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.
The Telescope Array (TA) observatory utilizes fluorescence detectors and surface detectors (SDs) to observe air showers produced by ultra high energy cosmic rays in Earth's atmosphere. Cosmic-ray ...events observed in this way are termed hybrid data. The depth of air shower maximum is related to the mass of the primary particle that generates the shower. This paper reports on shower maxima data collected over 8.5 yr using the Black Rock Mesa and Long Ridge fluorescence detectors in conjunction with the array of SDs. We compare the means and standard deviations of the observed X max distributions with Monte Carlo X max distributions of unmixed protons, helium, nitrogen, and iron, all generated using the QGSJet II-04 hadronic model. We also perform an unbinned maximum likelihood test of the observed data, which is subjected to variable systematic shifting of the data X max distributions to allow us to test the full distributions, and compare them to the Monte Carlo to see which elements are not compatible with the observed data. For all energy bins, QGSJet II-04 protons are found to be compatible with TA hybrid data at the 95% confidence level after some systematic X max shifting of the data. Three other QGSJet II-04 elements are found to be compatible using the same test procedure in an energy range limited to the highest energies where data statistics are sparse.
Plastic surgeons require experience in supermicroscopic vascular anastomosis. Herein, we report a simple, rapid, and cost-effective training method using chicken wings and colored water. The avian ...ventral metacarpal artery was selected for dissection and anastomosis to mimic supermicrosurgery. Over 14 weeks (one anastomosis per day), the ulnar artery in 100 chicken wings was exposed by dissection, cut proximally, and injected with blue food dye-colored water by an inexperienced surgeon. After ligating the artery branches, it was cut and subjected to end-to-end anastomosis. Next, colored water was injected into the ulnar artery to check for suture sufficiency. The vessel was re-dissected to inspect the lumen and sutures qualitatively. Of the 100 wings, the first and last 20 wings’ ventral metacarpal artery dissection, anastomosis times, and leakage frequency were compared. Avian ventral metacarpal artery diameter was recorded, and the cumulative anastomosis time where individual anastomosis times started decreasing was determined. Leakage rates before and after this point were compared. The avian ventral metacarpal artery diameter was 0.7–0.8 mm. The last 20 wings had significantly shorter median dissection times (12:27 vs. 17:45 min), anastomosis times (9:02 vs. 12:29 min), and leakage rates (15% vs. 70%); more even stitching and parallel ligature points; and less vessel layer inversion than the first 20 wings. After a cumulative anastomosis time of 10 h 26 min, individual times sharply decreased, and the leakage rate decreased significantly (58.3% vs. 23.8%). The proposed method significantly improved supermicrosurgical anastomosis. Thus, we believe that this method will help surgeons improve their supermicrosurgical skills.
The GRAPES-3 tracking muon telescope in Ooty, India measures muon intensity at high cutoff rigidities (15-24 GV) along nine independent directions covering 2.3 sr. The arrival of a coronal mass ...ejection on 22 June 2015 18:40 UT had triggered a severe G4-class geomagnetic storm (storm). Starting 19:00 UT, the GRAPES-3 muon telescope recorded a 2 h high-energy (∼20 GeV) burst of galactic cosmic rays (GCRs) that was strongly correlated with a 40 nT surge in the interplanetary magnetic field (IMF). Simulations have shown that a large (17×) compression of the IMF to 680 nT, followed by reconnection with the geomagnetic field (GMF) leading to lower cutoff rigidities could generate this burst. Here, 680 nT represents a short-term change in GMF around Earth, averaged over 7 times its volume. The GCRs, due to lowering of cutoff rigidities, were deflected from Earth's day side by ∼210° in longitude, offering a natural explanation of its night-time detection by the GRAPES-3. The simultaneous occurrence of the burst in all nine directions suggests its origin close to Earth. It also indicates a transient weakening of Earth's magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space.
Aims. A Forbush decrease (FD) is a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity. We seek to understand the relationship between the FDs and ...near-Earth interplanetary magnetic field (IMF) enhancements associated with solar coronal mass ejections (CMEs). Methods. We used muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We selected those FD events that have a reasonably clean profile, and magnitude >0.25%. We used IMF data from ACE/WIND spacecrafts. We looked for correlations between the FD profile and that of the one-hour averaged IMF. We wanted to find out whether if the diffusion of high-energy protons into the large scale magnetic field is the cause of the lag observed between the FD and the IMF. Results. The enhancement of the IMF associated with FDs occurs mainly in the shock-sheath region, and the turbulence level in the magnetic field is also enhanced in this region. The observed FD profiles look remarkably similar to the IMF enhancement profiles. The FDs typically lag behind the IMF enhancement by a few hours. The lag corresponds to the time taken by high-energy protons to diffuse into the magnetic field enhancement via cross-field diffusion. Conclusions. Our findings show that high-rigidity FDs associated with CMEs are caused primarily by the cumulative diffusion of protons across the magnetic field enhancement in the turbulent sheath region between the shock and the CME.
The GRAPES-3 extensive air shower (EAS) array has been designed to study cosmic rays from 10
13
–10
16
eV. It employs 400 scintillator detectors spread across 25,000 m
2
, mainly of cone-type and ...fiber-type, each covering a 1 m
2
area. These detectors record EAS particle densities and arrival times, which are crucial for determining primary particle energy and direction. A decade (2013–2022) of EAS data is analyzed to investigate the dependence of particle densities on ambient temperature and atmospheric pressure. Notably, ambient temperature exhibits a delayed response, with a more pronounced delay in fiber-type detectors, while cone-type detectors exhibit a higher observed temperature coefficient. In contrast, atmospheric pressure instantly and uniformly affects both detector types, with Monte Carlo simulations backing the observed pressure coefficient. These findings established a reliable pressure coefficient for EAS within this distinctive energy range and contributed to the refinement of correction algorithms, ultimately improving particle density precision for more accurate shower parameter estimates.
Aims. We seek to identify the primary agents causing Forbush decreases (FDs) in high-rigidity cosmic rays observed from the Earth. In particular, we ask if these FDs are caused mainly by coronal mass ...ejections (CMEs) from the Sun that are directed towards the Earth, or by their associated shocks. Methods. We used the muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We selected those FD events that have a reasonably clean profile, and can be reasonably well associated with an Earth-directed CME and its associated shock. We employed two models: one that considers the CME as the sole cause of the FD (the CME-only model) and one that considers the shock as the only agent causing the FD (the shock-only model). We used an extensive set of observationally determined parameters for both models. The only free parameter in these models is the level of MHD turbulence in the sheath region, which mediates cosmic ray diffusion (into the CME for the CME-only model, and across the shock sheath for the shock-only model). Results. We find that good fits to the GRAPES-3 multi-rigidity data using the CME-only model require turbulence levels in the CME sheath region that are only slightly higher than those estimated for the quiescent solar wind. On the other hand, reasonable model fits with the shock-only model require turbulence levels in the sheath region that are an order of magnitude higher than those in the quiet solar wind. Conclusions. This observation naturally leads to the conclusion that the Earth-directed CMEs are the primary contributors to FDs observed in high-rigidity cosmic rays.
The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies ...(SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9 yr period from 2008 May to 2017 May. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12 9 for the angular scale of the correlations. The energy threshold that we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1 and with the Auger result to within 1.4 , meaning that it is not capable to discriminate between these two hypotheses.
We present the measurement of the cosmic ray proton spectrum from 50 TeV to 1.3 PeV using 7.81×10^{6} extensive air shower events recorded by the ground-based GRAPES-3 experiment between 1 January ...2014 and 26 October 2015 with a live time of 460 day. Our measurements provide an overlap with direct observations by satellite and balloon-based experiments. The electromagnetic and muon components in the shower were measured by a dense array of plastic scintillator detectors and a tracking muon telescope, respectively. The relative composition of the proton primary from the air shower data containing all primary particles was extracted using the multiplicity distribution of muons which is a sensitive observable for mass composition. The observed proton spectrum suggests a spectral hardening at ∼166 TeV and disfavors a single power law description of the spectrum up to the Knee energy (∼3 PeV).
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 12h 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.
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