Important Particles You Often Hear Of 

Higgs Boson: The God particle

  • Higgs boson is another particle that you must have heard of. Back in 1960s scientists predicted the presence of a particle that is responsible for giving mass to other particles like electrons, quarks, neutrinos etc. It was called Higgs boson.
  • Higgs boson was discovered in 2012 for which Nobel prize was conferred upon in 2013.
  • It is Higgs boson that gives mass to everything.
  • It is because of Higgs boson that big-bang happened and everything including you and me were created. This is why it is aptly called the god particle.

Neutrino: The ghostly particles

What are neutrinos?

  • Neutrinos as you can see in the chart are fermions, particularly leptons.
  • Neutrinos are very light, nearly massless.
  • It is a lepton without a charge. (unlike electron which is a lepton with a charge)
  • Since they are within nucleus they are released whenever there is decay of the nucleus. (radioactivity)
  • Whenever a nucleus decays it can give rise to 3 kinds of radiation alpha, beta and gamma. 
    • Alpha: 2 protons and 2 Neutrons moving at high velocity. (very heavy and very fast so high energy)
    • Beta: Very fast electrons (not heavy but very fast)
    • Gamma: High energy radiation (very fast)
  • Neutrinos are released whenever there is beta decay. i.e. whenever nucleus of an atom decays with beta radiation there is an accompanying stream of neutrinos.
  • Source: Stars, Supernovae, Galaxies, (even) Nuclear reactors.

What is special about them?

  • Being almost massless and chargeless they don’t interact with matter. (unlike a photon which is stopped by a wall, your hand, atmosphere etc. or an electron which is neutralized by a proton)

So everything is transparent to neutrinos. Neutrinos pass through everything unimpeded. Note: Every other sub-atomic particle interacts with matter and is affected by it in some way or the other. (absorb, reflect or deflect)

Solar neutrinos

  • Neutrinos are present wherever there is radioactivity.
  • Sun or stars in general are engines of nuclear fusion where lighter nuclei are fusing to form heavier nuclei. (helium from hydrogen) In the process they release neutrinos.
  • Eg: 4 Hydrogen fuse to form 1 helium in our sun. Hydrogen has 1 proton and 1 electron and no neutron. Helium on the other hand has 2 protons, 2 electrons and 2 neutrons. So in a fusion 4 protons and 4 electrons are 2 protons 2 electrons and 2 neutrons. This happen through a series of steps. (details not important for us). Proton become neutron. In the process releases neutrinos.  Fusion in sun produces 10^38 neutrinos each second. About 10^14  solar neutrinos pass through each square meter of the Earth.
  • All the neutrinos that are emitted from the sun is coming to us unimpeded because remember they don’t interact with matter like a photon or electron or proton.
  • There are trillion and trillions of neutrinos that are hitting you as you are reading this every second and you don’t even feel it.

Neutrino Astronomy (cutting-edge)

  • Neutrinos are one of the gateways to heavens. Electromagnetic and gravitational radiations are others.
  • Significance: Unlike electromagnetic waves neutrinos travel unimpeded by matter and thus can reveal information about the source as is.
  • Recently we have detected neutrinos from a galaxy for the 1st time and this can tell us a lot about galaxy than a picture we get by detecting light from it. (remember neutrinos come unimpeded unlike photons) ICECUBE is the name of the observatory.

Neutrino Observatories

  • All neutrino detectors are built underground, under mountain or under ice. This is because all sub-atomic by-products of radiation are absorbed by earth except neutrinos.
  • While neutrinos pass unimpeded by matter, on rare occasions a neutrino will strike a neutron and convert it into a proton. This radioactivity that is induced by the neutrino is the basis of earliest neutrino detectors.
  • Note: See table below for names of observatories

Solar-neutrino problem: The ‘missing’ neutrinos

  • The amount of solar neutrinos detected by the earlier observatories did not match the calculations for the amount of solar neutrinos. Only about 1/3rd was detected.
  • This discrepancy in (missing gap of solar neutrinos) is called the solar neutrino problem.

Neutrino oscillation: Answer to ‘missing’ neutrinos

  • Physicists have found that neutrinos come in 3 different varieties. (see Standard Model chart)
  • In addition, these neutrinos change from one form to another in their journey (details of how it happens is not important for us)
  • But what is important is that only one of these types is produced in the Sun.
  • In its journey it is found that about two-thirds of solar neutrinos change its form and become other type. This effect is called neutrino oscillation.
  • So, neutrino oscillation is the answer to the ‘missing’ neutrinos’ (actually nothing was ‘missing’, only our detectors were not capable of detecting the other types)
  • Now we have observatories that detect all three types of neutrinos. (Sudbury Neutrino Observatory in Canada is one of them)
image 93

Important Neutrino Observatories


  • under-ice observatory
  • Near south pole
  • Recently detected neutrino coming from a galaxy. (1st time from a galaxy)


It can reveal details of blackhole at the center of the galaxy.

Note:  Neutrinos are created at the event horizon of the blackhole

Indian Neutrino Observatory

  • Proposed to be set up in Bodi Hills in Tamil Nadu.
  • TN is opposing the move as the proposed site will fall within the confines of Periyar tiger corridor and Mathikettan Shola National Park in the Western Ghats.


  • As the observatory will be at a depth of 1 km mountain rock will be subject to vertical stress and may create rock bust and roof collapse etc.
  • Harmful effects of radiation. (This is misplaced as neutrinos are harmless)

Cubic Kilometer Neutrino Telescope

European detector under construction off the coast of France, Italy, and Greece.

China’s planned neutrino observatory

China is planning to build the world’s largest neutrino observatory under ocean

Kamiokande and Super-Kamiokande (Japan)

Hyper-Kamiokande is a planned observatory. To be the world’s largest.

What Standard Model does not explain?

  • Gravity, dark matter, dark energy, reason why there is more matter than anti-matter in the universe.

Sensing using fundamental particles

  • The basic principle behind sensing we are familiar with is to study the interaction of photons with matter.
  • Instead of photons we may study the interaction of other fundamental particles with matter to sense various features.
  • Examples include PET scan which uses beam of positrons instead of photons, Muon tomography which used beam of muons to sense.

PET scan

  • Studies the hydrogen distribution in body.

Muon tomography

  • Was recently used to study a large cavity in Egyptian pyramid recently.
  • Muons being negative particles are deflected by electrons of atoms with large atomic number. If we can measure the amount of deflection we can construct volume maps.
  • Besides muon tomography is used in 3-D imaging of large structures. Eg: Recently 3D reconstruction of a nuclear reactor was done using muon tomography.
Online Counselling
Table of Contents
Today's Current Affairs
This is default text for notification bar