Springer Science and Business Media LLC

We present results of a hole burning study with thermal cycling and waiting time spectral diffusion experiments on a modified cytochrome - c protein in its native as well as in its denatured state. The experiments show features which seem to be characteristic for the protein state of matter and its associated dynamics at low temperature. The properties responsible for the observed patterns are organisation paired with randomness and, in addition, the finite size which gives rise to surface and solvent effects. We discuss some general model approaches which might serve as guide lines for understanding these features.

The measured noise in Mo/Au transition-edge sensor (TES) microcalorimeters produced at NASA has recently been shown to be well described by a two-body electro-thermal model with a finite thermal conductance between the X-ray absorber and the TES. In this article, we present observations of a high-frequency peak in the measured current noise in some of these devices. The peak is associated with an oscillatory component of the TES response that is not predicted in a single-body model but can be qualitatively described by the two-body model.

We have built a versatile, compact 3He test facility to evaluate high-purity Ge (HPGe) SuperCDMS (Cryogenic Dark Matter Search) detectors. We are able to rapidly identify photolithographic or other defects in the thousands of W-Al transition edge sensors (TESs) on each detector and to evaluate the performance of the underlying substrate. We describe our simple method to measure current-voltage (I–V) characteristics and R vs. T behavior of HPGe detector crystals with resistances up to 100 GΩ. This provides a way to quickly perform diagnostic physics studies. Results provide critical data that give early warning that a crystal may not be suitable for the SuperCDMS underground experiment. Data from tests made on several kg-scale detectors are presented.

New measurements of the static magnetization of 3He-B in contact with a variety of wall configurations are presented and compared with previous measurements in both A and B phases. At high pressure the data tend toward agreement with resonant-magnetism experiments, while near the polycritical point a large discrepancy between the results of the two methods remains.

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

The effects of resonant scattering by nonmagnetic localized states in the normal layer on the critical temperatures of proximity effect sandwiches are studied through the renormalization of the electron propagators in the McMillan proximity effect model. By treating both the resonant scattering of the normal layer electrons and the Coulomb correlation between electrons of opposite spins located on the same impurity site self-consistently, an expression for the decrease in the critical temperature that shows explicitly the dependences on the parameters that describe the impurity atoms is obtained. The decrease in the critical temperatures as a function of impurity concentration and of normal layer thickness is shown.

We discuss the effect of the zero-temperature transverse attenuation in spin-polarized Fermi liquids on related phenomena in helium and electron systems. In helium Fermi liquids, the magnetic dipole-dipole interaction leads to a transfer of transverse attenuation to longitudinal processes resulting in finite sound attenuation and effective viscosity even at zero temperature. In Heisenberg ferromagnetic metals, this Fermi-liquid effect affects the attenuation of ferromagnetic magnons as a result of exchange coupling between spins of ferromagnetic and conduction electrons.

We present a prototype of metallic magnetic calorimeters that we are developing for absolute activity measurements of low energy emitting radionuclides. We give a detailed description of the realization of the prototype, containing an 55Fe source inside the detector absorber. We present the analysis of first data taken with this detector and compare the result of activity measurement with liquid scintillation counting. We also propose some ways for reducing the uncertainty on the activity determination with this new technique.

A resonator has been constructed in which a rigid superleak, fixed at one point across an annular cavity filled with liquid 4He, behaves as a differential filter for superfluid flow. The boundary conditions which obtain at the superleak determine the motion of the total fluid in the annulus and, by its reaction force on the superleak, the motion of the resonator as a whole. The condition for resonance motion of the resonator when driven (externally) by a periodic torque has given information about the temperature dependence of the superfluid density in the superleak which, in these experiments, was porous vycor glass.