Science

Neutrino scare

Print edition : March 06, 2015

Preliminary work under way for the proposed neutrino observatory at Pottipuram in the Bodi hills on January 12. Photo: G. Karthikeyan

MDMK general secretary Vaiko addressing a public meeting in Bodi on February 4. Photo: G. Karthikeyan

In this 2005 photograph provided by CERN, the European Organisation for Nuclear Research, technicians check the magnets that will direct protons towards the target for the CERN Neutrinos to Gran Sasso project in Geneva. The project team fired a neutrino beam 730 kilometres underground from Geneva to Italy. They found it traveled 60 nanoseconds faster than light. That's 60 billionth of a second, a time no human brain can register. Photo: AP

India’s neutrino project, slated to come up in Bodi hills in Tamil Nadu, once again runs aground, this time following a petition filed by MDMK leader Vaiko, who has raised the spectre of the unknown dangers of “artificial neutrinos” and “factory-produced neutrinos”.

IT is a near rerun of the controversy an activist-politician duo of Kerala created in 2012 around the proposed project to build a world-class underground neutrino detector in the Bodi West Hills region of Theni district, about 110 kilometres west of Madurai in Tamil Nadu and about 60 km from the Kerala border. Only the State and the politician have now changed. The earlier campaign mode has transformed into a public interest litigation (PIL) petition in the Madurai High Court. The petition was moved on January 20 by Vaiko, the general secretary of the Marumalarchi Dravida Munnetra Kazhagam (MDMK).

All the other elements of the controversy, in particular the completely baseless and unscientific allegations the Kerala-based environmental-activist V.T. Padmanabhan made, remain the same and form the basis of Vaiko’s petition. The issues were countered squarely then, or at least one thought so, with the scientists concerned spending a good amount of their time in the public space to dispel the fears and explain the facts about the project through all forms of outreach, including press releases and FAQ sheets.

The controversy died down. But following the Union Cabinet’s approval on January 5 to set up the Rs.1,584-crore project, it has been revived. Scientists associated with the project have to file counter-affidavits and appear in courts to argue against the charges, most of which border on the ridiculous and had been previously answered publicly.

It must be pointed out that on the ground there is not much opposition to the project. In fact, the local population seems to be in favour of it. But, since a seasoned politician is opposing the project at various forums, the local media are giving his allegations unwarranted publicity.

Most abundant particle

A little background about the science of the project and its objectives will help one appreciate the project and see the sheer absurdity of the allegations. Neutrinos are subatomic particles and, like photons and electrons, are one of the fundamental particles of nature. Neutrinos are products of radioactive decay. Like the streaming photons that we see as light, neutrinos are streaming all over the universe in great abundance. In fact, after photons, neutrinos are the most abundant particles in the universe.

Scientists believe that the majority of neutrinos that are floating around were born around 15 billion years ago, soon after the birth of the universe. Since then, the universe has vastly expanded and cooled, and like the low-energy relic photons from the Big Bang that bathe the universe with microwave radiation, low-energy (about ten-thousandths of an electronvolt) neutrinos too constitute a cosmic background. Other neutrinos are being produced constantly—from terrestrial sources such as nuclear power stations and particle accelerators; in the atmosphere due to interactions of cosmic rays with nuclei resulting in what are called “atmospheric neutrinos”; and from cosmic sources such as the sun, and other cosmic phenomena such as births, collisions, and deaths of stars, particularly the explosions of supernovae.

Like photons, they do not carry any electric charge but unlike photons, which have zero mass, neutrinos have a tiny mass. Among the fundamental particles, neutrinos are a bit strange in that they interact very feebly with the rest of matter because of which all forms of matter in the universe—the earth and all objects and living things on it—are nearly transparent to them. About 100 trillion neutrinos from the sun and other cosmic sources pass through our bodies every second without us even realising it, let alone being harmed in any way. As Frederick Reines, who led the discovery of the neutrino in 1956 and confirmed Wolfang Pauli’s prediction in 1930 of its existence, once said: “[It is]… the most tiny quantity of reality ever imagined by a human being.”

Neutrino interactions being weak and rare, neutrinos are elusive and not easily detected. Therefore, not everything about them is well studied or well understood. The large background flux of other particles in cosmic rays compounds the problem of their detection. Neutrino detectors are, therefore, usually placed deep underground, typically a kilometre or still deeper. The large overburden of rock or earth above the detectors reduces the background cosmic ray particles by a million times or more.

While almost all neutrinos pass through freely, a few do interact in the detectors and can be detected. Many neutrino detection experiments are currently going on around the world, and with the growing interest in neutrino physics and the development of more sensitive detection techniques, many others are being proposed and built. The India-based Neutrino Observatory (INO), as the Indian underground laboratory in Bodi hills is called, is one such that has attracted interest worldwide. Neutrinos are known to come in three types—electron, muon and tau—associated with three charged particles of which the familiar electron is one, the others being the muon and the tau (see table).

Although known to have small masses, the individual masses of the three neutrinos remain unknown. Of the three neutrino types, or “flavours”, the heaviest has at least 10-millionth of the electron’s mass. Which neutrino is the heaviest? The ordering of the three neutrino masses too is unknown. This is the so-called “mass hierarchy” question, which the INO is well suited to investigate.

Neutrino oscillation

A peculiar aspect of these strange particles is that they can morph from one type or flavour to another as they pass through space, people, matter and the earth itself. This phenomenon is called neutrino oscillation. While the details of two oscillations—the electron type to the muon type and the muon type to the tau type—are known fairly well, the third, the switching of the tau type to the electron type, is not well characterised and forms one of the main objectives of the INO.

Why is a study of the elusive neutrinos important? Since neutrinos abound in the universe, even their tiny masses can have an effect on the evolution of the universe through their gravitational effects. Neutrino studies, such as at the INO, to determine their masses and other properties will thus be able to provide information that is complementary astrophysical measurements on the evolution of the universe. Thus, neutrinos hold the key to fundamental questions on the origin of the universe and energy production in stars. Since not everything about neutrinos is known, the INO and other future experiments will seek to find answers to many outstanding questions about the nature of the universe that we are a part of. The INO is thus an experimental project in basic sciences seeking to expand our knowledge horizon. The project has nothing to do with radioactivity or any other dangerous nuclear activity, nor does it have any defence or strategic objectives.

India was at the forefront of neutrino research in the 1960s. One of the earliest laboratories established to detect neutrinos in the world was located more than 2 km deep at the Kolar Gold Field (KGF) mines in Karnataka. It was at this laboratory that the atmospheric neutrinos were first detected in 1965. Unfortunately, this laboratory had to be shut down with the closure of the mines in the 1990s. With a growing interest in neutrino physics worldwide now, a new Indian neutrino observatory could provide Indian scientists an opportunity to re-establish their pre-eminence in neutrino research.

The INO was first proposed in 2000 at an international conference in Chennai. The proposal was further refined and consolidated at the 2001 neutrino meeting in Chennai, when the INO consortium of collaborating Indian institutions was formed. A formal proposal was submitted in 2002 to the Department of Atomic Energy (DAE), which is the nodal agency for the project. The INO is one of the mega science projects envisaged in the Twelfth Plan to be funded jointly by the DAE and the Department of Science and Technology (DST). At present, 26 Indian institutions and about 100 scientists are involved in the project, with the Tata Institute of Fundamental Research (TIFR), Mumbai, as the nodal institute. It will be the first mega collaborative experimental project to be undertaken in India and could set a precedent for large-scale collaborative efforts in basic sciences.

Bodi hills was chosen as a suitable site for locating the underground detector as the steep slopes of the Western Ghats provide ideal and stable rock conditions to build a large underground cavern for long-term use. The main detector, which will detect both natural and man-made neutrinos, is an indigenously built 50 kiloton magnetised iron calorimeter (ICAL) detector. It will be the world’s most massive neutrino detector. This will be located in a cavern 1.3 km below the mountain peak so that there is a material overburden of about 1,200 metres in all directions to filter out cosmic rays.

In Phase I, the INO will study neutrinos produced by cosmic rays in the earth’s atmosphere. In Phase II, which will be at least 10-15 years down the line, the INO could be used as a far detector for using beams from future accelerator-based “neutrino factories” in Japan, Europe and the United States in what is called a Long Baseline Neutrino Experiment (LBNE) with the distance from the neutrino source to the INO serving as the “long baseline”. The INO is expected to become operational in the next few years when the first module of the detector will start taking data.

What are neutrino factories? Unlike the sporadic neutrinos flying in all directions that a particle accelerator normally produces, a neutrino factory will create a focussed beam of neutrinos at one site on the earth and fire it downwards until the beams resurface at other points. The aim is to make enough neutrinos of the right type in a controlled way whose properties will be examined at the remote sites to determine how neutrinos evolve over time. Such a proposal is at a conceptual stage.

But, with their imagination running wild, the campaigners against the INO project have projected the proposed facility variously as a nuclear weapons facility, a nuclear waste dumping facility, and, most outrageously, as a facility being built at the behest of Fermilab (a U.S.-based particle accelerator facility, which has proposed to build a neutrino factory) to get information about neutrinos detected at the INO end “more or less like a hospital undertaking drug trials”, to quote Vaiko’s petition. The petition, most of which is a cut-and-paste job from the allegations levelled by Padmanabhan in his various articles written at various times, and that too incoherently, adds: “The project proposal was written by scientists of Fermilab and submitted to the Indian Planning Commission for funding in February 2006. U.S. is not likely to share the weapon developed with India.”

Both the activist-provocateur’s allegations and the Tamil Nadu politician’s petition based on them reveal a lack of basic understanding of science. For instance, the petition raises the spectre of the unknown dangers of “artificial neutrinos” and “factory-produced neutrinos”. “Even though billions of them [neutrinos] are flying around,” says the petition, “none of them are [ sic] similar to the factory-produced ones. One does not know if their passage through different layers of earth can cause major impacts like earthquakes because something like this has never happened before.”

The pursuit of science and its use in understanding the universe around us are based on the apparent universality of the laws of nature. So, neutrinos produced in nature or in a laboratory or in a neutrino factory are all the same. It is like saying that photons in the light from an electric bulb or even an oil lamp, which are man-made, are different from photons that we receive from the sun and the stars and so one should not light a lamp.

Imagined disaster situations

Vaiko’s petition also speaks of imagined disaster situations such as radioactive contamination due to “beam misdirection”, “radiation high-dose due to neutrino beams from Fermilab emerging through the land above the laboratory” and “radioactive particles like carbon-14 and tritium generated by the hadron shower at the point of emergence which would travel great distances along with stream and groundwater”. It refers to “studies conducted in the U.S. and Europe” and “papers written by health physicists working with accelerators in Fermilab, CERN etc.” to buttress its allegations though without giving any references. The phrases radioactivity and high-dose radiation damage are used interchangeably, and some arbitrary high-sounding words such as hadron shower are thrown in to cause confusion and fear in the minds of readers, including the judge who will hear the case.

First, it must be understood that while neutrinos are products of radioactive decays, they themselves are not radioactive. So merely detecting them, whichever source they come from, at the INO site does not cause any radioactivity. Yes, there have been studies looking at whole-body doses of neutrino radiation at different energies in the context of the proposed neutrino factories, which will generate focussed high-energy (of the order of trillion electronvolts, or teraelectronvolts, or TeV) neutrino beams, to have appropriate shielding around them to protect against potential high-intensity neutrino radiation-induced damage to people working at the sites and the materials around. Since the potential danger will fall off with distance, a protected safe zone of a few tens of kilometres from the facility would suffice for the safety of the people in the vicinity.

One is talking of TeV energies here, which are thousand to million times more energetic than the neutrino energies one would be detecting at the INO, which would be in the million electronvolt-gigaelectronvolt range. In any case, the number of events that the INO will detect will be at best a few a day in Phase-I. If at all the INO is used for long-baseline experiments with beams from Fermilab’s neutrino factory, neutrinos will lose their high energy as they traverse through the earth over 10,000 km and more to reach the INO. And these “factory-made” low-energy neutrinos will behave just like atmospheric or cosmic neutrinos and most of them will just pass through without disturbing anything—people or materials—along their path. So there is no danger of high-dose neutrino radiation damage at the INO end either to the scientists at the site or to the surrounding habitat.

We all know powerful lasers can damage tissues, cut through matter and can also be used as weapons for destruction. Lasers are intense and focussed beams of photons. But that does not deter us from using light in our day-to-day lives and in laboratory experiments. The same is true of neutrinos. Just because a focussed high-energy beam can cause some radiation damage should not mean that scientists should not set up a laboratory to study low-energy neutrinos that are harmless.

The other outrageous allegation is of neutrino-base weapons development. Quoting some studies by Japanese scientists in 2003, without understanding what the studies were about, the petition says: “The existing and planned research [with neutrinos] can lead to the weapon. The neutrino weapon issue has not been discussed by the global disarmament community.… The societal, ethical and other aspects of these studies should be discussed widely.”

The 2003 study by Hirotaka Sugawara from Hawaii University and Hiroyuli Hagura and Toshiya Sanami from the KEK neutrino laboratory in Japan showed the possibility of using ultra high-energy (1,000 TeV and more) neutrino beams to destroy nuclear weapons, not to make any weapons. The campaigners have misunderstood the objective of that study and have projected neutrinos as potential weapons of the future. There is a German study to suggest that neutrinos can be used to track nuclear weapons. In any case, these are futuristic ideas and have absolutely no bearing on the proposed activity at the INO.

Talking about the geological impact of excavation and tunnelling by blasting for building laboratory caverns, Vaiko’s petition, essentially drawing on the article written by Padmanabhan and J. Makkolil, titled “Mountain Tunnelling, aquifer and tectonics” in 2013, says: “[T]he main concerns are the impacts on quantity and quality of the waters in the aquifers and surface water bodies. Tunnelling can rupture underground aquifers and introduce new channels for water to flow. The flowing water will be laden with toxic chemicals used in plenty in the process of tunnelling…. The rivers and the dams receive the water stored in aquifers throughout the year… tunnelling can disrupt the groundwater flows and deplete the aquifers…”

The article, which based its arguments on events relating to the Gran Sasso underground laboratory in Italy, was duly and adequately countered by the geologist V. Balachandran, who was involved in the preparation of the geotechnical report on the proposed INO site in December 2010, which formed the basis of the environmental impact study and the final clearance by the Ministry of Environment and Forests on June 1, 2011. Balachandran writes: “The opinion article by Padmanabhan and Makkolil… contains factual inaccuracies, conceptual deficiencies and compares an apple with an orange.”

Balachandran pointed out that the authors had coined a new phrase “Idukki-Theni charnockite aquifer”, which did not make any sense. He said, “Charnockite is not an aquifer but a rock mass and in most of this area is massive with very little weathering. Expression of charnockite as an aquifer is used with the intent of misleading people to believe that the entire hill mass is charged with water, whereas, factually, in most places at depth the rock is bone dry.” Charnockite, as he pointed out, is a rock mass which cannot transmit water unless it is fractured by joints or riddled with fissures/faults, or intrusions.

The geologist said the article had wrongly mentioned that “this aquifer and the surface water bodies feed three river systems—Periyar, Vaippar and Vaigai”. “By citing various man-made reservoirs, including Idukki, and connecting them to INO indirectly or directly is outrightly [ sic] unscientific portrayal of the project,” he wrote. “The mean and flood discharges of all the rivers in the area are solely due to precipitation by rainfall,” he added.

Balachandran dismissed the authors’ implied connection between the L’Aquila earthquake of April 6, 2009, and the Gran Sasso project as illusory. “No report other than these authors has linked this earthquake to the presence of Gran Sasso laboratory,” he wrote. He also faulted their comparison of the Gran Sasso site and the INO site. “The Gran Sasso project area is occupied by limestone that too with karst features of caverns, grykes, etc. in contrast to Theni area, which is made up of massive charnockite/gneisses…. The hilly terrain of Theni is composed of rocks devoid of water, particularly along the proposed tunnel alignment. No water reservoirs imagined by the authors exist or are known inside the hill mass, so that the imaginary depletion can lead to catastrophe. [The] Gran Sasso area is located in a tectonically active zone. On the contrary, the proposed INO at Theni is located in a stable continental region. The geological milieu of Gran Sasso and Theni are as different as chalk and cheese.”

According to Naba Mondal of the TIFR, who is the spokesperson of the INO, the allegations were answered earlier by INO scientists and have been once again answered in the counter-affidavit filed recently on behalf of the Chairman of the Atomic Energy Commission and the Institute of Mathematical Sciences, Chennai, one of the key institutions involved in the project. The case is to come up for hearing on February 23.

“We have lost a lot of time already,” Mondal said. “A project conceived in 2000 is yet to take off and this has led to cost escalation. During this time, China has upstaged the INO in one of its main science objectives. Only in 2004, two years after our proposal, did China propose an experiment to study neutrinos from the Daya Bay nuclear reactor using a detector located in an underground tunnel in a nearby hill. In March 2012, that experiment succeeded in measuring a key parameter relating to the tau-neutrino/electron-neutrino oscillation. No major science project can take off and succeed in India under such conditions,” he said.

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