भारतीय प्रौद्योगिकी संस्थान (का.हि.वि.) वाराणसी

The ALICE Experiment at the LHC

Deep beneath the Franco-Swiss border, the Large Hadron Collider (LHC) at CERN accelerates particles to nearly the speed of light before smashing them together. Among the four giant detectors at the LHC, ALICE (A Large Ion Collider Experiment) is specially designed as a "time machine" to study the universe's first moments. Just after the Big Bang, matter was not made of atoms but of an ultra-hot, dense soup of quarks and gluons—a state called quark-gluon plasma (QGP). The behavior of these particles is governed by Quantum Chromodynamics (QCD) , the fundamental theory of the strong force. By colliding heavy ions (like lead nuclei), ALICE recreates this primordial soup in a tiny fireball, allowing scientists to study how quarks and gluons, normally confined inside protons and neutrons, break free and then recombine. Understanding this transition gives us profound clues about the strong force and the evolution of our universe.

My work within the ALICE collaboration focuses on understanding how tiny, exotic particles called quarkonia (specifically the J/ψ particle) are produced under extreme conditions. As part of my Ph.D., I analyzed data from proton-proton collisions to study how these particles behave when there is an unusually high number of other particles around. This research helps uncover whether "QGP-like" signatures can appear even in small collision systems, challenging our view of what creates the primordial soup. More recently, I have been analyzing the elliptic flow (v₂) of J/ψ particles in lead-lead and oxygen-oxygen collisions using Run 3 data from the LHC. By measuring how these particles flow azimuthally from the collision zone, we gain direct evidence of the QGP's collective motion and properties. A key aspect of this analysis is studying the thermalization of charm quarks—whether the relatively heavy charm quarks have enough time to equilibrate with the expanding QGP medium. Since elliptic flow arises from anisotropic pressure gradients, a non-zero v₂ for J/ψ mesons at low transverse momentum indicates that charm quarks participate in the collective flow, providing strong evidence for their thermalization in the deconfined medium.

The STAR Experiment at RHIC

On Long Island, New York, at Brookhaven National Laboratory, the Relativistic Heavy Ion Collider (RHIC) smashes heavy ions together at nearly the speed of light. Among its main detectors, STAR (Solenoidal Tracker at RHIC) is a powerful, house-sized camera designed to track thousands of particles emerging from each collision. Like ALICE at the LHC, STAR was built to study the quark-gluon plasma (QGP)—the ultra-hot, primordial soup of quarks and gluons that existed just after the Big Bang. But RHIC has a unique ability: it can vary its collision energy, allowing scientists to map out the QCD phase diagram and search for a predicted "critical point" where the QGP transitions into ordinary matter. By studying how particles flow and interact, STAR helps answer fundamental questions about the strong force, the structure of neutron stars, and the evolution of the early universe.

My work within the STAR collaboration focused on studying the electromagnetic field effect in heavy-ion collisions using isobar collisions (RuRu & ZrZr). When two heavy ions collide at high energy, they generate an extremely strong, brief magnetic field—one of the most intense fields ever created in a laboratory. This field induces a charge-dependent deflection of particles as they emerge from the collision, a phenomenon observable in the directed flow (v₁) . As part of my postdoctoral research at IMP, China, I analyzed how this charge-dependent $v_1$v₁ signal varies across different collision systems, particle species, and degree of overlaps of two colliding nuclei (centralities). Our results provided key experimental constraints on the electrical conductivity of the quark-gluon plasma—a fundamental transport property that tells us how well the QGP conducts electricity. 

The CEE Experiment at HIAF

In China, at the Heavy Ion Research Facility, a new experiment called CEE (Cooling Storage Ring External-target Experiment) is taking shape. Soon, it will be the first large-scale nuclear physics experiment at the HIAF (High Intensity heavy-ion Accelerator Facility) complex. Unlike the LHC and RHIC, which smash particles at the highest energies to create the quark-gluon plasma, CEE operates at much lower beam energies—from a few hundred million to about one/two billion electron volts per nucleon. This energy range is special because it allows scientists to explore the high-baryon-density region of the QCD phase diagram , where the nuclear matter is extremely dense but relatively cool. Here, researchers can search for the predicted QCD critical point—a phase transition "landmark" where ordinary nuclear matter turns into quark-gluon plasma . The CEE spectrometer, with its large tracking system including a Time Projection Chamber (TPC), will measure thousands of collision events per second to map out the properties of dense nuclear matter and the equation of state that governs neutron stars.

My work within the CEE collaboration focused on developing the track reconstruction software for the experiment's Time Projection Chamber (TPC)—the main tracking detector. When heavy ions collide at CEE, thousands of charged particles fly out in all directions. The TPC captures their paths, but the raw data must be converted into actual particle trajectories (called "tracks") before any physics analysis can begin. I helped design and implement a tracking algorithm based on two powerful techniques: a Cellular Automaton (CA) for pattern recognition (finding candidate track segments) and a Kalman Filter for precise track fitting and parameter estimation . I evaluated the performance of tracking algorithm under various TPC configurations, studying track-finding efficiency and spatial resolution. This software is essential for turning the raw electronic signals from the TPC into meaningful physics data—charge particle momenta, positions, and identities—that will allow CEE to study the properties of dense nuclear matter.

References

• ALICE @ LHC : https://alice-collaboration.web.cern.ch/

• STAR @ BNL : https://www.star.bnl.gov/

• CEE @ HIAF : https://english.imp.cas.cn/research/facilities/HIAF/

Fellowships & Prize

Selected Fellowships (Declined / Alternate)

*The following international fellowships were offered in 2026, not joined, as the priority was to accept the Assistant Professor position at IIT BHU and stay in India.

Link to full List of publications:

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