A5009045707- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Neutrino Physics Research
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Lightning and Electromagnetic Phenomena
- CCD and CMOS Imaging Sensors
- Particle Accelerators and Free-Electron Lasers
- Ionosphere and magnetosphere dynamics
- Atmospheric Ozone and Climate
- Radiation Detection and Scintillator Technologies
- Precipitation Measurement and Analysis
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Space Science and Extraterrestrial Life
- Scientific Research and Discoveries
- Particle accelerators and beam dynamics
- Photocathodes and Microchannel Plates
- Planetary Science and Exploration
Center for Astrophysics Harvard & Smithsonian
2022-2025
University of Utah
2015-2024
University of California, San Diego
2023
Harvard University
1991-2023
University of California, Berkeley
2023
University of Turku
2023
Niels Brock
2023
University of Copenhagen
2023
Main Astronomical Observatory
2023
Taras Shevchenko National University of Kyiv
2023
The High Resolution Fly's Eye (HiRes) experiment has observed the Greisen-Zatsepin-Kuzmin suppression (called GZK cutoff) with a statistical significance of five standard deviations. HiRes' measurement flux ultrahigh energy (UHE) cosmic rays shows sharp at an $6 \times 10^{19}$ eV, consistent expected cutoff energy. We observe ``ankle'' cosmic-ray spectrum as well, $4 10^{18}$ eV. describe experiment, data collection, analysis, and estimate systematic uncertainties. results are presented...
The Telescope Array (TA) experiment, located in the western desert of Utah,USA, is designed for observation extensive air showers from extremely high energy cosmic rays. experiment has a surface detector array surrounded by three fluorescence detectors to enable simultaneous detection shower particles at ground level and photons along track. TA started full hybrid March, 2008. In this article we describe design technical features detector.
We report studies of ultra-high energy cosmic ray composition via analysis depth airshower maximum (Xmax), for events collected by the High Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d<Xmax>/d(log(E)) 47.9 +- 6.0 (stat.) 3.2 (syst.)g/cm^2/decade energies between 1.6 EeV and 63 EeV, predominantly protonic rays when interpreted QGSJET01 QGSJET-II high-energy hadronic interaction models. These measurements constrain models in which...
We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57~EeV northern sky using data collected over a 5 year period by surface detector Telescope Array experiment. report on cluster events that we call hotspot, found oversampling 20$^\circ$-radius circles. The hotspot has Li-Ma statistical significance 5.1$\sigma$, and is centered at R.A.=146.7$^{\circ}$, Dec.=43.2$^{\circ}$. position about 19$^{\circ}$ off...
The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high cosmic rays with primary energies above 1.6 x 10^(18) eV. This measurement is based upon four years observation by surface detector component TA. shows a dip at an 4.6 eV and steepening 5.4 10^(19) which consistent expectation from GZK cutoff. We present results technique, new to analysis ray data, that involves generating complete simulation striking TA detector. procedure starts shower simulations using...
We have measured the cosmic ray spectrum above 10(17.2) eV using two air-fluorescence detectors of High Resolution Fly's Eye observatory operating in monocular mode. describe detector, phototube, and atmospheric calibrations, as well analysis techniques for detectors. fit to a model consisting galactic extragalactic sources.
The composition of Ultra High Energy Cosmic Rays (UHECR) is measured with the Resolution Fly's Eye cosmic ray observatory (HiRes) data using Xmax technique. Data were collected in stereo between 1999 November and 2001 September. are reconstructed well-determined geometry. Measurements atmospheric transmission incorporated reconstruction. detector resolution found to be 30 g cm^-2 13% Energy. elongation rate 10^18.0 eV 10^19.4 54.5 +/- 6.5 (stat) 4.5 (sys) per decade. This compared...
The Telescope Array observatory utilizes fluorescence detectors and surface to observe air showers produced by ultra high energy cosmic rays in the Earth's atmosphere. Cosmic ray events observed this way are termed hybrid data. depth of shower maximum is related mass primary particle that generates shower. This paper reports on maxima data collected over 8.5 years using Black Rock Mesa Long Ridge conjunction with array detectors. We compare means standard deviations $X_{\mathrm{max}}$...
We report on a measurement of the cosmic ray energy spectrum by Telescope Array Low-Energy Extension (TALE) air fluorescence detector. The TALE detector is also sensitive to Cherenkov light produced shower particles. Low rays, in PeV range, are detectable as "Cherenkov Events". Using these events, we measure from low $\sim 2$ an greater than 100 PeV. Above can detect rays using fluorescence. This allows for extension energies few EeV. In this paper, will describe detector, explain technique,...
Abstract Bursts of gamma ray showers have been observed in coincidence with downward propagating negative leaders lightning flashes by the Telescope Array Surface Detector (TASD). The TASD is a 700‐km 2 cosmic observatory located southwestern Utah, USA. In data collected between 2014 and 2016, correlated observations showing structure temporal development three shower‐producing were obtained 3‐D mapping array, electric field change measurements for an additional seven flashes, both cases...
One of the uncertainties in interpretation ultrahigh energy cosmic ray data comes from hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number muons observed at ground ray--induced showers is expected to depend upon model. may therefore test by comparing measured with MC prediction. In this paper, we present results studies muon densities extensive obtained analyzing signal surface detector stations which should have high purity. purity a station will on both...
In this paper we report the first close, high-resolution observations of downward-directed terrestrial gamma-ray flashes (TGFs) detected by large-area Telescope Array cosmic ray observatory, obtained in conjunction with broadband VHF interferometer and fast electric field change measurements parent discharge. The results show that TGFs occur during strong initial breakdown pulses (IBPs) few milliseconds negative cloud-to-ground low-altitude intracloud flashes, IBPs are produced a...
We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by Telescope Array (TA) detector in first 40 months operation. Following earlier studies, we examine event sets with energy thresholds 10 EeV, and 57 EeV. find that distributions right ascension declination are compatible an isotropic distribution all three sets. then compare previously reported clustering UHECR at small angular scales. No significant is found TA data. check E>57 EeV for correlations nearby...
The Dark Energy Survey (DES) is a 5000 deg<sup>2</sup> grizY survey reaching characteristic photometric depths of 24<sup>th</sup> magnitude (10 sigma) and enabling accurate photometry morphology objects ten times fainter than in SDSS. Preparations for DES have included building dedicated 3 CCD camera (DECam), upgrading the existing CTIO Blanco 4m telescope developing new high performance computing (HPC) enabled data management system (DESDM). DESDM will be used processing, calibrating...
The results on ultrahigh-energy cosmic rays (UHECR) mass composition obtained with the Telescope Array surface detector are presented. analysis employs Boosted Decision tree (BDT) multivariate built upon 14 observables related to both properties of shower front and lateral distribution function. classifier is trained Monte-Carlo sets events induced by primary protons iron. An average atomic UHECR presented for energies $1{0}^{18.0}--1{0}^{20.0}\text{ }\text{ }\mathrm{eV}$. particles shows no...
For the first time a proper comparison of average depth shower maximum ($X_{\rm max}$) published by Pierre Auger and Telescope Array Observatories is presented. The $X_{\rm max}$ distributions measured Observatory were fit using simulated events initiated four primaries (proton, helium, nitrogen iron). primary abundances which best describe data through (TA) Middle Drum (MD) fluorescence surface detector array. analyzed TA Collaboration same procedure as applied to their data. result version...
We report on a measurement of the cosmic ray composition by Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). By making use Cherenkov light signal in addition to from (CR) induced extensive showers, TALE FD can measure properties rays with energies as low $\sim 2$ PeV and exceeding 1 EeV. In this paper, we present results $X_{\rm max}$ distributions showers observed over energy range. Data collected period 4$ years was analyzed for study. The resulting are compared...