Narrow Results

The possibility of detecting neutrinos by coherent scattering on high Debye temperature monocrystals such as sapphire is presented and discussed. Preliminary estimations showed that 1 MeV neutrinos with a fluency density of 10¹² cm^-2 s^-1 could interact with a force of about 10^-6 dyn with a 100 g sapphire monocrystal. A torsion balance provided with 1 m length molybdenum wire and an optical autocollimator able to measure small rotation angles of about 0.1 arcsec could give positive results. The design of a high sensitivity torsion balance under construction provided with such a detector is presented and discussed.

The possibility of detecting solar neutrinos by coherent scattering in high-Debye temperature monocrystals such as sapphire is presented and discussed. Preliminary experimental results indicate that the solar neutrinos flux (0–430 keV) produces an observable torque of a high-sensitive torsion balance. Our experiments give a result for the diurnal force as predicted by Weber's theory of enhanced solar neutrinos coherent scattering.

To increase the accuracy of mechanical characterizations of microstructures and nanomaterials on the molecular- and nano-scale, the measurement standard of microforce ranging from 10^-6N to 10^-9N must be realized for calibrating the testing and measuring instruments. In this paper, a new scheme based on the equal-arm torsion balance is proposed. This precision torsion balance detects accurately the gravitational force between two mass standards, and links the small force measurement to the International System of Units and Newtonian gravitational constant G. Such a balance might serve as a force standard machine operating in the regime below 10^-6N with an accuracy of 0.1%.

The magnetic damping structure was used in measuring the gravitational constant G by torsion balance. The main purpose is to reduce the effect of pendulum vibration modes. This effect can affect the position of torsion balance. When we use the method A mentioned in OIML R111 to measure density, the pendulum vibration modes of the hanging pan will also be found. In this paper, we will try to introduce the magnetic damping structure to be used on the hanging pan and will present the results of density measurement with the magnetic damper used.

We report on the measurement of the Casimir force between a plate and a lens, both gold coated, in the range 5–10 microns employing a torsion balance. The results show deviation from the standard zero temperature Casimir force law indicating the first detection of the finite temperature correction.

Due to the weakness of gravity, the accuracy of the Newtonian gravitational constant G is essentially below the accuracy of other fundamental constants. The current value of G, recommended by CODATA in 2006, based on all results available at the end of 2006, is G = (6.67428 ± 0.00067) × 10^-11 m³kg^-1s^-2 with a relative error of 100 ppm. The modern history of G determination is considered. New experiments at a level of accuracy of 10 to 30 ppm are now in progress in some world gravitational laboratories. One of the problems of improving the accuracy of G is a precision measurement of the period of eigen oscillations of the torsion balance. The torsion balance responses to tiny environmental noises, which accordingly result in changes of the torsional oscillation period. The seismic environmental noise in the underground laboratory condition has been studied on the base of data of the Baksan Laser Interferometer. The dependence of the torsion period value and the error of its estimation on the level of the acting seismic noise has been simulated and studied. To measure the Newtonian gravitational constant at the accuracy level of 10 ppm, the environmental seismic noise must be below 10^-2 mGal.