  The possibility to build a SiPM-readout muon detector (SiRO), using plastic
scintillators with optical fibers as sensitive volume and readout by SiPM
photo-diodes, is investigated. SiRO shall be used for tracking cosmic muons
based on amplitude discrimination. The detector concept foresees a stack of 6
active layers, grouped in 3 sandwiches for determining the muon trajectories
through 3 planes. After investigating the characteristics of the photodiodes,
tests have been performed using two detection modules, each being composed from
a plastic scintillator sheet, $100 \times 25 \times 1\,$cm$^{3}$, with 12
parallel, equidistant ditches; each ditch filled with an optical fiber of
$1.5\,$mm thickness and always two fibers connected to form a channel. The
attenuation of the light response along the optical fiber and across the
channels have been tested. The measurements of the incident muons based on the
input amplitude discrimination indicate that this procedure is not efficient
and therefore not sufficient, as only about 30\% of the measured events could
be used in the reconstruction of the muon trajectories. Based on the studies
presented in this paper, the layout used for building the SiRO detector will be
changed as well as the analog acquisition technique will be replaced by a
digital one.
