Lawrence Berkeley National Laboratory

Abstract. The energy loss spectrum of 180 GeV muons has been measured with the 5.6 m long finely segmented Module 0 of the ATLAS hadron Tile Calorimeter at the CERN SPS. The differential probability $${\rm{d}}P/{\rm{d}}v$$ per radiation length of a fractional energy loss $$v = \Delta E_{\mu} / E_{\mu}$$ has been measured in the range $$ 0.025 \leq v \leq 0.97$$; it is compared with theoretical predictions for energy losses due to bremsstrahlung, production of electron–positron pairs, and energetic knock-on electrons. The iron elastic form factor correction $$\Delta_{Fe}^{el} = 1.63 \pm 0.17_{stat} \pm 0.23_{syst} {\pm^{0.20}_{0.14}}_{theor}$$ to muon bremsstrahlung in the region of no screening of the nucleus by atomic electrons has been measured for the first time, and is compared with different theoretical predictions.