Neutrino Observatory

Subject: Science and tech

Context:

Union Minister of State (Independent Charge) Dr. Jitendra Singh said in a written reply in Lok Sabha that Government has a proposal to set up Neutrino Observatory in the country.

Concept:

• Proton, neutron, and electron are tiny particles that make up atoms. The neutrino is also a tiny elementary particle, but it is not part of the atom. Such particles are also found to exist in nature.
• Neutrino has a very tiny mass, no charge and spin half. It interacts very weakly with other matter particles. So weakly that every second trillions of neutrinos fall on us and pass through our bodies unnoticed.
• Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated. They can also be produced in the lab.
• Neutrinos come in three types or “flavours” – electron neutrino, tau neutrino and muon neutrino.
• They can change from one flavor to another as they travel. This process is called neutrino oscillation and is an unusual quantum phenomenon.
• The India-based Neutrino Observatory (INO) will study atmospheric neutrinos only. Solar neutrinos have much lower energy than the detector can detect.
• Atmospheric neutrinos are produced from cosmic rays which consist of protons and heavy nuclei. These collide with atmospheric molecules such as Nitrogen to give off pions and muons which further decay to produce neutrinos.
• The mountain consists of 1km of solid rock that filters away most of the charged particles from the cosmic rays. The filtered set consist of a part of the incident cosmic ray protons and pions and practically all the neutrinos.
• If the detector was placed at the surface of the mountain, it would pick up billions of cosmic ray muons every hour and about 10 neutrino events per day. After placing inside the rock, it would detect only 300 muon events per hour and about 10 neutrino events per day of which 3 will be the desired muon neutrino events.

Applications:

• If the properties of neutrinos are understood better, they can be used in astronomy to discover what the universe is made up of.
• Neutrinos interact very little with the matter around them, so they travel long distances uninterrupted. Since they take time to cross these distances, they are in effect uninterrupted for very long times. The extragalactic neutrinos we observe may be coming from the distant past. These inviolate messengers can give us a clue about the origin of the universe and the early stages of the infant universe, soon after the Big Bang.
• Apart from direct future uses of neutrinos, there are technological applications of the detectors that will be used to study them. For instance, X-ray machines, PET scans, MRI scans, etc., all came out of research into particle detectors. Hence the INO detectors may have applications in medical imaging.