8 results on '"Rakshe, P. S."'
Search Results
2. Simulation of atmospheric pressure dependence on GRAPES-3 particle density
- Author
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Zuberi, M., Ahmad, S., Chakraborty, M., Chandra, A., Dugad, S. R., Gupta, S. K., Hariharan, B., Hayashi, Y., Jagadeesan, P., Jain, A., Jain, P., Jhansi, V. B., Kawakami, S., Mahapatra, S., Mohanty, P. K., Morris, S. D., Nayak, P. K., Oshima, A., Pattanaik, D., Rakshe, P. S., Ramesh, K., Rao, B. S., Reddy, L. V., and Varsi, F.
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- 2020
- Full Text
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3. The angular resolution of GRAPES-3 EAS array after correction for the shower front curvature
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Jhansi, V. B., Ahmad, S., Chakraborty, M., Dugad, S. R., Gupta, S. K., Hariharan, B., Hayashi, Y., Jagadeesan, P., Jain, A., Jain, P., Kawakami, S., Kojima, H., Mahapatra, S., Mohanty, P. K., Morris, S. D., Nayak, P. K., Oshima, A., Pattanaik, D., Rakshe, P. S., Ramesh, K., Rao, B. S., Reddy, L. V., Shibata, S., Varsi, F., and Zuberi, M.
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Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics - Instrumentation and Methods for Astrophysics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) - Abstract
The angular resolution of an extensive air shower (EAS) array plays a critical role in determining its sensitivity for the detection of point $��$-ray sources in the multi-TeV energy range. The GRAPES-3 an EAS array located at Ooty in India (11.4$^{\circ}$N, 76.7$^{\circ}$E, 2200 m altitude) is designed to study $��$-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$^{\prime}$ for energies E$>$5 TeV and improves to 17$^{\prime}$ at E$>$100 TeV and finally approaching 10$^{\prime}$ at E$>$500 TeV.
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- 2019
4. Was the cosmic ray burst detected by the GRAPES-3 on 22 June 2015 caused by transient weakening of geomagnetic field or by an interplanetary anisotropy?
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Mohanty, P. K., Arunbabu, K. P., Aziz, T., Dugad, S. R., Gupta, S. K., Hariharan, B., Jagadeesan, P., Jain, A., Morris, S. D., Nayak, P. K., Rakshe, P. S., Ramesh, K., Rao, B. S., Zuberi, M., Hayashi, Y., Kawakami, S., Subramanian, P., Raha, S., Ahmad, S., Oshima, A., Shibata, S., and Kojima, H.
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Astrophysics::High Energy Astrophysical Phenomena ,Physics::Space Physics ,FOS: Physical sciences ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The GRAPES-3 muon telescope in Ooty, India had claimed detection of a 2 hour (h) high-energy ($\sim$20 GeV) burst of galactic cosmic-rays (GCRs) through a $>$50$\sigma$ surge in GeV muons, was caused by reconnection of the interplanetary magnetic field (IMF) in the magnetosphere that led to transient weakening of Earth's magnetic shield. This burst had occurred during a G4-class geomagnetic storm (storm) with a delay of $\frac{1}{2}$h relative to the coronal mass ejection (CME) of 22 June 2015 (Mohanty et al., 2016). However, recently a group interpreted the occurrence of the same burst in a subset of 31 neutron monitors (NMs) to have been the result of an anisotropy in interplanetary space (Evenson et al., 2017) in contrast to the claim in (Mohanty et al., 2016). A new analysis of the GRAPES-3 data with a fine 10.6$^{\circ}$ angular segmentation shows the speculation of interplanetary anisotropy to be incorrect, and offers a possible explanation of the NM observations. The observed 28 minutes (min) delay of the burst relative to the CME can be explained by the movement of the reconnection front from the bow shock to the surface of Earth at an average speed of 35 km/s, much lower than the CME speed of 700 km/s. This measurement may provide a more accurate estimate of the start of the storm., Comment: Accepted for Publication in Physical Review D
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- 2018
5. Multi-channel programmable power supply with temperature compensation for silicon sensors.
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Shukla, R. A., Achanta, V. G., Dugad, S. R., Freeman, J., Garde, C. S., Gupta, S. K., Khandekar, P. D., Kurup, A. M., Lokhandwala, S. S., Los, S., Prabhu, S. S., and Rakshe, P. S.
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ENERGY research ,POWER resources ,PHOTOMULTIPLIERS ,PHOTODETECTORS ,PHOTODIODES - Abstract
Silicon Photo-Multipliers (SiPMs) are increasingly becoming popular for discrete photon counting applications due to the wealth of advantages they offer over conventional photo-detectors such as photo-multiplier tubes and hybrid photo-diodes. SiPMs are used in variety of applications ranging from high energy physics and nuclear physics experiments to medical diagnostics. The gain of a SiPM is directly proportional to the difference between applied and breakdown voltage of the device. However, the breakdown voltage depends critically on the ambient temperature and has a large temperature co-efficient in the range of 40-60 mV/°C resulting in a typical gain variation of 3%-5%/°C [Dinu et al., in IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE, 2010), p. 215]. We plan to use the SiPM as a replacement for PMT in the cosmic ray experiment (GRAPES-3) at Ooty [Gupta et al. Nucl. Instrum. Methods Phys. Res., Sect. A 540, 311 (2005)]. There the SiPMs will be operated in an outdoor environment subjected to temperature variation of about 15 °C over a day. A gain variation of more than 50% was observed for such large variations in the temperature. To stabilize the gain of the SiPM under such operating conditions, a low-cost, multi-channel programmable power supply (0-90 V) was designed that simultaneously provides the bias voltage to 16 SiPMs. The programmable power supply (PPS) was designed to automatically adjust the operating voltage for each channel with a built-in closed loop temperature feedback mechanism. The PPS provides bias voltage with a precision of 6 mV and measures the load current with a precision of 1 nA. Using this PPS, a gain stability of 0.5% for SiPM (Hamamatsu, S10931-050P) has been demonstrated over a wide temperature range of 15 °C. The design methodology of the PPS system, its validation, and the results of the tests carried out on the SiPM is presented in this article. The proposed design also has the capability of gain stabilization of devices with non-linear thermal response. [ABSTRACT FROM AUTHOR]
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- 2016
- Full Text
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6. Measurement of the radial diffusion coefficient of galactic cosmic rays near the Earth by the GRAPES-3 experiment.
- Author
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Kojima, H., Arunbabu, K. P., Dugad, S. R., Gupta, S. K., Hariharan, B., Jagadeesan, P., Jain, A., Mohanty, P. K., Rakshe, P. S., Ramesh, K., Rao, B. S., Hayashi, Y., Kawakami, S., Nonaka, T., Oshima, A., Shibata, S., Tanaka, K., and Tokumaru, M.
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DIFFUSION coefficients , *GALACTIC cosmic rays , *SOLAR wind - Abstract
The flux of galactic cosmic rays (GCRs) is isotropic in the interstellar space. However, in the heliosphere, the ram pressure of outward-moving solar wind convects the GCRs away from the Sun, thereby producing a density gradient in the radial direction. The diffusion of GCRs due to this gradient and scattering with the irregularities in the interplanetary magnetic field (IMF) induce variations in their flux that can be observed near the Earth. A framework for the diffusion-convection mechanism of GCR propagation developed by Parker and collaborators [Phys. Rev. 110, 1445 (1958); Planet. Space Sci. 13, 9 (1965); Astrophys. J. 772, 46 (2013); Space Sci. Rev. 78, 401 (1996); Astrophys. J. 234, 746 (1979); Astrophys. J. 361, 162 (1990); Space Sci. Rev. 176, 299 (2013)] offers a good description of this phenomenon. One of the outcomes of this framework is an anticorrelation of the variation in solar wind velocity (VSW) and the GCR flux. A second outcome of this gradient in the presence of IMF is the movement of GCRs perpendicular to the ecliptic plane called "Swinson flow." Therefore, (i) the correlated variations of VSW and GCR flux and (ii) the GCR radial density gradient obtained from Swinson flow can each be used to independently measure the radial diffusion coefficient of GCRs in the inner heliosphere. In an earlier work [Phys. Rev. D 91, 121303(R) (2015)], the GCR flux was shown to be anticorrelated with VSW at (-1.33±0.07)×10-3%(km s-1)-1. This anticorrelation yields a radial diffusion coefficient κ=0.97×1019 m² s-1 at 1 AU. In another work [Astropart. Phys. 62, 21 (2015)], the measurement of Swinson flow was used to obtain a GCR radial density gradient of 0.65 AU-1 at a median rigidity of 77 GV. Here, we report a measurement of radial diffusion coefficient κ=1.04×1019 m² s-1 at 1 AU from the above-mentioned density gradient, for a mean VSW of 450 km s-1. Thus, these two distinct approaches essentially yielded similar values of the radial diffusion coefficient κ=1019 m² s-1 at 1 AU, characterizing the diffusion of GCRs at 77 GV. From this value of κ, the mean free path length for parallel diffusion λ∥ was estimated to be 1.2 AU at 77 GV, consistent with earlier reports [Rev. Geophys. Space Phys. 20, 335 (1982); Astrophys. J. 420, 294 (1994); Astrophys. J. 604, 861 (2004)]. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
7. Was the cosmic ray burst detected by the GRAPES-3 muon telescope on 22 June 2015 caused by a transient weakening of the geomagnetic field or by an interplanetary anisotropy?
- Author
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Mohanty, P. K., Arunbabu, K. P., Aziz, T., Dugad, S. R., Gupta, S. K., Hariharan, B., Jagadeesan, P., Jain, A., Morris, S. D., Nayak, P. K., Rakshe, P. S., Ramesh, K., Rao, B. S., Zuberi, M., Hayashi, Y., Kawakami, S., Subramanian, P., Raha, S., Ahmad, S., and Oshima, A.
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COSMIC ray muons , *GALACTIC cosmic rays , *TELESCOPES - Abstract
The GRAPES-3 muon telescope in Ooty, India had claimed detection of a 2 hour (h) high-energy (∼20 GeV) burst of galactic cosmic-rays (GCRs) through a >50σ surge in GeV muons, was caused by reconnection of the interplanetary magnetic field (IMF) in the magnetosphere that led to transient weakening of Earth's magnetic shield. This burst had occurred during a G4-class geomagnetic storm (storm) with a delay of 1/2h relative to the coronal mass ejection (CME) of 22 June 2015 [P. K. Mohanty et al., Phys. Rev. Lett. 117, 171101 (2016)]. However, recently a group interpreted the occurrence of the same burst in a subset of 31 neutron monitors (NMs) to have been the result of an anisotropy in interplanetary space [P. Evenson et al., Proc. Sci., ICRC2017 (2017) 133] in contrast to the claim in P. K. Mohanty et al., [Phys. Rev. Lett. 117, 171101 (2016)]. A new analysis of the GRAPES-3 data with a fine 10.6° angular segmentation shows the speculation of interplanetary anisotropy to be incorrect, and offers a possible explanation of the NM observations. The observed 28 minutes (min) delay of the burst relative to the CME can be explained by the movement of the reconnection front from the bow shock to the surface of Earth at an average speed of 35 km/s, much lower than the CME speed of 700 km/s. This measurement may provide a more accurate estimate of the start of the storm. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
8. Measurement of the Electrical Properties of a Thundercloud Through Muon Imaging by the GRAPES-3 Experiment.
- Author
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Hariharan B, Chandra A, Dugad SR, Gupta SK, Jagadeesan P, Jain A, Mohanty PK, Morris SD, Nayak PK, Rakshe PS, Ramesh K, Rao BS, Reddy LV, Zuberi M, Hayashi Y, Kawakami S, Ahmad S, Kojima H, Oshima A, Shibata S, Muraki Y, and Tanaka K
- Abstract
The GRAPES-3 muon telescope located in Ooty, India records rapid (∼10 min) variations in the muon intensity during major thunderstorms. Out of a total of 184 thunderstorms recorded during the interval of April 2011-December 2014, the one on December 1, 2014 produced a massive potential of 1.3 GV. The electric field measured by four well-separated (up to 6 km) monitors on the ground was used to help estimate some of the properties of this thundercloud, including its altitude and area that were found to be 11.4 km above mean sea level and ≥380 km^{2}, respectively. A charging time of 6 min to reach 1.3 GV implied the delivery of a power of ≥2 GW by this thundercloud that was moving at a speed of ∼60 km h^{-1}. This work possibly provides the first direct evidence for the generation of gigavolt potentials in thunderclouds that could also possibly explain the production of highest-energy (100 MeV) gamma rays in the terrestrial gamma-ray flashes.
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- 2019
- Full Text
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