On 2008 March 19, one of the brightest gamma-ray bursts (GRBs) ever recorded was detected by several ground-and space-based instruments spanning the electromagnetic spectrum from radio to gamma rays. ...With a peak visual magnitude of 5.3, GRB 080319B was dubbed the "naked-eye" GRB, as an observer under dark skies could have seen the burst without the aid of an instrument. Presented here are results from observations of the prompt phase of GRB 080319B taken with the Milagro TeV observatory. The burst was observed at an elevation angle of 47degrees Analysis of the data is performed using both the standard air shower method and the scaler or single-particle technique, which results in a sensitive energy range that extends from ~5 GeV to > 20 TeV. These observations provide the only direct constraints on the properties of the high-energy gamma-ray emission from GRB 080319B at these energies. No evidence for emission is found in the Milagro data, and upper limits on the gamma-ray flux above 10 GeV are derived. The limits on emission between ~25 and 200 GeV are incompatible with the synchrotron self-Compton model of gamma-ray production and disfavor a corresponding range (2 eV-16 eV) of assumed synchrotron peak energies. This indicates that the optical photons and soft (~650 keV) gamma rays may not be produced by the same electron population.
Milagrito, a TeV air-shower array Atkins, R.; Benbow, W.; Berley, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2000, Letnik:
449, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Milagrito, a large, covered water-Cherenkov detector, was the world's first air-shower-particle detector sensitive to cosmic gamma rays below 1
TeV. It served as a prototype for the Milagro detector ...and operated from February 1997 to May 1998. This paper gives a description of Milagrito, a summary of the operating experience, and early results that demonstrate the capabilities of this technique.
We present the result of a search of the Milagro sky map for spatial correlations with sources from a subset of the recent Fermi Bright Source List (BSL). The BSL consists of the 205 most significant ...sources detected above 100 MeV by the Fermi Large Area Telescope. We select sources based on their categorization in the BSL, taking all confirmed or possible Galactic sources in the field of view of Milagro. Of the 34 Fermi sources selected, 14 are observed by Milagro at a significance of 3 standard deviations or more. We conduct this search with a new analysis which employs newly optimized gamma-hadron separation and utilizes the full eight-year Milagro data set. Milagro is sensitive to gamma rays with energy from 1 to 100 TeV with a peak sensitivity from 10 to 50 TeV depending on the source spectrum and declination. These results extend the observation of these sources far above the Fermi energy band. With the new analysis and additional data, multi-TeV emission is definitively observed associated with the Fermi pulsar, J2229.0+6114, in the Boomerang pulsar wind nebula (PWN). Furthermore, an extended region of multi-TeV emission is associated with the Fermi pulsar, J0634.0+1745, the Geminga pulsar.
Charge production in thin gap multi-wire chambers Mincer, A.I.; Dado, S.; Goldberg, J.J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2000, 2000-01-00, Letnik:
439, Številka:
1
Journal Article
Recenzirano
Resistive cathode thin gap chambers (TGCs) have been used as particle detectors in high-energy physics experiments for more than a decade. A quantitative understanding of charge production mechanisms ...in TGCs has been developed and a simulation program produced to accurately describe the expected response from a chamber as a function of its design and operating parameters. This simulation is based upon a description of the processes of electron cluster production, drift and avalanche effects and space charge contributions from residual ions. Improved measurements of chamber performance are presented, and the parameters of the simulation have been fitted to these data yielding values consistent with estimates based on the physical mechanisms involved. Sensitivity of chamber timing and amplification properties to operating parameters is discussed.
The Milagrito water Cerenkov detector near Los Alamos, New Mexico, was operated as a sky monitor at energies of a few TeV between 1997 February and 1998 May, including the period of the strong, ...long-lasting 1997 flare of Markarian 501. Milagrito served as a test run for the full Milagro detector. An event excess with a significance of 3.7 sigma from Markarian 501 was observed, in agreement with expectations.
PDF
