Studies of Quark-Gluon Physics

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

It is now a well-established fact that nucleons, protons and neutrons, are made up of more elementary particles called quarks. The main physics program supported by this grant is to study of the quark structure of nucleons. More information is needed about the details of this quark structure. One aspect that is particularly interesting is the existence of anti-quarks in the proton, which is a consequence of quantum mechanics. An experiment called Seaquest uses high-energy protons from the Fermilab accelerator to study these anti-quark distributions in the nucleon and in nuclei. This experiment will achieve unprecedented accuracy in the determination of the anti-quark distributions. Beyond the field of particle physics, these distributions are useful in cosmology as they seek to understand matter at the galactic scale. Beyond the scientific goals, the proposed detector commissioning, data acquisition and analysis activities will continue to offer education and research experience to undergraduates and graduate students. This three-year research program will study the ratio of anti-down quarks to anti-up quarks in the nucleon and in nuclei using the Drell-Yan reaction at Fermilab. At high momentum fraction these poorly known anti-quark distributions may provide a partonic understanding of the well known "pion cloud" model of classical nuclear physics. The reaction in nuclear targets will also be used to study quark energy loss. The Colorado group has nearly completed a new tracking detector for the Seaquest spectrometer, providing a larger acceptance and higher rate capabilities, and plans to complete, install, and commission this detector.