  For calorimeter applications requiring precise time stamping, the time
structure of hadronic showers in the detector is a crucial issue. This applies
in particular to detector concepts for CLIC, where a hadronic calorimeter with
tungsten absorbers is being considered to achieve a high level of shower
containment while satisfying strict space constraints. The high hadronic
background from gamma gamma to hadrons processes at 3 TeV in combination with
the 2 GHz bunch crossing frequency at CLIC requires good time stamping in the
detectors. To provide first measurements of the time structure in a highly
granular scintillator-tungsten calorimeter, T3B, a dedicated timing experiment,
was installed behind the last layer of the CALICE WHCAL prototype, a 30 layer
tungsten scintillator calorimeter. T3B consists of 15 small scintillator cells
with embedded silicon photomultipliers, read out with fast digitizers over a
time window of 2.4 us, and provides detailed measurements of the time structure
of the signal. The offline data reconstruction performs an automatic gain
calibration using noise events recorded between physics triggers and allows the
determination of the arrival time of each photon at the photon sensor. The T3B
setup, its calibration and data reconstruction, as well as first results of the
time structure of the calorimeter response for 10 GeV pions recorded at the
CERN PS confronted with Geant4 simulations using different physics lists are
discussed.
