Thursday, 23rd October 2014

Nepalnews Exclusive: A Nepali scientist involved in ground-breaking research in physics


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A Nepali physicist, Dr Yadav Pandit, is involved in a trailblazing research to find how the subatomic particles that filled the early universe transformed into the ordinary matter of today’s world.

Coming from an average Nepali family from Pyuthan district, Pandit, currently rubs shoulders with nuclear physicists and scientists involved in cutting edge researches in basic science.

A product of public school system of Nepal, Pandit has had an inspiring career in a subject that is considered too difficult and technical. Physics itself is considered to be a difficult subject and "nuclear physics" is an area where probably most talented brains work.

But humble backgrounds and simple upbringing did not pose any obstruction to Pandit’s progress,

Pandit is working with a team of scientists at the Brookhaven National Laboratory in the United States where they are trying to recreate matter at the extreme temperatures and densities that existed just after the Big Bang by smashing together ordinary atomic nuclei at the Relativistic Heavy Ion Collider<http://www.bnl.gov/rhic/> (RHIC).

At peak performance, this extraordinarily versatile atom smasher at the U.S. Department of Energy’s Brookhaven National Laboratory reproduces the primordial soup thousands of times per second. Using sophisticated detectors to track what happens as exotic particles emerge from the trillion-degree collision zone and “freeze out” into more familiar forms of matter, scientists are turning up interesting details about how the transition takes place.

“When we collide gold nuclei at RHIC, we observe particles flowing in a variety of ways from the point of the collision,” said Yadav Pandit, who produced these results as a graduate student at Kent State University. Dr Pandit is among a group of young scientists who have earned PhDs in physics by conducting detailed studies of RHIC collision data—in his case, by analyzing STAR data on one particular type of particle flow, called directed flow that is due to the residual motion of the particles that make up the colliding nuclei.

We can think of directed flow as similar to drag: If two gold nuclei collide off-center and heat up the surrounding area, pressure from the sudden expansion produces a twist in the momentum distribution of the particles as they continue on their way in opposite directions.

“When the collision takes place at energy close to a first-order phase transition, the expansion and the resulting deflection of the emitted particles is ‘softened,’” said Pandit, now a postdoctoral fellow at the University of Illinois. “Energy that would normally expand the system is instead going into changing the state of matter—melting the hadrons to free the quarks and gluons.”

The STAR data show that directed flow is strong at both the lowest and highest RHIC energies. But somewhere between 10 and 20 GeV, STAR observes a sudden switch in the twist of particles. The directed flow disappears, allowing other types of flow previously masked by the strong effect of drag to show up in particle distribution patterns. That disappearance, or collapse, of directed flow—when the expansion stops and then resumes once all the matter has gone through the change—is the “latent heat” signature of a first-order phase transition the physicists were looking for.

Details about this research are reported by top US scientific journals and papers including:

http://cnr2.kent.edu/FirstOrderPhaseTransition.pdf

http://www.newswise.com/articles/from-quark-soup-to-atoms-and-stars

http://www.symmetrymagazine.org/article/april-2014/from-quark-soup-to-ordinary-matter

Pandit and his team’s discovery of first order phase transition in dense nuclear matter (QGP) has been described as the third most important discovery in nuclear physics since the discovery of Higgs boson (so-called God’s particle) in 2012 and discovery of  inflationary gravitational waves from BICEP2 experiment early this year.

After acquiring M.Sc. in Physics from Tribhuvan University in 1996, Pandit was active in student politics and social work in Nepal and later did his Masters in Physics from the Kent State University in the USA. He completed Ph.D. in experimental nuclear physics from the same university in 2012.


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