Assessment of the Efficiency of the Counting Method for Processing Information in Multichannel Radiometric Testing Systems

Abstract

A modification of the counting method for the detection of ionizing radiation is proposed. The modification improves functional capacities of multichannel radiometric systems used for nondestructive testing of commercial products. The method involves recording the time needed for the accumulation of pulses that is set for the channel with the lowest counting rate. Statistical errors of measurements are compared and the efficiency of the method proposed is analyzed.The development and investigation of the systems for testing articles with significant variations in thickness constitute one of the most important directions in the development of radiometric testing methods [1][2][3]. In this paper we propose a method for generating, detecting, and processing informational signals by multichannel systems for radiometric testing of such articles and also assess the efficiency of this method.Two methods are mainly used to implement a counting (pulse) detection mode when measuring the intensity of a radiation flux during discrete scanning of a test object (TO) [2][3][4][5]. The first method is based on counting the number of particles recorded during a preset time interval (which is the same for each discrete position). The second method involves determining the time interval during which a preset number of particles is detected [3,4].The value of the statistical component of the measurement error, which is due to the quantum nature of radiation, is the key factor in the measurements of the spatial distribution of the radiation intensity using a multichannel radiometric system [5].When the first detection method is used, the statistical errors of measurements significantly depend on the channel. Moreover, in this method the testing performance is set; however, the relative error of measurements in each discrete scanning position remains unknown since the error depends on the measured parameters of the article that are a priori unknown. The second method, in contrast to the first, levels relative errors in each channel [3,5], and these errors are known. However, this method also has a disadvantage: some channels of the measurement system, where the apertures of the detectors correspond to a smaller radiation thickness of the tested article, are not operative after a given number of pulses has been accumulated. Thus, they feature a temporal "blind spot."In order to remove the shortcomings briefly described above for the detection procedure, we propose a third counting method that has the main features described below.(1) A number of the pulses to be detected ( N ) is set for all of the n channels in the linear array of detectors.(2) After N pulses have been accumulated in an arbitrary j th channel, an accumulation signal is sent to the control device. The device continues counting pulses in this channel until the last detector in the array records the preset number of pulses ( N ). Thus, the j th channel records N + N j pulses ( j = 1, 2, …, n ).(3) Time interval T is measured, during which the previously mentioned measure...