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An ADC is described, which is of the successive approximation type and makes use of Gatti's sliding scale principle 1 ) for channel width averaging. The use of commercially available modular converters for both the ADC and the averager DAC resulted in a very simple and reliable construction of high stability. Conversion time is 15 μs. Differential linearity is better than 0.2%. Integral linearity is less than 0.01% and gain stability is in the order of 10 ppm/°C. A mapping of the channel profile is given for both “averager off” and “averager on”. No significant degradation of the channel profile due to the averager action could be found because of the good initial differential linearity of the ADC module.

A new type of ADC is being developed to satisfy the requirements of the HEAO high spectral resolution gamma ray spectrometer. This 13 bit design utilizes a double successive approximation technique that overcomes the usual differential linearity problem. Stability of a few ppm/°C, differential linearity of 2% and integral linearity of 0.05% have been demonstrated.

The pulse amplitude divider and multiplier described in this article uses as the main element the Field Effect-Transistor (FET) working in the region before the pinch-off voltage. The integral linearity of the divider, with input changes of 1:20 and 1:10 respectively at the two inputs (1:200 ratio), is better than ±1.5% with a minimum pulse width of 2.5 μs. For the multiplier, the integral linearity for input changes of 1:20 at both inputs (output ratio 1:400) is better than ±1% with a minimum pulse width of 0.5 μs. The circuits are analog and with slight changes the pulse mode can be converted to a mode for continuous waveform.

An ADC with the following specifications has been designed and constructed: 8192 channels, amplitude range 0.05 to 10 V, positive, conversion time 12 μsec, max. integral linearity better than ± 2.5 × 10 −4 , stability of channel-width 0.5%. In a modification of the linear capacitor discharge a coarse and a fine measurement is executed subsequently, combined of a fast discharge and an interpolation with a slow discharge. The address oscillator works at 20 MHz, the address register is advanced during the coarse measurement in steps of 64 channels and during the fine measurement channel by channel. The discharge current generators are switched in exact synchronism with the pulses of the address oscillator; a two-step-synchronizing circuit is used. Special circuits have been developed for the pulsestretcher, the current-generators, current-switches and the discriminator. The high degree of stability and linearity is achieved through the proper use of field-effect-transistors, linear integrated circuits and fast digital intergrated circuits (emitter-coupled logic). Details of the tests performed and the testing methods are given.

A circuit is described for a digital pulse-height analyzer constructed wholly from commercially available computer logic and pulse-handling modules. The design combines the reproducible discrimination techniques of conventional analyzers for good differential linearity with a self-correcting successive approximation analog-to-digital converter for high speed and integral linearity.

The largest time interval, that can be measured by means of the vernier chronotrons working on the principle of beat between two generators of slightly different periods, is limited by the period of the slower generator. This present paper deals with the improvements brought to the vernier chronotrons system and which permit to use this device in order to define a very great number of channels without impairing their stability and differential linearity: indeed, the method used leads to measure in a homogeneous way the time intervals larger than one period. In order to verify the basic principle, a time analyzer with 3000 channels of one nanosecond width each has been built. The measurements exhibit a stability of the order of 3 × 10 −4 /°C and the first tests carried out have not allowed to detect any lack in differential or integral linearity.

Transistorized circuit details and performance characteristics of a linear gate with increased stability and lesser power consumption is described. The circuit operates on signal levels between 0.2 ∼ 5.0 V. A novel constant-delay sampling method assures an overall integral linearity of better than 0.5% between slow input pulses and narrow square output pulses of a linear gate. An application of the circuit to the measurement of alpha particle angular distributions from a thin Po 210 source is also given.

A TPHC is described which was designed for use with a post-acceleration deflection system operating at 3.525 MHz. The converter is started by a sharply differentiated pulse from the anode of a PM, and is stopped by a pulse derived from the sine-wave induced in a pick-up loop coupled to the tuned transformer of the deflector. A deadtime of a few μsec is provided after every conversion. The electronic resolution was measured to be 60 ps, determined with the aid of a circuit which provides a fast pulse at a low rate, synchronized with the input sine wave. The differential non-linearity was measured as ±2% over 90% of the range; the PHA which was employed for this measurement had a manufacturer's specified differential linearity of 2%. The integral linearity of the TPHC was determined by means of a new oscillator method developed in this laboratory. Start and stop pulses are derived from independent crystal-controlled sources, and the integral linearity curve can be determined without reference to calibrated delay lines. The time reference for the calibration is the period of the deflector oscillator. A comparison of the integral linearity so determined is made with that obtained using delay cables which had been calibrated by various methods. The integral linearity over the major part of the range is at least as good as that (0.4%) of the PHA which was employed.

This fast pulse-dc integrator accepts pulses from dc to less than 20 ns width, over an input dynamic range of 400:1 in amplitude (1 mV minimum) without range switching. The integral linearity (maximum absolute error as fraction of full scale) is 0.1 ppm at constant pulse height, 0.2% at constant pulse width. Any reading is accurate to within 2%. Temperature compensation and dc feedback ensure stability of operation. A fast voltage-to-current converter stable to 0.002% of full scale current provides the charge for capacitor storage.

A neutron time-of-flight spectrometer has been designed and constructed. It consists of a time-to-amplitude converter, a beam pulser and associated neutron detectors. The time-to-amplitude converter gives a time resolution of 3.5 × 10−10 sec using 56 AVP photomultipliers and small plastic scintillators. With two 10 × 5 cm NE213 liquid scintillators and 58 AVP photomultipliers the time resolution was 1.1 × 10−9 sec. From 10 to 100% of its range, the differential nonlinearity was ± 0.3% and the integral linearity ± 0.8%. The beam pulser produced beam pulses 2 nsec wide with a beam utilization of 10–12% and 1 nsec wide with a 6% utilization.

The design and performance of a sliding pulser with high repetition rate (≦ 10 6 pps) is described. The output of this pulser is useful for rapid testing of integral linearity of analog pulse circuits. Generation of the sliding pulse is based on the DA converter technique.

A principle of operation and a circuit diagram of the biased amplifier are described. Integral linearity equal to 0.1% for the range 0.2–10 V, temperature stability −5 × 10 −3 /°C per gain factor and long time stability −0.8 × 10 −4 were obtained.

A time-to-height conversion system has been developed which is useful for measuring time intervals from 10 ps to 200 μs. When driven by a mercury-relay pulse generator through appropriate fixed delays, the resolution of the system, FWHM, is 6 ps, the apparent time shift with temperature is less than 2 ps/°C, and the integral linearity is within ± 1%. The apparent time distribution through a type-58 AVP photo-multiplier tube driven by a mercury relay light pulser was less than 0.3 ns at a fixed light level equivalent to 10 3 photoelectrons per pulse. The apparent time shift was less than 0.5 ns for variations from 10 2 to 10 4 photoelectrons per pulse.

The Graf/Pen is a digitizing or data gathering device in which the operator simply holds a pen to point or to create graphical input for digital systems. Previous attempts to provide a natural graphical input have suffered from one or more disadvantages. The method in which strings extend from the cursor to mechanical or optical encoders (mangiospago) does not allow the operator to sketch as naturally as with a pen. The method of crossed wire grids and capacitive sensing known as the Rand Tablet is inherently expensive while being limited in size and format. Other methods using resistive sheets and capacitive sensing suffer from poor integral linearity, and in addition, require ADC's.Our own R & D group has long had all of the technology needed to solve the problems, but we were in a different area of science and were unaware of the need for a natural man-machine interface. A little accidental cross-fertilization between us and computer scientists prompted us to develop the extremely simple and versatile device I am about to describe.

Specifications of the linear gate: deviation from integral linearity less than 0.1% for pulses up to 10 V, a rise time of 5 ns at the input is increased at the output to 5.5 ns for a pulseheight below 1 V, to 50 ns for a pulseheight of 10 V, pedestal adjustable to zero, feedtrough (gate closed) 10 mV for a 10 V pulse.