Design and Kinematical Coverage of FNAL-E906 Spectrometer for Drell-Yan Measurement with 120-GeV Proton Beam

One of the major goals of the E906 experiment at FNAL is a precise measurement of the asymmetry between the distributions of $\bar{u}$ and $\bar{d}$ in the nucleon. With the 120 GeV proton beam and the liquid hydrogen and deuterium targets, muon pairs from the Drell-Yan process ($q + \bar{q} \to \gamma^* \to \mu^+ + \mu^-$) are measured. Particularly E906 focuses on the higher Bjorken-$x$ range ($>0.3$) of anti-quark distributions, at which a non-zero and unpredicted negative asymmetry has been observed by the FNAL-E866 experiment although it has a rather large experimental uncertainty. The E906 spectrometer has been designed to effectively collect high-$x$ events. This presentation will show the spectrometer design and its kinematical coverage of expected physics results.