Measurement of the nucleon structure function in iron using 215- and 93-GeV muons

Abstract

We have measured the inclusive deep-inelastic scattering of muons on nucleons in iron using beams of 93- and 215-GeV muons. To perform this measurement, we have built and operated the multimuon spectrometer (MMS) in the muon beam at Fermilab. Using the known form of the radiatively corrected electromagnetic cross section, we extract the structure function $F_2$(x,$Q^2$) with a typical precision of 2% over the range 5<$Q^2$<200 ${\mathrm{GeV}}^2$/${\mathrm{c}}^2$. We compare our measurements to the predictions of lowest-order quantum chromodynamics (QCD) and find a best-fit value of the QCD scale parameter ${\Lambda }_{\mathrm{LO}=230\mathrm{}\pm 40\left(\mathrm{stat}\right)\mathrm{}\pm 80\left(\mathrm{syst}\right)\mathrm{}}$ MeV/c, assuming R=0 and without applying Fermi-motion corrections. Comparing the cross sections at the two beam energies, we measure R=-0.06±0.06(stat)±0.11(syst). Our measurements show qualitative agreement with QCD, but quantitative comparison is hampered by phenomenological uncertainties. The experimental situation is quite good, with substantial agreement between our measurements and those of others.