Relatore
Summary
We present a fine granularity development of the KLOE lead-scintillating
fibers calorimeter. A 23x15x55 cm^3 prototype, made of 200 grooved lead
foils, 0.5 mm thick, glued with scintillating fibers at 1.35 mm pitch,
has been instrumented on one side with an array of 3x5 light guides and
PMTs each covering a 4.2x4.2 cm^2 cells, while on the opposite side
the granularity has been increased by a factor of 16 by means of small
light guides and multianode photomultipliers. Scintillating light is
collected on the calorimeter side surface in 1.05x1.05 cm^2 cells,
corresponding to about 64 scintillating fibers, by means of truncated
pyramid light guides made of UV trasparent material (Bicron BC800),
and is driven to 16 anode PMTs (Hamamatsu R8900-M16) with an area
reduction factor of 4. A total of 240 readout pixels is obtained in this way,
making of this detector a real tracking calorimeter.
Each multianode PMT corresponds to a single anode PMT on
the opposite calorimeter side. Also, the first raw is equipped with high
quantum efficiency multianode PMTs. Each multianode provide also an OR of the
16 last dynodes which can be udes for triggering. A dedicated electronic to
collect and amplify the multianode signals has been developed. Signals
are then split, summed to make trigger patterns and digitalized in ADCs and
TDCs using the standard KLOE calorimeter electronic chain.
Here we describe the construction details, the measurement of the multianode
PMTs response and intrinsic cross talk using a ps laser pulse, the measurement
of the optical cross talk between adjacent light guides using the same laser
to illuminate single scintillating fibers on the side opposite to the
readout, and finally a cosmic ray test of the full device. A first
comparison of cosmics data with a detailed simulation of the detector
based on the FLUKA code is also possible.
