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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Faster Dark Matter Calculations Using the GPU

Liem, Sebastian January 2011 (has links)
We have investigated the use of the graphical processing unit to accelerate the software package DarkSUSY. DarkSUSY is, among other things, used for calculating the dark matter relic density -- an measurable quantity -- given the supersymmetric neutralino, χ, as a dark matter candidate. Supersymmetric theories have many free parameters and we want to calculate the relic density for large areas of the parameter space. The results can then be compared with observations and to constrain the parameters. A faster DarkSUSY would allow for larger searches in the parameter space. We modified DarkSUSY using Nvidia's CUDA platform and wrote a program that, by using the GPU, calculates the χ + χ <-> W+ + W- contribution to the annihilation cross-section. Our initial try was only negligible faster than our non-CUDA program due to under-utilization of the GPU, but solving that the program was 47 times faster than the reference program. We also report on difficulties we faced, both solved and unsolved so the reader can make an informed decision on the worth of rewriting so that the heavy calculations in DarkSUSY use the GPU. / Vi har undersökt om man kan använda grafikkortet för att få mjukvarupaketet DarkSUSY snabbare. DarkSUSY används, bland annat, för att beräkna relikdensiteten av mörk materia -- en mätbar kvantitet -- användandes den supersymmetriska neutralinon, χ, som mörk materia-kandidat. Supersymmetriska teorier har många fria parametrar och vi vill beräkna relikdensiteten för stora områden av parameterrummet. Resultaten kan sedan jämföras med observationer för att begränsa parametrarna. Ett snabbare DarkSUSY skulle tillåta större sökningar i parameterrummet. Vi modifierade DarkSUSY med hjälp av Nvidias CUDA-platform och skrev ett program som, genom att använda grafikkortet, beräknar χ + χ <-> W+ + W- kanalens bidrag till annihilationstvärsnittet. Vårt första försök var bara försumbart snabbare än vårt icke-CUDA program på grund av underanvändning av grafikkortet. Men med det åtgärdat så var programmet 47 gånger snabbare än referensprogrammet. Vi rapporterar också de problem vi stött på, både de vi löste och de vi inte löste. Detta så att läsaren kan avgöra värdet av att omarbeta så att alla de beräkningsintensiva delarna av DarkSUSY använder grafikkortet.
2

Supersymmetric Dark Matter in IceCube

Silverwood, Hamish George Miles January 2012 (has links)
The Minimally Supersymmetric Standard Model (MSSM) provides us with a WIMP dark matter candidate particle, the neutralino. Neutralinos from the dark matter halo can potentially become captured by the sun and concentrated in the core, where they can undergo self-annihilation and so produce a distinct neutrino signal. The IceCube Neutrino Observatory has the potential to detect this neutrino signal and thus give indirect evidence of the presence and properties of neutralino dark matter. Although the full, unconstrained MSSM has 105 parameters this can be reduced to 25 parameters by the application of physically motivated assumptions. Scans of this MSSM-25 parameter space are conducted using the DarkSUSY software package and an adaptive scanning technique based on the Monte-Carlo VEGAS algorithm. The IceCube exclusion confidence level is then calculated for a set of points produced by these scans. Results indicate that the detection capability of IceCube exceeds that of current direct detection methods in certain regions of the parameter space. The use of a 25 dimensional parameter space reveals that there are new regions of observables with high exclusion confidence levels compared to earlier simulations performed with a seven dimensional parameter space.

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