[en] Some properties of the density of vortex lines produced by helium II thermal counterflow in wide channels (approx. 1.0 cm) are studied. The homogeneity of the steady state vortex line density is determined from local measurements of second sound attenuation at nine positions along a 40 cm. channel. The vortex line density has a moderately steep gradient near the heater and is fairly uniform over the remainder of the channel. The second sound attenuation produced by thermal counterflow is compared with that produced by rotation of the cryostat. This allows determination of the absolute vortex line density produced by the counterflow. This measurement agrees well with existing work. Fluctuations in the vortex line density are studied by observing the attenuation of second sound waves and ion currents. The root mean square amplitude of the fluctuations is approximatley three percent of the total attenuation. The power spectral density of the fluctuations is approximately constant for frequencies below about 0.1 Hz. Above this frequency the power decreases as a low power of the inverse frequency, reaching the background noise level at approximately 10 Hz. The coherence between fluctuations measured simultaneously by ions and second sound was determined. The greatest coherence was found at low frequencies and low heater powers

[en] We present the results of an investigation of thin-film dc super conducting quantum interference device (SQUID's) with very high energy resolution. The SQUID's were fabricated using integrated-circuit techniques appropriate for superconducting devices. A weakly coupled SQUID with very low inductance (1 pH) had an intrinsic energy sensitivity 6 x 10^-34 J/Hz = 0.9 h. A well-coupled SQUID (coupling constant a = 0.43) had an energy sensitivity referred to the input coil of 4.7 x 10^-32 J/Hz = 71 h

[en] We have built and operated several inductive type monopole detectors, the present one having three concentric, orthogonal loops operated in coincidence. The area of each loop is 200 cm² and the cross sectional area of the superconducting shield is 700 cm². The detector loops are in a trapped magnetic field of approximately 3 milligauss. The system is mechanically stable and is relatively insensitive to external disturbances, both mechanical and electromagnetic. The detector is quiet, having a signal-tonoise ratio for monopole detection of approximately 20. We have also investigated several sources of noise and spurious signals which might mimic a monopole event

No abstract available

[en] The first detailed report of the Rochester cryogenic resonant gravitational wave detector is presented. The authors describe in detail the transducer which makes use of several features, in a unique combination that already has made it possible to achieve the highest mechanical Q for aluminium in a gravitational wave detector (Q=2 x 10⁷). Also presented are results of preliminary tests and the values of the physical parameters needed to achieve a competitive ultimate sensitivity are calculated. A detailed analysis of the sensitivity and a description of the procedure for the calibration is also given. (author)

[en] We have measured the steady-state vortex-line density in turbulent counterflow using a second-sound-burst technique as a local probe. Contrary to the Vinen theory and previous assumptions, we find substantial line-density inhomogeneity and strong departures from the predict heat-current dependence. Anomalous behavior of the line density at higher heat currents provides evidence for a new secondary flow state

[en] We have fabricated and tested thin film, niobium edge junction, double transformer, dc superconducting quantum interference devices (SQUID's) that were stable under room-temperature storage and thermal cycling and that had very good noise performance. The input inductance, approximately 1.7 μH, was large enough to facilitate good matching to many experiments. When the SQUID was operated as a small-signal amplifier, the minimum detectable energy per unit bandwidth (S/sub e/) was 5 x 10^-33 J/Hz at 100 kHz, referred to the SQUID loop (uncoupled). The minimum detectable energy per unit bandwidth was 1.8 x 10^-31 J/Hz at 100 kHz, referred to the input coil. The SQUID's had good characteristics for flux-locked operation since the small signal S/sub e/ was low over a substantial range of bias current and magnetic flux. For operation in a flux-locked feedback circuit, S/sub e/ was 6 x 10^-32 J/Hz at 1 kHz

[en] The authors have designed, fabricated, and tested a Double Transformer (DT) coupled dc SQUID (Superconducting Quantum Interference Device) with low noise, an input inductance of 1μH and a smooth input-output characteristic. A transmission line model is presented to explain a resonance in the input-output characteristic of early versions of this device. Guided by the results of numerical simulations a new version of this device has been built and tested. Experimental results are presented that show that the resonance can be moved to a higher voltage by reducing the area of the SQUID loop. The voltage-external flux characteristic of some of these new devices agrees to within 10% with computer simulations. The minimum detectable energy per unit bandwidth (MDE) referred to the SQUID loop, is 10h, where h is Planck's constant. Computer simulations indicate an MDE of 6h

[en] The authors discuss the developments being made in the gravitational wave detector program. In particular they discuss high quality factor materials for antennas, transducer development, and SQUID development. (G.T.H.)

[en] This paper reports on a conventional SIS mixer, which is pumped by a single frequency local oscillator (LO) functions as a phase-insensitive linear amplifier and may achieve a noise level near the quantum limit of one-half photon added noise per unit bandwidth. A phase sensitive linear amplifier may have less noise than this quantum limit. The authors attempt to beat the quantum noise limit with an SIS mixer by employing a two-LO technique which makes the mixer's gain dependent upon the phase of the incoming signal The authors experimentally demonstrated the phase sensitive gain of our two-LO mixer, the gain variation from maximum to minimum is more than 20 dB. The authors also present theoretical predictions of the noise of the two-LO mixer