Angular resolution of the KGF experiment to detect ultra high energy gamma-ray sources

Acharya, B. S.; Bhat, P. N.; John, A.; Khairatkar, S. G.; Nagesh, B. K.; Rajeev, M. R.; Rao, K.S.; Rao, M. V. S.; Reddy, Α. V. R.; Sinha, S.; Sivaprasad, K.; Stanislaus, A. J.; Venkateshmurthy, B.L.; Vishwanath, P. R.; Viswanathan, K. S.; Unnikrishnan, P.; Upadhya, S. S.

doi:10.1088/0954-3899/19/7/016

Cited by 10 publications

(18 citation statements)

References 3 publications

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“…In the HAGAR array, arrival direction of the shower is estimated using the plane front approximation [Acharya et al 1993]. The arrival direction of the Cherenkov shower can be estimated by minimization of χ 2…”

Section: Data Reductionmentioning

confidence: 99%

VHE gamma-ray observation of Crab Nebula with HAGAR telescope array

et al. 2019

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HAGAR is a system of seven Non-imaging Atmospheric Cherenkov Telescopes located at Hanle in the Ladakh region of the Indian Himalayas at an altitude of 4270 meters amsl. Since 2008, we have observed the Crab Nebula to assess the performance of the HAGAR telescopes. We describe the analysis technique for the estimation of γ-ray signal amidst cosmic ray background. The consolidated results spanning nine years of the Crab nebula observations show long term performance of the HAGAR telescopes. Based on about 219 hours of data, we report the detection of γ-rays from the Crab Nebula at a significance level of about 20σ, corresponding to a time averaged flux of (1.64±0.09) ×10 −10 photons cm −2 sec −1 above 230 GeV. Also, we perform a -75013 2 B.B. Singh et al.detailed study of possible systematic effects in our analysis method on data taken with the HAGAR telescopes.

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Section: Data Reductionmentioning

confidence: 99%

VHE gamma-ray observation of Crab Nebula with HAGAR telescope array

et al. 2019

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“…While the size is proportional to energy of the PCR, the age characterizes the stage of the shower development. In recent past some attempts were made to study the relationship of the shower front curvature on shower size [16,18,19,20]. However, the work presented here is possibly the first systematic investigation of the dependence of shower front curvature on both the shower size and age.…”

Section: Introductionmentioning

confidence: 96%

“…The curved shower front is adequately described by a cone centred on the shower axis for distances up to 100-200 m [16,17]. By implementing curvature correction an angular resolution of 1.1 • at 150 TeV was reported for the KGF EAS array [16].…”

Section: Introductionmentioning

confidence: 99%

“…A discussion of the origin of shower front curvature and finite disc structure can be found in a monograph by Grieder [15]. The curved shower front is adequately described by a cone centred on the shower axis for distances up to 100-200 m [16,17]. By implementing curvature correction an angular resolution of 1.1 • at 150 TeV was reported for the KGF EAS array [16].…”

Section: Introductionmentioning

confidence: 99%

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The angular resolution of GRAPES-3 EAS array after correction for the shower front curvature

Jhansi,

Ahmad,

Chakraborty

et al. 2019

Preprint

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The angular resolution of an extensive air shower (EAS) array plays a critical role in determining its sensitivity for the detection of point γ-ray sources in the multi-TeV energy range. The GRAPES-3 an EAS array located at Ooty in India (11.4 • N, 76.7 • E, 2200 m altitude) is designed to study γ-rays in the TeV-PeV energy range. It comprises of a dense array of 400 plastic scintillators deployed over an area of 25000 m 2 and a large area (560 m 2 ) muon telescope. A new statistical method allowed real time determination of the propagation delay of each detector in the GRAPES-3 array. The shape of shower front is known to be curved and here the details of a new method developed for accurate measurement of the shower front curvature is presented. These two developments have led to a sizable improvement in the angular resolution of GRAPES-3 array. It is shown that the curvature depends on the size and age of an EAS. By employing two different techniques, namely, the odd-even and the left-right methods, independent estimates of the angular resolution are obtained. The odd-even method estimates the best achievable resolution of the array. For obtaining the angular resolution, the left-right method is used after implementing the size and age dependent curvature corrections. A comparison of the angular resolution as a function of EAS energy by these two methods shows them be virtually indistinguishable. The angular resolution of GRAPES-3 array is 47 ′ for energies E>5 TeV and improves to 17 ′ at E>100 TeV and finally approaching 10 ′ at E>500 TeV.

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“…Another possible treatment is to take the cone slope a function of EAS' other properties (e.g. a function of zenith angle [6]). In these circumstances, at first, the EAS' parameters should be found with an initial crude estimation (e.g.…”

Section: Introductionmentioning

confidence: 99%

A new model-independent approach for finding the arrival direction of an extensive air shower

2016

J. Cosmol. Astropart. Phys.

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Abstract.A new accurate method for reconstructing the arrival direction of an extensive air shower (EAS) is described. Compared to existing methods, it is not subject to minimization of a function and, therefore, is fast and stable. This method also does not need to know detailed curvature or thickness structure of an EAS. It can have angular resolution of about 1 degree for a typical surface array in central regions. Also, it has better angular resolution than other methods in the marginal area of arrays.

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Angular resolution of the KGF experiment to detect ultra high energy gamma-ray sources

Cited by 10 publications

References 3 publications

VHE gamma-ray observation of Crab Nebula with HAGAR telescope array

VHE gamma-ray observation of Crab Nebula with HAGAR telescope array

The angular resolution of GRAPES-3 EAS array after correction for the shower front curvature

A new model-independent approach for finding the arrival direction of an extensive air shower

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