This National Science Day let me tell you about the biggest experiment India has ever undertaken, an experiment which was discussed first in 1989, and years later after being formally sanctioned is still under progress. This experiment once completed will be the biggest in the world in its category and will make India’s stand in the field of Nuclear Physics stronger than ever. This blog post might be a bit long, but this is all because to make known to you the grandeur of this experiment and how it functions. ( A summary is written at the end, just in case)
If you haven’t guessed it yet, India is working on a neutrino detector and observatory, Indian Neutrino Observatory (INO) to detect and study some very strange properties of particles called ‘Neutrinos’. In 1965, one of India’s most important particle experiment came to a halt when the Kolar Gold Mines were closed which were used for studying ‘cosmic ray muons’ to know more about them, and the underground mines were the best place. Since then India lost its stronghold as a major research place for particle research. This was all until 1985, this was when a motivated group of nuclear physics enthusiasts met and discussed about constructing a neutrino detector, this topic was raised again in the first meeting of Neutrino Physics and Cosmology in a workshop on High-energy Particle Phenomology in Chennai, Jan 2000. The first formal meeting for this cause for held at Tata Institute of Fundamental Research (TIFR) in Mumbai, September 2001. The awarding of 2002 Nobel Prizes to the pioneers of neutrino physics also served as a motivation, and later the project was sanctioned by the Department of Atomic Energy (DAE) and after some discussions the final project site was decided to be at Bodi West Hill (BWH) region near Pottipuram village in Theni District, Tamil Nadu. The detector is supposed to be located underground at a depth of 1300m, inside a peak named rightly as the INO peak, in a chamber with the dimensions as 132m x 26m x 20m and several smaller chambers connected through a tunnel with the surface. The project also includes starting a graduate program to train interested graduates in the particular fields of Particle Physics and Astronomy under Homi Bhabha National Institute, a deemed university under the DAE. The project will be managed by National Centre for High Energy Physics at Madurai, though it has many participating Universities and Institutes as members and funders including TIFR, HBNI, PRL, BHU, DU, Calcutta University, Punjab University and some others. The project costs around 1500 crores.
The main subject of interest of this experiment is to study neutrino oscillations. According to the Standard Model of Physics, there are certain particles associated with matter and forces with certain properties. The matter particles include a class called leptons, which are those particles which do not interact with the Strong Forces, and electrons, muons, taus, and neutrinos fall under this class. Neutrinos are very high chargeless energetic particles which rarely interact with normal matter, which makes them very difficult to detect, as of now, millions of neutrinos are going through you. The INO detector’s location 1.3km underground makes it an ideal location to study them because almost all other radiations like cosmic rays have been filtered and only neutrinos can get through and thus there detection becomes comparatively easy. This experiment works as a successor to the findings of the Super Kamiokande detector in Japan which verified that while translating, neutrinos actually do oscillate between its three different forms, called ‘flavours’, one associated with electrons and the others with their heavier cousins the muon and the tau and also that they have a negligible though finite mass( until then they were thought to be massless). The INO aims at studying the reason and other properties related to this strange behavior of neutrinos, like earth-matter effects, and distinguish the properties of neutrinos and its anti-particle, anti-neutrino.
The particular type of neutrinos that we will be studying are the so-called atmospheric neutrinos produced by interactions of cosmic rays in the Earth’s atmosphere. Both neutrinos and antineutrinos of different species (flavours) are produced here. The detector is actually an Iron Calorimeter (ICAL). It basically contains 5000 tons of magnetized iron plates with Resistive Plate Chambers sandwiched between two successive iron plates. The 2900 RPC’s in a single detector act as the active detector which detects the presence of nuclear particles. The basic working principle is that neutrinos( and its antiparticle anti-neutrino) under charged current interactions produce leptons like muons( anti-leptons like anti-muons), and when these leptons (anti-leptons) travel in the uniform magnetic field of ICAL, their direction and path helps to determine the energy and momentum and charge, and using these along with other parameters the neutrino itself and its oscillations are studied, along with the ability to tell particle and anti-particle interactions apart . The detector will also study the spectra of these muons. Also, since ICAL can distinguish neutrino events from anti-neutrino events (by detecting muons of negative or positive sign in the detector, from a charge-current interaction), it can also study Earth-matter effects. This will enable it to study certain oscillation parameters which are not well-known.Right now, computer simulations are being used to get an idea of the experiments working. A 10m x 10m prototype of the detector is being tested and studied at the Variable Energy Cyclotron Centre(VECC) in Kolkata. The INO’s ICAL is the world’s most massive magnet and neutrino detector, almost 4x times as large as the 12500 tonne in the Compact Muon Solenoid at CERN, Geneva, Switzerland.
The location of INO has many other advantages. Its location near the equator helps it lie in the major path of the solar neutrinos coming from the atmosphere. It also lies in the path of neutrino beam that is released by Fermilab in USA, and also very close to the magic baseline, or as now called INO-CERN baseline, which is a region which is best suited to calculate a parameter related to the neutrino oscillations called ‘theta one three’, which is a part of 3×3 matrix of parameters used to study these oscillations, using the neutrino or muon beams coming from CERN’s LHC.
The experiment has received quite some protests from environmentalist and politicians, but the arguments were completely un-scientific. Drilling the 1.3km detector in the mountain is like making a 2-inch hole on a 10 foot wall. IT WONT AFFECT THE STABILITY OF THE STRUCTURE! The project has gained all the necessary papers and environment certificates required and has been proved time and again to not affect the surrounding once completed. Even while construction the detonations are controlled, not more than a few couple of times a day, and the surface vibrations are less than 1mm a few hundred metres away from the site.
This experiment will make India a centre for Scientific Research and bring it in the radar of the eminent scientific community, and help us know about our Universe in a much better way too! This will also helps physics graduates from all over the country to be a part of something this big. The project will be over in the near future, and will surely bring a revolution in neutrino physics. Once this milestone is reached, the pioneers are looking into other long term options to study in the same field, or supernova studies. Lets just hope that this experiment finishes without much friction and takes our scientific glory to new heights!
I know this one post was a bit too long, but I am sure if you are just as curious as me we learned a lot and are quite excited for this experiment, so control the cosmogasmic person in you, appreciate the scientific nerd in you, and keep the science going on! Happy Reading!
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-The Cosmogasmic Person
IN SHORT: India has undertaken a project to build a 1500cr experiment called, Indian Neutrino Observatory, which will use Iron Calorimeter Detectors located 1.3km underground to detect and study neutrino oscillations and related parameters, based on charged-current interactions. This project will bring India in the limelight of the scientific community all over the globe and open huge research opertunities too. This detector will be 4x times as large as the one ar CERN making it the biggest in the world in its category. PS: Do take out time to read more about this awesome science experiment.