Speaker
Stefano Gallorini
(Universita e INFN, Padova (IT))
Description
The LHCb tracking system consists of a Vertex Locator around the
interaction point, a tracking station with four layers of silicon strip
detectors in front of the magnet, and three tracking stations, using either
straw-tubes or silicon strip detectors, behind the magnet. This system
allows to reconstruct charged particles with a high efficiency (typically >
95% for particles with momentum > 5 GeV) and an excellent momentum
resolution (0.5% for particles with momentum < 20 GeV). The high momentum
resolution results in very narrow mass peaks, leading to a very good
signal-to-background ratio in such key channels as Bs -> mu mu. Furthermore
an optimal decay time resolution is an essential element in the studies of
time dependent CP violation. Thanks to the excellent performance of the
tracking system, a decay time resolution of ~50 fs is obtained, allowing to
resolve the fast B0s oscillation with a mixing frequency of 17.7 ps-1. In
this talk, we will give an overview of the track reconstruction in LHCb and
review its performance in Run I of the LHC. We will highlight the challenges
and improvements of the track reconstruction for the data taking period from
2015 on, discussing efforts to improve the timing in the online
reconstruction as well as approaches to unify the online and offline
reconstruction. The upgrade of the LHCb experiment will run at an increased instantaneous luminosity of 2x10^33 cm^-2 s^-1 with a fully software based trigger,
allowing to read out the detector at a rate of 40MHz. For this purpose, the
full tracking system will be newly developed. We will present the
performance of the tracking system for the LHCb upgrade, highlighting the
improvements with respect to the current tracking system of LHCb, and review
the track finding strategy. Special emphasize will be put on the need for
fast track reconstruction in the software trigger, also giving examples of
the potential use of parallelism in the pattern recognition. Finally, we
will give some prospects of the physics performance with the LHCb upgrade
for channels relying on excellent tracking capabilities.
Author
Stefano Gallorini
(Universita e INFN, Padova (IT))
