Telescope Array Fluorescence Detectors Research Articles

Results of the missions within JEM-EUSO program

The JEM-EUSO program includes several missions employing fluorescence detectors to make a proof-of-principle of the UHECR observation from space and to raise the technological level of the instrumentation to be employed in a space mission like K-EUSO and POEMMA. EUSO-TA, installed at the Telescope Array (TA) site in Utah in 2013, has already detected 9 UHECRs in coincidence with TA Fluorescence Detector. EUSO-Balloon flew on board a stratospheric balloon in 2014. It measured the UV intensity on forests, lakes and the city of Timmins as well as proved the observation of UHECR-like events by shooting laser tracks. EUSO-SPB was launched on board a Super Pressure Balloon (SPB) in 2017. It proved the functionality of all the subsystems of the telescope on a long term; observed the UV emission on oceans and had a self-trigger system to detect UHECRs. A more ambitious mission (EUSOSPB2) is planned. TUS, on board the Lomonosov satellite in orbit since 2016, has detected a few interesting signals in the UHECR trigger-mode. Mini-EUSO is in a final phase of integration and will be installed inside the International Space Station (ISS) in 2019. The main results obtained so far by these experiments are summarized.

Results from the first missions of the JEM-EUSO program

The origin and nature of Ultra-High Energy Cosmic Rays (UHECRs) remain unsolved in contemporary astroparticle physics. To give an answer to these questions is rather challenging because of the extremely low flux of a few per km2 per century at extreme energies such as E > 5 × 1019 eV. The objective of the JEM-EUSO program, Extreme Universe Space Observatory, is the realization of a space mission devoted to scientific research of cosmic rays of highest energies. Its super-wide-field telescope will look down from space onto the night sky to detect UV photons emitted from air showers generated by UHECRs in the atmosphere. The JEM-EUSO program includes different missions using fluorescence detectors to make a proof-of-principle of the UHECR observation from space and to raise the technological level of the instrumentation to be employed in a space mission. EUSO-TA, installed at the Telescope Array site in Utah in 2013, is in operation. It has already detected 9 UHECRs in coincidence with Telescope Array fluorescence detector at Black Rock Mesa. EUSO-Balloon flew on board a stratospheric balloon in August 2014. It measured the UV intensity on forests, lakesandthecityofTimminsaswellasprovedtheobservationofUHECR-likeeventsbyshootinglasertracks. EUSO-SPB was launched on board a super pressure balloon on April 25th and flew for 12 days. It proved the functionality of all the subsystems of the telescope on a typical duration of a balloon flight; observed the UV emission on oceans and has a self-trigger system to observe UHECRs with energy E > 3×1018 eV. TUS, the Russian mission on board the Lomonosov satellite in orbit since April 28th 2016, is now included in the JEMEUSO program and has detected so far in the UHECR trigger-mode a few interesting signals. Mini-EUSO is in its final phase of integration in Italy, where several performance tests are being held. Mini-EUSO will be installed inside the International Space Station (ISS) in 2019. The main results obtained so far by such missions are summarized and put in prospect of future space detectors such as K-EUSO and POEMMA.

Analysis of atmospheric attenuation using the Telescope Array central laser data

Located in the western desert of the state of Utah, the Telescope Array (TA) experiment measures the properties of ultra high energy cosmic ray (UHECR) induced extensive air showers. TA employs a hybrid detector comprised of a large surface array of scintillator detectors overlooked by three fluorescence telescopes stations. The TA Low Energy extension (TALE) detector has operated as a monocular Cherenkov/fluorescence detector for nearly five years, and has recently been complemented by a closely spaced surface array to operate in hybrid mode. The TAx4 upgrade is underway and aims to, as the name suggests, quadruple the size of the surface array to improve statistics at the highest energies (post-GZK events). The analysis of the TA fluorescence detectors (FD) data requires knowledge of the degree of the atmospheric attenuation of UV light produced by shower particles. This attenuation depends partially on the amount of aerosols present in the atmosphere at the time of shower observation. Being highly variable, real time measurement of the aerosols light attenuation is accomplished through the use of a central laser facility (CLF) located at the center of the surface array, and in the field of view of the three FDs, as well as, the TALE FD. In this proceeding we will describe the experiment, and the CLF data and analysis, and give results on measured aerosols attenuation, yearly averaged. FD measurements of shower energy and Xmax, involve corrections for atmospheric attenuation due to the presence of aerosols. We discuss the errors introduced into the shower parameters reconstruction due to uncertainty about aerosols attenuation.

EUSO-TA, a JEM-EUSO pathfinder at the Telescope Array site

EUSO-TA is one of the prototypes of the JEM-EUSO space telescope, realized in the framework of the EUSO project. Its aims are to calibrate the detector response, test its performance in air and vacuum, raise the technological readiness level of some of the components and improve our knowledge of the various detector systems.EUSO-TA is located at the Telescope Array (TA) site in Black Rock Mesa, Utah, USA and is mainly devoted to study the detector response in conjunction with the TA fluorescence detector. The telescope is housed in a shed located in front of one of the fluorescence detectors of the Telescope Array experiment, pointing in the direction of the ELS (Electron Light Source) and CLF (Central Laser Facility), i.e. the artificial light sources at the Telescope Array site.The detector consists of two Fresnel lenses, 1×1 □m each, with a field of view of 11°×11°, able to focus the ultraviolet light generated by cosmic-ray showers as well as from artificial sources, on a focal surface identical to the ones that will be employed in JEM-EUSO.

Prospects for strangelet detection with large-scale cosmic ray observatories

Quark matter which contains [Formula: see text]-quarks in addition to [Formula: see text]- and [Formula: see text]- could be stable or metastable. In this case, lumps made of this strange matter, called strangelets, could occasionally hit the Earth. When travelling through the atmosphere they would behave not dissimilar to usual high-velocity meteors with only exception that, eventually, strangelets reach the surface. As these encounters are expected to be extremely rare events, very large exposure is needed for their observation. Fluorescence detectors utilized in large ultra-high energy cosmic ray observatories, such as the Pierre Auger observatory and the Telescope Array are well suited for a task of the detection of these events. The flux limits that can be obtained with the Telescope Array fluorescence detectors could be as low as 2.5 × 10−22 cm−2s−1sr−1 which would improve by two orders of magnitude of the strongest present limits obtained from ancient mica crystals.

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in duration (∼ 10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. A novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. We report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.

Preliminary analysis of EUSO—TA data

The EUSO-TA detector is a pathfinder for the JEM-EUSO project and is currently installed in Black Rock Mesa (Utah) on the site of the Telescope Array fluorescence detectors. Aim of this experiment is to validate the observation principle of JEM-EUSO on air showers measured from ground. The experiment gets data in coincidence with the TA triggers to increase the likelihood of cosmic ray detection. In this framework the collaboration is also testing the detector response with respect to several test events from lasers and LED flashers. Moreover, another aim of the project is the validation of the stability of the data acquisition chain in real sky condition and the optimization of the trigger scheme for the rejection of background. Data analysis is ongoing to identify cosmic ray events in coincidence with the TA detector. In this contribution we will show the response of the EUSO-TA detector to all the different typologies of events and we will show some preliminary results on the trigger optimization performed on such data.

EUSO-TA prototype telescope

EUSO-TA is one of the prototypes developed for the JEM-EUSO project, a space-based large field-of-view telescope to observe the fluorescence light emitted by cosmic ray air showers in the atmosphere. EUSO-TA is a ground-based prototype located at the Telescope Array (TA) site in Utah, USA, where an Electron Light Source and a Central Laser Facility are installed. The purpose of the EUSO-TA project is to calibrate the prototype with the TA fluorescence detector in presence of well-known light sources and cosmic ray air showers. In 2015, the detector started the first measurements and tests using the mentioned light sources have been performed successfully. A first cosmic ray candidate has been observed, as well as stars of different magnitude and color index. Since Silicon Photo-Multipliers (SiPMs) are very promising for fluorescence telescopes of next generation, they are under consideration for the realization of a new prototype of EUSO Photo Detector Module (PDM). The response of this sensor type is under investigation through simulations and laboratory experimentation.

The Telescope Array Middle Drum fluorescence detector simulation on GPUs

In recent years, the Graphics Processing Unit (GPU) has been recognized and widely used as an accelerator for many scientific calculations. In general, problems amenable to parallelization are ones that benefit most from the use of GPUs. The Monte Carlo simulation of fluorescence detector response to air showers presents many opportunities for parallelization. In this paper we report on a Monte Carlo program used for the simulation of the Telescope Array Fluorescence Detector located at the Middle Drum site which uses GPU acceleration. All of the physics simulation from shower development, light production and atmospheric attenuation, as well as, the realistic detector optics and electronics simulations are done on the GPU. A detailed description of the code implementation is given, and results on the accuracy and performance of the simulation are presented as well. Improvements in computational throughput in excess of 50× are reported and the accuracy of the results is on par with the CPU implementation of the simulation.

Recent results of the energy spectrum and mass composition from Telescope Array Fluorescence Detector

The Telescope Array experiment is the largest hybrid detector to observe Ultra-High Energy Cosmic Rays in the northern hemisphere. The observation started in November 2007 for Fluorescence Detector (FD) and in March 2008 for Surface Detectors (SD). Here, we present the preliminary results of the energy spectrum and mass composition of the UHECRs measured by the FD and hybrid technique from the Telescope Array three year observations. The energy spectrum measured by the Middle Drum FD station, which is the refurbished HiRes-I detector is consistent with the results from HiRes. The energy spectrum with the two newly constructed FDs and SD is also in good agreement with the result from HiRes, especially for the energy scale. The mass composition study with the slant depth of the maximum shower development (Xmax) is obtained by using the stereo and hybrid analysis. The result of the mass composition is consistent with the proton prediction.

Trigger system for the TA fluorescence detector

The Telescope Array (TA) is a hybrid detector system consisting of fluorescence detectors (FDs) and a surface detector (SD) array to study ultra high energy cosmic rays. In this paper, we describe the development and status of the trigger system for the TA FDs. The trigger system consists of three components, those are the Signal Digitizer and Finder (SDF) module, the Track Finder (TF) module and the Central Trigger Distributor (CTD) module. The SDF module recognizes the fluorescence signal, TF finds air shower tracks and CTD controls data acquisition. We also report the first engineering run carried out in 2007.

Prevention of septic ventilatory depression with naloxone

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in duration (∼ 10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. A novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. We report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.