Electromagnetic Interactions In The Minos Detectors

MINOS is a long-baseline neutrino experiment designed to observe the oscillation of neutrinos traveling between two detectors, a Near Detector at Fermi National Accelerator Laboratory and a Far Detector at the Soudan Underground Laboratory in northern Minnesota. Precision measurement of the oscillation parameters requires a better than 5% absolute energy calibration which is derived using a calibration detector, called CalDet. A smaller version of the MINOS detectors, the CalDet was exposed to particle beams in the CERN PS East Area test beams in 2001–2003. This document describes the conditions under which the CalDet beam data were taken, establishes selection criteria to identify a sample of electrons, and discusses the characteristics of electromagnetic interactions in the CalDet. Showers initiated by electrons at a range of incident momenta are compared to Monte Carlo modeling and contrasted against hadronic showers. Finally, the detector electromagnetic response and energy resolution are parameterized as a function of incident momentum, and showers induced by single electrons are compared to showers induced by simulated neutrino interactions.