Highly granular scintillator-based calorimetry with novel photo-detectors 
for the future linear collider

CALICE collaboration

The precision physics programme at a future linear collider 
requires reconstruction of heavy bosons (W, Z, H) in hadronic 
final states in multi-jet events. We discuss the physics case 
for unprecedented jet energy resolution and show how it can 
be achieved by making optimal use of the tracking and calorimetry
detector information. In such a so-called particle flow approach,
each particle needs to be measured individually. This critically
depends on the spatial resolution of electromagnetic and hadronic
sampling calorimeters and motivates very fine longitudinal and
transverse segmentation. With novel photo-detectors, individual
read-out of small scintillator tiles (of area 10cm**2 or less)
becomes possible on a large scale. We present the principle 
characteristics of multi-pixel avalanche photodiodes working in
Geiger mode and report on the successful operation of a 108 channel
prototype calorimeter in the DESY electron testbeam. The design 
and expected performance of an 8000 channel prototype under 
construction for hadron test beams is also presented.