(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In ...this paper, a measurement of the atmospheric ... energy spectrum in the energy range 0.1-200 TeV is presented, using data collected by the ANTARES underwater neutrino telescope from 2008 to 2011. Overall, the measured flux is 25 % higher than predicted by the conventional neutrino flux, and compatible with the measurements reported in ice. The flux is compatible with a single power-law dependence with spectral index gamma sub(meas)=3.58 plus or minus 0.12. With the present statistics the contribution of prompt neutrinos cannot be established.
All but three (M87, BL Lac, and 3C 279) extragalactic sources detected so far at very high energy -rays belong to the class of high-frequency-peaked BL Lac objects. This suggested to us a systematic ...scan of candidate sources with the MAGIC telescope, based on the Donato et al. compilation of X-ray blazars. The observations took place from 2004 December to 2006 March and cover northern sky sources visible under small zenith distances image at culmination, constraining the declination to -2 degree to +58 degree . The sensitivity of the search was planned for detecting X-ray-bright image sources emitting at least the same energy flux at 200 GeV as at 1 keV. To avoid strong -ray attenuation close to the energy threshold, source redshift was constrained to image. Of the 14 sources observed, 1ES 1218+304 (for the first time at VHE) and 1ES 2344+514 (strong detection in a low flux state) were detected in addition to the known bright TeV blazars Mrk 421 and Mrk 501. A marginal excess of 3.5 capital sigma from the position of 1ES 1011+496 was observed and then confirmed as a VHE -ray source by a second MAGIC observation triggered by a high optical state. For the remaining sources, we present 99% c.l. upper limits on the integral flux image200 GeV. We characterize the HBL sample (including all HBLs detected at VHE so far) by looking for correlations between their multifrequency spectral indices determined from simultaneous optical, archival X-ray, and radio luminosities, finding that VHE-emitting HBLs do not seem to constitute a unique subclass. The HBLs' absorption-corrected -ray luminosities at 200 GeV are generally not higher than their X-ray luminosities at 1 keV.
In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant ...signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E –2 ν spectrum, these flux limits are at 1-10 ×10–8 GeV cm–2 s–1 for declinations ranging from –90° to 40°. Limits for specific models of RX J1713.7–3946 and Vela X, which include information on the source morphology and spectrum, are also given.
The CLUE experiment operating with 4 telescopes in La Palma Alexandreas, D; Bartoli, B; Bastieri, D ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Volume:
409, Issue:
1-3
Journal Article
Peer reviewed
The CLUE experiment has started operation with four of the nine telescopes that are foreseen for its beginning. These telescopes are at present at Roque de Los Muchachos in the Canary Islands, in the ...same site as the HEGRA experiment. In winter 1997 we started taking data with the telescopes pointing directly at the moon. A description of the telescopes and the performance of the detector are given.
The CLUE trigger: a VME based two level trigger for VHE experiments Alexandreas, D.; Bartoli, B.; Bastieri, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Volume:
409, Issue:
1-3
Journal Article
Peer reviewed
We describe a trigger architecture developed for shower selection in the CLUE Cherenkov telescopes. The selection is made first in each telescope of the array looking at the low resolution images ...produced by fast electronics, than requiring temporal coincidence between units. Big effort has been put to simplify the programming of trigger configurations to help the user to switch easily between different observational and calibration requests.
The MAGIC collaboration has recently reported the discovery of g-ray emission from the binary system LS I +61DG303 in the TeV energy region. Here we present new observational results on this source ...in the energy range between 300 GeV and 3 TeV. In total, 112 hr of data were taken between 2006 September and December covering four orbital cycles of this object. This large amount of data allowed us to produce an integral flux light curve covering for the first time all orbital phases of LS I +61DG303. In addition, we also obtained a differential energy spectrum for two orbital phase bins covering the phase range 0.5 < < 0.6 and 0.6 < < 0.7. The photon index in the two phase bins is consistent within the errors with an average index G = 2.6 - 0.2stat - 0.2sys. LS I +61DG303 was found to be variable at TeV energies on timescales of days. These new MAGIC measurements allowed us to search for intranight variability of the very high energy emission; however, no evidence for flux variability on timescales down to 30 min was found. To test for possible periodic structures in the light curve, we apply the formalism developed by Lomb and Scargle to the LS I +61DG303 data taken in 2005 and 2006. We found the LS I +61DG303 data set to be periodic with a period of (26.8 - 0.2) days (with a post-trial chance probability of 10-7), close to the orbital period.
We observed the first known very high energy (VHE) gamma -ray-emitting unidentified source, TeV J2032+4130, for 94 hr with the MAGIC telescope. The source was detected with a significance of 5.6 ...sigma . The flux, position, and angular extension are compatible with the previous ones measured by the HEGRA telescope system 5 years ago. The integral flux amounts to (4.5 plus or minus 0.3stat plus or minus 0.35 sub(sys)) x 10 super(-13) photons cm-2 5-1 above 1 TeV. The source energy spectrum, obtained with the lowest energy threshold to date, is compatible with a single power law with a hard photon index of Gamma = -2.0 plus or minus 0.3 sub(stat) plus or minus 0.2 sub(sys).
We observed the first known very high energy (VHE) g-ray-emitting unidentified source, TeV J2032+4130, for 94 hr with the MAGIC telescope. The source was detected with a significance of 5.6 s. The ...flux, position, and angular extension are compatible with the previous ones measured by the HEGRA telescope system 5 years ago. The integral flux amounts to (4.5 c 0.3stat c 0.35(sys)) x 10(-13) photons cm-2 5-1 above 1 TeV. The source energy spectrum, obtained with the lowest energy threshold to date, is compatible with a single power law with a hard photon index of G = -2.0 c 0.3(stat) c 0.2(sys).
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