ISSN:0033-7579    

DOI:10.1080/00337577508232992

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

This paper is a review of the transient effect of pulse ionization on the resonant frequency andQof quartz resonators. A number of different samples of both natural and synthetic quartz crystals have been used. Fifth-overtone 5, 32, and 125 MHz thickness shear (AT-cut) crystal units were fabricated and studied using several different oscillator circuits, one of which was designed such that the resistanceRs(αQ−1) of the crystal unit at series resonance as well as frequency could be measured after pulse exposure. With the exception of one purposely altered crystal, all the resonators exhibited a negative-transient frequency offset after irradiation which thereafter anneals as a function oft−1/2over nearly four decades of time. The pulse irradiation effect onQ−1is most striking at 5 MHz in natural quartz units, which suffer a thirty-fold increase in acoustic absorption after exposure to 104rad. The transient increase in the acoustic absorption in natural quartz anneals within 10 seconds to a value somewhat larger than the preirradiation absorption. Theoretical models are described which account for these observations.

ISSN:0033-7579    

DOI:10.1080/00337577508232993

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Crystal controlled oscillators have usually been designed to obtain optimum frequency stability; however, in some applications reliability in adverse operating environments is more important than frequency stability. This paper discusses some design tradeoffs between frequency stability and operational reliability as applied to oscillators used in a transient radiation environment. Experimental results have confirmed that design margins have been realized, and observed performance of crystal-controlled oscillators during exposure to transient ionizing radiation has led to new insight into the short-term effects of radiation on quartz crystals.

ISSN:0033-7579    

DOI:10.1080/00337577508232994

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A study has been made of temperature rises in quartz resonators using a combined photon-electron Monte Carlo transport code. This code was used to compute the energy deposited in resonator materials by pulsed (70 nanoseconds) 10 MeV Bremsstrahlung x-rays and 30 MeV electrons in geometries which model 5 MHz and 125 MHz 5th overtone quartz resonators. In general for the radiation sources considered, and for resonators operating near their frequencyvs.temperature turnover point, calculations indicate that thermal shock is a significant factor in causing transient frequency shifts. Frequency shifts in 5 MHz resonators of tenths of parts per million lasting fractions of a second are calculated for resonators exposed to a radiation pulse of 105rad.

ISSN:0033-7579    

DOI:10.1080/00337577508232995

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The charge carrier transport properties of a wide variety of quartz single crystals and fused silica have been measured by creating electron-hole pairs in the bulk of the samples with high energy x-rays. The very short x-ray pulses (3 nsec) allowed unprecedented time resolution, and in some cases separate measurements of carrier concentration, (a) lifetime, (τ) and mobility, (μ) as well as their product (αe μτ). Theαe μτproduct is sometimes called the radiation induced conductivity (RIC) and was found to vary over almost four orders of magnitude for different types of quaitz. In addition, substantial long term conductivity was discovered in some kinds of single crystal quartz with the electric field parallel with the c-axis. It is concluded from the available evidence that the long lived carriers are alkali metal ions which can be drifted across the entire crystal. The possible origin of the ions is discussed as well as their role in the short term annealing of the radiation-induced frequency offsets noted in quartz oscillators.

ISSN:0033-7579    

DOI:10.1080/00337577508232996

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Optical absorption and luminescence measurements have been made between 85 and 300 K on natural and synthetic quartz during and after60Co gamma-ray irradiation. Absorptionvs.dose curves can be resolved into the sum of a saturating exponential and a linear component. At 85 K the slope of the linear component is small, while at 300 K the linear term dominates the growth curves. The coloring induced by irradiation at 85 K decreased in a complex manner during anneal at a linear rate to 300 K. During this annealing process multiple-peak thermoluminescent (TL) glow curves were observed and recorded. The TL emission spectra are described accurately by single Gaussian-shaped bands, whereas the gamma-ray induced luminescence is comprised of several poorly resolved bands. All recorded TL glow curves are characterized by a set of four first order glow peaks between 150 and 220 K. The temperature dependence of radioluminescence intensity is described by a classical model in which a temperature-independent radiative transition competes with a thermally activated non-radiative process.

ISSN:0033-7579    

DOI:10.1080/00337577508232997

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The effect of high-temperature electrolysis in vacuum on the formation of color centers and on the OH-spectrum in natural α-quartz was investigated with numerous samples of different origin. The transformation of those OH-bands which are thermally unstable with respect to their spectral position into stable OH-bands at longer wavelength is strongly affected by electrolysis and seems to be related to the formation of color centers; it appears to take place at the leading edge of the color cloud. The OH-concentration in the crystal before electrolysis is directly proportional to the intensity of the coloration produced by electrolysis and is inversely proportional to the field induced propagation velocity of the color cloud as it moves from the anode to the cathode. The inverse proportionality of the absorption maxima of the C-band and 2.96-μm OH-band indicate a relationship which is interpreted as oxygen vacancy formation. Prolonged electrolysis in vacuum drastically reduces the integrated OH-spectrum and can virtually eliminate it. Since some of these OH-bands have been shown to be associated with interstitial monovalent impurities, the observed spectral changes give evidence that sweeping of α-quartz along the optical axis is possible through vacuum electrolysis at elevated temperatures. The results are of particular interest with respect to the fabrication of quartz resonators since theQand radiation sensitivity of quartz resonators are known to be strongly influenced by the presence of impurities.

ISSN:0033-7579    

DOI:10.1080/00337577508232998

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A review of the research literature dealing with the role of aluminum centers in α-quartz is presented, covering the developments of the last twenty years. The primary techniques (dielectric measurements, electron paramagnetic resonance and optical spectroscopy) have led to quite a detailed understanding of the structure and radiation chemistry of the centers in terms of aluminum ions at silicon sites, with various possibilities for nearby interstitial cations and electron holes on neighboring oxygen atoms.

ISSN:0033-7579    

DOI:10.1080/00337577508232999

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The time dependence of frequency recovery at 306 K of pulse-irradiated quartz is analyzed and shown to be inconsistent with the diffusion of a specie in three dimensions, but follows well diffusion in one dimension. The main feature which distinguishes these cases is at−1/2time dependence of the recovery. No extended region for at−1/2dependence is possible in three-dimensional diffusion. An extensivet−1/2dependence is predicted in one-dimensional diffusion, paralleling the observation that this holds for some three decades in time and over 80% of the recovery.

ISSN:0033-7579    

DOI:10.1080/00337577508233000

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor