K. Seidel

Top quark mass measurements at and above threshold at CLIC

We present a study of the expected precision of the top quark mass determination, measured at a linear e+e− collider based on CLIC technology. GEANT4-based detector simulation and full event reconstruction including realistic physics and beam-induced background levels are used. Two different techniques to measure the top mass are studied: The direct reconstruction of the invariant mass of the top quark decay products and the measurement of the mass together with the strong coupling constant in a threshold scan, in both cases including first studies of expected systematic uncertainties. For the direct reconstruction, experimental uncertainties around 100xa0MeV are achieved, which are at present not matched by a theoretical understanding on a similar level. With a threshold scan, total uncertainties of around 100xa0MeV are achieved, including theoretical uncertainties in a well-defined top mass scheme. For the threshold scan, the precision at ILC is also studied to provide a comparison of the two linear collider technologies.

Particle showers in a highly granular hadron calorimeter

Abstract The CALICE collaboration has constructed highly granular electromagnetic and hadronic calorimeter prototypes to evaluate technologies for the use in detector systems at a future Linear Collider. The hadron calorimeter uses small scintillator cells individually read out with silicon photomultipliers. The system with 7608 channels has been successfully operated in beam tests at DESY, CERN and Fermilab since 2006, and represents the first large scale tests of these devices in high energy physics experiments. The unprecedented granularity of the detector provides detailed information of the properties of hadronic showers, which helps to constrain hadronic shower models through comparisons with model calculations. Results on longitudinal and lateral shower profiles, compared to a variety of hadronic shower models, first results with a software compensation technique for the energy resolution and an outlook on the next generation detector prototype are presented.