Search for an Ultralight Scalar Dark Matter Candidate with the AURIGA Detector.

A search for a new scalar field, called moduli, has been performed using the cryogenic resonant-mass AURIGA detector. Predicted by string theory, moduli may provide a significant contribution to the dark matter (DM) component of our Universe. If this is the case, the interaction of ordinary matter with the local DM moduli, forming the Galaxy halo, will cause an oscillation of solid bodies with a frequency corresponding to the mass of moduli.

Energy repartition for a harmonic chain with local reservoirs.

We exactly analyze the vibrational properties of a chain of harmonic oscillators in contact with local Langevin heat baths. Nonequilibrium steady-state fluctuations are found to be described by a set of mode temperatures, independent of the strengths of both the harmonic interaction and the viscous damping. Energy is equally distributed between the conjugate variables of a given mode but differently among different modes, in a manner which depends exclusively on the bath temperatures and on the boundary conditions.

Thermal noise of mechanical oscillators in steady states with a heat flux.

We present an experimental investigation of the statistical properties of the position fluctuations of low-loss oscillators in nonequilibrium steady states. The oscillators are coupled to a heat bath, and a nonequilibrium steady state is produced by flowing a constant heat flux, setting a temperature difference across the oscillators. We investigated the distribution of the measurements of the square of the oscillator position and searched for signs of changes with respect to the equilibrium case.

Elasticity of mechanical oscillators in nonequilibrium steady states: experimental, numerical, and theoretical results.

We study experimentally, numerically, and theoretically the elastic response of mechanical resonators along which the temperature is not uniform, as a consequence of the onset of steady-state thermal gradients. Two experimental setups and designs are employed, both using low-loss materials. In both cases, we monitor the resonance frequencies of specific modes of vibration, as they vary along with variations of temperatures and of temperature differences.

A compact, passive setup for low vibration noise measurements in the frequency band (300-2000) Hz.

In this paper we report about the setup we designed to isolate at about 1.5 kHz from mechanical noise an experimental payload of about 6.6 kg mass.