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SeaQuest E-906 Trigger

Supported by Fermi National Accelerator Laboratory &
Physics Department, Mississippi State University
Fig.1. Schematic of SeaQuest E 906 experimental setup. ©Shiuan-Hao, FNAL

Fig.2. Expanded Feynman diagram of the Drell - Yan Process

SeaQuest is a fixed target experiment where the proton beam from the main injector of FermiLab at 120GeV impacts various targets such as hydrogen and deuterium. The experiment aims to investigate the asymmetry in the quark sea viz. ūƌ asymmetry. If we can pin point the Drell – Yan interactions, we could probe the number of ūƌ in the target hadrons. Refer to Fig.1 for a schematic diagram of the experimental setup. Notice that there are two magnets, one the near the target which is a focusing magnet and another is the old KTeV magnet which bends many unwanted muons out of spectrometer acceptance. The spectrometer consists of a number of hodoscopes which trigger and wire chambers which track the muons. The di-muon Drell-Yan (ref. Fig.2) which is one of the many processes that occur when two hadrons are collided has a low cross section i.e. very few muons coming out of the target are from Drell-Yan process. Therefore an effective triggering system is required to select out the appropriate processes. The hodoscopes consist of arrays of scintillators arrays along ‘x’ and ‘y’ directions perpendicular to the beam. We plan to trigger by looking out for two simultaneous scintillations symmetrically opposite (across the beam axis) to each other, since the two muons from Drell – Yan are oppositely charged. Also, we are going to look for coincidence between the many hodoscope stations to rule out stray muons. The above logic shall be coded onto a FPGA in VME 1495 module.