arXiv subjects

Chung-Lin Shan

Publications and source records attributed to Chung-Lin Shan.

41 records · Page 3Linked to original sources

arXiv2008

Improvement of the Determination of the WIMP Mass from Direct Dark Matter Detection Data

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. We developed a model-independent method for determining the WIMP mass by using data (i.e., measured recoil energies) of direct detection experiments. Our method is independent of the as yet unknown WIMP density near the Earth, of the form of the WIMP velocity distribution, as well as of the WIMP-nucleus cross section. It requires however positive signals from at least two detectors with different target nuclei. At the first phase of this work we found a systematic deviation of the reconstructed WIMP mass from the real one for heavy WIMPs. Now we improved this method so that this deviation can be strongly reduced for even very high WIMP mass. The statistical error of the reconstructed mass has also been reduced. In a background-free evironment, a WIMP mass of ~ 50 GeV could in principle be determined with an error of ~ 35% with only 2 times 50 events.

hep-ph↗

arXiv2008

Model-Independent Determination of the WIMP Mass from Direct Dark Matter Detection Data

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. We develop a model-independent method for determining the mass $m_χ$ of the WIMP by using data (i.e., measured recoil energies) of direct detection experiments. Our method is independent of the as yet unknown WIMP density near the Earth, of the form of the WIMP velocity distribution, as well as of the WIMP-nucleus cross section. However, it requires positive signals from at least two detectors with different target nuclei. In a background-free environment, $m_χ\sim 50$ GeV could in principle be determined with an error of $\sim 35%$ with only $2 \times 50$ events; in practice upper and lower limits on the recoil energy of signal events, imposed to reduce backgrounds, can increase the error. The method also loses precision if $m_χ$ significantly exceeds the mass of the heaviest target nucleus used.

hep-ph↗

arXiv2007

Determining the WIMP Mass from Direct Dark Matter Detection Data

Weakly interacting massive particles (WIMPs) are one of the leading candidates for Dark Matter. So far we can use direct Dark Matter detection to estimate the mass of halo WIMPs only by fitting predicted recoil spectra to future experimental data. Here we develop a model-independent method for determining the WIMP mass by using experimental data directly. This method is independent of the as yet unknown WIMP density near the Earth as well as of the WIMP-nuclear cross section and can be used to extract information about WIMP mass with O(50) events.

hep-ph↗

arXiv2007

Theoretical Interpretation of Experimental Data from Direct Dark Matter Detection

Weakly Interacting Massive Particles (WIMPs) are one of the leading candidates for Dark Matter. Currently, the most promising method to detect WIMPs is the direct detection of the recoil energy deposited in a low-background laboratory detector due to elastic WIMP-nucleus scattering. So far the usual procedure has been to predict the event rate of direct detection of WIMPs based on some model(s) of the Galactic halo from cosmology and of WIMPs from elementary particle physics. The aim of this work is to invert this process. In this thesis I present methods which allow to reconstruct (the moments of) the WIMP velocity distribution function as well as to determine the WIMP mass from the recoil energy spectrum as well as from experimental data directly. The reconstruction of the velocity distribution function has been further extended to take into account the annual modulation of the event rate. Moreover, the reconstruction of the amplitude of the annual modulation of the velocity distribution and an alternative, better way for confirming the annual modulation of the event rate have been discussed. On the other hand, the determination of the WIMP mass by combining two (or more) experiments with different detector materials has been developed. All formulae and expressions given here are not only independent of the model of Galactic halo but also of that of WIMPs. This means that we need neither the as yet unknown WIMP density near the Earth nor the WIMP-nucleus cross section. The only information which we need is the measured recoil energies and their measuring times.

astro-ph↗

arXiv2007

Reconstructing the Velocity Distribution of WIMPs from Direct Dark Matter Detection Data

Weakly interacting massive particles (WIMPs) are one of the leading candidates for dark matter. Currently, the most promising method to detect many different WIMP candidates is the direct detection of the recoil energy deposited in a low-background laboratory detector due to elastic WIMP-nucleus scattering. So far the usual procedure has been to predict the event rate of direct detection of WIMPs based on some model(s) of the galactic halo. The aim of our work is to invert this process. That is, we study what future direct detection experiment can teach us about the WIMP halo. As the first step we consider a time-averaged recoil spectrum, assuming that no directional information exists. We develop a method to construct the (time-averaged) one-dimensional velocity distribution function from this spectrum. Moments of this function, such as the mean velocity and velocity dispersion of WIMPs, can also be obtained directly from the recoil spectrum. The only input needed in addition to a measured recoil spectrum is the mass of the WIMP; no information about the scattering cross section or WIMP density is required.

astro-ph↗