System Size and Energy Dependence on Strangeness Production in 22 GeV Cu+Cu Collisions at RHIC

Abstract

Abstract : The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory collides different ions at a wide variety of energies in order to study the properties of nuclear matter in extreme conditions. Beams of ions are sent around an accelerator ring at relativistic speeds approaching the speed of light before they meet in an extremely high temperature collision. The Solenoidal Tracker at RHIC (STAR) experiment exists to examine and identify the particles produced in these collisions in order to gather information about the behavior of quarks and gluons, the smallest known building blocks of matter. The strange quark is of particular interest since no strange quarks are sent into the collision. Consequently, the existence of particles with strange quarks, such as K0-shorts, Lambdas, and Anti-Lambda baryons, shows that strange quarks were produced from the energy of the collision. Particles carrying strange quarks (strangeness), therefore, carry information about the matter produced in the collision. This matter is believed to be quark-gluon plasma, a state in which quarks and gluons become deconfined in a space of extremely high energy and temperature. This project determines the yield of strange quarks through measurements of K0-short mesons as well as Lambda and Anti-Lambda baryons in collisions of copper nuclei conducted at 22 GeV, one of RHIC's lowest collision energies. The measurement of strangeness production for varying ranges of beam energy contributes to the overall understanding of the phase diagram for nuclear matter. The relatively low collision energy aids in the search for a critical point in nuclear matter phase transition. This project compares strangeness yields and spectra with current results from collisions at other beam energies and system sizes to allow better understanding of the properties of nuclear matter in extreme conditions.