A Digital Hadron Calorimeter for the future
International Linear Collider
Abstract
The International Linear
Collider (ILC) is the upcoming
collider generation which
should push forward the high
energy physics towards new
frontiers. To face the
challenge, it requires the
upgrade of the detector
standards used in high energy
physics. New calorimeter
technology needs to be
developed .
The SiD detector concept is
one of the foreseen solutions
to track the particles and
discriminate their momentum.
Its capabilities will be based on
silicon detectors highly
segmented.
A digital hadronic calorimeter
(DHCAL) will be part of the SiD
detector. It is planned to
consist on stainless steel
layers to develop hadronic
showers spaced by active
volumes, where the particles
will deposit their energy, and a
solid state readout. A cm2
readout cells together with a
maximum of 8 to 10 mm
thickness of the active volume
is assumed to guarantee
excellent imaging capabilities.
The technology to be used in
the active cells of the DHCAL
is still an open issue and
several solutions compete.
When considering large areas,
a possible solution could be
the thick Gas Electron
Multiplier (THGEM). THGEMs
are considerable easier to
manufacture as the process is
reduced to mechanical hole
drilling on a PCB followed by
Cu-etching of the rims. Hence,
they are more cost effective,
robust and resistant to
damages induced by
discharges.
This work presents the first
beam tests of a THGEM based
prototype for DHCAL in order
to evaluate the feasibility of
minimum ionizing particles
(MIP) detection by a THGEM
architecture within the
requirements imposed by the
SiD detector concept.
Carlos Azevedo,
Ana Silva, Fábio Pereira, Pedro Correia, Lara Carramate, Ismael Castro, Luis Moutinho, Anabela Ribeiro,
Daniel Covita, João Veloso
Department of Physics (I3N/FSCOSD), University of Aveiro in collaboration with
University of Coimbra, Dept Phys, Portugal
Weizmann Inst Sci, Dept Particle Phys, Israel
University of Texas at Arlington, Dept Phys, USA
The SiD detector
The SiD is composed by: a vertex and tracking system at the
center; an electromagnetic calorimeter to provide information
about neutral particles; a hadronic calorimeter to related the
energy deposition of the charge particles with the paths identified
by the tracker; and a muon calorimeter. The goal is to achieve
excellent tracking capabilities together with outstanding energy jet
resolution (< 3-4%). The DHCal based in silicon detectors and high
granularity should provide excellent imaging capabilities and
energy resolution. The DHCal is planned to be about 1 m thick,
where 8 to 10 mm thick active cells are spaced by 20 mm thick
stainless steel layers to stop hadronic showers
Fig 4 / Pulse height distributions obtained with discrete electronics for muons by using a single
0.8 mm THGEM (left); and pions when employing a single 0.4mm THGEM structure (right).
New goal: 40x40 cm2 detector
HCal
R=2591 mm
Ecal
R=1250 mm
Fig 1 / A possible configuration of the SID detector concept: Quater section view where the
different detector shells are show (left); Inner section with the tracker, the elecromagnetic
calorimeter, the hadronic calorimeter and the solenoid (center); deteailed section view of the
electromagnetic and hadronic calorimeter (right).
THGEM based prototype
The measurements took place during two weeks at the CERNSPS/H4 beam line which can provide muons and pions up to
150 GeV.c-2. Four different detector geometries were tested by
using THGEMs 0.4 mm and 0.8 mm thick. Single and double
THGEM geometries were tested.
Fig 2 / Schematic of one of the single THGEM configurations (left) and double THGEM
configuration (right) tested.
Experimental Results (in-beam)
Fig 5 / Pictures of the new 40x40 cm² detector during the assembly: the pixelated anode (left)
and the installed THGEM (right).
A new detector with 40x40cm² was recently assembled being the
firsts tests in course. It is expectable to go for a test beam in
October/November 2014 using the new SRS electronic chain.
Conclusion
It was demonstrate that is possible to use a THGEM based
detector for hadronic calorimetry with a thickness bellow 8 mm.
The first prototypes with 10x10 cm² shown detection efficiencies
around 95% at stable operating conditions both for mouns and
pions. Although the achievable gain was rather moderate (~1000),
to avoid discharges and keep the detector stable, the signals were
unambiguously separated from the electronically noise with the
characteristic Landau distribution well defined.
A new step forward was achieve by building and assembly a
40x40cm² detector which should go to CERN for a test beam
before the end of the year.
References
Fig 3 / Efficiency study performed with muons at a flux of about 2-3kHz.cm -1 for a
single THGEM architecture (left) and a double THGEM configuration (right).
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