Electromagnetic Shower Profile Measurements in Iron with 500 MeV Electrons

The longitudinal and lateral shower profiles for 500 MeV electrons in iron are studied using dosimetry and activation techniques. The results are compared with Monte Carlo simulations and other previously published data. The agreement between the data and the EGS4 simulation results is good; a simple shower profile parametrization of type kz exp (−βz) does not represent the experimental data well at and around the shower maximum. The differences observed in the activation and dose profiles clearly show the role of photons in electromagnetic showers. The photon fraction increases as the shower develops deeper and they carry a larger energy fraction farther into the absorber. Photodisintegration reactions are responsible for the activation of iron and we identified Mn, Fe and Mn as more active isotopes among several others. These studies were performed for estimating the dose and its profile for the CMS quartz fiber calorimeter radiation damage work performed at LIL (CERN).