From the first collisions in March 2010 till two weeks before the Higgs boson announcement, Chennai-lad Rajivalochan Subramaniam was right there at the heart of the experiments. Here, he tells Education Plus readers the story, in simple language, of the great discovery that unfolded at European Center for Nuclear Research (CERN) lab, Geneva, Switzerland. And his own contribution.

I was involved in selecting interesting data from all the data collected at ATLAS detector. Let me explain what I mean by data. Hydrogen atom has one proton and one electron. If we strip off the electron from hydrogen atoms we will have protons.

In the Large Hadron Collider (LHC), we accelerate two counter rotating beams of protons to very high energy in a circular tunnel using superconducting magnets. Once the proton speed reaches near that of light, the two beams are allowed to collide. In such a situation each proton - proton collision is called an event or data.

If all the data from ATLAS were to be recorded, it would fill up 1,00,000 CDs per second. This would create a stack of CDs 450 feet high every second, which would extend up to the moon and back twice each year. The data rate is also equivalent to 50 billion telephone calls at the same time.

ATLAS actually only records a fraction of the data (those that may show signs of new physics) and that rate is equivalent to 27 CDs per minute. This is exactly the activity I was involved in. Along with other scientists, I designed a three-step process to check if the data needed to be saved or discarded. The time for this entire process is four micro seconds and so all these steps are automated. From time to time when the machine stops for maintenance we would have an opportunity to change these methods.

The discovery of the Higgs Boson-like particle did not happen on one day. It took two decades to build the machine. And we required enough statistics to actually declare the discovery. Any high school measurement experiment will involve several readings, and finally the average value of such readings will be computed. So this is somewhat similar to that but we were dealing with sizes that were much smaller than those at atomic scale and so we required two years of data to arrive at a conclusion.

On July 4, when the announcement was made, the atmosphere was electric. When I actually saw tears in the eyes of Peter Higgs who wrote this hypothesis 48 years ago I too felt very emotional. Everyone was under tremendous pressure and you were not spared for being a student. It is a several billion dollar experiment and we had to answer people.

The discovery was a great success. This is not the end as the entire characteristic of the new born particle is yet to be analysed. After all this, we were able to explain four per cent of the visible universe. Still, 96 per cent of the universe is dark energy and dark matter. In other words, we do not know anything about the mysteries of our universe.


A personal rediscovery at CERNJuly 16, 2012