We know the nucleon - proton and neutron - as the fundamental building blocks of nuclei in atoms and neutron stars. The nucleon itself is a composite object having complex sub-structure with quarks and gluons bound inside the proton or neutron. The interactions between quarks and gluons in the nucleon are described by the quantum field theory of the strong nuclear force: quantum chromo dynamics (QCD). Since Friedman, Kendall and Taylor's first experimental observation of quark sub-structure in deep inelastic electron-proton scattering at the Stanford Linear Accelerator in 1969 significant progress in understanding the quark and gluon structure of the nucleon has been made. However, many important questions remain open; in particular we are still left with only rudimentary understanding of the origin of the proton spin. We propose to study proton spin structure using a truly novel scientific technique: the observation of W-bosons in high energetic polarized proton-proton collisions with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Parity violating W production will lead to separate measurements of the spin contributions from up- and down-quarks and their corresponding anti-quarks to the proton spin. The proposed measurement will resolve the quark and anti-quark spin-distributions as a function of the relative quark momentum to the proton with excellent statistical precision and systematic accuracy. The fast muon trigger for PHENIX will be based on resistive plate counter stations (RPCs), their front-end electronics for read-out, and large fast programmable gate arrays for the implementation of algorithms that can signal the rare formation of a W-boson in a p+p collision. Since a W signal is expected to occur only about once per billion p+p collisions, the trigger allows selection and storage of these interesting rare events and rejection of abundant background events. The RPCs are compact, relatively inexpensive devices that will produce an electronic pulse when an ionizing particle passes through their bulk. The electronics to signal the creation of a W boson consists of custom designed circuit boards that amplify and process the raw electrical pulses from all of the individual elements of the RPCs, followed by electronics to analyze the signals from the individual elements to determine if they are consistent with the creation of a W boson. The proposed project offers an outstanding training ground for graduate and undergraduate students as well as young researchers, who will do analysis at the frontier of nuclear physics and will gain experience in the design, construction, and testing of state-of-the-art detectors and readout electronics. 13 undergraduate students, eight graduate students and nine postdoctoral fellows work on the project now. In the future, the project will strongly rely on teams of undergraduate students to carry out the assembly of the RPC detectors at BNL. Summer support for 16 undergraduate students at BNL has been budgeted. More than 80 graduate students and 67 postdoctoral researchers from 13 countries currently work on PHENIX, and a large fraction will utilize the new equipment once completed. Historically, a large number of women have been involved in PHENIX research as both undergraduate and graduate students, contributing to the diversity of the science and engineering workforce. The PHENIX muon trigger group is lead by the Nuclear Physics Laboratory at University of Illinois at Urbana Champaign and has collaborators from Abilene Christian University, the University of Colorado at Boulder, Columbia University in New York, Iowa State University at Ames, Kyoto University in Japan, Peking University in Beijing, China, the joint US-Japanese Riken BNL Research Center at Brookhaven National Laboratory and the University of California at Riverside.
