Colloquia

The SpinQuest experiment (Fermilab E1039) is designed to explore one of the fundamental questions in hadronic physics: the contribution of sea quarks to the nucleon’s spin. Utilizing a 120 GeV unpolarized proton beam directed at a polarized proton and deuteron target, SpinQuest aims to measure the Sivers function, which describes the correlation between the momentum direction of the struck quark and the spin of its parent nucleon. By focusing on both Drell-Yan and J/ψ production processes, SpinQuest seeks to provide critical insights into the spin and momentum structure of the nucleon, particularly the contribution of antiquarks to its overall spin. I will present the motivation behind the experiment, including the importance of the Sivers function and how SpinQuest can advance our understanding of spin-dependent phenomena in QCD. I will also discuss the experimental design and progress, highlighting recent milestones such as the successful commissioning of the polarized target system and the initial polarized data collection.  I will review ongoing analysis and the roadmap toward extracting the Sivers asymmetry. Additionally, I will outline the experimental challenges faced, future plans for data collection, and the expected contributions of SpinQuest to the global understanding of nucleon structure.