Speaker
Description
Increasing precision requirements on particle reconstruction in future collider experiments ask for calorimeter systems with a high granularity. These calorimeters offer a unique and detailed view into electromagnetic and hadronic particle showers. We have performed test measurements with a digital Si-W electromagnetic calorimeter prototype using high granularity Monolithic Active Pixel Sensors. The individual readout of the 24 sensor layers and the granularity of 30×30 µm2 allow measurement of showers in unprecedented detail.
Measured average shower distributions in 3 dimensions for electrons with beam energies between 2 and 244 GeV are presented. The lateral distributions per layer are unique measurements with this detector. These have been compared to different analytical functions. Because none of the earlier proposed functions provide a perfect description, a new parameterisation has been introduced, which provides a better fit.
Detailed shower measurements are a perfect tool for testing and improving shower simulation models. We compare the measured shower distributions to MC simulations with GEANT4. While the overall features are in good agreement, a number of deviations are observed which will be pointed out and discussed.
In addition, we will present first studies of event-by-event fluctuations of the shower development in our detector, such as the distributions of shower start position, shower depth and width in data and MC events.
