A measurement of the photonuclear interactions of 180 GeV muons in iron

Abstract.

The energy spectrum and the cross section of photonuclear interactions of 180 GeV muons in iron were measured at the CERN SPS using prototype modules of the ATLAS hadron calorimeter. The differential cross section $(N_{A}/A)v{d}\sigma/{d}v$ for a muon fractional energy loss $v = \Delta E_{\mu} / E_{\mu}$ was measured in the range 0.1<v<1. The integrated cross section $(N_{A}/A) \int_{0.1}^{1} v{d}\s igma/{d}v$ is $(0.26 \pm 0.03_{stat} \pm 0.03_{syst})\cdot 10^{-6}$ cm²g^-1 in agreement with the theoretical prediction of $0.267 \cdot 10^{-6}$ cm²g^-1. The best adjustment of the data to the theory is achieved for the value of $\sigma_{\gamma N} = (115 \pm 18_stat \pm 15_{syst})\mu {b}$ of the photon-nucleon cross section for photons with energies in the range from 18 to 180 GeV.