Dark Matter in the Cosmos - Its Direct Detection and the Role Of Nuclear Physics

TL;DR

This paper discusses the quest to detect dark matter directly in laboratories, emphasizing nuclear physics techniques, expected signals, and the importance of nuclear structure understanding for identifying weak interaction events.

Contribution

It reviews detection methods for dark matter, highlights the role of nuclear physics in event rate calculation, and explores characteristic signatures for identifying dark matter interactions.

Findings

Detection of dark matter via nuclear recoil signatures.

Significance of modulation and directional detection techniques.

Potential gamma-ray and electron signals from dark matter interactions.

Abstract

Exotic dark matter together with dark energy or cosmological constant seem to dominate in the Universe. An even higher density of such matter seems to be gravitationally trapped in our Galaxy. The nature of dark matter can be unveiled only, if it is detected in the laboratory. Thus the accomplishment of this task is central to physics and cosmology. Current fashionable supersymmetric models provide a natural dark matter candidate, which is the lightest supersymmetric particle (LSP). Since the LSP is much heavier than the proton, while its average energy is in the keV region, the most likely possibility for its direct detection is via its elastic scattering with a nuclear target. In order to evaluate the event rate one needs the nuclear structure (form factor and/or spin response function) for the special nuclear targets of experimental interest. Since the expected rates for neutralino-nucleus scattering are expected to be small, one should exploit all the characteristic signatures of this reaction. Such are: (i) In the standard recoil measurements the modulation of the event rate due to the Earth's motion. (ii) In directional recoil experiments the correlation of the event rate with the sun's motion. One now has both modulation, which is much larger and depends not only on time, but on the direction of observation as well, and a large forward-backward asymmetry. (iii) In non recoil experiments gamma rays following the decay of excited states populated during the Nucleus-LSP collision. Branching ratios of about 6 percent are possible. (iv) novel experiments in which one observes the electrons prodused during the collisionof the LSP with the nucleus. Branching ratios of about 10 per cent are possible.