• GRAPES-3 (GammaRay Astronomy PeV EnergieS phase-3) experiment is designed to study cosmic rays with an array of air shower detectors and a large area muon detector. It aims to probe acceleration of cosmic rays.

The objectives are to study:

• The origin, acceleration and propagation of >10¹⁴eV cosmic rays in the galaxy and beyond.
• Existence of “Knee” in the energy spectrum of cosmic rays.
• Production and/or acceleration of highest energy (~10²⁰eV) cosmic rays in the universe.
• Astronomy of multi-TeV γ-rays from neutron stars and other compact object.
• Sun the closest astrophysical object, accelerator of energetic particles and its effects on the Earth.
• The GRAPES-3 experiment has been started as a collaboration of the Tata Institute of Fundamental Research, Mumbai, India and the Osaka City University, Osaka, Japan.Currently it is getting upgraded to accurately determine the time taken for the solar storm to travel to the earth.

Benefits of upgradation

• The upgraded detector will have an increased coverage of the sky and improved capacity to determine the direction of incident cosmic rays.
• The latter property, of being able to discern the direction of detected particles, makes it unique among cosmic ray detectors in the world; it can also to measure the intensity of the particles.
• Since the enhanced facility can cover a wider field of view (from present 37% to 57%), the chances of spotting solar storms will be higher.
• It is important to know the time when plasma will reach the earth, accurately, so that preventive and protective measures can be put into place in case solar storms were to strike the earth. If the earth’s magnetic field were to be weakened by extreme solar storms, charged particles would shower on to the planet.
• Apart from rendering electronic devices defunct, charged particles in an extreme solar storm can also short current carrying over-head high voltage lines, leading to large-scale transformers burn out and thereby, power blackouts.