The main purpose of the Transition Radiation Detector (TRD) located in the central
barrel of ALICE (A Large Ion Collider Experiment) is electron identification
for separation from pions at momenta pt > 1 GeV/c, since in this momentum range
the measurements of the specific energy loss (dE/dx) of the Time Projection Chamber
(TPC) is no longer sufficient. Furthermore, it provides a fast trigger for high
transverse momentum charged particles (pt > 3 GeV/c) and makes a significant
contribution to the optimization of the tracking of reaction products in heavy-ion
collisions. Its whole setup comprises 18 supermodules out of which 13 are presently
operational and mounted cylindrically around the beam axis of the Large Hadron
Collider (LHC). A supermodule contains either 30 or 24 chambers, each consisting of
a radiator for transition radiation creation, a drift and an amplifying region followed
by the read-out electronics. In total, the TRD is an array of 522 chambers operated
with about 28 m3 of a Xe-CO2 [85-15%] gas mixture.
During the work of this thesis, the testing, commissioning, operation and maintenance
of detector parts, the gas system and its online quality monitor, improvements
on the detector control user-interface and studies about a new pre-trigger module
for data read-out have been accomplished.
The TRD gas system mixes, distributes and circulates the operational gas mixture
through the detector. Its overall optimization has been achieved by minimizing gas
leakage, surveying, controlling, maintaining and continuously improving it as well
as designing and carrying out upgrades.
Gas quality monitors of the type \GOOFIE" (Gas prOportional cOunter For drIfting
Electrons) can be used in gaseous detectors as on-line monitors of the electron
drift velocity, gain and gas properties. One of these devices has been implemented
within the TRD gas system, while another one surveys the gas of the TPC. Both
devices had to be adapted to the specific needs of the detectors, were under constant
surveillance and control, and needed to be further developed on both hardware and
software side.
To improve the operation of the TRD, modifications on its DCS software (Detector
Control System) used for monitoring, controlling, operating, regulating and configuring of hardware and computing devices have been carried out. The DCS is
designed to enable an operator to interact with equipment through user interfaces
that display the information from the system. The main focus of this work was laid
on the optimization of the usability and design of the user interface.
The front-end electronics of the TRD require an early start signal (\pre-trigger")
from the fast forward detectors or the Time-Of-Flight detector during the running
periods. The realization of a new hardware concept for the read-out of the TRD
pre-trigger system has been studied and first tests were performed. This new module
called PIMDDL (Pre-trigger Interface Module Detector Data Link) is meant to
acquire all data necessary to simulate and predict the full pre-trigger functionality,
and to verify its proper operation. Furthermore, it shall provide all functionalities of
the so-called Control Box Bottom as well as keep the functionalities of the already
existing PIM (Pre-trigger Interface Module) in order to combine and replace these
two modules in the future.