sPHENIX 

 

Main Project: 

sPHENIX is an upgrade of the PHENIX experiment at the Relativistic Heavy Ion Collider. It will study the extremely high-temperature, high-density matter created in collisions of large nuclei at RHIC. The properties of this material, the Quark Gluon Plasma, echo the conditions found in the earliest moments of the universe. This hot regime of quantum chromodynamics (QCD) lies at the intersection of nuclear physics with many-body quantum field theory, relativistic fluid dynamics, and condensed matter, and has implications for applications well outside the realm of subatomic physics. The evolution of a heavy ion collision is illustrated in Figure 1, indicating the different stages and time scales, and showing the various final-state particles that carry all accessible information.

sPHENIX

 

Research and Development:

Time Projection Chamber (TPC) : The Time Projection Chamber (TPC) is among several tracking components layered inside the 20-ton cylindrical superconducting magnet at the heart of the sPHENIX experiment. Its outstanding momentum resolution is key to capturing small differences among three states of particles called upsilons (made of heavy quark-antiquark pairs) as they interact with the QGP. sPHENIX’s ability to distinguish the mass of each upsilon variety will help physicists map the transition from the trillion-degree primordial QGP to ordinary nuclear matter. 

To reconstruct upsilons, sPHENIX will measure the trajectories of particles created when upsilon decays. Particles traversing TPCs gas volume leave a trail of ionization by knocking electrons off the gaseous atoms (about 100 freed electrons per interaction). It is hard to sense those 100s of electrons, to detect them amplification is required. For this purpose, TPC consists of several layers of gas electron multiplier (GEM) foils.