Browsing by Author "Marais, Mark"

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    Exact conservation of quantum numbers B, S and Q in the statistical description of high energy collisions
    (1997) Marais, Mark
    High energy collisions are studied assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The exact conservation of baryon number, strangeness and charge are explicitly taken into account. For heavy ions the effect arising from the neutron surplus becomes important and leads to a substantial increase in e.g. the π-/π+ ratio. Special emphasis is therefore put on the exact conservation of charge. Comparison with experimental results from the E866 collaboration at BNL is made.
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    The measurement and reduction of urban litter entering stormwater drainage systems: Paper 2 - Strategies for reducing the litter in stormwater drainage systems
    (2004) Marais, Mark; Armitage, Neil
    A previous South African study looked at the removal of litter from the drainage systems once it was already there. Yet the litter problem cannot be addressed in an effective and sustainable manner without an effective integrated catchmentwide litter management strategy. This strategy should include planning controls, source controls, and structural controls. The main focus of this paper is the source control of urban litter. It reviews international and local practice, and reports on the results of a two-year monitoring programme conducted in nine pilot catchments covering a range of different land uses, socio-economic levels and population densities in the City of Cape Town. It proposes preliminary guidelines for the reduction of urban litter loads entering the drainage system by dealing with litter pollution at its source.
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    Thermal modelling of ultrarelativistic heavy ion collisions conserving strangeness exactly
    (2003) Marais, Mark; Cleymans, Jean
    [ pg 56-60,87,88 missing] Thermal modelling of particle production in ultrarelativistic heavy ion collisions incorporating appropriate conservation principles with respect to the relevant quantum numbers, has been highly successful in determining chemical freeze-out conditions across a wide range of beam energies. This is done for heavy-ion collisions in the broad range of energy from SIS/GSI through AGS/BNL up to BPS/CERN and RHIC/BNL, assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The role of strangeness conservation and strangeness equilibration is a central feature in our considerations. Fits to the data from collaborations at the above facilities, and, comparisons with analysis done by other authors, are made. Energy dependence of the chemical freeze-out parameters is studied and, recently proposed criteria for freeze-out in terms of energy per particle and total baryon density are investigated. The chemical freeze-out trajectory is compared with the phase boundary between the hadron gas phase and the quark-gluon plasma in the temperature versus baryochemical potential plane.