Speaker
Description
The Belle-II experiment is a multipurpose particle detector which will
take data at the asymmetric electron positron collider SuperKEKB
operated at a design luminosity of $8\times 10^{35} cm^{-2} s^{-1}$.
Track reconstruction close to the interaction point in the Belle-II
experiment is provided by the Silicon Vertex Detector (SVD), consisting of
4 layers of double sided silicon strip detectors, and two layers of
pixel detectors (PXD). The SVD was designed to provide a high hit finding efficiency and
position resolution when operated in the high-luminosity environment
provided by the SuperKEKB collider.
In April 2016 a combined beam test of the SVD and
the PXD has been performed at DESY Hamburg to test
the full data acquisition chain which will be used
in the Belle-II experiment.
For this beam test a section of the SVD and the PXD have
been placed in a beam of high energy electrons.
Several runs of data taking have been recorded with
varying beam energies, ranging from 2 GeV up to 5 GeV, within
a magnetic field which strength was varied between 0 Tesla and 1 Tesla.
We use the data recorded at the beam test at DESY to perform
a measurement of the hit reconstruction efficiency and the resolution
of the reconstruction of hit positions of the
SVD-sensors. For this measurement we use reconstructed tracks
to predict the position of a hit on the SVD-sensor under test
and try to find reconstructed hits in the proximity of
the predicted position. Efficiencies are estimated by
counting how often a hit could be associated to
the reconstructed track. The spatial resolution of reconstructed
hits is estimated by analyzing the residuals of the
reconstructed hit positions with respect to the positions predicted by the
extrapolated track.
To avoid biases the SVD-sensor under test is not included
in the track finding and fitting procedure. The efficiency
is measured as a function of the position on the sensor.
