A5046956148- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Radiation Therapy and Dosimetry
- Radiation Detection and Scintillator Technologies
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Atomic and Subatomic Physics Research
- Astronomical Observations and Instrumentation
- High-Energy Particle Collisions Research
- Photocathodes and Microchannel Plates
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Muon and positron interactions and applications
- Ionosphere and magnetosphere dynamics
- Scientific Research and Discoveries
- Stellar, planetary, and galactic studies
- Nuclear physics research studies
- Nuclear Physics and Applications
- History and Developments in Astronomy
Pennsylvania State University
2014-2024
University of Michigan
1998-2023
The Ohio State University
2019-2023
Indiana University Bloomington
1998-2023
University of Chicago
1998-2023
McGill University
2017-2023
Northern Kentucky University
2017-2023
Highland Community College - Illinois
2023
Queen's University
2023
Chiba University
2019-2023
Using data collected at the Pierre Auger Observatory during past 3.7 years, we demonstrated a correlation between arrival directions of cosmic rays with energy above 6 × 10 19 electron volts and positions active galactic nuclei (AGN) lying within ∼75 megaparsecs. We rejected hypothesis an isotropic distribution these least 99% confidence level from prescribed priori test. The observed is compatible that highest-energy particles originate nearby extragalactic sources whose flux has not been...
The energy spectrum of cosmic rays above 2.5 x 10;{18} eV, derived from 20,000 events recorded at the Pierre Auger Observatory, is described. spectral index gamma particle flux, J proportional, variantE;{-gamma}, energies between 4 eV and 10;{19} 2.69+/-0.02(stat)+/-0.06(syst), steepening to 4.2+/-0.4(stat)+/-0.06(syst) higher energies. hypothesis a single power law rejected with significance greater than 6 standard deviations. data are consistent prediction by Greisen Zatsepin Kuz'min.
We describe the measurement of depth maximum, X{max}, longitudinal development air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed fluorescence detector Pierre Auger Observatory in coincidence with at least one surface station are selected for analysis. The average shower maximum was found to evolve energy a rate (106{-21}{+35}) g/cm{2}/decade below 10{18.24+/-0.05} eV, and (24+/-3) this energy. measured shower-to-shower fluctuations decrease from about 55 26...
Two measurements of the cosmic-ray positron fraction as a function energy have been made using High-Energy Antimatter Telescope (HEAT) balloon-borne instrument. The first flight took place from Fort Sumner, New Mexico, in 1994 and yielded results above geomagnetic cutoff 4.5 GeV. second flight, Lynn Lake, Manitoba, 1995, permitted over larger interval, 1 to 50 We present on based data Lake compare these with previously published Sumner flight. confirm that does not increase ≈ 10 GeV,...
We report a study of the distributions depth maximum, ${X}_{\mathrm{max}}$, extensive air-shower profiles with energies above $1{0}^{17.8}\text{ }\text{ }\mathrm{eV}$ as observed fluorescence telescopes Pierre Auger Observatory. The analysis method for selecting data sample minimal sampling bias is described in detail well experimental cross-checks and systematic uncertainties. Furthermore, we discuss detector acceptance resolution ${X}_{\mathrm{max}}$ measurement provide parametrizations...
Cosmic rays are atomic nuclei arriving from outer space that reach the highest energies observed in nature. Clues to their origin come studying distribution of arrival directions. Using 3 × 104 cosmic with above 8 1018 electron volts, recorded Pierre Auger Observatory a total exposure 76,800 km2 sr year, we determined existence anisotropy The anisotropy, detected at more than 5.2σ level significance, can be described by dipole an amplitude [Formula: see text] percent toward right ascension...
We present a combined fit of simple astrophysical model UHECR sources to both the energy spectrum and mass composition data measured by Pierre Auger Observatory. The has been performed for energies above 5 ⋅ 1018 eV, i.e. region all-particle so-called "ankle" feature. we adopted consists identical uniformly distributed in comoving volume, where nuclei are accelerated through rigidity-dependent mechanism. results suggest characterized relatively low maximum injection energies, hard spectra...
Using the data taken at Pierre Auger Observatory between December 2004 and 2012, we have examined implications of distributions depths atmospheric shower maximum (Xmax), using a hybrid technique, for composition hadronic interaction models. We do this by fitting with predictions from variety models variations in primary cosmic rays examining quality fit. Regardless what model is assumed, find that our are not well described mix protons iron nuclei over most energy range. Acceptable fits can...
The balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% the atmosphere. instrument is configured with complementary and redundant particle detectors designed to extend direct measurements cosmic-ray composition highest energies practical balloon flights. All elements protons iron nuclei are separated excellent charge resolution. Here we report results first two flights ~70...
Cosmic-ray proton and helium spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in Antarctica 2004–2005 austral summer season. High-energy cosmic-ray data were collected at an average altitude of ∼38.5 km atmospheric overburden ∼3.9 g cm−2. Individual elements are clearly separated a charge resolution ∼0.15 e (in units) ∼0.2 protons nuclei, respectively. The top atmosphere represented by power laws spectral index −2.66 ± 0.02 from...
We report a measurement of the proton-air cross section for particle production at center-of-mass energy per nucleon 57 TeV. This is derived from distribution depths shower maxima observed with Pierre Auger Observatory: systematic uncertainties are studied in detail. Analyzing tail maxima, $[505\ifmmode\pm\else\textpm\fi{}22(\mathrm{stat}{)}_{\ensuremath{-}36}^{+28}(\mathrm{syst})]\text{ }\text{ }\mathrm{mb}$ found.
Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during 2007-2008 Antarctic season. Energies of incident particles above 1 TeV are a calorimeter. Individual elements clearly separated charge resolution ~0.12 e (in units) and ~0.14 protons helium nuclei, respectively, using two layers silicon detectors. proton energy at top atmosphere harder than...
We present the first hybrid measurement of average muon number in air showers at ultra-high energies, initiated by cosmic rays with zenith angles between $62^\circ$ and $80^\circ$. The is based on 174 events recorded simultaneously Surface Detector array Fluorescence Pierre Auger Observatory. for each shower derived scaling a simulated reference profile lateral density distribution ground until it fits data. A $10^{19}$~eV angle $67^\circ$, which arrives an altitude 1450 m above sea level,...
Abstract A new analysis of the data set from Pierre Auger Observatory provides evidence for anisotropy in arrival directions ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative excess arrivals strong, nearby sources. The consist 5514 events above with zenith angles up to 80° recorded before 2017 April 30. Sky models have been created two distinct populations extragalactic gamma-ray emitters: active galactic nuclei second catalog hard Fermi -LAT sources (2FHL)...
Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on absolute calibration, and apply it events with primary 6–16 EeV (ECM=110–170 TeV), whose longitudinal development lateral distribution were simultaneously measured by Pierre Auger Observatory. The average shower is 1.33±0.16 (1.61±0.21) times larger than predicted using leading LHC-tuned EPOS-LHC...
We analyze the distribution of arrival directions ultra-high energy cosmic rays recorded at Pierre Auger Observatory in 10 years operation. The data set, about three times larger than that used earlier studies, includes with zenith angles up to $80^\circ$, thus covering from $-90^\circ$ $+45^\circ$ declination. After updating fraction events correlating active galactic nuclei (AGNs) V\'eron-Cetty and V\'eron catalog, we subject energies excess 40 EeV different tests for anisotropy. search...
We present a measurement of the flux neutrino-induced upgoing muons (<Eν>∼ 100 GeV) using MACRO detector. The ratio number observed to expected events integrated over all zenith angles is 0.74 ±0.036 (stat) ±0.046 (systematic) ±0.13 (theoretical). distribution for −1.0≤cosθ≤−0.1 does not fit well with no oscillation expectation, giving maximum probability χ2 0.1%. acceptance detector has been extensively studied downgoing muons, independent analyses and Monte Carlo simulations. other...
Measurements of the energy spectra negative electrons and positrons have been performed with High-Energy Antimatter Telescope (HEAT) in two balloon flights—1994 May from Fort Sumner, NM, 1995 August Lynn Lake, Manitoba. We present combined data set these flights, covering range 1-100 GeV. compare our results other groups discuss context diffusive propagation models. There is some evidence that primary above 10 GeV cosmic-ray nuclei exhibit same spectrum at source, but source becomes harder...
We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with balloon-borne HEAT-pbar instrument in spring 2000. The data presented here are compatible our previous measurements, obtained different instrument. combined from three HEAT flights indicate small flux nonstandard origin above GeV. compare earlier HEAT-e(+/-) instrument, during opposite epoch solar cycle, conclude that measurements do not support predictions charge sign dependent modulation abundance