First physics results from WARP 2.3 litre prototype

A method to measure the low energy nuclear recoils induced by weakly interactive massive particles (WIMPs) has been achieved by means of an ultra pure Liquid Argon detector. The simultaneous observation of scintillation and ionization occurring in the liquid Argon allow to obtain a very high rejection power against background sources. The first preliminary upper bounds on WIMP parameters obtained with a small 2.3 liter test chamber with an accumulated fiducial exposure of about 100 kg⋅day at the Gran Sasso Underground Laboratory is reported. This supports the validity of this method for a larger detector presently under construction with correspondingly increased sensitivities.