Speaker
Description
Future digital and semi-digital hadron calorimeters, will consist of 40-50 layers of thin
sampling elements interposed between absorber planes. The total area coverage of such
elements could reach a few thousands of square meters, thus requiring robust, cost-
effective solutions. The thin, single-element Resistive Plate WELL (RPWELL) detector
concept could be an effective solution for DHCAL, SDHCAL and for other applications
requiring particle tracking at moderate, sub-mm spatial resolutions.
The RPWELL comprises of a single-sided Thick Gas Electron Multiplier (THGEM)
electrode, coupled to a segmented readout anode through a resistive plate (~10 9 -10 11
Ωcm). The properties of the RPWELL have been demonstrated, on series of small- and
medium-size prototypes, with Semitron ESD225 plastic or doped silicate glass resistive
plates. Beam tests with relativistic muons and pions of a 300x300 mm 2 RPWELL
detector prototype, with SRS-APV25 readout electronics were recently carried out; they
have demonstrated its potential applicability to DHCAL & SDHCAL: high detection
efficiency at low average pad multiplicity, under discharge-free operation, in both neon
and argon-based gas mixtures. Argon based mixtures are economic and allow reducing
the drift gap and hence the design of few-millimeter thick detectors.
On the basis of the knowledge accumulated, a thin, self-supporting 500x500 mm 2 glass-
RPWELL detector prototype with anode-strips readout was designed and built for the
first time; it was assembled using a gluing technique under vacuum, with the resistive
plate coupled to the anode through a resistive-layer/epoxy film.
This large-area detector prototype, with SRS/APV25 electronics, yielded good
performance at the laboratory. It will undergo extensive test-beam investigations in July
2017, at CERN-SPS.
In the near future, new detector modules will be assembled with dedicated MICROROC
embedded electronics, developed for SDHCAL applications. This would be a crucial step
towards the integration of RPWELL sampling elements into a full SDHCAL prototype.
