XXth International Conference on Neutrino Physics and Astrophysics
J.Morales
Searching for Annual Modulation in the WIMP Signal:
The ANAIS Experiment at Canfranc
ANAIS (Annual Modulation with NaI's) is a large mass experiment
intended to investigate seasonal modulation effects in the signal of
galactic WIMPs using up to 10 NaI(Tl) hexagonal crystals (10.7 kg
each) in the Canfranc Underground Laboratory (2450 m.w.e). A prototype
is being developed in order to achieve the best performances of
background and energy threshold before the installation of the
complete set. The first version of the ANAIS prototype consist of one
single crystal in a stainless steel enclosure coupled to a low
background photomultiplier. Rejection of the thermoionic noise by
means of pulse shape discrimination and reduction of the energy
threshold have been efficiently achieved. Results corresponding to an
exposure of 2069.85 kg.d with a ~4 keV energy threshold and a
background level of ~1.2 c/(keV.kg.d) up to 10 keV are presented. New
improvements such as the implementation of two ultra-low background
photomultipliers and the removal of the stainless steel vessel are
being developed. A monitoring system for the control of radon, the N2
flux injected inside the shielding and the temperatures in the
laboratory and in the inner enceinte has been installed. The
stability of the detector response (counting rates, resolution, energy
calibration, pulse shape parameters, ...) has been tested through the
continuous data taking of the prototype along more than 10 months.