Improvements in Upper Limits of the Neutralino-Proton Cross Section through use of Model-Independent Nuclear Form Factors.
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Authors
Reifenberger, George
Issue Date
2007-07-11
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Thesis
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en_US
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Abstract
Theoretical calculations of neutralino cross sections with various nuclei are of great interest to direct dark matter searches such as CDMS, EDELWEISS, ZEPLIN, and other experiments. These cross sections and direct detection rates are generally computed with standard, one or two parameter model-dependent nuclear form factors, which may not exactly mirror the actual form factor for the particular nucleus in question. As is well known, elastic electron scattering can allow for very precise determinations of nuclear form factors and hence nuclear charge densities for spherical or near-spherical nuclei. We use charge densities derived from elastic electron scattering data to calculate model-independent form factors for various target nuclei important in dark matter searches, such as Si, Ge, S, Ca and others.|We have found that for nuclear recoils in the range of 10-50 keV significant differences in cross sections and rates exist when model-independent form factors are used in place of model-dependent ones. For example, for <sup>70</sup>Ge we find that there is as much as an 18% difference in the neutralino-proton cross section when using modelindependent form factors compared to model-dependent ones. We present quantitative results of these differences due to nuclear form factors for current and proposed experiments in their relevant data-taking energy ranges. The implementation of modelindependent form factors such as the Sum of Gaussian and Fourier-Bessel methods into a large scale numerical package, DarkSUSY, is also detailed.
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Creighton University
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Thesis-George Reifenberger.pdf