The STAR detector is one of the four experiments at the Relativistic Heavy Ion Collider

Relativistic Heavy Ion Collider

The Relativistic Heavy Ion Collider is one of two existing heavy-ion colliders, and the only spin-polarized proton collider in the world. It is located at Brookhaven National Laboratory in Upton, New York and operated by an international team of researchers...

 (RHIC) in Brookhaven National Laboratory

Brookhaven National Laboratory

Brookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...

, United States.

The primary physics task of STAR is to study the formation and characteristics of the quark gluon plasma (QGP), a state of matter believed to exist at sufficiently high energy densities. Detecting and understanding the QGP allows us to understand better the universe in the moments after the Big Bang

Big Bang

The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

, where the symmetries (and lack of symmetries) of our surroundings were put into motion.

Unlike other physics experiments where a theoretical idea can be tested directly by a single measurement, STAR must make use of a variety of simultaneous studies in order to draw strong conclusions about the QGP. This is due both to the complexity of the system formed in the high-energy nuclear collision and the unexplored landscape of the physics we study. STAR therefore consists of several types of detectors, each specializing in detecting certain types of particles or characterizing their motion. These detectors work together in an advanced data acquisition and subsequent physics analysis that allows final statements to be made about the collision.

The physics of STAR

Scientists believe that, in the fractions of a second after the Big Bang

Big Bang

The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

, the expanding matter was so hot and dense that protons and neutrons couldn't exist yet. Instead, the early universe was composed of tiny quarks and gluons, which in today's cool universe are confined to exist only within other particles like protons. Collisions of heavy nuclei at sufficiently high energies allow us to explore whether quarks and gluons do in fact become deconfined when subjected to high densities, and if so, what the properties of this matter (a.k.a. quark-gluon plasma

Quark-gluon plasma

A quark–gluon plasma or quark soup is a phase of quantum chromodynamics which exists at extremely high temperature and/or density. This phase consists of asymptotically free quarks and gluons, which are several of the basic building blocks of matter...

) are.