Nuclear Physics: An Overview

0. Nuclear Physics – a fascinating subject

E=mc² ... In class 9, I was taught this simple equation. This is one of the most popular equations of science and it was given by none other than Albert Einstein. What does it mean? It mathematically tells us that mass (which you can see or feel) can be converted to energy (which cannot be seen or felt) and vice-versa. This was given as a part of Einstein's Special Theory of Relativity which talks about things becoming longer, clocks slowing down and many more counter-intuitive and very interesting ideas.

Everyone might have heard about the nucleus. The nucleus has protons (positively charged) and neutrons, but how are they held together? Protons should be repelled by each other, isn't it? They are held together by an enormous force called “Nuclear Force”, which is several times stronger than the Coulomb force of repulsion between the protons. Existence of such a force also implies the presence of an enormous amount of energy. Where does this energy come from? Some of the mass of the nucleus is converted to provide this energy. Nature is clever! The mass lost in the conversion is termed as mass-defect and the energy produced is called binding-energy. More the binding-energy per nucleon more stable the nucleus is (find out the most stable nucleus). It is this binding energy which is of interest for us.

Humans are trying to tap this vast energy using two types of nuclear reactions called nuclear fission and nuclear fusion. Nuclear fission reaction is used in modern day nuclear reactors and the fuel used is uranium, plutonium or thorium. The atomic bombs dropped on Hiroshima and Nagasaki was based on the same principle. Nuclear fusion reactions have so far been out of human reach. Though we have made the H-Bomb or the Super Bomb which works on this, we are unable to control it and put it to better use. The sun gains all its energy from this reaction. Scientists have been trying to replicate that reaction in a controlled manner. India is a member of the seven member group working on a project called ITER (International Thermonuclear Experiment Reactor) working on these lines. The ITER program is anticipated to last almost 30 years and cost over $13billion, which makes it one of the most expensive modern techno scientific mega projects.

There are also other areas of modern day research going on; these include particle physics, nuclear structure, hadron physics, neutrino physics, nuclear astrophysics and so on. All these began as a part of nuclear physics but today they are vast subjects. They are many research facilities working round the clock in these areas. To name a few CERN, KEK, FERMILAB, Argonne, GSI, SLAC, DESY, Brookhaven, Budker INP, JINR and CEA. Every year billions of dollars are being spent on research in these fields. Can't we put the money to better use is a question always raised. Everything we discover has its pros and cons; it is for us to make a judicious use of the available technology.

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