  Precision physics at future multi-TeV lepton colliders such as CLIC requires
excellent jet energy resolution. The detectors need deep calorimeter systems to
limit the energy leakage also for very highly energetic particles and jets. At
the same time, compact physical dimensions are mandatory to permit the
installation of the complete calorimeter system inside high-field solenoidal
magnets. This requires very dense absorbers, making tungsten a natural choice
for hadron calorimeters at such a future collider. To study the performance of
such a calorimeter, a physics prototype with tungsten absorbers and
scintillator tiles with SiPM readout as active elements has been constructed
and has been tested in particle beams at CERN over a wide energy range from 1
GeV to 300 GeV. We report on the construction and on the operational experience
obtained with muon, electron and hadron beams.
