R. W. Ellsworth
A5013110276- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Gamma-ray bursts and supernovae
- Particle Detector Development and Performance
- High-Energy Particle Collisions Research
- Radio Astronomy Observations and Technology
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- Solar and Space Plasma Dynamics
- Radiation Therapy and Dosimetry
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Particle accelerators and beam dynamics
- Astronomical Observations and Instrumentation
- Computational Physics and Python Applications
- Experimental and Theoretical Physics Studies
- Radio, Podcasts, and Digital Media
- Noncommutative and Quantum Gravity Theories
- Precipitation Measurement and Analysis
- Particle Accelerators and Free-Electron Lasers
- Cosmology and Gravitation Theories
- Scientific Research and Discoveries
- Earthquake Detection and Analysis
University of Maryland, College Park
2012-2023
Campbell Collaboration
2023
George Mason University
2008-2019
University of Canterbury
2006
Uppsala University
2003
Istituto Nazionale di Fisica Nucleare
1989-1992
University of Bologna
1989-1992
Northwestern University
1989-1992
Cornell University
1989-1992
Fermi National Accelerator Laboratory
1989-1992
The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau or sterile neutrinos, as both hypotheses fit the data. Using recorded in 1100 live days of Super-Kamiokande detector, we use three complementary samples to study difference zenith angle distribution due neutral currents and matter effects. We find no evidence favoring reject hypothesis at 99% confidence level. On other hand, that oscillation between suffices explain all...
Muon neutrino disappearance probability as a function of flight length L over energy E was studied. A dip in the L/E distribution observed data, predicted from sinusoidal flavor transition oscillation. The constrained nu_mu <-> nu_tau oscillation parameters; 1.9x10^-3 < Delta m^2 3.0x10^-3 eV^2 and \sin^2(2theta) > 0.90 at 90% confidence level.
Exotic origin for cosmic positrons Several cosmic-ray detectors have found more arriving at Earth than expected. Some researchers interpret this as a signature of exotic physics, such the annihilation dark matter particles. Others prefer mundane explanation that involves positron generation pulsars followed by diffusion to Earth. Abeysekara et al. detected extended emission gamma rays around two nearby pulsars, generated high-energy electrons and positrons. The size was used calculate how...
The Crab Nebula is the brightest TeV gamma-ray source in sky and has been used for past 25 years as a reference astronomy, calibration verification of new instruments. High Altitude Water Cherenkov Observatory (HAWC), completed early 2015, to observe at high significance across nearly full spectrum energies which HAWC sensitive. unique its wide field-of-view, 2 sr any instant, high-energy reach, up 100 TeV. HAWC's sensitivity improves with energy. Above $\sim$1 driven by best background...
We present the first catalog of TeV gamma-ray sources realized with recently completed High Altitude Water Cherenkov Observatory (HAWC). It is most sensitive wide field-of-view telescope currently in operation, a 1-year survey sensitivity ~5-10% flux Crab Nebula. With an instantaneous field view >1.5 sr and >90% duty cycle, it continuously surveys monitors sky for gamma ray energies between hundreds GeV tens TeV. HAWC located Mexico at latitude 19 degree North was March 2015. Here, we 2HWC...
Abstract We present TeV gamma-ray observations of the Crab Nebula, standard reference source in ground-based astronomy, using data from High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two independent energy estimation methods that utilize extensive air shower variables such as core position, angle, and lateral distribution. contrast, previously published HAWC spectrum roughly estimated with only number photomultipliers triggered. This new methodology...
A survey of Galactic gamma-ray sources at a median energy ~20 TeV has been performed using the Milagro Gamma-Ray Observatory. Eight candidate emission are detected with pretrial significances >4.5 σ in region longitude l ∊ [30°, 220°] and latitude b [-10°, 10°]. Four these sources, including Crab Nebula recently published MGRO J2019+37, observed >4 after accounting for trials. All four also coincident EGRET sources. Two lower significance one is Geminga. The other two candidates Cygnus...
The diffuse gamma radiation arising from the interaction of cosmic-ray particles with matter and in Galaxy is one few probes available to study origin cosmic rays. Data Milagro gamma-ray observatory—a water Cerenkov detector that continuously views ~2 sr overhead sky—shows brightest extended region entire northern sky Cygnus Galactic plane. TeV image contains at least new source, MGRO J2019+37, which 10.9 σ above isotropic background, as well correlations density region. However, flux (after...
The 7 year data set of the Milagro TeV observatory contains 2.2 x 10(11) events which most are due to hadronic cosmic rays. These searched for evidence intermediate scale structure. Excess emission on angular scales approximately 10 degrees has been found in two localized regions unknown origin with greater than 12sigma significance. Both inconsistent pure gamma-ray high confidence. One a different energy spectrum isotropic cosmic-ray flux at level 4.6sigma, and it is consistent hard protons...
The relative sidereal variation in the arrival direction of primary cosmic ray nuclei median energy 10 TeV was measured using downward, through-going muons detected with Super-Kamiokande-I detector. projection anisotropy map onto right ascension axis has a first harmonic amplitude $(6.64\ifmmode\pm\else\textpm\fi{}0.98\text{ }\text{ }\mathrm{stat}\ifmmode\pm\else\textpm\fi{}0.55\text{ }\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and phase at maximum...
We report on the results of a three-flavor oscillation analysis using Super-Kamiokande I atmospheric neutrino data, with assumption one mass scale dominance ($\ensuremath{\Delta}{m}_{12}^{2}=0$). No significant flux change due to matter effect, which occurs when neutrinos propagate inside Earth for ${\ensuremath{\theta}}_{13}\ensuremath{\ne}0$, has been seen either in multi-GeV ${\ensuremath{\nu}}_{e}$-rich sample or ${\ensuremath{\nu}}_{\ensuremath{\mu}}$-rich sample. Both normal and...
We report on the measurement of all-particle cosmic ray energy spectrum with IceTop air shower array in range from 1.58 PeV to 1.26 EeV. The is surface component IceCube Neutrino Observatory at geographical South Pole. analysis was performed using only information IceTop. data used this work were taken June 1, 2010 May 13, 2011. During that period consisted 73 stations compared 81 its final configuration. measured exhibits a clear deviation single power law above knee around 4PeV and below...
We present the result of a search Milagro sky map for spatial correlations with sources from subset recent Fermi Bright Source List (BSL). The BSL consists 205 most significant detected above 100 MeV by Large Area Telescope. select based on their categorization in BSL, taking all confirmed or possible Galactic field view Milagro. Of 34 selected, 14 are observed at significance 3 standard deviations more. conduct this new analysis which employs newly optimized gamma-hadron separation and...
We present the results of time-integrated searches for astrophysical neutrino sources in both northern and southern skies. Data were collected using partially completed IceCube detector 40-string configuration recorded between 2008 April 5 2009 May 20, totaling 375.5 days livetime. An unbinned maximum likelihood ratio method is used to search signals. The data sample contains 36,900 events: 14,121 from sky, mostly muons induced by atmospheric neutrinos, 22,779 high-energy muons. analysis...
We report the first observation of an anisotropy in arrival direction cosmic rays with energies multi TeV region Southern sky using data from IceCube detector. Between June 2007 and March 2008, partially-deployed detector was operated a configuration 1320 digital optical sensors distributed over 22 strings at depths between 1450 2450 meters inside Antarctic ice. is neutrino detector, but are dominated by large background ray muons. Therefore, suitable for high-statistics studies sky. The...
Between 2009 May and 2010 May, the IceCube neutrino detector at South Pole recorded 32 billion muons generated in air showers produced by cosmic rays with a median energy of 20 TeV. With data set this size, it is possible to probe southern sky for per-mil anisotropy on all angular scales arrival direction distribution rays. Applying power spectrum analysis relative intensity map ray flux hemisphere, we show that not isotropic, but shows significant structure several scales. In addition...
IceCube has become the first neutrino telescope with a sensitivity below TeV flux predicted from gamma-ray bursts if are responsible for observed cosmic-ray above 10(18) eV. Two separate analyses using half-complete detector, one dedicated search neutrinos pγ interactions in prompt phase of burst fireball and other generic any emission these sources over wide range energies times, produced no evidence emission, excluding prevailing models at 90% confidence.
We report on the observation of anisotropy in arrival direction distribution cosmic rays at PeV energies. The analysis is based data taken between 2009 and 2012 with IceTop air shower array south pole. IceTop, an integral part IceCube detector, sensitive to 100 TeV 1 EeV. With current size set, searches for 10−3 level can, first time, be extended divide set into two parts median energies 400 2 PeV, respectively. In low energy band, we observe a strong deficit angular about 30° amplitude (−...