Dark matter spin-dependent limits for WIMP interactions on 19F by PICASSO

The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on F-19 using the Superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the rejection of non-particle induced events are described. First results are presented for a subset of two detectors with target masses of F-19 of 65 g and 69 g respectively and a total exposure of 13.75 +/- 0.48 kgd. No dark matter signal was found and for WIMP masses around 24 GeV/c(2) new limits have been obtained on the spin-dependent cross section on F-19 of sigma(F) = 13.9 pb (90% C.L.) which can be converted into cross section limits on protons and neutrons of sigma(p) = 0.16 pb and sigma(n) = 2.60 pb respectively (90% C.L.). The obtained limits on protons restrict recent interpretations of the DAMA/LIBRA annual modulations in terms of spin-dependent interactions. (C) 2009 Elsevier B.V. All rights reserved.