A new era in experimental nuclear physics has begun with the start-up of the
Large Hadron Collider at CERN and its dedicated heavy-ion detector system
ALICE. Measuring the highest energy density ever produced in nucleus-nucleus
collisions, the detector has been designed to study the properties of the created
hot and dense medium, assumed to be a Quark-Gluon Plasma.
Comprised of 18 high granularity sub-detectors, ALICE delivers data from
a few million electronic channels of proton-proton and heavy-ion collisions.
The produced data volume can reach up to 26 GByte/s for central Pb–Pb
collisions at design luminosity of L = 1027 cm−2 s−1 , challenging not only the
data storage, but also the physics analysis. A High-Level Trigger (HLT) has
been built and commissioned to reduce that amount of data to a storable value
prior to archiving with the means of data filtering and compression without the
loss of physics information. Implemented as a large high performance compute
cluster, the HLT is able to perform a full reconstruction of all events at the time
of data-taking, which allows to trigger, based on the information of a complete
event. Rare physics probes, with high transverse momentum, can be identified
and selected to enhance the overall physics reach of the experiment.
The commissioning of the HLT is at the center of this thesis. Being deeply
embedded in the ALICE data path and, therefore, interfacing all other ALICE
subsystems, this commissioning imposed not only a major challenge, but also a
massive coordination effort, which was completed with the first proton-proton
collisions reconstructed by the HLT. Furthermore, this thesis is completed with
the study and implementation of on-line high transverse momentum triggers.