JPH06180367A - Radiation measuring equipment - Google Patents

Abstract

(57) [Summary] [Purpose] In radiation detection, obtain accurate measurement results over a wide range of intensities. A radiation detection pulse counting means and a dose integrating means are provided, and when the counting rate obtained by the pulse counting means is below a predetermined upper limit level and the integrating means is above a certain lower limit level, the outputs of both means are output. Combine and use as the measurement output. [Effect] The pulse counting method is suitable when the intensity is low, the dose integration means is suitable for the high intensity region, and the measurement value is obtained from both outputs in the intermediate region, so accurate measurement results can be obtained in all regions. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring apparatus in the case where the detected ion beam intensity varies over a wide range like a triple collision fragmentation mass spectrometer.

[0002]

2. Description of the Related Art When measuring radiation such as ion rays, electron rays and X-rays, not only ions and electrons but also X-rays are photons, so basically the detection pulses of those particles within a certain period of time are counted. The intensity of the radiation is used as the radiation intensity, but if the radiation intensity becomes so strong that the particles incident on the detector cannot be distinguished one by one, the measuring device that counts the particles becomes unsuitable, and the number of particles per unit time cannot be directly measured. A measuring device that outputs a radiation intensity signal is suitable. Thus, there are basically two types of radiation measurement devices,
Each has its own suitable range of radiation intensity. Conventionally, either of these two types of measuring devices has been used depending on the purpose of the analysis device that handles radiation.

Conventionally, the range of radiation intensity handled by one analyzer is relatively narrow, and the object could be achieved by using any one of the above-mentioned measuring devices, but various new analysis methods were developed. In the analyzer that implements it, the dynamic range of the radiation intensity becomes larger than that of the conventional analyzer, and the dynamic range cannot be covered by any one type of measuring device.
Especially when the radiation intensity is weaker than a certain level, the counting type measuring device gives a good result, and when the radiation intensity is stronger than a certain level, a good result can be obtained by a measuring device which directly outputs the intensity signal. There was a problem that good results could not be obtained in the intermediate intensity region by any type of measuring device.

[0004]

Provided is a radiation measuring apparatus which can obtain a good measurement result in the whole range when the radiation intensity to be measured varies in a wide range.

[0005]

A radiation detector for converting incident radiation particles into a pulse signal, pulse counting means for counting the detection pulse for a certain period of time and outputting a count value, and outputting a signal according to the radiation intensity. Means, for example, a pulse integration means for converting into a signal according to the number of inputs of the detection pulse within a unit time, and when the output of the pulse counting means is a first set value a or more, the output of the integration means is radiation. Intensity, when the output of the integrating means is less than the other second set value b, the output of the counting means is taken as the radiation intensity, and the output of the pulse counting means is less than the first set value a and the integrating means When the output of the above is greater than or equal to the second set value b, that is, when the radiation intensity is in the intermediate region, the output of the pulse counting means and the output of the integrating means are respectively calculated to be a total value as the radiation intensity. output And configure the radiation measurement apparatus and that the data processing device.

[0006]

[Function] When the radiation intensity is low, the radiation can be counted as a particle by converting each particle into a pulse signal with a detector, and the count value within a certain period of time, that is, the counting rate becomes the radiation intensity. . When the radiation intensity becomes even smaller and the radiation detection pulses are overlapped with each other, the radiation particles are counted down, and the apparent count rate is not proportional to the radiation intensity. In the present invention, in the data processor, when the count rate is equal to or less than a certain value, it is assumed that the radiation particles are not counted and the count rate is output as the radiation intensity. On the other hand, when the output of the integrator that outputs a signal corresponding to the number of detected pulses in a unit time is at a certain level or higher, it represents the radiation intensity when the radiation intensity is strong. The data processing device discriminates the intensity of the radiation based on the outputs of the two measuring means, and switches the output of which means as the radiation intensity. When the radiation intensity is in the intermediate region, the outputs of both measuring means are combined into the radiation intensity to cover the entire measurement range.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit of a device according to an embodiment of the present invention.
A particle detector 1 uses a secondary electron multiplier in this embodiment. A preamplifier 2 at high speed amplifies the output pulse of the particle detector 1. The output of the high speed preamplifier 2 is simultaneously input to the two circuits A and B. The circuit A is an integrating circuit having an attenuation characteristic, and the integrated output attenuates with a constant time constant. That is, the operational amplifier 3 and the integrating capacitor 4 are connected, and the resistor 5 is connected in parallel with the capacitor 4. Therefore, for a constant DC input, an output proportional to the input is obtained, and for a pulse input, It outputs a signal according to the number of pulse incidents per unit time. In the integration circuit having no attenuation characteristics, the output gives a monotonically increasing output with respect to the pulse input, but in the integration circuit of this embodiment, the output is settled to a value according to the number of incident pulses per unit time. The output is converted into digital data by the A / D converter 10 and output. Circuit B is a counting circuit,
It comprises a high speed operational amplifier 6, a comparator 7 and a high speed counter 8. A fixed reference level is set in the comparator 7 so that only pulses of this level or higher in the input are sent to the counter to remove noise generated from the particle detector 1 to the operational amplifier 6. The outputs of these two circuits A and B are input to the high speed data processing device 9.

FIG. 2A shows that the particle beam detector 1 has one radiation particle.
The output pulse when incident on the individual is shown. High speed amplifier 2,
6 amplifies this pulse waveform as it is. FIG. 2B shows an output waveform when the pulse signal is applied to the circuit A. After reaching the maximum value near the end of the input pulse signal, the pulse waveform attenuates and returns to 0 again. The pulse width is 2 to 3 μsec, and the width of the output waveform is about 6 μsec. Since the circuit A has such a characteristic, if the state in which the next pulse is input before the output signal of one input pulse becomes 0 continues, the output gradually rises and saturates per pulse time. Reaches a value proportional to the number of inputs. FIG. 2C shows an output waveform of the comparator 7 corresponding to the input pulse signal of FIG. A, which is converted into a rectangular wave pulse, and this output pulse is counted by the counter 8. Since the particle detection pulses have a time width, when the radiation intensity becomes strong and the particle detection pulses overlap each other, the pulses are missed.

FIG. 3 is a flow chart of the operation of the data processor of the high speed data processor 9. First, the outputs from each of the circuits A and B are normalized (a) This is because the displayed numerical values in the pulse counting method and the integration method for the same radiation intensity are different. Output data is the number of particles detected per unit time, the output numerical value of the circuit A when the number of detected particles per unit time is a certain value is calculated in advance, and the output numerical value of the circuit A is This is an operation in which the coefficient is multiplied to determine the number of particles detected per unit time at that time, and the output value of the circuit A is multiplied by this coefficient. Next, it is checked whether the normalized output of the circuit A is the second reference value b or less (b). Below standard value (Y
In the case of (ES), the count value of the radiation particle detection pulse which is the output of the circuit B, that is, the count rate, is sent to the host computer as the radiation intensity (c), and when it is the second reference value b or more (NO). In step (d), it is checked whether the count output of the circuit B is the first reference value a or more, and when it is the first reference value a or more (YES), the normalized value of the output of the circuit A is It is sent to the host computer as strength (e),
When the value is equal to or less than the first reference value a (NO), the output data of the circuits A and B are subjected to a total operation and sent to the host computer (f). With this configuration, the radiation intensity is 1 Mcps
In the case of, the output of the circuit A is output, and in the case of 10 Kcps or less, the output of the circuit B is output, and the outputs of both circuits are arithmetically processed and output between 10 Kcps and 1 Mpcs.

The contents of the above-mentioned comprehensive calculation are as follows. FIG. 4 is an explanatory diagram of the contents of this calculation. The horizontal axis shows the radiation intensity, the vertical axis shows the measured output, and the diagonal line of 45 ° shows the ideal measured output. In the detection pulse counting method of the circuit B, the radiation intensity from 0 to B1, that is, the output of the circuit A is ideal from the second reference value b, and the output becomes lower than the ideal at the point beyond that. On the other hand, the output of the circuit A is A1 or more, that is, the circuit B
Is ideal when the first reference value is a or more, but is lower than the ideal when the value is b or less. The area sandwiched between these (A1, B1) is the area to be calculated here, and the target of the operation is to connect the points PQ in this figure with a straight line of 45 ° using the output data of the circuits A and B. Is. The correction value for the output A of the A circuit is O at point Q and + (B1-b) at point P, and + (B1-b) * (A1-A) / for any A.
(A1-b). Similarly, considering the correction value for the output B of the B circuit, O at the point P and + (A1-
In a), for any B circuit output B, + (A1-a)
X (B-B1) / (a-B1). Therefore, the formula that gives the correct measured value between PQ using the outputs of both A and B circuits is (A + B) / 2 + (B1-b) (A1-A) / 2 (A1
-B) + (A1-a) (B-B1) / 2 (a-B1) In the above formula, (B1-b) / 2 (A1-b), (A1-a) of the second and third terms / 2 (a
-B1) is a constant, so if these are α and β, the above equation is (A + B) / 2 + α (A1-A) + β (B-B1) .... (1) Performs expression calculations.

The above-mentioned place is an example of the data processing method in the intermediate intensity region, and there is another data processing method. The above example is an approximate method because it is assumed that the output data of the circuits A and B have a linear relationship with the radiation intensity even in the intermediate region. A more accurate method is to use the corrected values as f (A) A + g (B) B and the functions f (A) and f (B) when the outputs of the circuits A and B are A and B, respectively, in the intermediate region. There is a method to decide appropriately. Here, in the function f (A), A is 1, and A1 is A1.
A function that becomes smaller and smaller and becomes 0 at some point,
In g (B), B is 1 in the first reference value B1, and B is B
Functions that decrease as they become larger than 1 and become 0 at some places. These functions are experimentally or calculated in advance by appropriately assuming the input-output functional forms of the circuits A and B in the intermediate region. A method of making a decision is also possible.

In the above embodiment, the intermediate region is a range below the upper limit of the output of the particle detecting pulse counting means B and above the lower limit of the output of the circuit A which outputs a signal according to the number of particles per unit time. The upper and lower limit levels may be set so that the intermediate region is equal to or higher than the upper limit of the output of the detection pulse counting means and lower than or equal to the lower limit of the output of the circuit A.

[0013]

According to the present invention, two measuring means are provided for radiation, and a weak area to which one measuring means fits and a strong area to which the other measuring means fits. Divided into intermediate regions that lose proportionality to strength,
In the intermediate region, the outputs of the above two measuring means are combined to obtain a correct result. Therefore, even in an analyzer having a remarkably wide dynamic range of ion intensity, such as a triple collision fragmentation mass spectrometer, the total measurement is possible. Correct measurement results can be obtained over a range.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a partial operation of the above circuit.

FIG. 3 is a flowchart of a data processing operation in the above circuit.

FIG. 4 is an explanatory diagram of calculation contents in the above data processing operation.

[Explanation of symbols] 1 particle detector 2 high-speed preamplifier 3 operational amplifier 4 capacitor 5 resistor 6 high-speed operational amplifier 7 comparator 8 digital counter 9 digital data processor 10 A / D converter

Claims (1)

[Claims] 1. A radiation particle counting means, a means for outputting a signal according to the radiation intensity, and a discrimination of the radiation intensity above a predetermined range, within that range, or below a range, and when within the above range Comprehensive calculation is performed on the outputs of both means, a signal corresponding to the radiation intensity is transmitted in the area above the range, the count output of the counting means is transmitted in the area below the range, and the comprehensive calculation result in the intermediate area. A radiation measuring device comprising a data processing device for transmitting the radiation.