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[en] The ZED-2 (Zero Energy Deuterium) reactor is an experimental low-power critical facility located at the Atomic Energy of Canada Limited Chalk River Laboratories in Ontario, Canada. The facility is used to perform physics experiments in support of the CANDU and Advanced CANDU Reactor (ACR) programs. The reactor core is a large cylindrical vessel in which reactor fuel rods are positioned vertically. A heavy water moderator is pumped into the vessel to make the reactor critical. The ZED-2 design is very versatile: it can accommodate mixed fuel types in a variable number of fuel rods each with or without CANDU-type or ACR-type channels; channel coolants can be light or heavy water, or air, and can vary from channel to channel; lattices can be square or hexagonal with continuously variable lattice pitch; and some CANDU-type channels can be heated. Many of the experiments performed involve uniform cores containing the same type of fuel and channel in each fuelled location. However, at times a smaller number of fuel rods and channels are placed in the centre of a larger region of reference fuel to form a critical core assembly. These are called substitution experiments. The purpose of this paper is to describe why substitution experiments are performed, detail how they have historically been conducted and analyzed to extract the desired data from the test fuel, and finally how they are performed and analyzed today using specialized software.
[en] Lowering the string scale in the TeV region provides a theoretical framework for solving the mass hierarchy problem and unifying all interactions. The apparent weakness of gravity can then be accounted by the existence of large internal dimensions, in the sub-millimeter region, and transverse to a braneworld where our universe must be confined. I review the main properties of this scenario and its experimental implications. (author)
[en] We present lattice QCD simulation results from the European Twisted Mass Collaboration (ETMC) for the light, strange and charm quark contents of the nucleon. These quantities are important ingredients to estimate the cross-section for the detection of WIMPs as Dark Matter candidates. By employing a particular lattice QCD formulation, i.e. twisted mass fermions, accurate results of the light and strange scalar contents of the nucleon can be obtained. In addition, we provide a bound for the charm quark content of the nucleon. (author)
[en] Strange quark nuggets (SQNs) could be the relics of the cosmological QCD phase transition, and they could very likely be the candidate of cold dark matter if survived the cooling of the later Universe, although the formation and evolution of these SQNs depend on the physical state of the hot QGP (quark-gluon plasma) phase and the state of cold quark matter. We reconsider the possibility of SQNs as cold dark matter, and discuss the astrophysical consequences of primordial SQNs in the early and present universe. In the early Universe, the formation of black holes inside primordial halos could be faster than that in the standard scenario, and speed up the formation of the supermassive black holes at high redshift. In the present Universe, the capture of SQNs by pulsars could trigger star-quakes, which could be the mechanism for pulsar-glitches. (author)
[en] A simple parallelization approach using General Purpose computation on Graphics Processing Unit was applied for solving the MHD equations using the CIP-MOCCT method. We investigated the efficiency of this parallelization approach and found that the computational speed of the modified code is significantly improved despite the simple modification. (author)