In a landmark move, the Government of India’s Union Cabinet recently approved the India-based Neutrino Observatory project. Coming soon after the approval of the 30-metre telescope which will be located in Hawaii, this decision will cause India to step into big fundamental science. “A pioneer in the field of neutrino science, India was a world leader in 1965. In the mid-1990s, with the closing of the Kolar Gold Fields which was the site of the experiments, experimental neutrino research in India came to a halt, and the INO is expected to revive the lost advantage,” says Prof. G. Rajasekaran of the Institute of Mathematical Sciences, Chennai, a founder member of the INO.
The three types of neutrinos, which were initially thought to be mass-less, are now believed to have a small mass.
This was shown by observations of neutrino oscillation, which is a phenomenon by which one type of neutrino transforms into another.
There is a hierarchy among the masses of these three types of neutrino and the experiments at the INO will study this mass ordering using a magnetised iron calorimeter (ICAL). The ICAL is a massive detector which will be made of iron — 50,000 tonnes of it! The project will be housed in the 63 acres of land, about 2 km away from the settlement, in the Bodi West Hills about 100 km from Madurai, Tamil Nadu.
One might wonder at the need for such a massive detector and for drilling underground. The reason is that the neutrinos interact very weakly with the surroundings. We are all being washed by a stream of neutrinos every passing minute as they just pass through us without leaving a trace. Since they interact so weakly, detecting them over other interactions is impossible. We need to have a barrier of at least 1 km of earth to block out other radiation and particles, such as muons from cosmic rays. This is the reason scientists are now going underground. They will construct a tunnel at a depth of 1,300 metres below the peak and which is 2 km by 7.5m by 7.5m. This will lead to a chamber that will house the detector.
Questions have been raised as to whether this tunnel will harm the mountain. D. Indumathi, physicist and outreach co-ordinator of INO says, “This is exactly like making a 2-inch hole to insert a pipe through a 10-foot-high wall. It will not affect the stability of the hill.” About the ecological impact of the construction process, Dr, Indumathi says, “There will be hardly any disturbance after the construction period. During construction, we will take a lot of precautions and proceed in a controlled manner. Controlled blasting of the rock will last a few seconds, twice a day. At a few hundred metres from the site, this will produce a ground vibration less than 1 mm per sec.”
The members of INO had to deal with many more questions such as the effect of the construction on distant dams and the impact of the development on the villagers, and, according to her, detailed answers to questions on the impact of various aspects of the project are outlined in the INO website.
“In Idukki itself, there are more than 200 quarries, which are working without impacting the dam.
Even the Chennai Metro Rail project can dig just metres under the buildings without damaging them because of advances in technology,” she says.
While experiments around the world are being set up in the South Pole, on top of mountains and even in outer space, big basic science projects are still new in India. The INO’s project director Naba Mondal says, “This will be the largest experimental facility to come up in the country and students will get a chance to work with cutting edge technology and build sophisticated instruments.
It will be a boon for students all over the country, especially Tamil Nadu.”
For instance, S. Pethuraj, who passed out of Madurai Kamaraj University, has joined the INO’s PhD programme at TIFR, Mumbai. “Meeting the INO scientists at the university was inspiring, and the exposure I get at TIFR is of a very high level,” he says.