J. Pollanen

Direct measurement of the N-14(p, gamma) O-15 S-factor

The 14N(p,gamma)15O reaction regulates the rate of energy generation in the stellar CN cycle. Because discrepancies have been found in the analysis and interpretation of previous capture data, we have measured the 14N(p,gamma)15O excitation function for energies in the range E(lab)(p)=155-524 keV. Fits of these data using R-matrix theory yield a value for the S factor at zero energy of 1.68+/-0.09(stat)+/-0.16(syst) keV b, which is significantly smaller than the previous result. The corresponding reduction in the stellar reaction rate for 14N(p,gamma)15O has a number of interesting consequences, including an impact on estimates for the age of the Galaxy derived from globular clusters.

Anomalous Attenuation of Transverse Sound in 3He

We present the first measurements of the attenuation of transverse sound in superfluid 3He-B. We use fixed path length interferometry combined with the magnetoacoustic Faraday effect to vary the effective path length by a factor of 2, resulting in absolute values of the attenuation. We find that attenuation is significantly larger than expected from the theoretical dispersion relation, in contrast with the phase velocity of transverse sound. We suggest that the anomalous attenuation can be explained by surface Andreev bound states.

Impurity effects of aerogel in superfluid He

The discovery of superfluid

Surface specific heat of 3He and Andreev bound states.

^{3}

Strong coupling corrections to the Ginzburg-Landau theory of superfluid He3

He in high porosity silica aerogels, and subsequent experimental and theoretical work, have led to a better general understanding of quasiparticle scattering from impurities in unconventional pairing systems. It is immensely helpful for understanding impurity effects in the case of superfluid

New chiral phases of superfluid 3He stabilized by anisotropic silica aerogel

^{3}

Identification of superfluid phases of He3 in uniformly isotropic 98.2% aerogel

He that the structure of its order parameter is well-established. An overview of impurity effects is presented with emphasis on those experiments which have a quantitative interpretation in terms of theoretical models for homogeneous and inhomogeneous scattering. The latter can account successfully for most experimental results.

Globally Anisotropic High Porosity Silica Aerogels

High resolution measurements of the specific heat of liquid 3He in the presence of a silver surface have been performed at temperatures near the superfluid transition in the pressure range of 1-29 bar. The surface contribution to the heat capacity is identified with Andreev bound states of quasiparticles that have a range of half a coherence length.

Modification of the He3 phase diagram by anisotropic disorder

In the Ginzburg-Landau theory of superfluid

Magnetoacoustic spectroscopy in superfluid 3He-B.

^{3}\mathrm{He}