This work summarizes the cosmic ray energy spectrum measurement by the Telescope Array Experiment (TA) in the energy range from 4 PeV to over 100 EeV. The TA is a hybrid detector that uses 3 air fluorescence detectors (FDs) overlooking a ground array of scintillation counters of 1200 m spacing. In May 2016, TA has collected 8 years of data. The TA low energy extension (TALE) extends the energy...
The energy spectrum joint working group was re-established with membership from the Pierre Auger Observatory (Auger) and the Telescope Array experiment (TA). In-depth discussions on the energy determination and systematic uncertainties in the two experiments were made, resulting in a detailed comparison of the UHECR energy spectra observed in the southern and the northern hemispheres. The flux...
We report on an experiment to measure the air-fluorescence from artificial air showers produced at the SLAC National Accelerator Laboratory. The showers have an energy of ~ 10^18 eV and are the result of a superposition of 10^9 10 GeV electons in a picosecond wide pulse. This electron pulse is pre-showered in 1, 2 or 3 radiation lengths of alumina ( Al2O3) and then allowed to develop in...
Current data on the cosmic ray spectrum and composition from the knee to the GZK range provide important information and reveal interesting features, which shed new light about the transition from Galactic to extragalactic cosmic rays. A general description and understanding of this transition it shown to be possible within a simple framework involving only two components, a Galactic one with...
Among other questions, there are two long-standing mysteries about cosmic rays at the highest energies: are they mostly composed by protons or nuclei? Are their sources steady or transient? In this work, we aim to exam one out of the four scenarios led by these questions, namely, the possibility that the highest-energy particles are protons from steady sources. We start out by discussing the...
It will be argued that the detection of anisotropies at ultra-high energies brings important constraints on the composition of ultra-high energy cosmic rays. In particular, the pattern of anisotropies seen by the Telescope Array experiment suggests that protons are present at these energies. This, in turn, puts strong constraints on the sources.
These constraints as well as the physics of...
We report on a cosmic ray energy spectrum measurement by the Telescope Array Low-Energy extension (TALE) fluorescence detector (FD). The TALE FD is an air fluorescence detector which is also sensitive to the Cerenkov light produced by shower particles. Low energy cosmic rays, in the PeV energy range, are detectable by TALE as "Cerenkov Events". Using these events, we measure the energy...
The existence of a knee at a few PeV in the all-particle cosmic ray energy spectrum has been well established by several experiments but its physical origin has eluded researches for a long time. It is believed that keys to disentangle the mystery could be found in the spectrum and the composition of cosmic rays between 1 PeV and 1 EeV. A first detailed look into the elemental chemical...
There are three extensive air showers (EAS) arrays aimed to the study of Cosmic Rays (CR) in the different energy ranges in the Tunka Valley. The first of them is Atmospheric Cherenkov Light Array Tunka-133, containing 175 single PMT detectors at the area of about 3 km2. It ‘s operating since 2009 and has the energy range 5•1015 – 1018 eV. The second one is a low threshold observatory...
The determination of the primary energy of extensive air showers using the fluorescence technique requires an estimation of the energy carried away by particles that do not deposit all their energy in the atmosphere.
This estimation is typically made using Monte Carlo simulations and thus depends on the assumed primary particle mass and on model predictions for neutrino and muon production....
Since cosmic ray was discovered about 100 years ago, the mechanism which generates huge energy has been always the subject of interest.
In order to study the origin of the extremely high energy cosmic ray, highly precise data of extended air shower has been acquired by two huge detectors
(Telescope Array and Pierre Auger Observatory) which have started observation from the beginning of the...
For long-term UHECR observations, the gain calibration of photo-multiplier tubes (PMTs) in the Fluorescence Detector (FD) of the Telescope Array (TA) is crucially important to determine UHECR energies. Current uncertainty of PMT gain in TA FD is estimated to be 11% by adding 8% uncertainty of gain calibration using CRAYS in 2008 and 8% uncertainty of on-site monitoring using YAP pulser in...
The method of composition studies with the Telescope Array surface detector (SD) data is presented. The method is based on the multivariate decision tree analysis of SD observables. Preliminary results of the study will be reported at the conference.
We are developing a unmanned aerial vehicle (UAV), which is called "Opt-copter", carrying a calibrated light source for fluorescence detector (FD) calibration of the Telescope Array (TA) experiment.
The "Opt-copter" is equipped with a high accuracy GPS device and a LED light source in the shape of a dodecahedron. A positioning accuracy of the GPS mounted on the UAV is 0.1 m, which meets the...
In near future, it is expected that sources of ultra-high-energy cosmic rays (UHECRs) can be identified, because the Telescope Array experiment reported that there is a Hotspot in the UHECR arrival direction. However, it is required to observe UHECRs with higher statistics. Moreover, the mass composition should be determined, which is important information for anisotropy study. Then, we should...
The data acquisition (DAQ) system of the surface detectors (SDs) of the TAx4 and the TALE experiment will be presented. Each SD records signals with 50MHz FADCs and sends the data to a central communication center (or the “communication tower”) via a wireless network system. The techniques employed here are based on the currently-running DAQ system of the Telescope Array, and there are some...
An important and remained problem for the observation of UHECRs by air shower experiments is the uncertainty arising from the hadronic interaction models.
Since we rely on particle production, namely air shower development of UHECRs described by the interaction models, it is necessary to verify these interaction models at accelerators as high energy as possible.
Large Hadron Collider forward...
The uncertainty when inferring the mass composition from Xmax distributions comes mainly from unknown uncertainties on $<$Xmax$>$ predictions. Different hadronic models have different $<$Xmax$>$ predictions for proton showers (the separation between proton and Iron $<$Xmax$>$ is similar in all models). Therefore, the estimated mass composition has a strong dependence on the hadronic model...
For any experiment aiming at the observation of Ultra High Energy Cosmic Rays (UHECR's) from space, one key measurement is related to the UV emissions produced in the Earth’s atmosphere. In view of planned missions under study (KLYPVE/K-EUSO, JEM-EUSO, EUSO-FF) at the International Space Station (ISS) and on board of free-flyer satellites, a small, compact UV telescope, Mini-EUSO, is being...
Diffractive and non-diffractive collisions are totally different hadronic interaction processes, the diffractive processes are hardly predicted theoretically. This leads to the significant differences in the treatments of diffraction in the hadronic interaction model. Due to the very forward detector has unique sensitivity to the diffractive processes, it can be a powerful detector for the...
The Non-Imaging CHErenkov Array (NICHE) is a low energy extension to Telescope Array and TALE using an array of closely spaced (70--100 m) light collectors covering an area of up to 1/4 square km. The target is cosmic rays with energies above the "knee", including the "transition region" above which Galactic cosmic rays are no more confined by the galactic magnetic field. It will be deployed...
Telescope Array (TA) is international joint experiment observing ultra-high energy cosmic rays. TA employs fluorescence detection technique to observe cosmic rays. In this technique, the existence of cloud significantly affects quality of data. Therefore, cloud monitoring provides important information. We are developing two new methods for evaluating night sky weather with pictures taken by...
The estimation of invisible energy is central for experiments where only the electromagnetic component of the air shower is measured. This estimation is based on complex Monte Carlo simulations where the influence of the parameters describing the high energy hadronic interactions is difficult to unravel.
The Heitler-Matthews cascade model has been shown to be a powerful tool to
understand the...
The UHECR data collected by the TA and Auger collaborations show some interesting differences in the spectrum as well as in possible anisotropies. Assuming that they do not simply reflect some statistical and/or systematic uncertainties, but on the contrary capture distinct features associated with different regions in the sky, it is interesting to investigate the implications of such...
Three fluorescence detector experiments, HiRes, Telescope Array, and Pierre Auger, agree that the cosmic ray composition is light, probably protonic in 10^18.0 to 10^18.5 eV range. This energy range is well above the critical energy of the galactic magnetic field (GMF). Our simulations of the GMF field show that if these cosmic rays were of galactic origin, there would be an anisotropy in...
The number of muons from the ultra-high energy cosmic rays (UHECRs) is measured with the surface detectors (SDs) on the ground. Its MC prediction depends on hadronic interaction models and the composition. By comparing the measured number of muons with the MC prediction, hadronic models can be tested.
The Pierre Auger Observatory reported that the number of muons measured by water Cherenkov...
The Telescope Array experiment installed the electron accelerator in order to calibrate the fluorescence detector by shooting 40 MeV electrons into the atmosphere. This accelerator is also useful to investigate the radio detection techniques for the cosmic ray observation. Using this accelerator, four experimental groups have studied individual radio detection method at different frequency...
The purpose of the RHICf(Relativistic Hadron Ion Collider forward) experiment is the verification of hadronic interaction models, which is necessary to precisly understand air-shower developments induced by high energy cosmic-rays.We measure the forward neutral particles by using a calorimeter detector installed near the STAR detector. The RHICf detector is the LHCf - Arm1 detector brought...
The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for the next generation of ultra-high energy cosmic ray (UHECR) observatories, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the low flux of cosmic rays at the highest energies. In the FAST design, a large field of view is covered by a few pixels at...
The Large Hadron Collider forward (LHCf) experiment is designed for verification of hadronic interaction models used in cosmic ray physics. We have measured neutral particles, especially neutrons, in very forward region of √s = 13TeV proton-proton collision at CERN-LHC in order to measure inelasticity. For the purpose, the LHCf detector was updated in 2014 by using GSO scintillator to improve...
Two types of orbital detectors of ultra high energy cosmic rays are being developed nowadays: telescope with reflecting optical systems (TUS/KLYPVE and OWL mission with Schmidt optics) and complex lens system (EUSO/JEM-EUSO mission). They will cover much larger areas than existing ground-based arrays and almost uniformly monitor the celestial sphere. The TUS detector is the pioneering mission...
The Telescope Array (TA) experiment is located in the western desert of Utah, USA, and observes ultra high energy cosmic rays in the northern hemisphere. In the region of highest energies, the shape of cosmic ray energy spectrum may contain information on the source density distribution and chemical composition. In this study, using observed events with the Telescope Array surface detector, we...
The absence of UHECR clustering toward largest cluster of galaxy, Virgo, the presence of a smeared hot spot toward Cen A and M82, the presence of rarest nearest size multiplet along our galactic plane, all stand in favor of a very light UHECR composition. Their propagation from 20 Mpc Virgo is forbidden by photo-nuclear dissociation opacity, while it is allowed from few nearby AGN around 2-4...
The chemical composition of ultrahigh energy cosmic rays (UHECR) is studied primarily through observations of the depth of airshower maximum (Xmax), as seen by nitrogen fluorescence telescopes. The Telescope Array (TA) observatory measures Xmax using both stereo fluorescence detectors and fluorescence/ground array hybrid detection to accurately determine extensive air shower geometry. We...
The muon content of extensive air showers produced by the ultra-high energy cosmic rays is an observable sensitive to the composition of the primary particle and to the properties of hadronic interactions driving the air-shower cascade. We present different methods to estimate the muon number at the ground and the muon production depth using measurements of the longitudinal, lateral, and...
Recent measurements at the LHC of the p-p total cross section have reduced the uncertainty in simulations of cosmic ray air showers, in particular of the depth of shower maximum. However, there is a remaining uncertainty due to the total cross section, multiplicity, and elasticity. Uncertainties due to extrapolations from accelerator data in the p-p center of mass, to 250 TeV...
Hadronic cross sections relevant to the air shower development are difficult to calculate from the first principle. Instead, phenomenological models are developed, and they are tested using the accelerator data. Because the Large Hadron Collider provides the highest collision energy, 13TeV in the center-of-momentum system and 10^{17} eV cosmic-ray equivalent energy, it is the best tool to...
The LHCf experiment is one of the LHC forward experiment. The LHCf aims to provide critical data for evaluation of hadronic interaction models which are used in MC simulations of air shower developments induced by high energy cosmic-rays. The LHCf detectors measures neutral particles, photons, neutrons and neutral pions, emitted in the very forward region of a LHC interaction point. The...
The study of anisotropies in the arrival directions of ultra-high energy cosmic rays can give vital clues to understand their origin.
Here we report the recent results related to the search of anisotropies in the arrival directions of ultra-high energy cosmic rays
measured at the Pierre Auger Observatory.
We focus on the search for large scale patterns.
Prominent is a search within...
We will summarize the search for anisotropy of the ultra-high-energy cosmic rays with the Telescope Array (TA), making use of the surface detector data that have been collected during full 8 years of the TA operation. We will present the global event distribution, the auto-correlation function, the correlation with the matter distribution in the local Universe, a blind search for localized...
In the same way as for previous series of international symposia on future directions in UHECR physics, an inter-collaborative anisotropy working group has been established with membership from the Pierre Auger Observatory (Auger) and the Telescope Array experiment (TA) with the task to compile a balanced view about the current status of anisotropy searches in the arrival directions of...
We will discuss the expectations for the UHECR anisotropy under the assumption that the UHECR sources trace the matter distribution in the Universe. The effect of cosmic magnetic fields and charge composition of UHECR will be considered. The experimental signatures and their possible discovery strategies will be discussed.
The trajectory of ultra-high-energy cosmic rays (UHECRs) is affected by the galactic magnetic field (GMF). The GMF has been extensively studied, but the GMF toward the high galactic latitude is yet uncertain. Assuming the deflection of UHECR trajectory by the GMF is mainly dependent on the galactic latitude, b, we analyze the correlation between the arrival direction distribution of UHECRs...
IceCube is a cubic kilometer scale, deep-ice Cherenkov neutrino
detector at the South Pole. IceCube’s cosmic neutrino searches cover
an energy region all the way from below TeV to EeV and higher. In the
EeV energy region, a flux of 'cosmogenic' neutrinos generated by
interactions of ultra-high energy cosmic rays on intervening radiatio
backgrounds is expected. We have analysed 7 years of...
In the transient sky are found the most violent phenomena in the universe. These phenomena are the best known spots to supply enough energy and flux to ultrahigh energy astroparticles at the observed level. In this talk, we will focus on some of these powerful objects (e.g., gamma-ray bursts, young pulsars, magnetars, superluminous supernovae, black hole mergers) and estimate their expected...
Cosmogenic UHE neutrino fluxes are discussed. These fluxes can be detectable by Ice- Cube and future big neutrino detectors only in case the primary UHECR flux is proton dominated. The strong upper limit on proton component of UHECR is given by diffuse flux of HE photons measured recently by Fermi LAT detector up to energy 1 TeV. We argue that this limit still allows the proton-dominated...
We present a novel study connecting UHECRs, neutrinos, and gamma-rays with the objective to identify common counterparts of the three astrophysical messengers. In the test presented here, we first identify potential hadronic sources by selecting gamma-ray emitters that are in spatial coincidence with IceCube neutrinos. Subsequently, these objects are correlated against UHECRs detected by the...
With the newest version of our Monte Carlo code, CRPropa 3, the propagation of ultra-high-energy cosmic rays (UHECRs) from their sources to Earth, including all relevant interactions, deflections in galactic and extragalactic magnetic fields (EGMFs) as well as secondary neutrino and electromagnetic cascade production and propagation can be simulated. The modular structure of the code allows...
Terrestrial Gamma Ray Flashes (TGFs) detected by satellite observations have been shown to be generated by upward propagating negative leaders at altitudes of about 10 to 12 km MSL, and have durations ranging between a few hundred microseconds and a few milliseconds. The Telescope Array Cosmic Ray observatory, designed to observe air showers induced by ultra high energy cosmic rays, includes a...
The Pierre Auger Observatory, designed to observe cosmic rays at the highest energies, can be also a valid ground based instrument for the observation of transient luminous events and for studying modulation of galactic cosmic rays due to solar activity. In more detail, the Fluorescence Detector can observe elves. They are transient luminous emissions from altitudes between 80 and 95 km above...
The data collected with the Pierre Auger Observatory have led to a number of unexpected discoveries. While a strong suppression of the particle flux at the highest energies has been established unambiguously, the dominant physics processes related to this suppression cannot yet be identified. Within the energy range covered by fluorescence detector observations with sufficient statistics, an...
The Telescope Array (TA) experiment consists of a surface detector (SD) array covering 700 km$^2$ in area and three fluorescence detector (FD) stations and explores the origin of ultra-high-energy cosmic rays. We found the evidence of a hotspot in the arrival directions of cosmic rays with energies above 57 EeV (Abbasi ${\it et}$ $\it{al.}$ 2014). New SDs and FDs are planned to be constructed...
TALE, the Telescope Array Low Energy extension is designed to lower the energy threshold to about 10^16.5 eV. TALE has a surface detector(SD) array made up of 103 scintillation counters (40 with 400 m spacing, 36 with 600 m spacing and 27 with 1.2 km spacing) and a Fluorescence Detector (FD) station consisting of ten FD telescopes working with the Telescope Array Middle Drum FD station, which...
Gamma-ray astronomy has had a major breakthrough in the last years with the impressive results obtained using ground- and space-based gamma-ray detectors. While it was not possible to pinpoint the highest energy accelerators within our Galaxy, cosmic rays must be accelerated up to energies of 1 PeV or higher. The new TAIGA project is proposed to solve a number of fundamental problems of high...
TUS (Tracking Ultraviolet Set-up) is the first orbital detector of extreme energy cosmic rays (EECRs), which works as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission is to test the technique of registering fluorescent and Cherenkov radiation of the secondaries born by EECRs in the atmosphere with a space telescope, and to collect information necessary...
An established technique to study ultra-high-energy cosmic rays is the detection of extensive air showers induced in the atmosphere of the earth. Thereby cascades of secondary particles are produced consisting of a hadronic, an electromagnetic and a muonic component. Especially the determination of the number of muons and the amount of fluorescence light produced during the shower development...
Evidence is growing for the existence of a diffuse flux of astrophysical neutrinos with energies up to a few x $10^{15}$ eV. This has spurred considerable interest in developing new techniques that can extend the search to even higher neutrino energies. Promising new efforts over the past half-decade focus on the radio-Cherenkov technique in polar regions with cold, highly transparent ice. I...
