  The International Large Detector (ILD) is a concept for a detector at the
International Linear Collider, ILC. The ILC will collide electrons and
positrons at energies of initially 500 GeV, upgradeable to 1 TeV. The ILC has
an ambitious physics program, which will extend and complement that of the
Large Hadron Collider (LHC). A hallmark of physics at the ILC is precision. The
clean initial state and the comparatively benign environment of a lepton
collider are ideally suited to high precision measurements. To take full
advantage of the physics potential of ILC places great demands on the detector
performance. The design of ILD is driven by these requirements. Excellent
calorimetry and tracking are combined to obtain the best possible overall event
reconstruction, including the capability to reconstruct individual particles
within jets for particle ow calorimetry. This requires excellent spatial
resolution for all detector systems. A highly granular calorimeter system is
combined with a central tracker which stresses redundancy and efficiency. In
addition, efficient reconstruction of secondary vertices and excellent momentum
resolution for charged particles are essential for an ILC detector. The
interaction region of the ILC is designed to host two detectors, which can be
moved into the beam position with a push-pull scheme. The mechanical design of
ILD and the overall integration of subdetectors takes these operational
conditions into account.
