We study the superfluid transition of 4He in aerogel by Monte Carlo simulations and finite size scaling analysis. Aerogel is a highly porous silica glass, which we model by a diffusion limited cluster aggregation model. The superfluid is modeled by a three dimensional XY model, with excluded bonds to sites on the aerogel cluster. We obtain the correlation length exponent nu=0.73+/-0.02, in reas...

Targets have been developed to measure supersonic radiation transport in aerogel foams using absorption spectroscopy. The target consists of an aerogel foam uniformly doped with either titanium or scandium inserted into an undoped aerogel foam package. This creates a localized doped foam region to provide spatial resolution for the measurement. Development and characterization of the foams is a...

Superfluid He-A shares the properties of spin nematic and chiral orbital ferromagnet. Its order parameter is characterized by two vectors d̂ and l̂. This doubly anisotropic superfluid, when it is confined in aerogel, represents the most interesting example of a system with continuous symmetry in the presence of random anisotropy disorder. We discuss the Larkin-Imry-Ma state, which is characterize...

The phonon-roton excitations of liquid He immersed in aerogel of 95% porosity have been measured using inelastic neutron scattering. Excitations having wave vectors at the phonon (Q50.2 Å ), maxon, roton, and beyond the roton (Q52.4 Å ) regions of the dispersion curve were investigated at temperatures between T50.5 K and T52.25 K. Aerogel grown with deuterated materials not exposed to air was u...

The Cerenkov counters in TASS0 consist of 3 elements, one filled with aerogel and two with Freon 114 and CO2. The 1700 liters of aerogel cover an area of 11.8m2 with a thickness of 13.5 to 18 cm. Most cells are filled with an index of refraction between 1.023 and 1.026. In a running period of 2 months after installation = 3.9 + 0.2 photoelectrons were observed. The mean valu: over 17 months...

Introduction: The hypervelocity impacts of comet particles at 6.1 km/s have left tracks in the Stardust aerogel. The terminal particles are usually coarse grained minerals but abundant material is also present along the track walls as illustrated by synchrotron X-rays fluorescence spectroscopy [1]. This configuration suggests that the Wild 2 particles are made of poorly cohesive assemblages tha...

We have designed an experiment to study the role of global anisotropic quasiparticle scattering on the dirty aerogel superfluid He system. We observe significant regions of two stable phases at temperatures below the superfluid transition at a pressure of 25 bar for a 98% aerogel.

The diffusion of methane confined in nano-porous carbon aerogel with the average pore size 48 Å and porosity 60% was investigated as a function of pressure at T = 298 K using quasi-elastic neutron scattering (QENS). The diffusivity of methane shows a clear effect of confinement: it is about two orders of magnitude lower than in bulk at the same thermodynamic conditions and is close to the diffu...