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Update on the angular resolution of GRAPES-3 experiment based on Moon shadow analysis
by D. Pattanaik, S. Ahmad, M. Chakraborty, S. R. Dugad, U. D. Goswami, S. K. Gupta, B. Hariharan, Y. Hayashi, P. Jagadeesan, A. Jain, P. Jain, S. Kawakami, H. Kojima, S. Mahapatra, P. K. Mohanty, R. Moharana, Y. Muraki, P. K. Nayak, T. Nonaka, A. Oshima, B. P. Pant, M. Rameez, K. Ramesh, L. V. Reddy, S. Shibata, F. Varsi, M. Zuberi
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Submission summary
| Authors (as registered SciPost users): | Diptiranjan Pattanaik · Fahim Varsi |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202209_00002v1 (pdf) |
| Date submitted: | 2022-09-01 13:30 |
| Submitted by: | Pattanaik, Diptiranjan |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 21st International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI2022) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Experimental |
Abstract
Moon creates a shadow in the isotropic cosmic ray flux by blocking them in its direction. The Moon shadow method is used to calibrate the angular resolution and pointing accuracy of air shower arrays. The GRAPES-3 is an extensive air shower array located at Ooty (11.6$^\circ$ N, 76.7$^\circ$ E, 2200 m a.s.l.) in southern India. The angular resolution of the GRAPES-3 array was improved by correcting the shower front curvature based on the shower size and age. Here, we present the results of the angular resolution and pointing accuracy of the array through observation of the Moon shadow. We have analyzed the data for the period of 2014-2016 containing $\sim$3×10$^9$ air shower events with a median energy of 15 TeV. A significant improvement in the angular resolution has been observed compared to the earlier analysis by the group through the Moon shadow method and is comparable to the arrays located at a 2 km higher altitude than the GRAPES-3 experiment.
Current status:
Reports on this Submission
Strengths
The paper shows that the angular resolution can be improved by incorporating more information in the shower reconstruction algorithm.
Weaknesses
The Grammar has quite a few errors, and some explanations are lacking (e.g. left-right method in fig. 3).
Report
In general, it is nice to see the impact of an improvement to the directional reconstruction directly in the moon shadow. This is a fitting topic for a proceeding.
Requested changes
General:
What is the difference between angular resolution and pointing accuracy? This should explained shortly in the introduction, or at the latest in the analysis method section. Currently, there is only a small description in the results section of pointing.
Abstract:
I would leave out the first two sentences.
The angular resolution of the GRAPES-3 array was ... -> Recently, the angular resolution of the GRAPES-3 array has been ..
Introduction:
is tiny -> is small
large cosmic ray -> cosmic-ray
This makes the detection ... -> This generally makes the detection
However, with an excellent ... Sentence sounds wrong here, it should be changed to say something like : However, improvements of the angular resolution can help to distinguish between cosmic rays and gamma rays.
of Pevatron -> of a Pevatron
by detecting the gamma rays -> by detecting gamma rays
The recent result from the GRAPES-3 -> A recent result ...
However, the absolute angular resolution can be determined -> The absolute angular resolution ... (Why "However" here?)
The GRAPES-3 experiment
The GRAPES-3 -> GRAPES-3
Recently the commerically -> Recently, the commercially
the shower arrival time could now be ... -> the shower arrival time can be
Analysis method:
.. imposed on shower age ... What is the definition of "shower age" ?
Fake-Moon -> fake-Moon
were kept the same as Moon -> werre kept the same as the moon
eq 1) Why is the angular moon diameter in the formula and not pi ? Is this explained in ref (9) ? I could not access that reference unfortunately.
Results:
What are "integral energies"?
Fig. 3:
What is the difference between left-right vs the other method? I cannot find a description in the text.
Conclusion:
It should be mentioned, that the angular resolution is improved compared to an older reconstruction that does not take into account shower front curvature corrections.
Hence the GRAPES-3 experiment is
suitable for detecting the multi-TeV .. -> Hence the GRAPES-3 experiment is
suitable for detecting multi-TeV ..