The construction and use of a dual radiator Ring Imaging Čerenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV, which is essential to these studies. The instrument uses...

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...

Low-refractive index silica aerogel is the most convenient radiator for threshold-type Cherenkov counters, which is used for particle identification in high-energy physics experiments. For the BELLE detector at the KEK B-Factory, we have produced about 2 m of hydrophobic silica aerogels of n = 1.01 1.03 using a new production method. The particle identification capability of the aerogel Cherenk...

In this paper, the Diffusion Limited Cluster Aggregation (DLCA) method is employed to reconstruct the three-dimensional network of silica aerogel. Then, simulation of nitrogen adsorption at 77 K in silica aerogel is conducted by the Grand Canonical Monte Carlo (GCMC) method. To reduce the computational cost and guarantee accuracy, a continuous-discrete hybrid potential model, as well as an adso...

A high-resolution calorimetric study has been made on the smectic-A to nematic phase transition in liquid crystals perturbed by the dispersion of 70-Å-diam silica spheres ~aerosils!. The specific heat peak of this transition decreases in amplitude and shifts to lower temperatures with increasing silica density. However, it remains sharp in comparison to the effects of aerogel confinement at the...

The longitudinal acoustic velocity in silica aerogel is presented as a function of the interstitial gas type and pressure. This was measured using air-coupled ultrasonic transducers configured for differential pulse transit time measurements. The results are interpreted in terms of the thermal relaxation of the acoustic pulse. The microscale temperature oscillations of the gas and solid phases ...

BACKGROUND Aerogels are a versatile group of nanostructured/nanoporous materials with physical and chemical properties that can be adjusted to suit the application of interest. In terms of biomedical applications, aerogels are particularly suitable for implants such as membranes, tissue growth scaffolds, and nerve regeneration and guidance inserts. The mesoporous nature of aerogels can also be ...

Superfluid He has important implications in studying condensed matter physics, specifically in its phases at very low temperatures. The understanding of these phases not only expands our knowledge of He itself, but is also a paradigm for recently discovered unconventional superconductors such as strontium ruthenate (SrRuO3) and uranium platinum three (UPt3). Superfluid He’s relation to supercon...