optimisation Talk presented at the International Workshop on Future Linear Colliders (LCWS13)

The ILD, International Large Detector, is one of the detector concepts for a future linear collider. Its performance is investigated using Monte-Carlo full simulation and PandoraPFA. Among several options, a combination of the silicon-tungsten electromagnetic calorimeter (SiW ECAL) and the semi-digital hadronic calorimeter (sDHCAL) presenting the highest granularity calorime-ters, is here investigated. It is shown that by reducing the radius and length of the entire detector by a factor of ∼ 1.3 with respect to the baseline dimensions, the jet energy resolution is degraded by 8 to 19 % in the range of 45 and 250 GeV. The price of ILD which scales roughly quadratically with the ILD dimensions may be reduced by a factor of nearly two. A similar study made with the SiW ECAL and the analog hadronic calorimeter (AHCAL) shows that for an inner radius of ECAL of about 1.4 m, the performance is comparable between sDHCAL and AHCAL.