An elusive detector for an elusive particle

(This article originally appeared in The Hindu on March 31, 2014.)

In the late 1990s, a group of Indian physicists pitched the idea of building a neutrino observatory in the country. The product of that vision is the India-based Neutrino Observatory (INO) slated to come up near Theni district in Tamil Nadu, by 2020. According to the 12th Five Year Plan report released in October 2011, it will be built at a cost of Rs.1,323.77 crore, borne by the Departments of Atomic Energy (DAE) and Science & Technology (DST).

By 2012, these government agencies, with the help of 26 participating institutions, were able to obtain environmental clearance, and approvals from the Planning Commission and the Atomic Energy Commission. Any substantial flow of capital will happen only with Cabinet approval, which has still not been given after more than a year.

If this delay persists, the Indian scientific community will face greater difficulty in securing future projects involving foreign collaborators because we can’t deliver on time. Worse still, bright Indian minds that have ideas to test will prioritise foreign research labs over local facilities.

‘Big science’ is international

This month, the delay acquired greater urgency. On March 24, the Institute of High Energy Physics, Beijing, announced that it was starting construction on China’s second major neutrino research laboratory — the Jiangmen Underground Neutrino Observatory (JUNO), to be completed at a cost of $350 million (Rs. 2,100 crore) by 2020.

Apart from the dates of completion, what Indian physicists find more troubling is that, once ready, both INO and JUNO will pursue a common goal in fundamental physics. Should China face fewer roadblocks than India does, our neighbour could even beat us to some seminal discovery. This is not a jingoistic concern for a number of reasons.

All “big science” conducted today is international in nature. The world’s largest scientific experiments involve participants from scores of institutions around the world and hundreds of scientists and engineers. In this paradigm, it is important for countries to demonstrate to potential investors that they’re capable of delivering good results on time and sustainably. The same paradigm also allows investing institutions to choose whom to support.

India is a country with prior experience in experimental neutrino physics. Neutrinos are extremely elusive fundamental particles whose many unmeasured properties hold clues about why the universe is the way it is.

In the 1960s, a neutrino observatory located at the Kolar Gold Fields in Karnataka became one of the world’s first experiments to observe neutrinos in the Earth’s atmosphere, produced as a by-product of cosmic rays colliding with its upper strata. However, the laboratory was shut in the 1990s because the mines were being closed.

However, Japanese physicist Masatoshi Koshiba and collaborators built on this observation with a larger neutrino detector in Japan, and went on to make a discovery that (jointly) won him the Nobel Prize for Physics in 2002. If Indian physicists had been able to keep the Kolar mines open, by now we could have been on par with Japan, which hosts the world-renowned Super-Kamiokande neutrino observatory involving more than 900 engineers.

Importance of time, credibility

In 1998, physicists from the Institute of Mathematical Sciences (IMSc), Chennai, were examining a mathematical parameter of neutrinos called theta-13. As far as we know, neutrinos come in three types, and spontaneously switch from one type to another (Koshiba’s discovery).

The frequency with which they engage in this process is influenced by their masses and sources, and theta-13 is an angle that determines the nature of this connection. The IMSc team calculated that it could at most measure 12°. In 2012, the Daya Bay neutrino experiment in China found that it was 8-9°, reaffirming the IMSc results and drawing attention from physicists because the value is particularly high. In fact, INO will leverage this “largeness” to investigate the masses of the three types of neutrinos relative to each other.

So, while the Indian scientific community is ready to work with an indigenously designed detector, the delay of a go-ahead from the Cabinet becomes demoralising because we automatically lose time and access to resources from potential investors.

“This is why we’re calling it an India-based observatory, not an Indian observatory, because we seek foreign collaborators in terms of investment and expertise,” says G. Rajasekaran, former joint director of IMSc, who is involved in the INO project.

On the other hand, China appears to have been both prescient and focussed on its goals. It purchased companies manufacturing the necessary components in the last five years, developed the detector technology in the last 24 months, and was confident enough to announce completion in barely six years. Thanks to its Daya Bay experiment holding it in good stead, JUNO is poised to be an international collaboration, too. Institutions from France, Germany, Italy, the U.S. and Russia have evinced interest in it.

Beyond money, there is also a question of credibility. Once Cabinet approval for INO comes through, it is estimated that digging the vast underground cavern to contain the principal neutrino detector will take five years, and the assembly of components, another year more. We ought to start now to be ready in 2020.

Because neutrinos are such elusive particles, any experiments on them will yield correspondingly “unsure” results that will necessitate corroboration by other experiments. In this context, JUNO and INO could complement each other. Similarly, if INO is delayed, JUNO is going to look for confirmation from experiments in Japan, South Korea and the U.S.

It is notable that the INO laboratory’s design permits it to also host a dark-matter decay experiment, in essence accommodating areas of research that are demanding great attention today. But if what can only be called an undue delay on the government’s part continues, we will again miss the bus.


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