Quest to gauge neutrino mass
doi:10.1038/nindia.2008.267 Published online 31 August 2008
New research at the Neutrino Observatory (INO) in the Nilgiri mountains of South India might provide clues to masses of three types of neutrinos1. INO's magnetized iron calorimeter detector (ICAL) will detect signals from incoming streams of neutrinos spawned at CERN, Geneva. This experiment will demystify secrets such as neutrino burst in supernova explosions and dark matter.
There are three types of neutrinos — electrons, muons and tau neutrinos. Each neutrino has antiparticles called anti-neutrino. Recent research has shown that neutrino has mass. But the exact masses of the three types of neutrinos and details of how they mix with each other remain largely unexplored. To know these aspects, researchers have planned an ambitious project that will build an experimental set-up between CERN and INO.
At CERN, accelerated protons hit a target to produce radioactive ions. These unstable radioactive ions are collected, fully ionized, bunched and accelerated to extremely high energy (giga electron volts) and stored in storage rings. This produces beta beam containing neutrinos (either electron neutrinos or electron anti-neutrinos). On their journey to INO, which is 7152 km away from CERN, these neutrinos oscillate and convert themselves into muon neutrinos or muon anti-neutrinos. These neutrinos give birth to muons, which interact with iron molecules at the INO detector.
"Studying these interactions at the INO detector, we can trace back the conversions of neutrinos from one type to another and how they mix with each other and even get a clear picture of neutrino masses," says co-researcher Sanjib Kumar Agarwalla. "It may even provide clues to so-called grand unified theory (GUT) that unifies the four forces (strong, weak, electromagnetic and gravitational) of nature to one fundamental force," he adds.
The authors of this work are from: Harish-Chandra Research Institute, Jhunsi, Allahabad, India and Department of Physics, University of Calcutta, Kolkata, India.
- Agarwalla, K. S. et al. Unraveling neutrino parameters with a magical beta-beam experiment at INO. Nucl. Phys. B. 798, 124-145 (2008)