Relatore
Summary
High-precision jet spectroscopy will be increasingly important in future high-energy
accelerator experiments, particularly at a Linear e+e− Collider. DREAM (Dual REAd-
out Method) calorimeters seem to be well suited for this task. The key aspect of
DREAM
detectors is the simultaneous measurement of scintillation light and
Cherenkov light generated in the shower development process. By comparing these
two signals,
the electromagnetic shower fraction can be measured event by event, both for single
hadrons and
for jets, and the detrimental effects of fluctuations in this fraction can be eliminated.
The merits of this technique were first illustrated with a calorimeter in which the
two signals are provided by two different types of optical fibers. More recently, we
have been concentrating on crystals (PbWO4 and BGO), which have the potential of
eliminating (or at least reducing) the contributions of the next two important sources
of fluctuations: photoelectron statistics and sampling fluctuations. I will describe the
techniques used to unravel the signals from these crystals into Cherenkov and
scintillation
components. The detailed time structure measurements we performed for these
studies
also make it possible to measure the contributions of neutrons to the signals. This
would
help to reduce the effects of fluctuations in nuclear binding energy losses, which is the
last frontier in the quest for ultimate hadronic calorimetric performance.
