TO CATCH A NEUTRINO

A neutrino is an elusive particle, but not for want of numbers. Every cubic centimetre of the universe has around 330 of them. So bring two fingers together until they almost touch, imagine 330 dots in the gap, multiply it for all space in existence, and do the math. After photons, the particles that make light, neutrinos are the second most abundant, unleashed from the very beginning of time when the universe big banged itself into being.

The hierarchy of fundamental particles in school science speaks of molecules, made up of atoms, made up of electrons, protons and neutrons. But it doesn’t end there. Go further and you have quarks and leptons also as subatomic particles. Neutrinos belong to the lepton family. But unlike, say, an electron or proton, a neutrino has no electric charge and for all practical purposes does not interact with matter. If someone shoots neutrinos at a human body, the particles will go right through without leaving a scratch. And, indeed, trillions have already passed through your body, you just didn’t know it.

A human who however chose to interact with neutrinos recently was the Tamil politician Vaiko of the Marumalarchi Dravida Munnetra Kazhagam, leaving some of India’s best scientists somewhat worried. One of them, seated in a cabin at the Tata Institute of Fundamental Research (TIFR), is Professor Naba Mondal. In Mumbai, a city grey with concrete packed together on every horizon, TIFR, at its very southern edge, is a spacious sylvan patch overlooking the sea. Mondal first came here in the late 70s on a visit while doing his MSc in West Bengal, and, struck by its grandeur, decided that this was where he wanted to pursue his PhD. He did it on underground experiments in Kolar Gold Fields looking for the stability of protons. It is also here that he, as project director, now helms the Indian Neutrino Observatory (INO), India’s largest pure- sciences project ever.

For scientists like Mondal who have spent more than a decade trying to bring it to fruition, the INO project, which entails creating a huge cavern in the middle of a mountain in an effort to catch neutrinos, is India’s moment under the sun for experimental physics. And yet Mondal says during the course of an interview, “The type of opposition we get, it is so much that you get frustrated and start questioning whether it is worth doing or not. I have spent a lot of time for this, and I believe that it is possible. I thought that anybody will welcome such a move. That something is happening in the country. This kind of opposition…”

Recently, Vaiko filed a Public Interest Litigation at the Madurai bench of the Chennai High Court asking for the project to be suspended, the latest salvo in a campaign against the INO. Mondal is worried because so far it was environmental activists who were opposing the project, but now politicians are getting involved. The INO is a collaboration of around 25 Indian research institutes, universities and IITs. Its scientists wanted to find the properties of neutrinos; crossing paths with activists and politicians was not something anyone envisioned. But the forces of Creation are peculiar and equally strange are those that govern Indian society.

Professor G Rajasekaran of the Institute of Mathematical Sciences (IMSC), Chennai, has been a particle physicist for 60 years, the last 20 of them spent also on neutrino research. He is also involved with the INO, and it was at IMSC that the idea was first conceived during a high-energy physics meeting in 2000.

There was a reason why scientists felt the need for it. India has had a long tradition of experimental physics going all the way back to the 50s with Dr Homi Bhabha. Rajasekaran says, “He sent one group of people to Kashmir to measure cosmic ray intensity as a function of height [above sea level]. He set up the world’s highest cosmic ray laboratory in Gulmarg. At the same time, he sent another group of researchers to Kolar Gold Fields’ mines to measure cosmic ray intensity as a function of the depth in the earth.”

The Kolar mines were the world’s deepest, and when the group reached a kilometre or so underground, they found that they could not detect any cosmic ray intensity. At that depth, they realised, the mines were a fit place to conduct experiments to detect neutrinos. There are two reasons for this. Neutrinos are present deep underground where other particles are not because they don’t interact with matter and easily pass though rocks. Second, they aren’t detected above ground because the detector gets swamped by other stronger particles in cosmic rays. Mondal explains it using the analogy of a telescope. There are stars in the sky even during the day, but you only look through the telescope at night because there is no sunlight to overwhelm the star light. Similarly, neutrino detectors need to be deep inside the earth where everything else is filtered out and only neutrinos remain. In Kolar, Indian physicists first detected atmospheric neutrinos in 1965. “This year is the golden jubilee of that milestone,” says Rajasekaran, “We should be celebrating it.”

Kolar was where, in the 70s and 80s, young particle physicists like Mondal went to do research on cosmic rays, but in 1992, the mine was closed down because it was making losses. The scientific community asked the Government to keep it open for research, but were told that it was prohibitively expensive. Since then, they had felt the need for another place in India to do such research. “KGF was the last major underground facility where we could do such experiments. Once it closed down, the only option for particle physicists in India was to go abroad and participate in experiments in CERN in Geneva, in Fermilab, USA, and in Japan. We were doing that, but it was always felt that India is such a large country we must have facilities of our own,” says Mondal.

After the idea was first proposed at the IMSC meeting, it took a few more years to take shape. In 2005, the scientists approached the Department of Atomic Energy (DAE) and Department of Science and Technology (DST), funding agencies for fundamental research in India. Then they went to the Geological Survey of India (GSI) to find a suitable site to set up an underground laboratory. Many things had to be considered. It couldn’t be in a high seismic activity zone, for example, and the quality of rocks had to be good enough to hold a lab, apart from the usual requirements of accessibility, availability of water, electricity and so on. The GSI told them south India was better suited to such a lab because the alternative, the Himalayas, was prone to quakes among other dangers. They were offered a site, but soon unexpected problems began to crop up.

The INO will be a huge laboratory dug inside a mountain. The cavern, as planned, will be 132 metres long (the length of a small cricket stadium), 26 metres wide (the distance of an Olympic swimming pool) and 20 metres high (the height of a six-storey building).

Near Pottipuram village in the district of Theni, 110 km west of Madurai in Tamil Nadu, the Western Ghats rise like a wall separating the state from Kerala. From the side of a mountain here, a seven-metre tunnel will be burrowed inwards for 2 km. At this point, beneath the top of the mountain, which is about 1.3 km high, the cavern will be dug to house the laboratory.

Inside will be installed a massive instrument made up of 50,000 tonnes of magnetised iron. It is called an Iron Calorimeter and comprises a series of steel sheets that sandwich Resistive Plate Chambers (RPCs), each made of two glass plates separated by a gap in which a gas flows.

Neutrinos can come from many sources. All fundamental particles were created during the Big Bang, but they turned into different elements that created matter. Because neutrinos do not interact, they have been roaming around ever since. But that is not the only time neutrinos are created. They are also generated by the sun or sun-like stars when hydrogen burns within them, producing helium. When a star dies, they cause supernova explosions and neutrinos are produced. Cosmic rays, when they come and hit the earth’s atmosphere, produce unstable particles that decay and produce neutrinos. The earth’s core has a lot of thorium and uranium that decays to deliver neutrinos. Nuclear reactors everywhere yield neutrinos as well. “These are all neutrino sources along with those that are there since the time of the Big Bang,” says Mondal.

For the INO, the source will be atmospheric neutrinos, which will have 50,000 tonnes of iron nuclei of the Calorimeter to interact with and produce charged particles called Muons—which will then go through the RPCs and leave their tracks in the gas flowing between the plates. “We will be able to reconstruct the path of the Muon, measure its energy, its direction. From there, you can infer that the neutrino has interacted,” says Mondal.

But such events, where a neutrino is detected, will still be rare. Most of the trillions of neutrinos will simply pass through without even noticing the iron nuclei. “Maybe a few events per month will come and that is not enough. So we have to wait for years in order to accumulate enough data that will provide the actual physics information which is sought,” says Rajasekaran.

It will cost money to do all this. The budget for the project is Rs 1,500 crore. A little under Rs 500 crore will be required for civil construction like the tunnel and underground lab, and Rs 600 crore just for the Iron Calorimeter. There is then the question of why go through all this trouble and take on the expense: what makes neutrinos so important for scientists to study? The answer is an entirely new physics, a better understanding of the building blocks of the universe.

In 2012, the Higgs Boson particle was discovered using the Large Hadron Collider in CERN, Geneva. It had been predicted as far back as the 1970s by what is known as the Standard Model of Physics. One of the important components of this model is the Higgs mechanism, which gives mass to elementary particles. “Electrons, quarks get mass from the Higgs mechanism. But neutrinos do not get mass from this mechanism. The Standard Model is now in very good shape thanks to the actual discovery of the Higgs Boson,” says Rajasekaran. There is, however, an anomaly: by the model, neutrinos are massless, but in 1998 it was discovered that neutrinos do have mass, even if very little. “So you have already broken the Standard Model through neutrinos. That is the importance of neutrinos. They will serve us as a portal to go beyond the Standard Model,” says Rajasekaran. “In science, nothing stops at one theory or one model. It doesn’t mean the old things are comp- letely wrong. Newton is not thrown away because of Einstein. Newton gets incorporated into a bigger structure in Einstein’s theory. Obviously there is a bigger structure than the Standard Model for which neutrinos will provide evidence. That is the importance of the INO. We are already trying to go beyond the Standard Model.”

It has been established that neutrinos have mass, but once we know exactly how much mass, then a new leap in physics will be possible. “Once we have the neutrino masses, we are getting some hints in which direction to go,” says Mondal, “This is our first [piece of] evidence that there is life beyond the Standard Model. That is why neutrinos are an exciting area of research.”

If, as expected, the digging of the mountain starts in a few months, the INO will be ready by 2020. But it will be even longer before sufficient data is collected for the first research findings to come in. When the idea for such an observatory came up in 2000, nobody thought it would take 20 years for it to be operational. The present site in Theni was actually a second choice. The first site they zeroed in on, in 2009, was Singara in the Nilgiris. They got an environmental clearance, pending forest clearance, but the latter never came. In early 2010, the Government declared it a Tiger Reserve and the site was no longer available. After short-listing more sites, they then decided on one near Pottipuram that offered good rock quality and had the least environmental impact.

Professor D Indumathi, a physicist of the Institute of Mathematical Science, Chennai, is also the INO’s outreach coordinator, in charge of helping people understand what the project is about and clearing up their apprehensions. The primary confusion they had to address was the difference between a ‘neutrino’ and a ‘neutron’. A neutron is a particle used in the making of atomic bombs, but since ‘neutrino’ is similar on the ear, it sounds ominous to those not very well versed with science. What worsens the anxiety is the DAE’s funding of the INO project, for which there is an explanation. “Homi Bhabha had two hats,” says Rajasekaran, “On the one hand, he set up the DAE and BARC (Bhabha Atomic Research Centre). On the other, he set up TIFR because he was also a basic science researcher. Because of that historical reason, DAE has the mandate of supporting fundamental research. Since the INO comes under fundamental research DAE supports it.”

To explain what the project was about, Indumathi and her colleagues would go house to house and hold roadside meet- ings. The questions they were asked ranged from whether there was any danger from it, to whether goats and cattle would be prevented from grazing. In a large meeting called by the collector, the Panchayat finally gave its assent to the project.

In 2012, however, the opposition suddenly heightened, sparked by an article written by an activist-cum-science researcher, VT Padmanabhan, in Counter Currents. Vaiko’s recent PIL borrows heavily from his arguments. Padmanabhan, who was also active in the movement against the Kudankulam nuclear reactor, says that around 2011, he was approached by locals near the INO site and told about a big project coming up. They spoke of movement of trucks and complained of issues like dust, which he was not really interested in. But as he looked at the project in closer detail, he couldn’t help getting involved.

Padmanabhan’s concerns are three— radiological, geological and hydrological. He argues that the INO is in some way an appendage of the US because, at a later stage of the project, high-energy neutrinos from a neutrino factory in Fermilab will be beamed here, creating a radiological hazard. He says that even if that is still some time away, there are other pressing issues affecting people. Like how nearby dams in Kerala are going to get affected by the tunnelling in the mountain. There are major dams in Idukki and Mullaperiyar between 30 and 50 km away, and the aquifers and water channels that supply them could be affected.

“We are not talking of any direct impact on the dams. The laboratory is set right in the middle of Suruli shear zone. This particular place where the lab is coming up has a lot of fissures and faultlines through which water goes. You don’t know where water could be, unless someone goes and studies it. There could be a huge aquifier [that could get affected],” he says, adding that a geotechnical study done by the INO only drilled and took samples from the foothills and not where the lab is to be located. “It takes nearly one year to undertake this study. Here they have done this by being in the field for five days.”

Another charge Padmanabhan makes is the possibility of the facility being used as a storage for radioactive waste. He deduces this from an application that appeared on the website of the Tamil Nadu State Environment Assessment Authority, which categorises the project as a ‘nuclear’ one (the INO later issued a press release saying it was an error that had been corrected). He also speaks of the INO unwittingly becoming part of a secret US project to build a weapon out of neutrinos. In order to test it, they would need a laboratory at the other end of the earth—India, that is. “It is something like this,” he says, “If I told you on 5 August 1945 that somebody is going to use 45 grams of a material called uranium and burn an entire city, you would have just laughed it away.”

Padmanabhan professes to not be against big science projects, but does not want them to be at the cost of people’s livelihoods, farmlands or water channels. “The INO should suspend all their activities and undertake all these studies with people who are qualified to do so—independent people. It will take nearly one year to complete this study and the entire thing should be transparent,” he says.

On the other side, INO scientists say that they have addressed all of Padmanabhan’s points in public and that there is no merit in any of them. After responding in 2012, when he first wrote on it, they thought the issue had died down. In January this year, the Union Cabinet finally gave its long- pending approval, and the opposition too returned almost instantly. Vaiko’s PIL was one instance; another was a case filed by an NGO in the National Green Tribunal. The anti-Kudankulam reactor agitation leader SP Udaykumar and social activist Medha Patkar have also got involved in the issue recently.

Early this month, the DAE issued a statement affirming that the project was a basic science one and had nothing to do with nuclear energy, weapons or defence applications. The press release said that the DAE ‘categorically states that no nuclear waste will be stored there at any time and INO laboratory will be used only for the purpose of basic science research in the field of neutrino physics’.

Indumathi says she fails to understand why such objections are even being raised. To the charge that INO’s tunnel will affect nearby dams, she says that hydroelectric projects have much bigger tunnels. In fact, she says, Idukki Dam—the one said to be in danger—already has a tunnel 2 km long right under it. “Actually, this tunnel was built after the dam was commissioned, a few metres below it. And there was no damage to the dam. There are examples of tunnel construction in Tamil Nadu itself which have not affected any of the dams. This can be done. It is routine activity.”

She finds the neutrino weapon allegation bizarre. “It’s a myth that this is a Fermilab project, like how drug trials are done in India on unsuspecting populations. That we will do this project and create a neutrino weapon that we will give back to Fermilab and they will not even share the details of the weapons developed with us. I don’t know how we can develop a weapon without knowing about it.”

Mondal says the study of beams from a neutrino factory is not even on the agenda right now. “The parameter that I wanted to measure using this neutrino factory has already been measured by using reactor neutrinos in China in 2012. So the requirement for that facility is not there anymore,” he says. “The global neutrino community is not thinking of making a neutrino factory and sending a beam which is 7,500 km away. So we will be using atmospheric neutrinos only.”

Indumathi or one of her colleagues go to court for hearings nowadays, not something physicists are used to. “We don’t know any of these procedures. We are so badly informed on all these issues, but we are finding out. How we have learnt about dams and environmental sustainability, we will learn about law also,” she laughs.

If the opposition is not countered, she says, people will believe what is being said against the INO. Scientists are used to working in labs far away from the public eye, but big science can’t be done that way. “If we keep losing these public spaces by not interacting with the public often enough, every future [big] science project is going to be in jeopardy… We may win or lose, but if we don’t fight on [for the] INO, then we will lose the trust of people.”

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