Researchers at the Tata Institute of Fundamental Research in Ooty, India, have made a groundbreaking discovery in the cosmic-ray proton spectrum, uncovering a new feature at approximately 166 tera-electron-volt (TeV) energy. This finding challenges our current understanding of cosmic-ray sources, acceleration mechanisms, and their propagation within our galaxy, potentially leading to a re-evaluation of existing theories.
Cosmic rays, the most energetic particles in the universe, have been bombarding Earth from outer space for over a century. These particles, which include electrons, photons, muons, protons, and neutrons, enter the Earth’s atmosphere and induce a shower of particles that travel to the ground at nearly the speed of light.
Observed over a wide energy range, from 108 to 1020 eV, cosmic rays exhibit a steep decrease in flux with increasing energy, following a power law distribution.
The “Knee,” a kink in the cosmic-ray proton spectrum at about 3 PeV, has long been considered the maximum energy for cosmic-ray acceleration within Galactic sources. However, the recent discovery by the GRAPES-3 experiment reveals a new feature above 100 TeV and below the Knee, challenging previous models and theories.
By utilizing a dense array of plastic scintillator detectors and a large-area muon detector, the researchers were able to collect data with a collection area thousands of times larger than space-based detectors, providing a more detailed examination of cosmic rays above 100 TeV, where space-based measurements lack precision due to low statistics.
2024-02-04 02:00:04
Original from phys.org