We study spin models within the mean field approximation to elucidate the topology of the phase diagrams of systems modeling the liquid-vapor transition and the separation of 3He-4He mixtures in periodic porous media. These topologies are found to be identical to those of the corresponding random field and random anisotropy spin systems with a bimodal distribution of the randomness. Our results...

We report the first observation of longitudinal sound propagation in three dimensionally distributed Bose and Fermi superfluids in an acoustic investigation of phase separated 3He-4He mixtures confined to aerogel. At mK temperatures, this inhomogeneous system exhibits simultaneous 3He and 4He superfluidity leading to two "slow modes" along with the conventional sound mode. We also infer the sup...

The viscosity is measured for a Fermi liquid, a dilute 3He-4He mixture, under extremely high magnetic field/temperature conditions (Bor=1.5 mK). The spin-splitting energy microB is substantially greater than the Fermi energy kBTF; as a consequence the polarization tends to unity and s-wave quasiparticle scattering is suppressed for T<<TF. Using a novel composite vibrating-wire vis...

We report the first direct measurement of helium isotope ratio, 3He/4He, outside Local Interstellar Cloud, as part science verification observations with upgraded CRyogenic InfraRed Echelle Spectrograph (CRIRES). Our determination 3He/4He is based on metastable HeI* absorption along line-of-sight towards Tet02 Ori A in Orion Nebula. measure a value 3He/4He=(1.77+/-0.13)x10^{-4}, which just ~40 ...

We have studied the elasticity of solid 4He in relation with its possible supersolidity. For this we have measured acoustic resonance frequencies in a 1 cm3 cell filled either with polycrystals or with single crystals of 4He. We have observed a large stiffening at low temperature as first observed by Day and Beamish in polycrystals. The 3He impurity content has been varied from 300 ppb to 0.4 p...

We have developed an analytical system to measure atmospheric 3He/4He ratios precisely by using a static vacuum operation mass spectrometer and an ultrahigh-vacuum purification line. After purification of the sample, helium was introduced into the mass spectrometer. Ion beams of 3He and 4He were measured at the same time by a double collector system. A resolving power of about 700 at the 5% lev...