On the Direct Detection of Dark Matter

Abstract

Various issues related to the direct detection of supersymmetric dark matter are reviewed. Such are: 1) Construction of supersymmetric models with a number of parameters, which are constrained from the data at low energies as well as cosmological observations. 2) A model for the nucleon, in particular the dependence on the nucleon cross section on quarks other than u and d. 3) A nuclear model, i.e. the nuclear form factor for the scalar interaction and the spin response function for the axial current. 4) Information about the density and the velocity distribution of the neutralino (halo model). Using the present experimental limits on the rates and proper inputs in 3)-4) we derive constraints in the nucleon cross section, which involves 1)-2). Since the expected event rates are extremely low we consider some additional signatures of the neutralino nucleus interaction, such as the periodic behavior of the rates due to the motion of Earth (modulation effect), which, unfortunately, is characterized by a small amplitude. This leads us to examine the possibility of suggesting directional experiments, which measure not only the energy of the recoiling nuclei but their direction as well. In these, albeit hard, experiments one can exploit two very characteristic signatures: a)large asymmetries and b) interesting modulation patterns. Furthermore we extended our study to include evaluation of the rates for other than recoil searches such as: i) Transitions to excited states, ii) Detection of recoiling electrons produced during the neutralino-nucleus interaction and iii) Observation of hard X-rays following the de-excitation of the ionized atom.