Xe/D2 cross-section ratio at low xBj from muon scattering at 490 GeV/c

In this paper first measurements from the E665 experiment at Fermilab on the relative cross-sections of 490 GeV/c muons scattered from deuterium and xenon targets are presented. The scattered muons were in the kinematic range Q2 > 0.1(GeV/c)2 and very low xBj (0.001 < xBj < 0.1). Triggering on events in this kinematic region was accomplished with a special Small Angle Trigger which projected individual beam muons to form a veto region 30 meters from the target. Using this trigger, muons with scattered angles as small as 0.5 milliradians were detected