摘要:

Gold-germaniump-njunctions for the detection of α-particles and fission fragments are reported in the References. The present investigation, using protons, deuterons, α-particles and He3ions, shows that the output pulse is proportional to the incident energy, providing the particle range does not exceed the effective junction thickness. Measurements on the maximum pulse heights obtainable from protons and deuterons agree on the effective junction thickness; however, the exact value varies with method and conditions of manufacture and increases with the voltage across the junction. The output pulse height is not dependent on the type of particle provided the junction bias is maintained above the minimum value (about 1 volt) required to prevent recombination. The pulse height is independent of crystal temperature if the voltage on the crystal is fixed, but as the temperature decreases the signal/noise ratio increases. At liquid-nitrogen temperature the resolution of 5 MeV α-particles (2–3%) is not determined by the signal/noise ratio. A value of 2.84 ± 0.12 eV, in accord with that previously reported, has been found for the energy required to produce an electron-hole pair in germanium. Pulse rise times have been shown to be less than 3 millimicrosec and are believed to be much shorter than this.Applications of these detectors in charged-particle spectroscopy are discussed.

DOI:10.1049/pi-b-2.1959.0137

出版商:IEE    

年代:1959

数据来源: IET

摘要:

Quantitative observations of pile-neutron effects in germanium and silicon suggest their use as fast-neutron dosimeters, especially in mixed neutron-γ fields. In order to provide a firm basis for such techniques, or, in other words, to determine neutron-response characteristics of semiconductor materials for general dosimetry applications, more information is needed on the extent to which the damage is actually energy dependent. In the present state of the art, the development of semiconductor dosimeters for fast neutrons of known energy spectrum should be rewarding. On the other hand, it is well known that thermal-neutron captures by lattice nuclei have only a small effect on the electrical properties of germanium or silicon crystals. Slow-neutron reactions yielding fast charged particles or ions may result in enhanced, highly localized damage of practical interest for thermal-neutron dosimetry. A suitable arrangement combining a high-resistivityp-type germanium foil with thin linings of lithium-6 appears to be a convenient tool for the estimation of biologically significant thermal-neutron doses. Analytical and experimental work done on semiconductor dosimeters designed according to the above-mentioned lines is presented.

DOI:10.1049/pi-b-2.1959.0138

出版商:IEE    

年代:1959

数据来源: IET

摘要:

A number of papers on transistor convertors have been published, but they have been mainly concerned with types using a single transistor, although, for some years, transistor convertors have been used in push-pull systems. The paper analyses waveforms in push-pull transistor convertors and presents a simple method of design.Transistor push-pull convertors, unlike those using a single transistor, do not need cores which can store magnetic energy. Thus materials with rectangular hysteresis loops as well as those with constant permeability can be used.

DOI:10.1049/pi-b-2.1959.0139

出版商:IEE    

年代:1959

数据来源: IET

摘要:

The paper begins by showing that various well-known simple oscillator circuits, usually analysed separately, are essentially equivalent to one another if certain reasonable assumptions are made, and appreciation of this fact simplifies the design problem.A discussion follows concerning class-C oscillators and the difficulty of combining high efficiency with a satisfactory degree of independence of transistor parameters. The problem of avoiding squegging is also considered.A simple push-pull high-efficiency oscillator is then described, in which substantially constant current flows in each transistor for the whole of its 180° conduction angle. This oscillator is believed to possess a unique combination of desirable features.Another unusual high-efficiency oscillator is then presented, which is more elaborate than the previous one but which has advantages in certain respects.The paper ends with a description of an oscillator based on the ‘long-tailed-pair’ circuit. The oscillator is exceptionally easy to design and make, and is suitable for applications where high efficiency is not important. It can supply either a sine wave or a square wave, or both.

DOI:10.1049/pi-b-2.1959.0141

出版商:IEE    

年代:1959

数据来源: IET

摘要:

A description is given of a small and inexpensive germanium pointcontact diode which has been developed for the high-speed switching of a carrier at 35000 Mc/s. The diode can typically modulate several hundred milliwatts of carrier power with a response time less than 3 millimicrosec. A novel modulator is described in which the insertion loss with such a diode is less than 2 dB.

DOI:10.1049/pi-b-2.1959.0142

出版商:IEE    

年代:1959

数据来源: IET

摘要:

The risk of instability when negative feedback is applied to a multistage amplifier is minimized by dividing the amplifier into sections, each with its own feedback. If there are not more than two 90° phase-shifts in each feedback loop, the circuit will be stable. Since the interaction between cascaded stages depends on their input and output impedances, various methods of controlling these impedances have been examined. Several practical wide-band amplifier circuits are described, and it is shown that such circuits can be made to accept wide variations in transistor characteristics.When operation is required near the cut-off frequency of the transistor, a transformer coupling is proposed. The relatively poor low-frequency response of this circuit is improved by the addition of anRCcoupling.Bias currents in the transistor circuits are fixed by a d.c. feedback which is decoupled at signal frequencies. Operation at very low frequency (<1 c/s) is considered.

DOI:10.1049/pi-b-2.1959.0143

出版商:IEE    

年代:1959

数据来源: IET

摘要:

The paper describes a transistorized teleprinter receiver for airborne use. The specification is based on experimental work carried out on the North Atlantic route, and an account is given of the way in which the requirements of the specification have been translated into circuit terms, together with details of special features which have been incorporated in the design.Both the receiver and the associated test set are fully transistorized.

DOI:10.1049/pi-b-2.1959.0144

出版商:IEE    

年代:1959

数据来源: IET

摘要:

The amplifier and discriminator described in the paper are component parts of a completely transistorized frequency-lock loop. Each is contained in a compact potted block; the amplifier uses printed circuits.Interesting features of the amplifier include its excellent a.g.c. performance and its elegant circuit configuration. The input stage uses biased silicon diodes as variable gain/loss elements; a gain range of over 90 dB is obtained, with negligible distortion or change in overall response, and with a substantially linear control characteristic. Following this are three synchronously-tuned common-base stages, with finally an output stage and detector. The maximum overall voltage gain is 106, with a bandwidth of 4 kc/s. The complete amplifier contains 11 transistors and 8 diodes.The discriminator is unusual in combining crystal control with a linear response over a wide bandwidth. Basically, discrimination is effected by beating the incoming signal with a reference signal generated by a local crystal oscillator, and measuring the beat frequency. The system is very suitable for use with transistors, since most of the circuits handle only low frequencies. The complete circuit contains nine transistors; a linear response of high slope and excellent zero stability is obtained.

DOI:10.1049/pi-b-2.1959.0145

出版商:IEE    

年代:1959

数据来源: IET

摘要:

A simple free-running emitter-coupled multivibrator, using germanium transistors, is described in which changes in the ambient temperature and supply voltages have only a second-order effect. It is a designable circuit in which the oscillation frequency can be calculated to within ½%.The basic multivibrator, with additional circuits, can be changed into a monostable trigger circuit, in which the delay time is linearly related to a resistance. The linearity is of the order of ¼% of the maximum delay.The basic multivibrator can also be synchronized to a train of input pulses and used as a fixed frequency divider.

DOI:10.1049/pi-b-2.1959.0147

出版商:IEE    

年代:1959

数据来源: IET

摘要:

A time-base circuit is described that produces a linear saw-tooth current waveform suitable for driving the magnetic deflection system of a cathode-ray tube. The current waveform, which has a peak amplitude of 1 amp, is obtainable at a minimum sweep duration of 120 microsec and a repetition frequency of 2 kc/s. A linearity of better than 1% is obtainable.The circuit is a feedback amplifier of the Miller integrator type. The output transistor has a resistive load in its emitter circuit, and the feedback capacitor is fed from this point. A linear voltage saw-tooth waveform is produced across the emitter resistor, and the resulting linear current saw-tooth waveform flows through the deflection coil placed in the collector circuit. A transistor used as a switch in the feedback path sets the quiescent conditions, and this switch is opened for the duration of the sweep.The circuit uses germanium transistors and operates satisfactorily at an ambient temperature of 50° C. Compensation circuits are to reduce temperature effects, and a rise in ambient temperature from 15 to 50° C changes the time-base velocity by less than 1%.

DOI:10.1049/pi-b-2.1959.0148

出版商:IEE    

年代:1959

数据来源: IET