Browsing by Author "Vilakazi, Zeblon"

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    Development of a high-level trigger for the dimuon spectrometer of the ALICE experiment at the large hadron collider
    (2006) Becker, Bruce; Vilakazi, Zeblon; Cleymans, Jean
    The ALICE experiment at CERN's Large Hadronic Collider will mark the beginning of a new phase in the study of ultra-relativistic heavy ion-collisions. It will be possible to explore in great detail phenomena discovered or hinted at in the course of experiments at the Relativistic Heavy Ion Collider, in particular the signals of the quark-gluon plasma. One of the most promising signals of the creation of this new state of matter is the anomalous suppression of the Υ (bb) and J/v(cc) families. One of the main decay channels of these mesons is into dimuons and ALICE has a dedicated dimuon spectrometer in order to study the spectra of these interesting particles. The signal is, however, swamped by a large background from several other muonic sources. Due to the large data rate expected for ALICE and the limited bandwidth, a highly efficient and selective trigger is required for the experiment - the dimuon high-level trigger (dHLT). This thesis concerns the context, development and implementation of the ALICE dimuon high-level trigger. The physics context ot the experimentation is described, as well as the technical requirements of the system. The performance of the prototype is investigated with the use of Monte-Carlo simulations. An investigation into the performance estimates of system in the expected physics environment was performed, which validated the benchmarks, as well as investigation of the effect of possible modifications of quarkonia yields due to QGP formation on the response of the dHLT.
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    Heuristic optimisation and parameter estimation methods for modern cosmological surveys
    (2006) Elson, E C; Bassett, Bruce; Van der Heyden, Kurt; Vilakazi, Zeblon
    Includes bibliographical references.
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    Implementation of a Custom Muon High Level Trigger Monitoring System
    (2010) Mohlalisi, Seforo; Fearick, Roger; Buthelezi, Zinhle; Vilakazi, Zeblon
    A Large Ion Collider Experiment (ALICE) is one of the 4 major experiments at the Large Hadron Collider (LHC) at CERN. Its main aim is to investigate the physics of strongly interacting matter in proton-proton, nucleus-nucleus and nucleus-proton or proton-nucleus collisions at ultra high energy densi- ties, where the Quark Gluon Plasma (QGP) is expected to form. The experiment is expected to produce data at very high rates of about 25 Gbytes/s however the bandwidth to permanent storage is limited to about 10% (1.25 Gbyte/s) of the total expected data rates. In order to reduce data to permanent storage a special level of selecting interesting/relevant physics events is required. In ALICE the trigger (selection) of signals is issued based on a series of levels varying from levels 0 (L0) up to the High Level Trigger (HLT). For the ALICE muon spectrometer, the role of the trigger is to select events containing muon tracks, with the transverse momentum (pt) above a given threshold. Due to the limited spatial resolution of the muon trigger chambers a pt cut above a few GeV with the L0 trigger is not possible. While the L0 signal for the muon spectrometer is issued at about 700 - 800 ns, the HLT is delivered at about 1 ms. The role of the HLT is to perform online and o ine reconstruction of the ALICE muon spectrometer data in order to improve the measured (L0) pT resolution. In this way a better separation between relevant physics events and unwanted events (background) can be attainable, which could eventu- ally lead to lower trigger rates. The HLT is designed to improve signal- to-background ratio in the raw data transferred to the storage. In order to facilitate online/o ine data analysis the HLT monitoring system which will enable the user to graphically view the events during the reconstruc- tion phase was developed in this study. The system will read and decode the reconstructed events from the HLT analysis chain using the HLT Online Monitoring Environment including ROOT (HOMER) and displaying them on the ALICE Event Visualization Environment (ALIEVE). In addition, the ii utility, dHLTdumpraw, that inspects, with ner detail, the contents of all muon HLT internal data blocks and the detector data link (DDL) raw data stream is also described.