uncertainties in the black hole cross section weaken attempts to constrain TeV gravity based solely on differences between predicted and observed event rates. The large multiplicity of secondaries in black hole fragmentation enhances the detectability of TeV gravity effects. We simulate TeV black hole air showers using PYTHIA and AIRES, and find that black hole-induced air showers are quite distinct from standard model air showers. However, the limited amount of information registered by realistic detectors together with large air shower fluctuations limit in practice the ability to distinguish TeV gravity events from standard model events in a shower by shower case. We discuss possible strategies to optimize the detectability of black hole events and propose a few unique signatures that may allow future high statistics detectors to separate black hole from standard model events.