Search for emission of gamma-ray bursts with the ARGO-YBJ detector

The ARGO-YBJ experiment has been designed to decrease the energy threshold of tipical Extensive Air Shower arrays by exploiting the high altitude location (Tibet P.R. China, 4300 m a.s..l.) and the full coverage. The lower energy limit of the detector (a few GeV) is reached with the single particle technique, recording the counting rate at fixed time intervals. We present the first results concerning the search for emission from Gamma-Ray Bursts in coincidence with satellite detections

Status of the ARGO-YBJ experiment

The ARGO-YBJ experiment, under construction at the Yangbaijing Laboratory (P.R. China, 4300 m a.s.l.), is a full coverage detector of dimension 74£78 m2 made by a single layer of Resistive Plate Counters. About 10% of the final active area (» 700 m2) is in stable operation to check the detector performance and the reconstruction algorithms. In this paper the status of the experiment and the analysis of the first data are presented

First results on the angular resolution of the ARGO-YBJ detector

We present the first results on the angular resolution of the ARGO-YBJ detector in data taking at the Yangbajing Laboratory (Tibet, P.R. China, 4300 m a.s.l.)

Multiscale image analysis applied to gamma/h discrimination for VHE gamma-astronomy with ARGO-YBJ

Intrinsic differences in processes involved in the electromagnetic and hadronic shower development in the atmosphere have been avidenced by means of a careful analysis of the event image given by ARGO-YBJ detector

Very High Energy Gamma Ray Astronomy and Cosmic Ray Physics with the ARGO-YBJ experiment

Gamma ray astronomy at energies 1011 1013 eV, which are strictly related to the identication and study of the cosmic ray acceleration sites, is the main scientic goal of the ARGO-YBJ experiment. The detector, which is now being assembled in Tibet (China) at 4300 m a.s.l., is a full coverage Extensive Air Shower array consisting of a carpet of Resistive Plate Chambers covering a surface of about 7000 m2. The high altitude ( atmospheric depth 600 g/cm2 ) and the full coverage ensure a very low primary photon energy threshold at few hundreds GeV (close to the limits of the satellite technology), while the detector time resolution st 1ns gives a good pointing accuracy, thus allowing a high sensitivity to g -ray sources. Moreover the large eld of view and the high duty-cycle ensure the continuous monitoring of the sky in the declination band 20 d 80 . The detector layout, performance and location, offer a unique possibility to make also a deep study of several characteristics of the hadronic component of the cosmic ray ux up to energies of hundreds of TeV. In particular, the structure of the shower core, the lateral distribution, the energy spectra and the angular (e.g. anisotropies) and time (e.g. solar ares) ux modulations can be measured with high sensitivity. Moreover, the use of a full coverage detector with a high space granularity gives detailed images of the shower front, that can be used to test different hypotheses on the cosmic ray interactions, the shower development in the atmosphere and particle physics at very high energies. In this work the general layout of the detector and its performance will be described, together with some of the rst results coming from the data analysis of a relevant fraction of the apparatus that is already operating

Search for WH production with a light Higgs boson decaying to prompt electron-jets in proton-proton collisions at s\sqrt{s}=7 TeV with the ATLAS detector

A search is performed for WH production with a light Higgs boson decaying to hidden-sector particles resulting in clusters of collimated electrons, known as electron-jets. The search is performed with 2.04 fb-1 of data collected in 2011 with the ATLAS detector at the LHC in proton-proton collisions at $\sqrt{s}$=7 TeV. One event satisfying the signal selection criteria is observed, which is consistent with the expected background rate. Limits on the product of the WH production cross section and the branching ratio of a Higgs boson decaying to prompt electron-jets are calculated as a function of a Higgs boson mass in the range from 100 GeV to 140 GeV.Peer Reviewe

Measurement of the isolated diphoton cross-section in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The ATLAS experiment has measured the production cross-section of events with two isolated photons in the final state, in proton-proton collisions at sqrt(s) = 7 TeV. The full data set acquired in 2010 is used, corresponding to an integrated luminosity of 37 pb^-1. The background, consisting of hadronic jets and isolated electrons, is estimated with fully data-driven techniques and subtracted. The differential cross-sections, as functions of the di-photon mass, total transverse momentum and azimuthal separation, are presented and compared to the predictions of next-to-leading-order QCD.Comment: 15 pages plus author list (27 pages total), 9 figures, 2 tables, final version to appear in Physical Review