RU2165674C1 - Method and device for shaping spectrometric pulses (alternatives) - Google Patents

Abstract

FIELD: nuclear physics. SUBSTANCE: method intended for processing spectrometric pulses arriving from ionizing radiation detectors under heavy loads includes discrimination of moment when rise time of pulse exceeds levels 0,5; 1,6; 1,6² above rated value of input pulse. Single pulse is shaped at moment of increase above 0.5 level, two pulses when rise time is above 1.6 level, and three pulses when it is above 1,6² level. Number of input pulses arriving during measurement period is determined as sum of all pulses shaped within same period. Spectrometric pulse shaping device implementing proposed method has three discriminators, three short-pulse shapers, three delay lines, and three OR gates. Discriminator outputs are connected to respective shaper inputs. Second spectrometric pulse shaping device has three discriminators, three pulse shapers, three count-to-code converters, and processing unit. Shaper outputs are connected to inputs of respective count-to- code converters; output of each converter is connected through bus to processing device. EFFECT: facilitated procedure, reduced power requirement of device. 3 cl, 2 dwg, 1 tbl

Description

 The invention relates to the field of nuclear physics, and in particular to methods and devices for processing spectrometric pulses from an ionizing radiation detector.

 A known method and device for the formation of spectrometric pulses (1).

 The method for generating spectrometric pulses includes determining the moment of exceeding the front of the input pulse of the lower and upper discrimination levels, generating a short pulse, its delay, generating a short pulse and its delay for a duration equal to half the duration of the front of the input pulse, generating an additional short pulse of the output signal from the upper discriminator . The formation of one pulse when the delayed and additional pulses coincide, in the absence of coincidences, the formation of one short pulse and additional pulses according to the number of additional pulses. The forming device comprises an ionizing radiation sensor, an amplifier, a reference signal source, a divider, two comparators, an additional short pulse shaper, a pulse shaper half the length of the front of the input pulse, a delay line, an OR gate, and an output shaper.

 The disadvantage of this method and device is the complexity of the process of detecting the number of input pulses and, accordingly, the low accuracy of the formation of pulses when they are two to three times overlapping.

 A known method and device for the formation of spectrometric pulses (2).

The method includes determining the moment of exceeding the front of the input pulse of the lower level and multiples of 1.6 ^{n-1 of the} nominal value of the amplitude of the pulse, the formation of one pulse in the absence of a signal from the discriminator of the upper level. The formation of additional pulses in the presence of a signal from the discriminator of the upper level.

 The pulse-forming device contains the nth number of discriminators and a decoder assembled on the elements of EXCLUSIVE OR.

The disadvantage of this method is the need to accurately determine the moments of intersection of the recession of the input pulse, which is quite difficult for pulses, the amplitude and period of occurrence of which are random. Therefore, the device must be performed on the element base, which has the highest possible speed and, therefore, power consumption. The device also does not detect imposition of pulses if their total amplitude is less than levels that are multiples of 1.6 ^n-1 from the nominal value of the pulse.

 The objective of the invention is to simplify the method of forming spectrometric pulses and reduce power consumption of the device.

The problem is solved in that in the known method, including determining the moment of exceeding the front of the input pulse levels equal to 0.5; 1.6; 1.6 ^{2 of the} nominal value of the input pulse, at the moment of exceeding the signal of level 0.5, one pulse is formed, at the moment of exceeding the level of 1.6 two pulses are formed, and at the moment of exceeding the level of 1.6 ² three pulses are formed.

 The number of input pulses for the measurement period is defined as the sum of all generated pulses for the same period.

Distinctive features of the proposed method is the formation of a certain number of pulses depending on the level of discrimination of the input signal, and due to this the signal processing becomes easier, since for this it is necessary to determine only the moments when the signal level exceeds 0.5; 1.6; 1.6 ² .

 The problem is also solved by the fact that in the known device containing the nth number of discriminators and a decoder, assembled on the elements EXCLUSIVE OR, three short-pulse shapers, three delay lines, three OR elements are introduced. The outputs of each discriminator are connected to the input of its shaper. The output of the first driver is connected to the input of the first delay line and the first input of the first OR element. The output of the first delay line is connected to the input of the second delay line and the second input of the first OR element, the third input of which is connected to the output of the second delay line. The output of the first OR element is connected to the first input of the second OR element, the second input of the OR element is connected to the output of the third OR element. The first input of the third OR element is connected to the input of the second driver, and its second input is connected to the output of the third delay line. The third input of the second OR element is connected to the input of the third driver. The output of the second OR element is the output of the device.

 The signs that distinguish the proposed device from the prototype — the presence of three formers, three delay lines, three OR elements — determines the formation of output pulses without superimposing one another and allows simplifying the formation of pulses without determining the moments of level crossing when the input pulse drops.

 To achieve an additional technical result, which consists in reducing the power consumption of the device, a device according to the second embodiment is proposed, comprising three discriminators, into which three shapers, three count-code converters and a processing device are introduced. A feature that distinguishes the proposed device from the prototype is the organization of the transmission of pulses from each shaper to its own converter with an account code in three channels, which allows to reduce the load level on each channel and execute them on 561, 1554, 1564 series microcircuits with low power consumption.

 The determination of the number of incoming signals for the measurement period is as follows.

The comparator 597CA1 determines the moment when the front of the input signal exceeds the level 0.5 and generates a pulse by the shaper assembled on the 500LP105 microcircuit. A pulse is generated by the comparator when the front exceeds a signal level of 1.6 and two pulses are formed. The comparator determines the moment of exceeding the level of 1.6 ² and form three pulses.

 The frequency meter Ch3-32 is considered the total number of generated pulses for the measurement period, the duration of which is inversely proportional to the load.

So, when loading 10 ⁶ pulses / s, the measurement period is 10 ms, and when loading 10 pulses / s, the measurement period is 100 s with a measurement accuracy of 2%.

 The proposed method has been tested by mathematical modeling for signals whose amplitude is a random variable with a distribution according to the normal law, and the number of pulses that appear is determined by the law of the Poisson distribution.

 In FIG. 1 and FIG. 2 shows a diagram of devices that implement this method.

A device for implementing this method (Fig. 1) contains three discriminators 1 ₁ , 1 ₂ , 1 ₃ with discrimination levels of 1.6 ² ; 1.6; 0.5, three pulse shapers 2 ₁ , 2 ₂ , 2 _{3 of} duration (6-7) ns, three delay lines 3 ₁ , 3 ₂ , 3 _{3 of} duration (12-14) ns and three elements OR 4 ₁ , 4 ₂ , 4 ₃ .

 The forming device operates as follows.

When the signal exceeds the level of 0.5 from the nominal value of the input signal at the output of the driver 1 ₃ , a high level signal is generated, which is fed to the input of the driver 2 ₃ . At its output the impulse duration (6-7) ns, which, via OR gate April ₂ arrives at the device output.

When the load increases, the output pulses are superimposed, and when the level exceeds 1.6 from the nominal value of the signal, a high signal level is formed at the output of the discriminator 1 ₂ . At the output of the shaper 2 ₂ a short pulse is formed, which is fed to the first input of the OR 4 ₃ element and the delay line 3 ₃ . The delayed pulse is applied to the second input member 4, _3, and two pulses are generated at its output which, through the OR April ₂ fed to the device output.

When loading, when the input pulses are packs of superimposed pulses, their amplitude reaches 1.6 ² of the nominal value of the signal and a high level signal is generated at the output of discriminator 1 ₁ , which is fed to driver 2 ₁ . From the output of the shaper, a pulse of duration (6-7) ns is supplied to the first input of the OR element 4 ₁ and the delay line 3 ₁ and then to the second input of the element 4 ₁ and the input of the next delay line 3 ₂ . The pulse from the output of the delay line 3 _{2 is} supplied to the third input of the element 4 ₁ . At the output of element 4 ₁ , three pulses are formed, which through the element OR 4 ₂ are fed to the output of the device.

The measurement results obtained by simulation for the indicated levels with an input pulse duration of τ _and = 120 ns are shown in the table.

The second device for implementing the method (Fig. 2) contains three discriminators 1 ₁ , 1 ₂ , 1 ₃ with discrimination levels of 1.6 ² ; 1.6; 0.5, three pulse shapers 2 ₁ , 2 ₂ , 2 ₃ with a duration of 50 ns, three controllable count-code converters 3 and a processing device 4.

The device operates as follows. When a signal arrives at the input of discriminator 1 ₃ at the moment of exceeding the level of 0.5, a high level signal is generated at the output of discriminator 1 ₃ , which is fed to the input of former 2 ₃ . An output of 50 ns is generated at the output of the former 2 ₃ . When the input signal level increases at the output of discriminators 1 ₂ and 1 ₁ , high-level signals are also sequentially generated, and at the outputs of the shapers 2 ₂ , 2 ₁ pulses are fed to the inputs of their converters account code 3. Addition of codes according to the rule N ₃ + 2N ₂ + 3N ₁ (where N _1, N _2, N ₃ - the number of pulses formers), the choice of measurement duration, the formation of the measurement results is carried out a processing device 4. The data exchange and control commands executed via line between the transducers account code and apparatus processing.

 Thus, the proposed method and apparatus for generating spectrometric signals can simplify the formation of signals, and the device can be performed on microcircuits of the 561, 1554, 1564 series, whose energy consumption is 10-100 times less than that of the 500 series microcircuits, which provide signal processing in the known device.

List of references
1. RF patent N 1400301, G 01 T 1/16.

 2. RF patent N 1648185, G 01 T 1/16. (Prototype).

Claims (3)

1. The method of forming spectrometric pulses, including determining the moment of exceeding the front of the input pulse levels equal to 0.5; 1.6; 1.6 ^{2 of the} nominal value of the input pulse, characterized in that at the moment of exceeding the levels of 0.5 they form one pulse, at the moment of exceeding the levels of 1.6 - two pulses, and at the moment of exceeding the level of 1.6 ² - three pulses, the number of input pulses for the measurement period is defined as the sum of all generated pulses for the same period.  2. A spectrometric pulse generating device comprising three discriminators, characterized in that three short-pulse shapers, three delay lines, three OR elements are introduced, the outputs of each discriminator being connected to the input of its short-pulse shaper, the output of the first shaper connected to the input of the first delay line and the first input of the first OR element, the output of the first delay line with the input of the second delay line and the second input of the first OR element, the third input of which is connected to the output of the second th delay line, and the output of the first OR element with the first input of the second OR element, the second input of which is connected to the output of the third OR element, the first input of the third OR element with the output of the second driver, and its second input with the output of the third delay line, the third the input of the second OR element is connected to the output of the third driver, the output of the second OR element is the output of the device.  3. A spectrometric pulse shaping device comprising three discriminators, characterized in that three pulse shapers, three count-code shapers and a processing device are introduced, the output of each discriminator being connected to its shaper, the output of which is connected to the input of its count-code converter, outputs which are connected via a trunk to a processing device.

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