On the impossibility of measuring a galvano-gravitomagnetic effect with current carrying semiconductors in a space-based experiment
In this paper we investigate the feasibility of a recently proposed space-based experiment aimed to detect the effect of the Earth's gravitomagnetic field in space-borne semiconductors carrying radial electric currents and following identical, in principle, circular equatorial orbits along opposite directions. Identical voltages of gravitomagnetic origin would be induced across the orbiting semiconductors, while equal and opposite gravitoelectric larger voltages would be generated. It turns out that the deviations from the proposed idealized orbital configuration due to the unavoidable orbital injection errors would make impossible the measurement of the gravitomagnetic voltage of interest.
Application of high performance DC SQUIDs in precision measurement technique
In this review the performance of a DC SQUID system with Nb-NbO/sub x/-Pb/In/Au window-type Josephson junctions is described. The SQUIDs and the SQUID control units were developed for universal applications in precision measurement technique. Under optimum conditions a flux noise level of 2/spl times/10/sup -6/ /spl Phi//sub 0///spl radic/Hz was achieved corresponding to an energy resolution of 3/spl times/10/sup -31/ J/Hz. The contribution gives the design of the DC SQUID device and summarizes recent results of its application in precision measurement technique. The applications include a cryogenic current comparator for non-destructive measurement of the beam intensity produced in a particle accelerator, a high-sensitive SQUID voltmeter for investigations of the low-field Hall coefficient of high purity metals, the upgrade of a multichannel RF SQUID neuromagnetometer for biomagnetic research, and a planned high-precision experiment in fundamental physics.<<ETX>>
Tidal Satellite Perturbations and the Lense-Thirring Effect.
The tiny general relativistic Lense-Thirring effect can be measured by means of a suitable combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. This observable is affected, among other factors, by the Earth' s solid and ocean tides. They induce long-period orbital perturbations that, over observational periods of few years, may alias the detection of the gravitomagnetic secular trend of interest. In this paper we calculate explicitly the most relevant tidal perturbations acting upon LAGEOSs and assess their influence on the detection of the Lense-Thirring effect. The present day level of knowledge of the solid and ocean tides allow us to conclude that their influence on it ranges from almost 4% over 4 years to less than 2% over 7 years.