I am a PhD student in nuclear physics at UC Davis. Currently, I am analyzing data from fixed target collisions at STAR. I am also contributing to hardware development for the future Electron-Ion Collider (EIC). My master's project concerned the analysis of flow in small systems with ALICE. I am proud to have my thesis on file at the Royal Danish Library. Below is a summary of the topic of my research. Here is a short video about our group's research activities, created for the American Physical Society March meeting 2023.
The Strong Force and the Quark Gluon Plasma
The atom is composed of two parts: electrons and the nucleus. Inside of the nucleus are protons and neutrons, which are in turn composed of fundamental particles called quarks and gluons. Studying how quarks and gluons interact is crucial if we wish to gain a fundamental understanding of the universe. Our best understanding of quarks and gluons is described by the theory of quantum chromodynamics (QCD), which tells us that gluons are the mediators of what is known as the "strong nuclear force", which interacts with quarks (and themselves) and binds them together in the protons, neutrons, and other hadronic matter we see in nature. An interesting characteristic of quarks is that they are normally not found alone - they are grouped together into (mostly) groups of 2 or 3 called mesons and baryons, respectively. This phenomenon is known as confinement - quarks are confined to exist within baryons and mesons - baryons being the protons and neutrons, and other particles with three valence quarks. However, under extreme conditions, such as those present shortly after the Big Bang, quarks and gluons are believed to forego their usual confinement and melt away into a state of matter consisting of free quarks and gluons known as the quark-gluon plasma. Great experimental effort is dedicated to measuring different QGP properties using modern particle collider endeavours, such as the Large Hadron Collider (LHC) and the relativistic heavy ion collider (RHIC).
At such experiments, heavy ions such as gold and lead are smashed together in an effort to understand more about strongly interacting matter and the QGP. Through studying the collisions we can learn about properties of the QGP such as its viscosity, temperature, and evolution. A critical question concerns the onset of deconfinement - when do particles like protons and neutrons give way to free streaming quarks and gluons? How hot, and how dense do things have to be to reach this new phase of matter? The question is akin to asking under what conditions do "everyday" substances like water change phase. Instead of asking at what temperature and pressure does water go from solid to liquid, we can instead ask at what temperature and baryon chemical potential does matter change from a hadronic gas to a QGP? This can be illustrated by a QCD phase diagram.
The QCD phase diagram is a graph that shows the different states of matter as a function of temperature and energy density. It represents the phase transitions that occur in the strong interaction, as the temperature and density of the system change. The phase diagram is divided into several regions, including the hadronic phase, which is made up of protons, neutrons, and mesons, and the quark-gluon plasma (QGP) phase, in which quarks and gluons are no longer confined within hadrons and are free to move independently. The QCD phase diagram also shows the critical point, which marks the change from a first-order phase transition to a crossover transition. Beyond the critical point, the change from the hadronic phase to the QGP occurs smoothly and continuously, rather than abruptly. Studying the QCD phase diagram helps us to understand the behaviour of matter under extreme conditions and provides insights into the nature of the strong force, and thus matter. Experimentalists like myself wish to map this phase diagram using heavy ion collisions.
Simple model of an atom
A sketch of a baryon containing three quarks, bound together by gluons
QCD Phase Diagram
RHIC and STAR
The Relativistic Heavy Ion Collider (RHIC) is a particle accelerator located at Brookhaven National Laboratory. It is used to study the behavior of matter under extreme conditions of temperature and energy, specifically the quark-gluon plasma (QGP), a state of matter that is believed to exist in the early universe. At RHIC, heavy ions, such as gold or lead nuclei, are accelerated to high speeds and then collided with each other, creating temperatures and energy densities high enough to facilitate QGP creation. We study the resulting matter to learn about its properties and behavior, as well as to gain insights into the early universe and the nature of the strong force.
The Solenoidal Tracker at RHIC (STAR) is a large particle detector located at RHIC. STAR is used to study the properties of matter under extreme conditions of temperature and energy. The detector is designed to track the movement of particles produced in the collisions of heavy ions, allowing us to study the behaviour of nuclear matter. The data collected by the STAR detector has provided valuable insights into the properties of the QGP and the nature of the strong force.
