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The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known(More)
We report the results of the observation of the nearby satellite galaxy Segue 1 performed by the MAGIC-I ground-based gamma-ray telescope between November 2008 and March 2009 for a total of 43.2 hours. No significant gamma-ray emission was found above the background. Differential upper limits on the gamma-ray flux are derived assuming various power-law(More)
Geiger-mode Avalanche Photodiodes (GAPD) bear the potential to significantly improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are currently building the First G-APD Cherenkov Telescope (FACT) by refurbishing an old IACT with a mirror area of 9.5 square meters and construct a new, fine pixelized camera using novel G-APDs. The main goal(More)
Between 2004 and 2009 a sample of 28 X-ray selected highand intermediate-frequency peaked blazars with a X-ray flux larger than 2μJy at 1 keV in the redshift range from 0.018 to 0.361 was observed with the MAGIC telescope at energies above 100GeV. Seven among them were detected and the results of these observations are discussed elsewhere. Here we(More)
Within the FACT project, we construct a new type of camera based on Geiger-mode avalanche photodiodes (G-APDs). Compared to photomultipliers, G-APDs are more robust, need a lower operation voltage and have the potential of higher photon-detection efficiency and lower cost, but were never fully tested in the harsh environments of Cherenkov telescopes. The(More)
An annihilation signal of dark matter is searched for from the central region of the Milky Way. Data acquired in dedicated on-off observations of the Galactic center region with H.E.S.S. are analyzed for this purpose. No significant signal is found in a total of ∼9  h of on-off observations. Upper limits on the velocity averaged cross section, ⟨σv⟩, for the(More)
The acceleration of particles up to GeV or higher energies in microquasars has been the subject of considerable theoretical and observational efforts in the past few years. Sco X-1 is a microquasar from which evidence of highly energetic particles in the jet has been found when it is in the so-called Horizontal Branch (HB), a state when the radio and hard(More)
A. Abramowski, F. Acero, F. Aharonian, 4, 5 F. Ait Benkhali, A.G. Akhperjanian, 5 E. Angüner, G. Anton, S. Balenderan, A. Balzer, 11 A. Barnacka, Y. Becherini, 14, 15 J. Becker Tjus, K. Bernlöhr, 7 E. Birsin, E. Bissaldi, J. Biteau, C. Boisson, J. Bolmont, P. Bordas, J. Brucker, F. Brun, P. Brun, ∗ T. Bulik, S. Carrigan, S. Casanova, 3 M. Cerruti, 24 P.M.(More)
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