Contemporary imaging air Cherenkov telescopes (IACT) for ground-based very high energy (VHE) gamma ray astronomy have prime focus optical design. Typically these telescopes have a 2-4 deg wide field of view (FoV). They use f/0.7-f/1.2 optics and provide 3-10 arcmin resolution in the FoV. Generally, a well designed telescope that includes more than one optical element will offer some advantages not available in prime focus designs, such as a wider FoV, a more compact size, a higher and more homogeneous resolution and a lower degree of isochronous distortion of light rays focused onto the focal plane. Also, they allow monitoring the gamma ray activity in a sizeable portion of the sky in a single observation. This would allow one to perform a sensitive all-sky survey in a relative short time. We present an f/0.8 15 deg wide FoV telescope design, which provides a high and near uniform resolution and low isochronous distortion across the entire FoV.
Using air showers induced by TeV gamma-rays from Mrk 501, the radial distribution of Cherenkov light is investigated. The shower geometry is reconstructed from the stereoscopic shower images obtained with the telescopes of the HEGRA IACT system. We observe a change in the shape of the light pool with shower energy, and with zenith angle. Data are well reproduced by Monte-Carlo air shower simulations.
The shower simulation code CORSIKA has been used to investigate the electron energy and angular distributions in high-energy showers. Based on the universality of both distributions, we develop an analytical description of Cherenkov light emission in extensive air showers, which provides the total number and angular distribution of photons. The parameterisation can be used e.g. to calculate the contribution of direct and scattered Cherenkov light to shower profiles measured with the air fluorescence technique.
Imaging air Cherenkov telescopes (IACTs) detect the Cherenkov light from extensive air showers (EAS) initiated by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is vital. The influence of the geomagnetic field (GF) on the development of EAS can further complicate the imaging air Cherenkov technique. The amount and the angular distribution of Cherenkov light from EAS can be obtained by means of Monte Carlo (MC) simulations. Here we present the results from dedicat…
The general aim of this work is to obtain the lateral distribution of atmospheric Cherenkov light in extensive air showers produced by different primary particles precisely by. protons, Helium, Iron, Oxygen, Carbon, Nitrogen, Calcium, Silicon and gamma quanta in wide energy range at high mountain observation level of Chacaltaya cosmic ray station. The simulations are divided generally in two energy ranges 10GeV-10 TeV and 10 TeV-10 PeV. One large detector has been used for simulations, the aim being to reduce the statistical fluctuations of the obtained characteristics. The shape of the obtain…
In this article we discuss the possibility of using the observations by GLAST of standard gamma sources, as the Crab Nebula, to calibrate Imaging Air Cherenkov detectors, MAGIC in particular, and optimise their energy resolution. We show that at around 100 GeV the absolute energy calibration uncertainty of Cherenkov telescopes can be reduced to <10% by means of such cross-calibration procedure.
The history of application of the Cherenkov light emission in the atmosphere to cosmic ray and gamma-ray astronomy studies is briefly outlined with an emphasis on the pioneering activity of A.E. Chudakov. The present-day situation and some new ideas are also discussed.
Ground-based atmospheric Cherenkov telescopes are proven to be effective instruments for observations of very high energy (VHE) gamma-radiation from celestial objects. For effective use of such technique one needs detailed Monte Carlo simulations of gamma-ray- and proton/nuclei-induced air showers in Earth atmosphere. Here we discuss in detail the algorithms used in the numerical code ALTAI developed particularly for the simulations of Cherenkov light emission from air showers of energy below 50 TeV. The specific scheme of sampling the charged particle transport in the atmosphere allows the pe…
The Yakutsk array observes the Cherenkov light emitted by UHECR in atmosphere. Recently, an autonomous subarray is added consisting of photomultipliers to measure the showers in the knee region. Our aim is to analyze the combined data set in order to derive the cosmic ray spectrum in the energy range as wide as possible using the same technique. The advantage of the air Cherenkov light measurement is the model independent estimation of the EAS primary energy using the total light flux emitted in the atmosphere. A set of the light lateral distributions observed in the extended energy range is p…
A Monte-Carlo study to reconstruct energy and mass of cosmic rays with energies above 300 TeV using ground based measurements of the electromagnetic part of showers initiated in the atmosphere is presented. The shower properties determined with two detector arrays measuring the air Cherenkov light and the particle densities as realized at the HEGRA experiment are processed to determine the energy of the primary particle without the need of any hypothesis concerning its mass. The mass of the primary particle is reconstructed coarsely from the same observables in parallel to the energy determina…
We have detected Cherenkov light from air showers with Geiger-mode APDs (G-APDs). G-APDs are novel semiconductor photon-detectors, which offer several advantages compared to conventional photomultiplier tubes in the field of ground-based gamma-ray astronomy. In a field test with the MAGIC telescope we have tested the efficiency of a G-APD / light catcher setup to detect Cherenkov light from air showers. We estimate a detection efficiency, which is 60% higher than the efficiency of a MAGIC camera pixel. Ambient temperature dark count rates of the tested G-APDs are below the rates of the night s…
Imaging Air Cherenkov Telescopes (IACTs) detect the Cherenkov light flashes of Extended Air Showers (EAS) triggered by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is rather difficult, in particular at energies below 100 GeV. The influence of the Geomagnetic Field (GF) on the EAS development can further complicate this discrimination and, in addition, also systematically affect the gamma efficiency and energy resolution of an IACT. Here we present the results f…
Cherenkov telescopes image the Cherenkov emission from air showers. A priori, it is not obvious if the `best' images are achieved by measuring Cherenkov photon angles, i.e. focusing the telescope at infinity, or by considering the air shower as an object to be imaged, in which case one might focus the telescope on the central region of the shower. The issue is addressed using shower simulations.
A Monte-Carlo study is presented using ground based measurements of the electromagnetic part of showers initiated in the atmosphere by high energetic cosmic rays to reconstruct energy and mass of primary particles with energies above 300 TeV. With two detector arrays measuring Cherenkov light and particle densities as realized in the HEGRA experiment shower properties are reconstructed and interpreted to determine energy and energy per nucleon of the primary particle.
Magic Telescope may observe and reveal at horizons lights from air-shower Cherenkov reflections. The ground, the sea, the cloudy sky (below the mountain) may reflect PeVs-EeV UHECR Cherenkov lights observable by MAGIC telescopes. Even rarest UHE neutrino skimming the atmosphere or skimming the Earth may induce upward-horizontal airshowers: a new Neutrino Astronomy. These fluorescence signals or the Cherenkov reflections in upper cloudy sky may flash in correlated BL-Lac or GRB shining at opposite edges. Geomagnetic splitting of Horizontal Air-showers may offer a new spectroscopy of UHECR from …
GAW (Gamma Air Watch) is a new imaging Cherenkov telescope designed for observation of very high-energy gamma-ray sources. GAW will be equipped with a 3 meter diameter Fresnel lens as light collector and with an array of 300 multi-anode photomultipliers at the focal plane. The pixel size will be 4 arcmin wide for a total field of view of 10.5 degrees. Whith respect to the planned imaging Cherenkov telescopes (CANGAROO III, HESS, MAGIC, VERITAS) GAW follows a different approach for what concerns both the optical system and the detection working mode: the Cherenkov light collector is a single ac…
High-energy cosmic rays passing through the Earth's atmosphere produce extensive showers whose charges emit radio frequency pulses. Despite the low density of the Earth's atmosphere, this emission should be affected by the air refractive index because the bulk of the shower particles move roughly at the speed of radio waves, so that the retarded altitude of emission, the relativistic boost and the emission pattern are modified. We consider in this paper the contribution of the boosted Coulomb and the Cherenkov fields and calculate analytically the spectrum using a very simplified model in orde…
Measurements of the lateral distribution of Cherenkov photons with the wide-angle atmospheric Cherenkov light detector array AIROBICC and of the charged particle lateral distribution with the scintillator matrix of the HEGRA air-shower detector complex in air showers are reported. With the atmospheric shower-front sampling technique these detectors measure the electromagnetic component of an extensive air shower via the lateral density distribution of the shower particles and of the Cherenkov photons. The data are compared with events generated with the CORSIKA program package with the QGSJET …
Atmospheric air Cherenkov telescopes are successfully used for ground-based, very high-energy (VHE) gamma ray astronomy. Triggers from the so-called single muon and other long-flying relativistic charged particle events are an unwanted background for the Cherenkov telescope. Because of low rate at TeV energies the muon background is unimportant. It is much more intense for telescopes with high photon sensitivity and low energy threshold. Below a few hundred GeV energy, the so-called muon background becomes so intense, that it can deteriorate the sensitivity of telescopes (the so-called muon-wa…
Since February 1997 the BL Lac object Mkn 501 is in a ``high state'' of gamma-ray emission. The HEGRA collaboration has studied Mkn 501 with their air Cherenkov telescopes on La Palma. Here we report on observations with the 5 m^2 telescope (threshold approx. 1.5 TeV) operated in a stand alone mode. We observed a rapidly varying flux between 0.5 to 6 times of that from the Crab Nebula. On average an integral flux above 1.5 TeV of (2 + 1.3 - 0.5) x 10^-11 cm^-2 s^-1 has been determined. The spectrum extends at least up to 10 TeV with an integral power law coefficient of 1.8 +- 0.2 and seems to …
In terms of the quark-gluon string model the analysis of the classic procedure to estimate the energy of giant air showers with help of the parameter s(600) (a density of energy deposition in the scintillator at a distance of 600 m from the shower core) have been carried out. Simulations of the signal s(600) with help of the CORSIKA code in terms of the hybrid scheme show energy estimates which are approximately a factor of 1.6 times lower than adopted at the Yakutsk array. The energy estimates calculated with the help of the Cherenkov radiation coincide with the experimental data. Simulations…
The sensitivity of ground-based imaging atmospheric Cherenkov gamma-ray observatories depends critically on the primary particle identification methods which are used to retain photon-initiated events and suppress the spurious background produced by cosmic rays. We suggest a new discrimination technique which utilizes differences in the fluctuations of the light intensity in the images of showers initiated by photons and those initiated by protons or heavier nuclei. The database of simulated events for the proposed VERITAS observatory has been used to evaluate the efficiency of the new techniq…
Extensive air shower products are fractal in nature. Both simulated and experimental Cherenkov images display multifractal properties. In this paper we explore the possibility of searching multifractal features in Cherenkov arrival times.
In this poster contribution we highlight the equivalence between an Imaging Air Cherenkov Telescope (IACT) array and an Intensity Interferometer for a range of technical requirements. We touch on the differences between a Michelson and an Intensity Interferometer and give a brief overview of the current IACT arrays, their upgrades and next generation concepts (CTA, AGIS, completion 2015). The latter are foreseen to include 30-90 telescopes that will provide 400-4000 different baselines that range in length between 50m and a kilometre. Intensity interferometry with such arrays of telescopes att…
Based on the Monte Carlo simulations we have studied the performance of the HEGRA system of imaging air Cherenkov telescopes (IACTs) in its present configuration of 4 IACTs as well as in its future final configuration of 5 IACTs. Here we present the results on the basic characteristics of the IACT system which are used in the standard data analysis procedure, i.e., the collection areas, the detection rates, the angular resolution, the energy resolution, and the gamma/hadron-separation efficiency. By comparing several key Monte Carlo predictions with experimental results it is possible to check…
We propose to build a large water-Cherenkov-type muon-detector array (Tibet MD array) around the 37,000 m$^{2}$ Tibet air shower array (Tibet AS array) already constructed at 4,300 m above sea level in Tibet, China. Each muon detector is a waterproof concrete pool, 6 m wide $\times$ 6 m long $\times$ 1.5 m deep in size, equipped with a 20 inch-in-diameter PMT. The Tibet MD array consists of 240 muon detectors set up 2.5 m underground. Its total effective area will be 8,640 m$^{2}$ for muon detection. The Tibet MD array will significantly improve gamma-ray sensitivity of the Tibet AS array in t…
We present a new method of image cleaning for imaging atmospheric Cherenkov telescopes. The method is based on the utilization of wavelets to identify noise pixels in images of gamma-ray and hadronic induced air showers. This method selects more signal pixels with Cherenkov photons than traditional image processing techniques. In addition, the method is equally efficient at rejecting pixels with noise alone. The inclusion of more signal pixels in an image of an air shower allows for a more accurate reconstruction, especially at lower gamma-ray energies that produce low levels of light. We pres…
The present generation of ground-based Very High Energy (VHE) gamma-ray observatories consist of arrays of up to four large (> 12m diameter) light collectors quite similar to those used by R. Hanbury Brown to measure stellar diameters by Intensity Interferometry in the late 60's. VHE gamma-ray observatories to be constructed over the coming decade will involve several tens of telescopes of similar or greater sizes. Used as intensity interferometers, they will provide hundreds of independent baselines. Now is the right time to re-assess the potential of intensity interferometry so that it can b…
The gamma/hadron separation in the imaging air Cherenkov telescope technique is based on differences between images of a hadronic shower and a gamma induced electromagnetic cascade. One may expect for a large telescope that a detection of hadronic events containing Cherenkov light from one gamma subcascade only is possible. In fact, simulations show that for the MAGIC telescope their fraction in the total protonic background is about 1.5% to 5.2% depending on the trigger threshold. It has been found that such images have small sizes (mainly below 400 photoelectrons) which correspond to the low…
Atmospheric Cherenkov technique is an established methodology to study TeV energy gamma rays. Here we carry out systematic monte carlo simulation studies of the timing information of Cherenkov photons. Extensive studies have already been carried out in this regard. Most of these are carried out at higher energies with the aim of studying the elemental composition of cosmic rays. However not much attention is paid to the species dependent signatures at TeV energies. In this work, functional fits have been carried out to the spherical Cherenkov shower fronts and the radii of curvature have been …
A simple 3D-reconstruction method for gamma-ray induced air showers is presented, which takes full advantage of the assets of a system of Atmospheric Cherenkov Telescopes combining stereoscopy and fine-grain imaging like the High Energy Stereoscopic System (H.E.S.S.). The rich information collected by the cameras allows to select electromagnetic showers on the basis of their rotational symmetry with respect to the incident direction, as well as of their relatively small lateral spread. In the framework of a 3D-model of the shower, its main parameters -- incident direction, shower core position…
Arrays of imaging air Cherenkov telescopes (IACTs) like VERITAS, HESS have been recently proposed as the instruments of the next generation for ground based very high energy gamma-ray astronomy invading into 50-100 GeV energy range. Here we present results of design studies for the future IACT arrays which have been performed by means of Monte Carlo simulations. We studied different trigger strategies, abilities of cosmic ray rejection for arrays of 4 and 16 telescopes with 10 m reflectors, equipped with cameras comprising 271 and 721 pixels of 0.25 and 0.15 degree, respectively. The comparati…
Cherenkov images of air showers can also be classified using multifractal and wavelet parameters, as compared to the conventional Hillas image parameters. This technique was applied to the images recorded by the cameras of the stereoscopic imaging air Cherenkov-telescopes operated by the HEGRA collaboration. With respect to the identification of particles, the performance of multifractal and wavelet parameters was examined using a data sample from the observation of the active galaxy Mkn 501 that showed a high gamma-ray flux. The multifractal parameters were also combined with the Hillas param…
Cherenkov radiation produced in Extensive Air Showers shows a net polarization. This article discusses its properties and physical origin, and proposes an arrangement of polarizers potentially useful for Imaging Atmospheric Cherenkov Telescopes.
Between early 1997 and late 2002, the HEGRA collaboration operated a stereoscopic system of 4 (later 5) imaging atmospheric Cherenkov telescopes. In this paper we present the calibration schemes which were developed for the system, and report on the performance of the detector over the years. In general, the telescope system was very well understood, regarding both the absolute calibration and the slight changes in performance over the years. The system had an energy threshold of 500 GeV for observations at zenith and under optimum detector conditions. With the corresponding calibration scheme…
The performance of Cherenkov instruments for the detection of very high energy gamma rays is ultimately limited by the fluctuations in the development of air showers. With particular emphasis on the angular resolution, the ultimate performance limits are investigated on the basis of simulations.
The BL Lac object Mkn 501 has shown very high emission in TeV gamma-rays from March to October, 1997. During this period the source was continuously monitored with the HEGRA stereoscopic system of 4 imaging air Cherenkov telescopes for a total exposure time of 110 hours. The unprecedented statistics of about 38,000 TeV photons, combined with the good energy resolution of ~20 % over the entire energy range and with detailed simulations of the detector response, allowed a determination of the average energy spectrum from 500 GeV to 24 TeV. Although the gamma-ray flux varied strongly with time, t…
The Crab Nebula has been observed by the HEGRA (High-Energy Gamma-Ray Astronomy) stereoscopic system of imaging air Cherenkov telescopes (IACTs) for a total of about 200 hrs during two observational campaigns: from September 1997 to March 1998 and from August 1998 to April 1999. The recent detailed studies of system performance give an energy threshold and an energy resolution for gamma-rays of 500 GeV and ~ 18%, respectively. The Crab energy spectrum was measured with the HEGRA IACT system in a very broad energy range up to 20 TeV, using observations at zenith angles up to 65 degrees. The Cra…
Evidence of azimuthal asymmetries in the time structure and signal size has been found in non-vertical showers as a function of zenith angle. These asymmetries arise because of the different paths traveled by particles in the upper and lower sides of the plane perpendicular to the shower axis to reach detectors at the same axial distances. The shower particles are differentially attenuated as they traverse the atmosphere. Furthermore, most particles are not propagating strictly in the shower direction but are on average going away from the axis. This geometrical projection effect also contribu…
A search for gamma-ray bursts (GRBs) above 20 TeV within the field of view (1 sr) of the HEGRA AIROBICC Cherenkov array (29N, 18W, 2200 m a.s.l.) has been performed using data taken between March 1992 and March 1993. The search is based on an all-sky survey using four time scales, 10 seconds, 1 minute, 4 minutes and 1 hour. No evidence for TeV-emission has been found for the data sample. Flux upper limits are given. A special analysis has been performed for GRBs detected by BATSE and WATCH. Two partially and two fully contained GRBs in our field of view (FOV) were studied. For GRB 920925c whic…
Imaging air Cherenkov telescopes are usually triggered on a coincidence of two or sometimes more pixels, with discriminator thresholds in excess of 20 photoelectrons applied for each pixel. These thresholds required to suppress night-sky background are significantly higher than expected on the basis of a Poisson distribution in the number of night-sky photoelectrons generated during the characteristic signal integration time. We studied noise trigger rates under controlled conditions using an artificial background light source. Large tails in the PMT amplitude response to single photoelectrons…
The HEGRA system of Imaging Atmospheric Cherenkov Telescopes (IACTs) detects Cherenkov light produced by air showers. The concept of stereoscopic observation with the five HEGRA telescopes allows the reconstruction of various shower parameters, for example the shower direction, the location of the shower core and the energy of cosmic rays. One of the telescopes was modified so that measurements of the spectrum and the polarization of Cherenkov light with the HEGRA system were possible. The experimental setup is described and preliminary results presented.
Blazars have traditionally been separated into two broad categories based upon their optical emission characteristics; BL Lacs, with faint or no emission lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission lines. The spectral energy distribution of FSRQs has generally been thought of as being more akin to the low-peaked BL Lacs, which exhibit a peak in the infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs), which exhibit a peak in UV/X-ray region of the spectrum. All blazars currently confirmed as sources of TeV emission are HBLs. Recent surveys…
The gamma-ray energy region between 20 and 250 GeV is largely unexplored. Ground-based atmospheric Cherenkov detectors offer a possible way to explore this region, but large Cherenkov photon collection areas are needed to achieve low energy thresholds. This paper discusses the development of a Cherenkov detector using the heliostat mirrors of a solar power plant as the primary collector. As part of this development, we built a prototype detector consisting of four heliostat mirrors and used it to record atmospheric Cherenkov radiation produced in extensive air showers created by cosmic ray par…
We suggest a new approach to study the cosmis ray (CR) mass composition in the energy region from 30 TeV/nucleus up to the "knee" region, i.e. up to a few PeV/nucleus, using an array of imaging atmospheric Cherenkov telescopes (IACTs) of a special architecture. This array consists of telescopes with a relatively small mirror size (~10 square meters) separated from each other by large distances (~500 meters) and equipped by multichannel cameras with a modest pixel size (0.3-0.5 degree) and a sufficiently large viewing angle (6-7 degree). Compared to traditional IACT systems (like HEGRA, HESS or…
Ground-based composition measurements of high-energy cosmic rays can be significantly improved by using the direct Cherenkov method. This technique targets the Cherenkov light produced by the primary particle prior to its production of an extensive air shower. With the appropriate time and angular resolution, the direct Cherenkov photons can be separated from those produced in the extensiveair shower. By utilizing the 0.15 degree angular and 2 nanosecond timing resolution of the very high energy gamma-ray telescope system, VERITAS, the charge and energy of cosmic rays at TeV energies can be id…
The Crab supernova remnant has been observed regularly with the stereoscopic system of 5 imaging air Cherenkov telescopes that was part of the High Energy Gamma Ray Astronomy (HEGRA) experiment. In total, close to 400 hours of useful data have been collected from 1997 until 2002. The spectrum extends up to energies of 80 TeV and is well matched by model calculations in the framework of inverse Compton scattering of various seed photons in the nebula including for the first time a recently detected compact emission region at mm-wavelengths. The observed indications for a gradual steepening of t…
GAW, acronym for Gamma Air Watch, is a path-finder experiment to test the feasibility of a new generation of imaging atmospheric Cherenkov telescopes that join high flux sensitivity with large field of view capability. GAW is conceived as an array of three identical imaging telescopes disposed at the vertexes of an equilateral triangle, about 80 m side. Two main features characterize GAW with respect to all the existing and presently planned ground-based Cherenkov telescopes. The first difference concerns the optics system: GAW uses a Fresnel refractive lens (2.13 m diameter) as light collecto…
The lateral distribution of Cherenkov light at ground level records important information on the development of the cosmic ray air shower which produces it. We have constructed an array of 144 non-imaging Cherenkov detectors at the CASA-MIA experiment site in Dugway, Utah. The various arrays can sample simultaneously the lateral distributions of electrons, muons, and Cherenkov light at many locations. We describe the design and operation of the CASA-BLANCA experiment and its potential to address the composition of primary cosmic rays between 300 and 30,000 TeV.
For air showers observed simultaneously by more than two imaging atmospheric Cherenkov telescopes, the shower geometry is overconstrained by the images and image information should be combined taking into account the quality of the images. Different algorithms are discussed and tested experimentally using data obtained from observations of Mkn 501 with the HEGRA IACT system. Most of these algorithms provide an estimate of the accuracy of the reconstruction of shower geometry on an event-by-event basis, allowing, e.g., to select higher-quality subsamples for precision measurements.
Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong atmospheric absorption affecting the data quality and resulting in a reduced gamma flux. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method …
Milagrito, a large, covered water-Cherenkov detector, was the world's first air-shower-particle detector sensitive to cosmic gamma rays below 1 TeV. It served as a prototype for the Milagro detector and operated from February 1997 to May 1998. This paper gives a description of Milagrito, a summary of the operating experience, and early results that demonstrate the capabilities of this technique.
The atmosphere is an intrinsic part of any ground based Cherenkov gamma-ray telescope, and the telescope response is therefore sensitive to unpredictable changes in the atmospheric transparency which are difficult to measure and interpret in the absence of a calibrated beam of high energy gamma-rays. In this paper, we use the detector response to Cherenkov emission from cosmic ray initiated air showers to obtain a relative calibration for data obtained under different instrumental and atmospheric conditions as well as over a range of source angles to the Zenith. We show that such a relative ca…
There are currently no experiments, either satellite or ground-based, that are sensitive to astrophysical gamma-rays at energies between 20 and 250 GeV. We are developing the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) to explore this energy range. STACEE will use heliostat mirrors at a solar research facility to collect Cherenkov light from extensive air showers produced by high energy gamma-rays. Here we report on the results of prototype test work at the solar facility of Sandia National Laboratories (Albuquerque, NM). The work demonstrates that the facility is suitable for…
A simulation study of the effects resulting from creation of quark--gluon plasma in high energy collisions of cosmic iron nuclei with the air has been carried out. The Cherenkov light emission has been found to reveal some features of the dynamics of high energy hadronic interactions.
Cherenkov Telescopes (as Magic, Hess and Veritas), while pointing horizontally should reveal also the fluorescence flare tails of nearby down-going air-showers. Such air-showers, born at higher (tens km) altitudes, are growing and extending up to lowest atmospheres (EeVs) or up to higher (few km) quotas (PeVs). Viceversa, as it has been foreseen and only recently observed, the opposite takes place. Fluorescence Telescopes made for UHECR detection may be blazed by inclined Cherenkov lights. The geomagnetic splitting may tag the energy as well as the inclined shower footprint as seen in a recent…
