SU805076A1 - Method of measuring amplitude-frequency response of a photomultiplier - Google Patents

Description

The invention relates to photographic equipment and can be used in all areas of science and technology, where it is necessary to deal with the registration of light signals distributed in a wide frequency band using a photomultiplier, namely, in lidar technology, nuclear physics, optical communication, radioelectronic , spectroscopy, space technology and cybernetics. There is a method for determining the amplitude-frequency characteristic of a photomultiplier, operating in the registration mode of strong light fluxes, in which the photocathode of the photomultiplier is illuminated with a strong light flux modulated by the intensity in a wide frequency band / and by the modulation depth of the output current of the photomultiplier from the frequency about the amplitude-frequency characteristic of the PMT RZ. The disadvantages of the known method include the low sensitivity due to the long duration of the measurement process, considerable complexity and limited functionality, since this method is not applicable to study the frequency characteristics of PMTs operating in one-electron registration mode of weak light fluxes. . . There is also known a method for determining the amplitude-frequency characteristic of a photomultiplier, including illuminating the photocathode with a light flux and recording the output signal from the anode of the photomultiplier 2. This method has complexity, low expertise and limited functionality. The purpose of the invention is to simplify the method, increase its speed and expand the functional possibilities. This goal is achieved by the method of determining the amplitude-frequency characteristic of a photomultiplier, including the light flux of the photocathode and recording the output signal from the photomultiplier anode, illuminates the photocathode with a short light pulse, records the signal from this pulse at the anode and determines the temporal position of its center then light up the photocathode with the same light pulse, register the signal from this pulse at the last dynode, and determine the time position of its center of gravity,

after that, the input chamber of the photomultiplier is disconnected from the power source, does not change the power mode of the multiplying system, illuminates the first dynod with the same light pulse, records the signal from this pulse at the anode, determines the temporary position of its center of gravity and, based on the values obtained, determines amplitude-frequency characteristic of a photomultiplier operating in the current mode of registration of strong light fluxes, according to the formula

SjOyt: 1

(() / (, 1Н / Я

 t

and a photomultiplier operating in the single-electrode mode of recording weak light fluxes using the formula Stol: 1,

° ()

where W is the circular frequency;

average time of flight electl, ronov in the input chamber of the photomultiplier

the average time of flight of electrons in the multiplying cascade;

g

average time of flight in the area last dynod-ano

t is constant load time of the PMT; n is the number of identical multiplying cascades of PMT. Thus, a significant distinction between the proposed method and the known method is that the amplitude-frequency characteristic of the photomultiplier is determined based on the time parameters of the photomultiplier, namely, the average electron transit time in the photomultiplier chamber, in its multiplying system, and in the area of the last dynodate.

The drawing shows a block diagram of a device implementing the method

 The device contains a source of 1 short light pulses, investigated by a photomultiplier 2, an oscilloscope 3, a system 4 for automatically reading and processing information from an oscilloscope screen.

The device works as follows.

The source 1 of short light pulses produces a short light pulse, which irradiates the photocathode of the photomultiplier under investigation 2. The oscilloscope sweep 3 is synchronized by the source 1 of short light pulses, and the output of the photomultiplier is fed to the input of the oscilloscope 3. The system of automatic reading and processing of information from the screen of the oscilloscope 4 calculates the temporal position of the photomultiplier of the output pulse of the photomultiplier, (to achieve the required accuracy, a series of identical measurements are made). To determine the temporal characteristics of the photomultiplier under study 2 G, -cd and T. t three series of consecutive. measurements: measure the temporal position of the center of gravity of the output pulse of the PMT by turning on the PMT; measure the temporal position of the center of gravity of the output pulse of the PMT Tr from the last dynode of the multiplier system of the PMT; measure the temporal position of the center of gravity of the output pulse of the photomultiplier Tz with the input chamber turned off, irradiated with a short light pulse of the first dynode of the multiplier of the photomultiplier system. To calculate the temporal characteristics of the photomultiplier under investigation, the following expressions are used.

 -T-f-T -F.d-, -1 k--I o i

The proposed method for determining the amplitude-frequency characteristic of a photomultiplier is distinguished from those known for its simplicity of implementation, high efficiency and wide functionality, allows you to reduce the required measurement time by more than standard, and can be used for two different modes of photomultiplier lends itself to automation.

Claims (2)

1. Dukor S.G. Investigation of the frequency properties of a photomultiplier. -Electronics, 1968, ser. 4, issue. 4, s, 51-67. 2. Siemin A.M. Wideband Noise Generators on Temporary Photomultiplier X.-PTE, 1970, 4, with. 194 (prototype).