First Results on Dark Matter Annual Modulation from the ANAIS-112 Experiment.

ANAIS is a direct detection dark matter experiment aiming at the testing of the DAMA/LIBRA annual modulation result, which, for about two decades, has neither been confirmed nor ruled out by any other experiment in a model independent way. ANAIS-112, consisting of 112.5 kg of sodium iodide crystals, has been taking data at the Canfranc Underground Laboratory, Spain, since August 2017. This Letter presents the annual modulation analysis of 1.5 years of data, amounting to 157.55 kg yr. We focus on the model independent analysis searching for modulation and the validation of our sensitivity prospects. ANAIS-112 data are consistent with the null hypothesis (p values of 0.67 and 0.18 for [2-6] and [1-6] keV energy regions, respectively). The best fits for the modulation hypothesis are consistent with the absence of modulation (S_{m}=-0.0044±0.0058 cpd/kg/keV and -0.0015±0.0063 cpd/kg/keV, respectively). They are in agreement with our estimated sensitivity for the accumulated exposure, which supports our projected goal of reaching a 3σ sensitivity to the DAMA/LIBRA result in five years of data taking.

White-light speckle method of measurement of flow velocity distribution.

A white-light speckle technique for measurement of flow velocities is described. The speckle patterns are formed by incoherent light at the image plane of the fluid illuminated section. The convection flow generated in a rectangular cell filled with silicone oil is studied with this technique. The flow velocities are obtained as the result of a point-by-point analysis. Alternatively, an overall picture of their spatial distribution is obtained by means of a whole-field filtering technique. The accuracy of the two methods of analysis is studied.

Intensity transmitted by a Fabry-Perot etalon with another internal Fabry-Perot interferometer.

The intensity transmitted by a device made up of a F.P. etalon that contains another internal tunable F.P. has been studied. The theoretical predictions about the wavelengths of the intensity transmission maxima of the device are derived as functions of the optical path length of the internal F.P. An experimental check of the theoretical predictions is also presented.