POSSuMUS

The development of a modular designed large scale scintillation
detector with a two-dimensional position sensitivity is presented
in this thesis. This novel POsition Sensitive Scintillating MUon
SiPM Detector is named POSSuMUS. The POSSuMUS detector is capable
to determine the particle’s position in two space dimensions with a
fast trigger capability. Each module is constructed from two
trapezoidal shaped plastic scintillators to form one rectangular
shaped detector module. Both trapezoids are optically insulated
against each other. In both trapezoids the scintillation light is
collected by plastic fibers and guided towards silicon
photomultipliers (SiPMs). SiPMs are light sensors which are capable
to detect even smallest amounts of light. By combining several
detector modules, position sensitive areas from 100 cm2 to few m2
are achievable with few readout channels. Therefore, POSSuMUS
provides a cost effective detector concept. The position
sensitivity along the trapezoidal geometry of one detector module
is achieved by the path length dependent amount of detected light
for crossing particles. The ratio of the light yields in both
trapezoids is calculated. This value corresponds to the position of
the particle traversing the detector. A spatial resolution in the
order of several mm is foreseen. The position sensitivity along the
scintillator module is determined by the propagation time of light
to the SiPMs located on opposite sides of the detector. A spatial
resolution of few cm is expected for this direction. The POSSuMUS
detector is applicable as large area trigger detector with a two
dimensional position information of crossing particles. This is
suitable in detector tests of large area precesion detectors or for
measuring the small angle scattering of cosmic muons. At the
beginning of this thesis, the determination of important SiPM
characteristics like the breakdown voltage is presented. In the
course of this work the detector principle is proven by the test of
the first prototype detector with straight tracks during an
experiment at CERN. In particular, a position sensitivity in both
directions is demonstrated. After this experiment the detector
development focuses on the enhancement of the amount of detected
light per event. Here several studies with results are presented.
The gained knowledge is realized in a second prototype detector,
whereby the results of straight and inclined tracks are presented.
A position sensitivity due to the trapezoidal geometry is obtained,
with a spatial resolution of up to 13 mm. This thesis concludes
with an outlook on the ongoing developments and to the future use
of the POSSuMUS detector.