J. M. Conrad
A5021088707- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Atomic and Subatomic Physics Research
- Pulsars and Gravitational Waves Research
- Radiation Detection and Scintillator Technologies
- Astrophysical Phenomena and Observations
- High-Energy Particle Collisions Research
- Muon and positron interactions and applications
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Quantum Chromodynamics and Particle Interactions
- Computational Physics and Python Applications
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Radio Wave Propagation Studies
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Astronomy and Astrophysical Research
Massachusetts Institute of Technology
2016-2025
AlbaNova
2013-2024
Stockholm University
2014-2024
The University of Texas at Arlington
2021-2024
Southern University and Agricultural and Mechanical College
2021-2024
Clark Atlanta University
2021-2024
University of Alaska Anchorage
2021-2024
Providence College
2021-2024
Moscow Institute of Thermal Technology
2016-2024
University of Wisconsin–Madison
2004-2023
(Abridged) The Large Area Telescope (Fermi/LAT, hereafter LAT), the primary instrument on Fermi Gamma-ray Space (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering energy range from below 20 MeV to more than 300 GeV. This paper describes LAT, its pre-flight expected performance, and summarizes key science objectives that will be addressed. On-orbit performance presented in detail a subsequent paper. LAT pair-conversion telescope with precision...
We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in 100 MeV–300 GeV range. Based on first 4 yr science data from Gamma-ray Space mission, it is deepest yet this energy Relative to Second LAT catalog, 3FGL incorporates twice as much data, well a number analysis improvements, including improved calibrations at event reconstruction level, an updated model for Galactic diffuse γ-ray emission, refined procedure detection, and methods associating with...
ABSTRACT We present a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT), primary science instrument on Fermi Gamma-ray Space (Fermi) , during first 11 months phase mission, which began 2008 August 4. The First -LAT (1FGL) contains 1451 and characterized in 100 MeV to GeV range. Source detection was based average flux over month period, threshold likelihood Test Statistic is 25, corresponding significance just 4σ. 1FGL includes source location regions,...
We present the second catalog of high-energy gamma-ray sources detected by Large Area Telescope (LAT), primary science instrument on Fermi Gamma-ray Space (Fermi), derived from data taken during first 24 months phase mission, which began 2008 August 4. Source detection is based average flux over 24-month period. The Second Fermi-LAT (2FGL) includes source location regions, defined in terms elliptical fits to 95% confidence regions and spectral power-law, exponentially cutoff or log-normal...
The Double Chooz experiment presents an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. An observed-to-predicted ratio events 0.944±0.016(stat)±0.040(syst) was obtained in 101 days running at the nuclear power plant France, two 4.25 GW(th) reactors. results were from a single 10 m(3) fiducial volume detector located 1050 m cores. flux prediction used Bugey4 measurement after correction for differences core composition. deficit can be...
The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some most dark matter (DM) dominated objects known. We report on gamma-ray observations dSphs based 6 years Fermi Large Area Telescope data processed with new Pass 8 event-level analysis. None significantly detected in gamma rays, and we present upper limits DM annihilation cross section from a combined analysis 15 dSphs. These constraints among strongest robust to date lie below canonical thermal relic for mass $\lesssim$...
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purpose underground liquid scintillator detector, was proposed with the determination of neutrino mass hierarchy as primary physics goal. It is also capable observing neutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse background, geoneutrinos, atmospheric solar well exotic searches such nucleon decays, dark matter, sterile etc. We present motivations anticipated...
A high-energy neutrino event detected by IceCube on 22 September 2017 was coincident in direction and time with a gamma-ray flare from the blazar TXS 0506+056. Prompted this association, we investigated 9.5 years of observations to search for excess emission at position blazar. We found an events, respect atmospheric backgrounds, that between 2014 March 2015. Allowing time-variable flux, constitutes 3.5σ evidence 0506+056, independent prior flaring episode. This suggests blazars are...
(Abridged) We have conducted a detailed investigation of the broad-band spectral properties \gamma-ray selected blazars Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated gamma-ray spectra with Swift, radio, infra-red, optical and other hard X-ray/gamma-ray data, collected within three months LBAS data taking period, we were able to assemble high-quality quasi-simultaneous Spectral Energy Distributions (SED) for 48 blazars.The SED these sources is similar that...
Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with large acceptance exceeding 2 m;{2} sr at 300 GeV. Building on analysis, we have developed efficient detection strategy which provides sufficient background rejection for measurement of steeply falling spectrum up to 1 TeV. Our high precision data show that falls energy E-3.0 and does not exhibit prominent spectral features. Interpretations in terms conventional diffusive...
This catalog summarizes 117 high-confidence ⩾0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on Fermi satellite. Half are neutron stars discovered LAT through periodicity searches in and radio around unassociated source positions. The pulsars evenly divided into groups: millisecond pulsars, young radio-loud radio-quiet pulsars. We characterize pulse profiles energy spectra derive luminosities when distance information exists. Spectral...
The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, a residual all-sky component commonly called isotropic background (IGRB). IGRB comprises all extragalactic emissions too faint or resolved in given survey, as well any foregrounds that are approximately isotropic. first measurement Large Area Telescope (LAT) on board Fermi Gamma-ray Space (Fermi) used 10 months sky-survey...
The IceCube Neutrino Observatory is a cubic-kilometer-scale high-energy neutrino detector built into the ice at South Pole. Construction of IceCube, largest to date, was completed in 2011 and enabled discovery astrophysical neutrinos. We describe here design, production, calibration digital optical module (DOM), cable systems, computing hardware, our methodology for drilling deployment. also online triggering data filtering systems that select candidate cosmic ray events analysis. Due...
The gamma-ray sky >100 MeV is dominated by the diffuse emissions from interactions of cosmic rays with interstellar gas and radiation fields Milky Way. Observations these provide a tool to study cosmic-ray origin propagation, medium. We present measurements first 21 months Fermi-LAT mission compare models emission generated using GALPROP code. are fitted data incorporate astrophysical input for distribution sources, fields. To assess uncertainties associated input, grid created varying...
The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years scientific operation is presented. LAT AGN (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are with a test statistic (TS) greater than 25 and associated statistically AGNs. However, some these affected analysis issues multiple Consequently, we define Clean Sample which 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310...
We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because instrument does not have an onboard magnet, we distinguish two species by exploiting Earth's shadow, which is offset in opposite directions for charges due to magnetic field. estimate subtract proton background using different methods that produce consistent results. report electron-only spectrum, positron-only fraction between 20 GeV 200 GeV. confirm rises energy 20-100 range. The...
Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Burst Monitor and Large Area Telescope onboard Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades gammaray energy. In September 2008, observed exceptionally luminous GRB 080916C, with largest apparent release yet measured. high-energy gamma rays to start later persist longer than lower photons. A simple spectral form fits entire...
The NuTeV Collaboration has extracted the electroweak parameter sin(2)theta(W) from measurement of ratios neutral current to charged nu and (-)nu cross sections. Our value, sin(2)theta((on-shell))(W) = 0.2277 +/- 0.0013(stat) 0.0009(syst), is 3 standard deviations above model prediction. We also present a independent analysis same data in terms neutral-current quark couplings.
The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It based on (3FGL) sources between 100 MeV and 300 GeV with a Test Statistic (TS) greater than 25, 2008 August 4 2012 July 31. 3LAC includes 1591 AGNs located at high Galactic latitudes (|b|>10{\deg}), 71% increase over second 2 years data. There are 28 duplicate associations, thus 1563 2192 high-latitude gamma-ray 3FGL AGNs. Most them (98%) blazars. About half newly blazars unknown type, i.e.,...
Satellite galaxies of the Milky Way are among most promising targets for dark matter searches in gamma rays. We present a search consisting weakly interacting massive particles, applying joint likelihood analysis to 10 satellite with 24 months data Fermi Large Area Telescope. No signal is detected. Including uncertainty distribution, robust upper limits placed on annihilation cross sections. The 95% confidence level range from about 10(-26) cm3 s(-1) at 5 GeV 5×10(-23) 1 TeV, depending final...
We have remotely mapped optical scattering and absorption in glacial ice at the South Pole for wavelengths between 313 560 nm depths 1100 2350 m. used pulsed continuous light sources embedded with AMANDA neutrino telescope, an array of more than six hundred photomultiplier tubes buried deep ice. At greater 1300 m, both coefficient absorptivity follow vertical variations concentration dust impurities, which are seen cores from other Antarctic sites track climatological changes. The varies by...
This white paper addresses the hypothesis of light sterile neutrinos based on recent anomalies observed in neutrino experiments and latest astrophysical data.
The MiniBooNE experiment at Fermilab reports results from an analysis of $\bar \nu_e$ appearance data $11.27 \times 10^{20}$ protons on target in antineutrino mode, increase approximately a factor two over the previously reported results. An event excess $78.4 \pm 28.5$ events ($2.8 \sigma$) is observed energy range $200<E_\nu^{QE}<1250$ MeV. If interpreted two-neutrino oscillation model, $\bar{\nu}_{\mu}\rightarrow\bar{\nu}_e$, best fit to has probability 66% while background-only...