The angular resolution of the GRAPES-3 array from the shadows of the Moon and the Sun

Cosmic ray antiprotons provide an important probe to study the cosmic ray propagation in the interstellar space and to investigate the existence of dark matter. Acting the Earth-Moon system as a magnetic spectrometer, paths of primary antiprotons are deflected in the opposite sense with respect to those of the protons in their way to the Earth. This effect allows, in principle, the search for antiparticles in the direction opposite to the observed deficit of cosmic rays due to the Moon (the so-called "Moon shadow''). The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., 606 g/cm(2)), is particularly effective in measuring the cosmic ray antimatter content via the observation of the cosmic rays shadowing effect due to: (1) good angular resolution, pointing accuracy and long-term stability; (2) low energy threshold; (3) real sensitivity to the geomagnetic field. Based on all the data recorded during the period from July 2006 through November 2009 and on a full Monte Carlo simulation, we searched for the existence of the shadow cast by antiprotons in the TeV energy region. No evidence of the existence of antiprotons is found in this energy region. Upper limits to the (p) over bar /p flux ratio are set to 5% at a median energy of 1.4 TeV and 6% at 5 TeV with a confidence level of 90%. In the TeV energy range these limits are the lowest available

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“…[37]. In the following years this effect has been confirmed by other EAS-arrays (CASA-MIA [38], HEGRA [39], GRAPES [40]). …”

Section: B the Moon Shadowing Effectmentioning

confidence: 65%

Measurement of the cosmic ray antiproton/proton flux ratio at TeV energies with the ARGO-YBJ detector

Bartoli¹,

Bernardini²,

Bi³

et al. 2012

Phys. Rev. D

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“…An important feature of the angular distribution of cosmic rays is the presence of a relative deficit in the flux of cosmic rays coming from the direction of the Moon. This effect, due to the absorption of cosmic rays by the Moon, was first predicted by Clark in 1957 [4], and its observation has been used by several experiments as a way of calibrating the angular resolution and the pointing accuracy of their particle detectors (see [5][6][7][8], or [9] for recent results. )…”

Section: Introductionmentioning

confidence: 99%

Observation of the cosmic-ray shadow of the Moon with IceCube

Aartsen¹,

Abbasi²,

Abdou³

et al. 2014

Phys. Rev. D

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We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector. The study of this "Moon shadow" is used to characterize the angular resolution and absolute pointing capabilities of the detector. The detection is based on data taken in two periods before the completion of the detector: between April 2008 and May 2009, when IceCube operated in a partial configuration with 40 detector strings deployed in the South Pole ice, and between May 2009 and May 2010 when the detector operated with 59 strings. Using two independent analysis methods, the Moon shadow has been observed to high significance (> 6 sigma) in both detector configurations. The observed location of the shadow center is within 0.2 degrees of its expected position when geomagnetic deflection effects are taken into account. This measurement validates the directional reconstruction capabilities of IceCube.Comment: Submitted to Physical Review

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“…The angular resolution of the GRAPES-3 EAS array was estimated by using three different methods, namely, the even-odd, the left-right as well as from the observation of the shadow of the Moon on the isotropic flux of the cosmic rays. The angular resolution was estimated to be 0.7 o for the showers of energy as low as 30 TeV [76].…”

Section: High Energy Astroparticle Physics At Ooty and The Grapes-3 Ementioning

confidence: 99%

High Energy Astroparticle Physics at Ooty and the GRAPES-3 Experiment

Gupta¹

2014

Proceedings of the Indian National Science Academy

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The astroparticle studies at Ooty have their roots going way back into the fifties, when studies using cosmic rays were initiated with cloud chambers of progressively larger sizes as the primary detector and measuring device to obtain properties of hadrons at high energies. This study was subsequently strengthened with the installation of a total absorption calorimeter and a modest extensive air shower array to probe the composition of the primary cosmic rays to very high energies. The discovery of pulsars provided a thrust for the exploration of these compact objects as the sources of γ-rays at TeV energies with the aid of atmospheric Cerenkov detectors in the seventies. With the rapid technological advances occurring during the subsequent years in detectors, electronics and computers, physicists world-wide were able to set up very large and remarkably sensitive experiments that were hard to imagine a decade earlier. With the increasing sophistication and complexity the modern experiments require participation of very large teams of scientists. This development has made the formation of collaboration of large number of physicists both experimental and theoretical, engineers, technicians etc., from a number of institutions and universities, a prerequisite for setting up any major experimental facility. The GRAPES-3 experiment is a collaboration of 34 scientists from 13 institutions, including 8 from India and 5 from Japan. The GRAPES-3 experiment contains a dense extensive air shower array operating with ~ 400 scintillator detectors and a 560 m 2 tracking muon detector (Em > 1 GeV), at Ooty in India. 25 % of scintillator detectors are instrumented with two fast photomultiplier tubes (PMTs) for extending the dynamic range to ~ 5x10 3 particles m -2. The scintillators, signal processing electronics and data recording systems were fabricated in-house to cut costs and optimize performance. The muon multiplicity distribution of the EAS is used to probe the composition of primary cosmic rays below the 'knee', with an overlap with direct measurements. Search for multi-TeV γ-rays from point sources is done with the aid of the muon detector. A good angular resolution of 0.7 o at 30 TeV, is measured from shadow of the Moon on the isotropic flux of cosmic rays. Sensitive limit on the diffuse flux of 100 TeV γ-rays is placed by using muon detector to filter out the charged cosmic ray background. The tracking muon detector allows sensitive measurements on the coronal mass ejections and solar flares through Forbush decrease events. We have major expansion plans to enhance the sensitivity of the GRAPES-3 experiment in the areas listed above. PACS

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The angular resolution of the GRAPES-3 array from the shadows of the Moon and the Sun

Cited by 19 publications

References 47 publications

Measurement of the cosmic ray antiproton/proton flux ratio at TeV energies with the ARGO-YBJ detector

Measurement of the cosmic ray antiproton/proton flux ratio at TeV energies with the ARGO-YBJ detector

Observation of the cosmic-ray shadow of the Moon with IceCube

High Energy Astroparticle Physics at Ooty and the GRAPES-3 Experiment

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