Measurement Dead Time Research Articles

A method for the dead-time measurement of an individual particle detecting system

A simple method is presented for the determination of the dead time of an individual particle detecting system. Based on a general relation valid for non-extended dead times, it is applicable to a wide variety of experiments where the classical two-source method is not adapted.

Measurement of the dead time of a fluorescence stopped-flow instrument

Measurement of the dead time of a fluorescence stopped-flow instrument

Study of gas chromatographic dead-time measurement

A rigorous investigation of the determination of gas chromatography column dead times has been carried out using air and methane data and also by the method of Peterson and Hirsch using n-alkanes. It is shown that for polar and non-polar columns and a wide range of working temperature, methane is not retarded and gives identical times with an air peak allowing its use in conjunction with flame-ionization detectors. It has also been demonstrated that the Peterson and Hirsch method of calculating t m from n-alkane retention data is subject to very large errors over which the operator has no control and the use of this method in the evaluation of corrected retention times should be discontinued.

Dead-time correction in dynamic radionuclide studies by computer.

Several methods for the measurement of dead time and for evaluation of the dependencies required to correct dynamic studies for dead-time losses are described. Two program variants were written to produce time-activity curves in the selected areas of interest of the dynamic studies with computer's correction of dead-time losses; these variants are part of the system of programs for complex processing of scintigraphic studies set up for a Clincom instrument. The first variant performs correction on the basis of the registered count rate in the whole image, while the second variant makes us of the additional reference source positioned on the periphery of the camera visual field.

The accurate dead time measurement of single channel gamma ray counters by means of the proportional source method

A method is presented to fit a dead time model to observed count rates. The elimination of errors in the proportional source method, the choice of a correct dead time model based on two dead times θ, τ, the mathematical methods involved in the estimation of the dead times and the stability of dead time as a function of time are examined. It is demonstrated that in this way the aim of the present investigation of measuring true count rates up to 1·5 × 10 5 s −1 with an overall uncertainty of the order of 0·1 per cent is met.

Dead-time calibrator

A method of dead-time measurement based on the time interval density measurement is proposed.

Deadtime of scintillation camera systems--definitions, measurement and applications.

Fast quantitative dynamic studies with scintillation camera systems require deadtime correction. Although such systems are semiparalyzable, they are most conveniently treated either as paralyzable or nonparalyzable. Paralyzing deadtime (τ) is that deadtime during which a system is unable to provide a second output pulse unless there is a time interval of at least τ between two successive events. Paralyzable systems are characterized by Poisson statistics, so that the “true” counting rate , where R is the observed counting rate. Nonparalyzing deadtime (T) is that deadtime during which a system is insensitive after each observed event. The period of insensitivity is not affected by any additional “true” events before full recovery occurs. For nonparalyzable systems the corrected counting rate . A two‐source method protocol is presented for deadtime measurement. The paralyzing deadtime is calculated by a 5‐dimension Newton–Raphson iteration. The nonparalyzing deadtime is calculated by a quadratic equation. Approximation equations are also presented not requiring a computer. Deadtimes are fitted to polynomial equations as dependent variables of measured counting rate. Algorithms incorporating the polynomials are presented for the deadtime correction of histogram curves. Using either the paralyzing or the nonparalyzing approach, precise deadtime corrections are demonstrated.

The source and nature of deadtime in X-ray counting systems used in electron microprobe analysis

In an investigation of X-ray counting circuits the fundamental quantity governing component interaction and system counting efficiency was the pulse duration associated with a single counting event. Theoretical expressions governing the behaviour of counting systems consisting of two components were derived assuming either nonself- prolonging (nsp) or self-prolonging (sp) behaviour for each component. In an experimental study, preamplifiers, amplifiers pulse height analysers and scalers were found to be sp, sp, nsp and nsp respectively. It was found that many commercial counting chains could be reduced to two-component systems consisting of an sp amplifier with pulse duration tau and an nsp pulse height analyser with pulse duration lambda . Experimental measurements of system losses for tau > lambda revealed that the efficiency was given by m/n=exp(-n tau ) where m and n are the measured and true intensities respectively. When lambda > tau , the efficiency was found to be m/n=1/(exp(n tau )+n( lambda - tau )). The range of applicability of these expressions is discussed, as are the effects of pulse amplitude shifts, baseline selection and X-ray energy. Recommendations are made concerning the measurement of deadtime, the use of the proper correction model, and equipment testing and selection.

Measurement of system dead time with commercially available NIM modules

Abstract A procedure to measure the dead time of a counting system with a commercially available NIM type gate and delay generator and a gated scaler is described. A gate method was used to determine the dead time of a 4π proportional counter to within 0.1 μsec1 as a routine part of the counting procedure; agreement was found when comparison was made with the two source method.

Influence of the pulse shape on the dead time of a 4π proportional counting system

A universal equation for the calculation of additional dead time produced by the pulse undershoot is given. For a 4π proportional methane counter of 20 mm height and 60 mm dia., with time constants of double RC shaping of 0ȧ6 μs and 1 μs the dead time varies within the range from 0ȧ1 μs to 0ȧ41 μs related to discriminator dead time and the maximal beta energy. The methods of dead time measurements are discussed as well as the more accurate formula for dead time calculation from the measuring results with paired sources.

Dead time measurement of G.M. counters

Dead time measurement of G.M. counters

Bernoulli trials and counting correlations in nuclear particles detection

An application of statistical methods to the theoretical and experimental analysis of some counting processes is realized. A theory of the correlations due to non-ideal measuring instrumentation is derived and various experiments involving sources, of random and correlated events are presented. This correlation method suggests a simple measurement of dead-time for counting devices. It also allows a correct experimental approach to the short-time probability methods (i.e. prompt neutron lifetime measurements in nuclear reactors) which have been elsewhere described and applied by the same author.

Dead Time and Non-Linearity Characteristics of the Geiger-Counter X-Ray Spectrometer

The satisfactory use of Geiger-counter methods for the measurement of diffracted x-ray intensities demands that the observed counting rates be corrected for the non-linear response of the counter. Both the multiple foil method of calibrating the non-linearity of response and the two-source method of Beers for measuring counter dead time have been found to be unsatisfactory approaches to this problem. The experience of this laboratory indicates that electronically controlled oscillographic techniques for the direct measurement of dead time are much more satisfactory. With a knowledge of the dead time, τ, the true counting rate, N, can be calculated from the observed counting rate, No, by employing the formula N=No/(1−Noτ). For a pulsating x-ray source the effective counting rate is faster than the observed by a factor which is characteristic of the type of rectification employed, the target material, and the voltage applied to the x-ray tube. A sufficiently accurate value of this factor can be arrived at by oscillographic observation of the pulse pattern and in some cases by mathematical analysis.

Two Methods of Measurement of Dead Time in Geiger-M ller Counters

The insensitive period following a count in a Geiger counter is measured by two methods. Each relates only to the periods following fully recovered pulses. The first method is an extension of the oscillograph method of Trost (1) and of Ruark and Branmer (2). A pulse interval discriminator is described which triggers the oscilloscope only when the counter is in a fully recovered state. This method is accurate for measurements of the dead time of a counter associated with a given recording circuit. By the second method, the time of recovery to any preselected fraction of the full pulse amplitude is measured. This is done by means of an electronic gate which automatically sets its length equal to the recovery time. This period is displayed on a meter.

The Effect of Measurement Dead Time in the Control of Certain Processes

Abstract The purpose of this paper is to report on a series of automatic-control tests which demonstrate the importance of instantaneous controller-mechanism response in self-balancing potentiometer controllers. The automatic-control tests were made with both two-position and proportional-reset control. Other tests, dealing with the importance of measurement dead zone of the controller, are included, noting the relation between dead zone of measurement and dead time of controller response.

Closure to “Discussion of ‘The Effect of Measurement Dead Time in the Control of Certain Processes’” (1946, Trans. ASME, 68, pp. 710–711)

Closure to “Discussion of ‘The Effect of Measurement Dead Time in the Control of Certain Processes’” (1946, Trans. ASME, 68, pp. 710–711)