GRAPES-3: A cosmic-ray tracker, Pg2

Key Highlights:

• The GRAPES-3 telescope in Ooty, Tamil Nadu, was used by researchers from India and Japan to study the impact of Earth's upper atmosphere temperature and the Sun's magnetic field on muons.
• By analyzing 22 years of data, the team developed a highly accurate method for real-time monitoring of changes in the upper atmosphere.
• The findings are scheduled for publication in the August issue of Astroparticle Physics.

Detailed Insights:

• The GRAPES-3 experiment, which stands for Gamma Ray Astronomy PeV EnergieS phase-3, is operated by the Tata Institute of Fundamental Research (TIFR), Mumbai, in collaboration with several Japanese universities.
• Located at an altitude of 2200 meters in Ooty, India, its near-equatorial placement offers a unique advantage for comprehensive measurements.
• Unlike traditional telescopes, GRAPES-3 functions as a muon detector, utilizing 16 modules, each containing 232 proportional counters. [Article, 25]
• Muons are subatomic particles formed when high-energy cosmic rays from deep space collide with Earth's upper atmosphere. [Article, 9, 13, 15]
• The detector's design, with four layers of tubes separated by reinforced concrete, enables precise tracking of the path and angle of these high-energy particles. [Article]
• Monitoring the upper atmosphere is critical due to its influence on satellite-based technologies like global navigation systems and high-frequency radio communication.
• Changes in the Sun's magnetic field and overall solar activity significantly affect the Earth's upper atmosphere, impacting space weather and potentially causing geomagnetic storms.

Scientific/Technical Concepts Involved:

• Muons: Unstable subatomic particles, heavier than electrons, produced by cosmic ray interactions in the atmosphere, known for their penetrating power.
• Cosmic Rays: High-energy particles, primarily atomic nuclei, originating from various astrophysical sources, that continuously bombard Earth's atmosphere.
• Proportional Counters: Gas-filled detectors that measure ionizing radiation by generating an electrical pulse whose strength is proportional to the energy deposited.
• Astroparticle Physics: An interdisciplinary field that investigates elementary particles of astronomical origin and their connections to astrophysics and cosmology.