The SpinQuest experiment will make use of the same spectrometer used in SeaQuest; this spectrometer was described in great detail in this article. On this web page, we give only a summary of the functions of each spectrometer element.

The primary goal of the spectrometer is to identify pairs of positive and negative muons from the leptonic decay of a virtual photon produced via quark–anti-quark annihilation, the so-called Drell-Yan process. This electromagnetic process has a much smaller yield than the strong-interaction processes that occur in the beam-target interaction, and so it is necessary to filter out the many hadrons produced, using thick iron absorbers. In our spectrometer there are two such absorbers.

The SpinQuest polarized target will replace the liquid H2, D2, and solid targets used in SeaQuest, and will be placed farther upstream to improve our ability to distinguish between target and beam-dump events.

The FMag is a combination hadron absorber, bending magnet, and beam dump. It both absorbs the enormous number of charged hadrons (primarily pions and kaons) produced in the target, and performs the first bending of the muons that we seek to detect.

Immediately following the FMag are a set of hodoscopes and wire chambers (Station 1) that provide the first triggering and tracking information, respectively.

The KMag, originally used in the KTeV experiment, is an open magnet that additionally bends the tracks of the muons, and is our primary tool for measuring the momentum of the muons.

Immediately following the KMag are a set of hodoscopes and drift chambers (Station 2); after an open drift space another set of hodoscopes and drifts chambers (Station 3) are in place.

Following Station 3 is a solid iron Hadron Absorber. This is needed because not every hadron is absorbed in the FMag; if a track seen in Stations 1-3 disappears in the Hadron Absorber, then it was probably not a muon.

The triggering and tracking package is completed by the Station 4 hodoscopes and proportional tubes following the Hadron Absorber.