Quartz Bars Research Articles

Detection of internally reflected Cherenkov light, results from the BELLE DIRC prototype

Abstract The DIRC (Detector of Internally Reflected Cherenkov light) is a new type of ring imaging Cherenkov detector which utilizes precisely machined quartz bars as Cherenkov radiators. Bar quality is determined by both laser and cosmic ray measurements. The Cherenkov photons are transported several meters along the bar until they reach the detector cavity where they are proximity focussed on an array of conventional photomultiplier tubes. Results from a prototype device comprising a 2 × 4 × 240 cm 3 quartz bar read by an array of 480 PMTs are presented. Sample images, which are the first observed in this type of detector, are also shown. Measurements of the light yield (approximately 20 photoelectrons per image) and the angular resolution, which are both in good agreement with Monte Carlo predictions, are shown to lie well within the expected operating tolerances of the DIRC.

The Cherenkov correlated timing detector: beam test results from quartz and acrylic bars

Several prototypes of a Cherenkov Correlated Timing (CCT) Detector have been tested at the KEK-PS test beam line. We describe the results for Cherenkov light yields and timing characteristics from quartz and acrylic bar prototypes. A Cherenkov angle resolution is found to be 15 mrad at a propagation distance of 100 cm with a 2 cm thick quartz bar prototype.

A 670 nm external-cavity single mode diode laser continuously tunable over 18 GHz range

It is demonstrated that a 670 nm visible diode laser, operating in external cavity and without any additional anti-reflection coating treatment on the output facet, can perfectly operate in a single mode regime and can be continuously tuned over a frequency range larger than 18 GHz. The external cavity is closed by a grating and it does not need etalons or other frequency selective devices. The very wide single mode scanning has been obtained by a servo system which locks the internal laser solitary cavity to the external one that is supported by three quartz bars. An example of a linear single frequency scanning is reported where the absorption spectrum corresponding to the 2S→2P transition of 7Li is shown.

光学式簡易変位センサの試作開発

The purpose of this paper is to describe a simple non-contact displacement sensor by means of optical method. Scattered light from rough work surface is separated into two light spots by passing through two apertures. The spots are detected with two photo-electric devices shifted by its radius of detecting area to the aperture axis. Intensity ratio, ρ=(Ib- Ia) (Ib+Ia), is proportional to the displacement of work surface. The displacement sensor with this principle has been developed. The sensor is 70 mm in height and 54 mm in diameter. The sensor consists of two photodiodes, two quartz glass bars, one LED as a light sorce and one condensing lens. It is effective for many kinds of work materials having the surface roughness of more than 1 μm Rz, The sensor measures 8 mm of range and the resolution for 5 mm range is approximately 2 μm with ±2 μm repeatability. The sensor also measures the tilted work surface displacement up to 6 degree from the optical axis.

X-ray-induced luminescence in crystalline SiO2

The x-ray-induced ‘‘blue’’ emission from commercially available, high-quality synthetic quartz has been studied between 80 and 300 K. Three overlapping bands, each having a different quenching temperature, have been experimentally resolved in the as-grown crystals. These bands peak at 440, 425, and 380 nm; their half-widths are 0.64, 0.75, and 0.92 eV; and they thermally quench in the 120–160, 170–210, and 220–270 K regions, respectively. An intense electron irradiation at room temperature or an electrodiffusion (sweep) in a hydrogen atmosphere eliminates the band at 380 nm. Our results suggest that the 380-nm band arises from recombination of an electron with a hole trapped adjacent to an alkali-compensated aluminum ion (i.e., an Al–M+ center). The origins of the bands at 440 and 425 nm remain unknown. As an application of these results, a screening test is described which could assist quality control during selection of quartz bars for use in precision frequency control devices.

Neutron diffraction by two vibrating quartz single crystals. I. Rocking curve effects

The broadening of double-crystal rocking curves of two nearly perfect quartz single-crystal bars in (1,−1) setting has been investigated in three cases, i.e., when the first or the second or both crystals were excited in longitudinal vibrations. The quartz single-crystal bars had equal dimensions and therefore they were vibrating with the equal fundamental resonance frequency of longitudinal vibrations. In the course of these experiments the increase of the integrated intensity of diffracted neutrons has been observed in connection with vibrations of one or of both the single crystals. The observed experimental data are interpreted on the basis of the kinematical theory using the structure of the “crystalline layers” of the vibrating single crystal. [Russian Text Ignored].

An influence of the electrodes on the frequency of piezoelectric bars

An influence of the vacuum deposited electrodes on the frequency of longitudinally vibrating piezoelectric quartz bars was studied. Both theoretical considerations and measurements show a linear dependence of the frequency on the mass and elastic properties of the electrodes. The influence of the electrodes on the frequency can be eliminated for certain ratio of the length of electrodes to the length of bar (l1/l0)0. A discrepancy between the theoretical and experimental value of this ratio is ascribed to various values of Young's modulus of the bulk metal and a vacuum deposited layer.

The application of neutron diffraction to the determination of the quality of synthetic quartz crystals

The diffraction of a collimated beam of monoenergetic neutrons by the lattice plane (200) of bars from natural and synthetic quartz was measured. It was found that, from the ratio of the intensity of a neutron beam diffracted by vibrating and non-vibrating quartz bars, it is possible to estimate the relative quality of the material from which the investigated bar is produced.

Parametric interaction between two contour modes of vibration in X-cut quartz bars

Degenerate-type parametric interaction has been observed between the length-extensional mode and the length-width-flexural mode of X-cut quartz bars.

Quartz bars of an X90�, ?-cut for underground generators

Quartz bars of an X90�, ?-cut for underground generators

Anelasticity of Quartz

By means of the piezoelectric effect, measurements have been made of the variation with temperature of (1) the $Q$ of quartz bars executing free acoustical oscillations in torsion, and (2) the equivalent series electrical resistance of bars driven at their natural frequencies of longitudinal acoustical oscillations. For each of the bars studied, it was found that the internal dissipation had a maximum value at a temperature between room temperature and the quartz inversion temperature of 573\ifmmode^\circ\else\textdegree\fi{}C. Measurements of resistance were made on one bar at several different frequencies. These data showed that part of the dissipation was due to a relaxation effect, whose decay time varied with temperature according to an Arrhenius equation. An activation energy of 22 kcal/mole and a relaxation-time constant of 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}14}$ sec were deduced from the data, which showed also that the fraction of energy lost during each sinusoidal cycle of strain was independent of the frequency of vibration. Estimates of the activation energies and relaxation-time constants were deduced for the other bars measured. In one case, the dissipation was due to the migration of gold atoms from the electrodes into the quartz lattice.

Use of the Piezoelectric Gauge for Internal Friction Measurements

The addition of an auxiliary quartz crystal to the usual composite piezoelectric resonator provides a convenient strain gauge, which simplifies the measurement procedure and permits the evaluation of amplitude dependent decrements over a wide range of strain amplitudes. A unique feature of the new procedure is that virtually instantaneous values of the decrement are obtained, thus bringing transient internal friction phenomena under observation. Mechanical resonance frequencies may be precisely determined for high as well as low decrement specimens. The numerical evaluation of terms is carried out for a recommended driver-gauge construction of 18.5° X-cut quartz bars.