Orateur
M.
Lei Xia
(Argonne)
Description
For several years, CALICE has been testing highly granular calorimeter
prototypes using analogue readout. These devices are envisaged for particle
flow application in a future linear collider detector. A novel alternative,
especially interesting for the hadron calorimeter, is to use digital readout,
with a very small cell size. In the past year the first large scale (1m³)
digital HCAL has been operated by CALICE in test beams at Fermilab. This
detector uses glass RPCs for readout within an iron absorber structure. The
RPCs are read out through 1x1 cm² pads with a single threshold, providing a
digital image of the shower with high spatial resolution. Including a similarly
equipped tail catcher, the system contains almost 500,000 readout channels. We
report on the technical performance of this calorimeter, and show first physics
results on shower reconstruction.
A related approach is to use RPCs with two-bit readout, providing three
threshold values, referred to as a "semi-digital" HCAL. This approach is being
pursued under the aegis of EUDET. Already in 2010 a full 1m² plane was tested
in a beam, and a full 1m³ is being tested at CERN in 2011. The current status
is reported. In addition, tests in 2010 demonstrated the performance of these
RPCs in a 3T magnetic field, and also showed that there was no degradation of
performance when the electronics was "power pulsed", a technique which is
envisaged to reduce power dissipation in an ILC detector. Alternative
technologies for a digital HCAL are also being studied, both Micromegas, for
which 1m² planes have already been tested in beams, and GEMs for which 30x30 cm²
units are currently being tested.
Second generation analogue devices are also under construction, and we
report progress here. The focus of this work is to develop technical solutions
which could be scaled up to a full-sized detector.
The development of a highly segmented electromagnetic calorimeter based on
silicon sensors with 5x5 mm² segmentation will be described, covering
developments in sensor design, readout electronics and the mechanical and
thermal issues of detector integration. The plan is to test one full-length
module along with a fully instrumented 18x18 cm² tower. Modules are also being
constructed using an alternative technology based on scintillator-strip sensors.
The second generation analogue HCAL is based on scintillating tiles that are
individually read out by silicon photomultipliers. The prototype will contain
about 2500 detector channels, corresponding to one calorimeter layer and aims at
demonstrating the feasibility of building a detector with fully integrated
front-end electronics.
Auteur principal
M.
Lei Xia
(Argonne)
