17 research outputs found
The cosmic ray proton plus helium energy spectrum measured by the ARGO-YBJ experiment in the energy range 3-300 TeV
The ARGO-YBJ experiment is a full-coverage air shower detector located at the
Yangbajing Cosmic Ray Observatory (Tibet, People's Republic of China, 4300 m
a.s.l.). The high altitude, combined with the full-coverage technique, allows
the detection of extensive air showers in a wide energy range and offer the
possibility of measuring the cosmic ray proton plus helium spectrum down to the
TeV region, where direct balloon/space-borne measurements are available. The
detector has been in stable data taking in its full configuration from November
2007 to February 2013. In this paper the measurement of the cosmic ray proton
plus helium energy spectrum is presented in the region 3-300 TeV by analyzing
the full collected data sample. The resulting spectral index is . These results demonstrate the possibility of performing an accurate
measurement of the spectrum of light elements with a ground based air shower
detector.Comment: 18 pages, 8 figures, preprint submitted to Phys. Rev.
High Altitude test of RPCs for the ARGO-YBJ experiment
A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory
(Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive
Air Showers was studied. Efficiency and time resolution measurements at the
pressure and temperature conditions typical of high mountain laboratories, are
reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
Observation of TeV gamma-rays from the unidentified source HESS J1841-055 with the ARGO-YBJ experiment
We report the observation of a very high energy \gamma-ray source, whose
position is coincident with HESS J1841-055. This source has been observed for
4.5 years by the ARGO-YBJ experiment from November 2007 to July 2012. Its
emission is detected with a statistical significance of 5.3 standard
deviations. Parameterizing the source shape with a two-dimensional Gaussian
function we estimate an extension \sigma=(0.40(+0.32,-0.22}) degree, consistent
with the HESS measurement. The observed energy spectrum is dN/dE =(9.0-+1.6) x
10^{-13}(E/5 TeV)^{-2.32-+0.23} photons cm^{-2} s^{-1} TeV^{-1}, in the energy
range 0.9-50 TeV. The integral \gamma-ray flux above 1 TeV is 1.3-+0.4 Crab
units, which is 3.2-+1.0 times the flux derived by HESS. The differences in the
flux determination between HESS and ARGO-YBJ, and possible counterparts at
other wavelengths are discussed.Comment: 17 pages, 4 figures, have been accepted for publication in Ap
TeV GAMMA-RAY SURVEY OF THE NORTHERN SKY USING THE ARGO-YBJ DETECTOR
The Astrophysical Radiation with Ground-based Observatory at Yang Ba Jing (ARGO-YBJ) detector is an extensive air shower array that has been used to monitor the northern Îł-ray sky at energies above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from â10⊠to 70âŠ, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to âŒ1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than five standard deviations. Several excesses are also reported as potential Îł-ray emitters. The features of each source are presented and discussed. Additionally, 95% confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV Îł-ray active galactic nuclei inside the ARGO-YBJ field of view are reported. The effect of the absorption of Îł-rays due to the interaction with extragalactic background light is estimated
Results from the analysis of data collected with 50 m2 RPC carpet at Yangbajing
An RPC carpet covering&104m2 (ARGO-YBJ experiment) will be installed in the YangBaJing Laboratory (Tibet,
People's Republic of China) at an altitude of 4300 m a.s.l. A test-module of&50m2 has been put in operation in this laboratory and about 106 air shower events have been collected. The RPC performance at high altitude and the carpet
capability of reconstructing the shower features are presented. ( 2000 Elsevier Science B.V. All rights reserved
Performance of RPC for the ARGO-YBJ detector operated at the Yangbajing Laboratory
Bakelite RPCs, assembled according to the ARGO design, have been operated in the high altitude Laboratory of
YBJ using dedicated electronics to pick-up the streamer signal. Here we report on the results concerning absorbed current, single counting rate, efficiency and time resolution. Environmental data concerning the operating temperature
inside the ARGO experimental hall are also reported
Radon contribution to single particle counts of the ARGO-YBJ detector
The ARGO-YBJ experiment is an air shower detector for gamma ray astronomy and cosmic ray studies
with an energy threshold of ~500 GeV. Working in âsingle particle modeâ, i.e. counting the single particles
hitting the detector at fixed time intervals, ARGO-YBJ can monitor cosmic ray and gamma ray
transients at energies of a few GeV.
The single particle counting rate is modulated by the atmospheric pressure and temperature, and is
affected by the local radioactivity from soil and air. Among the radioactive elements, radon gas is of
particular importance since its concentration in air can vary significantly, according to environmental
conditions. In this paper we evaluate the contribution of the radon daughter gamma ray emitters to the
single particle counting rate measured by ARGO-YBJ. According to our analysis, the radon gas contribution
is roughly 1e2%, producing a counting rate modulation of the same order of magnitude of the
atmospheric effects
Operation and performance of RPCs in the ARGO-YBJ experiment
The ARGO-YBJ array for EAS detection at high altitude (4300m a.s.l.) is the largest RPC-based detector in
operation at present (active area of 6700m2 out of a total instrumented surface of about 104m2). The
constant monitoring of the main operational and environmental parameters is essential for both
keeping the detector status under control and understanding the detector behaviour more deeply.
Exploiting the information provided by the ARGO-YBJ Detector Control System, the present status of the
detector is described and some correlations between the environmental and the operational parameters
of the ARGO-YBJ RPCs are shown. This study was performed using the monitored data from the
complete ARGO-YBJ array which has been in operation since October 2007. Preliminary results on the
observations of the Moon shadow and of g-ray point sources are also presented
Search for gamma ray bursts with the ARGO-YBJ detector in scaler mode
The ARGO-YBJ experiment has been designed to decrease the energy threshold of typical Extensive Air Shower arrays by exploiting
the high altitude and the full coverage, consisting of a 6700m2 carpet of Resistive Plate Chambers located at Yangbajing (Tibet, PR
China, 4300m a.s.l.). The lower energy limit of the detector (1 GeV) is reached with the ââScaler Modeââ, recording the counting rate at
fixed time intervals. Here we present results concerning the search for emission from Gamma Ray Bursts (GRBs) in coincidence with
satellite detections