Test of Bjorken scaling in deep inelastic muon scattering at 150 and 56.3 GeV

A test of Bjorken scaling has been made at Fermilab in deep inelastic muon scattering by comparing two sets of data taken at 150 and 56 GeV. The muon beam was obtained from the decay of pions and kaons produced by letting the 300 GeV extracted proton beam strike the production target. The incident muon beam was detected by proportional chambers and the scattered muons from the iron target were reconstructed from a spectrometer consisting of wire spark chambers, scintillation counters and toroidal iron magnets. The apparatus had a large aperture and an azimuthally symmetric acceptance. It was designed so that the events with the same values of scaling variables, e.g., x = Q2/2Mν and y = ν/E0, go through the same region of the detectors at the two energies. Most of the systematic uncertainties cancel in comparing the two sets of data, thus increasing the sensitivity to the scaling behavior. The kinematic range investigated is Q2 up to 40 (GeV/c)2 and ν up to 100 GeV. The Q2 dependence of the ratio of 150 and 56 GeV data was corrected by Monte Carlo calculations to take out remaining nonscaling contributions. A possible breakdown of scaling was expressed in the propagator form, νW2(x,Q2) = νW2(x). N/(1 + Q2/Λ2)2. By constraining N to 1 +- 0.05, Λ-2 = (27 +- 36) . 10-4 (GeV/c2)-2 (9.3 percent confidence) was obtained and a lower limit to Λ was obtained to be 10 GeV/c2 in 95 percent confidence. Thus the result presented here is consistent with the scaling prediction. It is emphasized however, that the result is based on subsets of data analyzed assuming a particular form of breakdown