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A method has been discussed to measure the drift velocity of electrons in a mixture of argon and nitrogen using a gas scintillation drift chamber. The variations of drift velocities with the drift field and the nitrogen concentration have been investigated. An approximate method has been used to calculate the drift velocity in the gas mixture utilizing the data for pure argon and nitrogen. The comparison shows the similarity between the calculated and the measured variation of the drift velocity with drift field and with nitrogen concentration. A broad maximum of drift velocity has been observed at a nitrogen concentration of about 2.5%.

Using the novel technique of UV laser-induced ionization, drift angles and drift velocities have been measured for various gas mixtures. In the region where the drift velocity is linearly dependent on the drift field and up to 10 kG, the measured values agree well with predictions by computations also described in this article. Two gas mixtures were found which give small drift angles at low drift velocities. This is important for the operation of a time expansion chamber (TEC).

Hole transits have been observed in evaporated pure As 2 S 3 but the hole lifetime limits such observation to >70°C. Doping with iodine, Mg, Zn, Cd, Hg, Sn, Pb, Ga, and In increases the lifetime so that transits can be recorded at room temperature, but in most cases the mobility is reduced. The mobility is found to depend on drift field in a Poole-Frenkel like manner. Its zero-field activation energy is ≅0.6 eV in all cases. The invariance of this value with doping and the field dependence suggest transport by trap-limited hopping, the traps being negatively charged valence-alternation centres.

We describe a chamber in which the drift field is controlled by the deposition of electrostatic charge on an insulating surface. The chamber operates with good efficiency and precision for observed drift distances of up to 45 cm, promises to be extremely robust and adaptable and offers a very cheap way of making particle detectors.

By combining optical strain‐birefringence with stroboscopic illumination, acoustoelectric domains in CdS have been made visible. Domain widths of 50 to 200 μ have been observed in crystals with drift field perpendicular to the C axis. In crystals with E parallel to C axis the domain travels at 30° with respect to C and forms a complex reflection pattern.

The MOST V-I static characteristics were investigated in Part I [1], taking the mobility µ only as variable with the drift field. In this part, the analysis is extended to include the simultaneous variations of the mobility µ and the bulk charge Q B along the channel. From the mobility point of view, the analysis follows that of Part I with the two approaches of piecewise and continuous mobility variations. However, in this case the resulting equations are only solvable numerically, and the computed results are plotted. The results show that effects due to the additional variation in Q B along the channel are in the same sense and enhance those due to variation in mobility alone. Also, higher doping and greater oxide thickness show themselves in a way as though the mobility were approaching the limit of velocity saturation. The overall effects show more reduction in current levels as well as output and mutual conductances, and increased tendency of earlier saturation. As far as these effects are concerned, the results favor a MOST of small oxide thickness and long channel. However, since a long channel impairs the gain and high-frequency characteristics, the results given in this paper help to show how a compromise may be obtained.

The observation of acoustoelectric current saturation and domain propagation in n‐type InP single crystals is reported. The electromechanical coupling constant K and the dominant acoustic frequency f are obtained from the variation of the incubation time for current decay with applied drift field. K2 = 1.0×10−3 and f = 17 GHz. The enhancement of acoustic gain in a transverse magnetic field is examined and compared to the predictions of the microscopic theory. Semiquantitative agreement can be obtained by assuming a slight scan of the dominant accoustic frequency with magnetic field.

An analytical study of the losses at the surface and in the bulk of a drift-field photovoltaic cell has boon made and their influence on the performance of the device has been evaluated. The study has been made with particular reference to the drift field in the base region, surface recombination velocity and base width.

A drift-tube\char22{}mass-spectrometer apparatus has been used to determine the mobilities of mass-identified atomic ions in the noble gases as a function of $\frac{E}{p}$ (drift field/gas pressure) at $T=295$ K. The measured values of the reduced mobilities ${\ensuremath{\mu}}_{0}$ of ${\mathrm{He}}^{+}$ in He, ${\mathrm{Ne}}^{+}$ in Ne, and ${\mathrm{Ar}}^{+}$ in Ar are in agreement with earlier investigations that did not employ mass identification. The measured value at $\frac{E}{p}=O$, ${\ensuremath{\mu}}_{0}({H}^{+} \mathrm{in}\mathrm{He})=({31.0}_{\ensuremath{-}1.0}^{+0.5})$ ${\mathrm{cm}}^{2}$ ${\mathrm{V}}^{\ensuremath{-}1}$ ${\mathrm{sec}}^{\ensuremath{-}1}$, is in good agreement with quantum-mechanical calculations, but the observed decrease of ${\ensuremath{\mu}}_{0}$ with ion energy is somewhat slower than that predicted by theory. The measured mobility of each of the noble-gas ions ${\mathrm{Ne}}^{+}$, ${\mathrm{Ar}}^{+}$, ${\mathrm{Kr}}^{+}$, and ${\mathrm{Xe}}^{+}$ in He is found to be $\ensuremath{\sim}(6\ensuremath{-}12)%$ lower than that of the corresponding alkali-metal ion (as determined by Tyndall's group).

The amplification of longitudinal acoustic waves in tellurium at 77 °K has been investigated in the frequency range 10 to 500 MHz. Both electric current and acoustic propagation were along the binary axis. Selenium epitaxial transducers were used to avoid bonding problems. The measured insertion losses agreed fairly well with theoretical calculations. The attenuation versus drift field is interpreted for low drift fields using the classical theory of Hutson and White. With respect to the known constants, a gain is observed higher than expected. This casts some doubt on the values of the electro-mechanical coupling constant and the electrical conductivity at high frequencies. On a etudie l'amplification des ondes acoustiques longitudinales dans le tellure a 77 °K, pour la gamme des frequences s'etendant de 10 a 500 MHz. Le courant electrique et le vecteur d'onde acoustique etaient orientes selon un axe binaire. Pour s'affranchir des problemes de collage, on a utilise des transducteurs de selenium epitaxies, dont les pertes d'insertion mesurees etaient en bon accord avec le calcul theorique. L'attenuation en fonction du champ electrique a ete interpretee aux faibles champs a l'aide de la theorie classique de Hutson et White. Par rapport aux constantes admises, on observe un gain superieur a ce qui est attendu. Ceci nous amene a douter des valeurs du coefficient de couplage et de la conductivite electrique a haute frequence.

Threshold field current oscillation due to phonon buildup decreases remarkably if acoustic wave packets are injected into the amplifying CdS from the cathode. The life time of the injected phonons could be estimated from the decrease of the threshold field under varying time interval between phonon injected and drift field application.

For pt.I see abstr. A71791 of 1971. The quadrupole field component of a nonuniform r.f. field can cause harmonic mass peaks. This effect is mathematically analysed. It is shown theoretically and experimentally that these spurious peaks can be suppressed by a d.c. drift field.

Poisson's equation is solved for two common types of diffused p-n junctions in a manner similar to that of previous authors. By a suitable transformation, the field in the junction and capacitance-voltage relation for all junctions are shown to be presentable as a single family of curves with no approximation other than the assumption of negligible drift field. The abrupt and graded regions are discussed in detail. The zero-bias potential and capacitance are also discussed.

An investigation is made of Brillouin scattering of acoustoelectric domains in semicon-duzting ZnO and CdS, in the case where the crystal is oriented with the electric drift field parallel to the hexagonal axis. The domains consist of off-axis shear waves. Angular dispersion due to strong elastic anisotropy is studied, and it is shown that the angle of maximum gain depends on the applied voltage and is limited by the sample geometry. The development of the angular spectrum for several acoustic frequencies is determined. The frequency spectrum of the domain is dominated by frequencies well below the frequency of maximum linear gian. Es wird die Brillouinstreuung von akustoelektrischen Domanen in halbleitendem ZnO und CdS fur den Fall untersucht, das die elektrisiche Feldstarke parallel zur hexagonalen Achse orientiert ist. Die Domanen bestehen aus transversalen „off-axis”- Wellen. Die Winkelverteilung der Energie in den anisotropen Kristallen wird bezuglich der Verteilung der Schallgeschwindigkeit der laufenden Domanen untersucht und gezeigt, das der Winkel fur maximale akustoelektrische Verstarkung vom angelegten elektrischen Feld und vom Querschnitt des Kristalls abhangt. Die Winkelverteilung verschiedener akustischer Frequenzen wurde untersucht und gefunden, das Frequenzen dominieren, die betrachtlich kleiner als die Frequenz maximaler linearer Verstarkung sind.

We have measured in a drift-tube mass spectrometer the mobilities of N${\mathrm{O}}^{+}$, N${\mathrm{O}}^{+}$ \ifmmode\cdot\else\textperiodcentered\fi{} NO, and ${\mathrm{K}}^{+}$ ions in NO at 300 \ifmmode^\circ\else\textdegree\fi{}K. The measurements were made over a substantial range of $\frac{E}{N}$, where $E$ is the drift field intensity and $N$ is the gas number density. The zero-field reduced mobilities were found to be 1.91 \ifmmode\pm\else\textpm\fi{} 0.06, 1.78 \ifmmode\pm\else\textpm\fi{} 0.05, and 2.245 \ifmmode\pm\else\textpm\fi{} 0.067 ${\mathrm{cm}}^{2}$/V sec, respectively. Measurements were also made of the longitudinal diffusion coefficients of N${\mathrm{O}}^{+}$ and ${\mathrm{K}}^{+}$ ions in nitric oxide at 300 \ifmmode^\circ\else\textdegree\fi{}K as a function of $\frac{E}{N}$. Our results are in fair agreement with those predicted by the Einstein equation from the experimental zero-field mobilities.

Carrier diffusion effects within the depletion region can have a large influence in determining the window thickness x_w of surface barrier detectors. If the surface is assumed to be a perfect sink, carrier diffusion (against the drift field) to the surface leads to x_w ≈ kT/qE where E is the field at the surface. Calculated values of x_w are in reasonable agreement with previously published values of window thicknesses. Surface preparation techniques can influence the amount of charge lost, as can plasma erosion times.

The rate coefficients for the reactions of ${\mathrm{O}}^{\ensuremath{-}}$ ions with ${\mathrm{O}}_{2}$ molecules have been measured in a drift-tube mass spectrometer at 300 \ifmmode^\circ\else\textdegree\fi{}K as a function of $\frac{E}{N}$, the ratio of the electric drift field to the gas number density. Two different measurement techniques were employed. One technique was based on the observation of the attenuation of the parent ${\mathrm{O}}^{\ensuremath{-}}$ ion species with increasing drift distance; the other involved examination of the shape of the product ion arrival-time spectra. The rate coefficient for the reaction ${\mathrm{O}}^{\ensuremath{-}}$ + ${2\mathrm{O}}_{2}$ \ensuremath{\rightarrow} ${\mathrm{O}}_{3}^{\ensuremath{-}}$ + ${\mathrm{O}}_{2}$ was measured on the $\frac{E}{N}$ range 6-29 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}17}$ V ${\mathrm{cm}}^{2}$. The rate coefficient was found to be (1.0 \ifmmode\pm\else\textpm\fi{} 0.2) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}30}$ ${\mathrm{cm}}^{6}$/sec over the entire $\frac{E}{N}$ range. The reaction ${\mathrm{O}}^{\ensuremath{-}}$ + ${\mathrm{O}}_{2}$ \ensuremath{\rightarrow} ${\mathrm{O}}_{2}^{\ensuremath{-}}$ + O was observed with a rate that increased sharply with $\frac{E}{N}$. The rate coefficient was found to increase from (2.5 \ifmmode\pm\else\textpm\fi{} 1.5) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}14}$ ${\mathrm{cm}}^{3}$/sec at an $\frac{E}{N}$ of 63 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}17}$ V ${\mathrm{cm}}^{2}$ to a value of (3.4 \ifmmode\pm\else\textpm\fi{} 1.0) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{3}$/sec at an $\frac{E}{N}$ of 140 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}17}$ V/${\mathrm{cm}}^{2}$.

The mobility of ions in liquid hexane has been determined by a variety of methods at fields between 0·4 and 7 kv cm−1 using both air-saturated and outgassed liquid. X-rays or β particles were used to produce ion injection. At room temperature and with a drift field of 1 kv cm−1 mobilities ranging between 1·2 × 10−4 and 2·4 × 10−3 cm2 v−1 s−1 were found, depending on the method of measurement and the geometry of the cell. There appeared to be little difference between the behaviour of positive and negative ions and dissolved air had no effect. The variation in apparent mobility is attributed to liquid motion which is induced by and augments the ion velocity, and depends on the hydrodynamic properties of the test cell. Experiments demonstrate clearly the importance of this effect and suggest that the true ion mobility is very small. In a low-temperature cell the mobility of positive ions was found to decrease from 1·9 × 10−4 cm2 v−1 s−1 at 20°C to about 4·5 × 10−5 cm2 v−1 s−1 at -50°C with an activation energy of 8·7 × 10−2 ev. This value is close to the activation energy reported from viscosity studies and, contrary to earlier views, suggests that Walden's rule is obeyed provided that liquid motion is eliminated.

The time dependence of the current decay due to the acousto-electric effect was measured in p-type tellurium at 77 K. The dependence of the current decay on the crystallographie orientation, the carrier density, and the carrier mobility was investigated. The experimental results for drift fields parallel to the x- or y-axis agree with the theory of acousto-electric amplification. A current decay was also found for a drift field along the z-axis. This coupling is about a third of that in the x-direction, but according to the theory of piezoelectric effect in tellurium no coupling is expected. Die durch den akustoelektrischen Effekt hervorgerufene zeitliche Stromabnahme wurde an p-Tellur bei 77 K gemessen. Der Einflus der kristallografischen Richtung, der Ladungstragerkonzentration und der Beweglichkeit auf die Stromabnahme wurden untersucht. Die Mesergebnisse fur die x- und y-Richtung stimmen mit der Theorie fur akustoelektrische Verstarkung uberein. In z-Richtung wird ebenfalls eine akustoelektrische Kopplung gefunden die um den Faktor 1/3 geringer als in x-Richtung, aber theoretisch noch nicht zu deuten ist.

The injection efficiency of a point contact has been measured as a function of the field strength of the normal drift field, at different emitter currents.

The complex internal short-circuit current gain, αd, of a type 2N247 plane alloy-junction germanium transistor has been determined from measurements of the external short-circuit current gain, by taking account of the effects of the emitter and collector depletion-layer capacitances and the ohmic base resistance. Measurements have been made up to 105 Mc/s and over a range of emitter current from 50 μA to 8 mA. It has been found that the loci of αd may be interpreted in terms of Kroemer's theoretical treatment, which is based on the existence of a uniform drift field across the base. The value of ΔV/kT is found to be 5 at room temperature.

The Weinreich relation between the acoustic absorption coefficient and the acoustoelectric field in semi‐conductors is found to be modified by carrier trapping. In the presence of dc fields, the acoustoelectric field and the absorption coefficient pass through zero at different values of drift field. The effects of the trapping are particularly important when the trapping time is of the same order as the acoustic‐wave period. The experimental evidence indicates that the above explanation for the effect of trapping is valid, with the dominant traps having a trapping time of about 10−9 sec. Some anomalies in the absorption were found which can be explained by the generation of a shear mode which does not interact with the carriers. Nonlinear interactions with this shear mode are found to occur at much lower power levels than those associated with second‐order effects in the theory of Hutson and White.

In CdS crystals oriented with the electric drift field parallel to the c axis, acoustoelectric domains consist of off-axis shear waves. This is because there is no acoustoelectric gain for shear waves traveling along the hexagonal axis, while the gain may be large in an off-axis direction. The particular angle at which the gain is a maximum depends on the angular dependence of the electromechanical coupling coefficient and the component of the electron drift velocity along that angle. These factors combine to make the angle of maximum gaina function of drift velocity along the c axis. Using a stroboscopic strain-birefringent methowde, observed the off-axis domains directly. The domain tilt angle has been found to depend on drift velocity in roughly the same way as predicted from the small-signal angular dependence theory. Discrepancies may be the result of large-signal effects or of angular dispersion.

A solid converter consisting of alternate sheets of brass and insulating material has been placed above a multi-wire proportional chamber 1 ). X-rays were converted to photo electrons in this dense material and the electrons drifted through holes in the sheets into the chamber where they were detected. It was found that a drift field inside the converter of only a few hundred volts per cm was required to drift the electrons into the chamber. The spectra of pulse heights from the chamber have been measured.

The short-circuit current of a CdTe drift-field photodetector is calculated for lifetimes from 5 × 10-10to 10-7s. It is shown that the optimal drift-field region thicknesses for visible and near-infrared light are between 0.4 and 5 µm. A method for producing such structure is proposed.

It is shown that Kuno’s modified relation ts/τeff =ln[1+(JF/JR)]+B, is valid for all diodes irrespective of whether or not heavy doping effects are important and whether the emitter and base thickness are small or large provided ts is large or JR/JF is small). The slope of the ts vs ln[1+(JF/JR)] straight line plot gives τeff. For a large base thickness, τeff≂τB. For a short base, 1/τeff=1/τB+1/t1, where t1 depends on the base thickness, the emitter properties, and the surface recombination velocity at the base contact. For small ts/τB, B is not constant anymore, and the ts vs ln[1+(JF/JR)] plot becomes curved in all cases. The effects of photoexcitation and of drift field in the quasineutral regions are also considered.

Measurement results on CdS ultrasonic amplifiers which were operated with continuous drift fields at room temperature are presented. A material gain of 26 dB was obtained for a 200‐MHz transverse‐wave signal. Comparisons are made with pulsed‐field data obtained from the same samples. The presence of saturation‐level ultrasonic flux significantly reduces the maximum gain obtainable under continuous operation.

Intrinsic common-base, short-circuit current gain analysis of drift transistors may be aided by means of a simplified approximation equation. The accuracy of the equation may be controlled by the investigator. A graphic solution for determining this parameter of moderate drift field transistors may be obtained by using the arcs of circles. The interrelation between the graphic analysis and the theoretic approximation provides a flexible yet accurate method of analyzing this parameter.

The effect of elastic and acoustoelectric anisotropy on acoustoelectric domain propagation in semiconducting CdS has been studied by Brillouin scattering, in the case where the c-axis of the crystal is obliquely oriented with respect to the electric drift field. In the 45° configuration (the angle between E and c is 45°) angular focussing of energy is observed.

Drift fields of 100–1000 Td. were used to co11isiona1ly dissociate ions (which were directly sampled from the lower atmosphere) to aid in their chemical idenitfication. The ions being studied make up only one part in 1017 of the gas in which they are found, and their mass spectrometric analysis is accomplished near the high sensitivity limit of the present apparatus. Since the chemical identity of the sampled ions can often not be determined from their mass alone, additional identification methods are needed. They must not, however, cause ionization in the far more abundant neutral gas or reduce the number of ions being detected. Under the appropriate conditions collisional dissociation of the ions being studied can accomplish both of the above goals, and also make available a continuously variable range of collision energies. At low field strengths ligand detachment from the parent ion can be observed. while fragmentation of the more strongly bound core ion is accomplished at fields near 1000 Td. An example of ligand removal is the gradual conversion of an atmosphericion family believed to be NH 4+·(H2O)n (mass 36, 54, 73…) into a single mass peak at mass 18 at 300 Td. in a nitrogen buffer gas. At 800 Td. an ion believed to be NO3– is seen to be largely dissociated into a fragment at mass 46 (probably NO2–) thus helping to confirm the identification of the parent ion as NO3–.

For the electronic measurement of the decays of the new particles one would like to have a drift chamber with as high a space resolution as possible. Known critical factors are a. the primary ionisation density b. the widening of the tracks due to the range of the knock-on electrons c. the diffusion of the drifting electron in the direction of drift d. the homogeneity of the drift field e. the mechanical accuracy f. the accuracy in timing.

We report a recent study undertaken at the Council for the Central Laboratory of the Research Councils (CCLRC) Rutherford Appleton Laboratory to evaluate the performance of a gas electron multiplier (GEM) coupled with a microstrip gas counter (MSGC) for X-ray spectroscopy. The parameters investigated during this study were effective gain, effective gain stability, and energy resolution at 8.05 keV using Cu-K X-rays. These parameters were studied as a function of drift field, induction field, and potential differences across the GEM holes and that across the MSGC anodes and cathodes. This study demonstrates that a single stage GEM can sustain effective gains up to 6000 whilst retaining adequate X-ray energy resolution. By utilizing the MSGC as well as the GEM amplification the gains easily exceed 100 000 and allow the MSGC operation at much lower voltages. This study also demonstrates that the introduction of the GEM preamplification to the MSGC enables the operation of the latter at much higher effective gains (30 000) before any degradation in the X-ray energy resolution

The theory of stochastic differential equations is exploited to derive the Hopf's identities for a passive scalar advected by a Gaussian drift field delta-correlated in time. The result holds true both for compressible and incompressible velocity field., 7 pages TEX. Amended version, one error corrected

It is shown that the ultrasonic velocity in semiconducting CdS, in the presence of an applied electric drift field, can exceed the piezoelectrically stiffened value for the insultating material, if the electron-trapping relaxation time is nonzero.

Measurements of the rf-admittance of an interdigital electrode structure on oxydized Si-surface show that its conductance becomes negative if the charge carriers in the semiconductors are subjected to a sufficiently high drift field. Spontaneous rf-oscillation has been observed.

Measurements of the ultrasonic velocity for piezoelectrically stiffened transverse waves in CdS were made as a function of applied electric drift field, electrical conductivity, and acoustic‐wave frequency. By modifying White's theory [J. Appl. Phys. 33, 2457 (1962)] to include the effects of electron trapping with nonnegligible relaxation time [I. Uchida et al., J. Phys. Soc. Japan 19, 674 (1964)], we obtain a theoretical expression that gives good agreement with the experimental results, covering a frequency range of 30–350 MHz, and a range of electrical conductivities from 10−5 to 10−2 (ohm‐cm)−1 Additionally, when strong electron‐trapping relaxation phenomena occur, the theory predicts, for the case of an applied electric field with electron drift opposite to the acoustic‐wave propagation direction, an enhancement of the ultrasonic velocity in semiconducting CdS, above the piezoelectrically stiffened value for the insulating material. Experimental data verifying this effect are given. [This research w...