Sensitive temperature gradiometer for use at low temperatures.
A device capable of very sensitive temperature gradient measurements in the presence of relatively large ambient temperature fluctuations is described. The device uses a pair of ''matched'' superconducting thin films in a bridge arrangement, with a SQUID magnetometer probe as the null detector.
A high-sensitivity paramagnetic salt second-sound detector
We describe a second sound detector based on the observation of temperature-dependent magnetization changes in paramagnetic materials. The sensitive element consists of a small pill of powdered paramagnetic salt placed in a region of high magnetic field and surrounded by a superconducting pickup loop connected to a SQUID magnetometer. At 10 Hz, the ac sensitivity was estimated to be 3×10−9 K/√Hz, increasing to 1×10−10 K/√Hz for dc signals. The device is particularly useful for experiments near the lambda point, which can be approached much more closely than with superleak transducers.
Explicit solutions for N-dimensional Schrödinger equations with position-dependent mass
With the consideration of spherical symmetry for the potential and mass function, one-dimensional solutions of nonrelativistic Schrodinger equations with spatially varying effective mass are successfully extended to arbitrary dimensions within the frame of recently developed elegant nonperturbative technique, where the BenDaniel-Duke effective Hamiltonian in one dimension is assumed like the unperturbed piece, leading to well-known solutions, whereas the modification term due to possible use of other effective Hamiltonians in one dimension and, together with the corrections coming from the treatments in higher dimensions, are considered as an additional term like the perturbation. Application of the model and its generalization for the completeness are discussed.