On the direct search for spin-dependent WIMP interactions
  We examine the current directions in the search for spin-dependent dark matter. We discover that, with few exceptions, the search activity is concentrated towards constraints on the WIMP-neutron spin coupling, with significantly less impact in the WIMP-proton sector. We review the situation of those experiments with WIMP-proton spin sensitivity, toward identifying those capable of reestablishing the balance. 
T. A. Girard and F. Giuliani (Centro de Fisica Nuclear, Universidade   de Lisboa)