Method for calculating relative dead time in particle detection

Abstract

The present application relates to particle detection method, specifically relates to a kind of relative dead time calculation method in particle detection, solve the technical problems that the uncertainty of existing relative dead time calculation method is larger when measuring high input count rate, and significantly larger with the increase of measurement time.Relative dead time is calculated based on the probability distribution principle of particle detection process, and the ratio of effective pulse signal count and total pulse signal count is calculated, the method process is simple, and the measurement uncertainty will also decrease with the increase of measurement time, has significant technical advantage in high input count rate measurement, can also consider the particle detection application scene of high, low input count rate.The present application replaces absolute dead time accumulation with pulse signal count, and the measurement object is more convenient and accurate, and the relative dead time obtained is more accurate;Effective pulse signal number in slow forming pulse series is corrected using independent pulse width, which can further improve the calculation accuracy of relative dead time.

Description

Technical Field

[0001] This invention relates to particle detection methods, specifically to a method for calculating relative dead time in particle detection. Background Technology

[0002] Relative dead time is one of the key parameters in particle detection technology, and its accuracy directly affects the uncertainty of the final measurement data. The ratio of absolute dead time to the actual measurement time is called relative dead time. In low input count rate measurements, due to the weak accumulation effect between pulse signals, the relative dead time is generally less than 10%. Even if the measurement uncertainty of the relative dead time reaches 10%, its contribution to the uncertainty of the final data is only 1%. Therefore, in this case, the requirement for the accuracy of relative dead time measurement is not high. However, in high input count rate measurements, if the uncertainty contribution of the relative dead time needs to be controlled within 1%, then the uncertainty of the relative dead time cannot exceed 2%. Since the measurement uncertainty of the relative dead time in high input count rate measurements is usually above 50%, reducing the measurement uncertainty of the relative dead time is of great significance for improving the accuracy of high input count rate measurements.

[0003] Currently, the main method for calculating relative dead time in digital particle detector spectrometers is as follows: the original pulse signal is processed through fast and slow shaping to obtain two pulse signals. The fast-shaped pulse signal is used to statistically analyze the pulse interval time and form de-stacking logic, with (3t) r +2t f The absolute dead time is continuously accumulated using a baseline threshold, t. r For the rise time of slow forming, t f The peak-topping time is the time for slow-forming peak formation, thus obtaining the relative dead time.

[0004] Because of t in this method r and t f Setting it to a constant value fails to fully account for the changing characteristics of the signal rise time. In high input count rate applications, short forming times are required. In this case, the proportion of the signal rise time in the entire forming time becomes significantly larger. The constantly changing signal rise time makes the uncertainty of the final relative dead time significantly larger as the measurement time increases, which is a challenge that needs to be overcome. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that existing methods for calculating relative dead time have large uncertainties in high input count rate measurements, and these uncertainties increase significantly with the increase of measurement time. Therefore, this invention provides a method for calculating relative dead time in particle detection.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for calculating relative dead time in particle detection, characterized by the following steps:

[0008] Step 1: Perform fast prototyping and slow prototyping on the original digital signal series obtained from particle detection to obtain fast prototyping pulse series and slow prototyping pulse series respectively;

[0009] Step 2: Calculate the total number of pulse signals N in the rapid prototyping pulse series based on the number of identifiable pulse signals and the time width of the identifiable pulse signals. f ;

[0010] Step 3: Identify the pulse signals of the slow forming pulse series based on the time interval between every two adjacent pulses in the fast forming pulse series, and obtain the number N of effective pulse signals in the slow forming pulse series. S ;

[0011] Step 4: Calculate the relative dead time R of particle detection according to the following formula. d :

[0012]

[0013] Furthermore, step 2 specifically involves:

[0014] 2.1 Count the number of identifiable pulse signals and the time width of the identifiable pulse signals in the rapid prototyping pulse series;

[0015] 2.2 Calculate the total number of pulse signals in the rapid prototyping pulse series using the following formula:

[0016]

[0017] Among them, T R N represents the total measurement time. fR T represents the number of identifiable pulse signals in a rapid prototyping pulse series. i Let i be the time width of the i-th identifiable pulse signal, where i is an integer and 1 ≤ i ≤ N. fR .

[0018] Furthermore, step 3 specifically involves:

[0019] 3.1 Define the de-stacking logic level and time threshold T th The initial value of the de-stacking logic level is 1, and the time threshold T th The value is the sum of the rise time and flat-top time of the independent pulses in the slow forming pulse series;

[0020] 3.2 Statistical analysis of the time interval T between every two adjacent pulses in the rapid prototyping pulse series. W ;

[0021] 3.3 Compare the time interval T between two adjacent pulses in the rapid prototyping pulse series. W With time threshold T th The size between;

[0022] If T W ≤T th Then, taking the arrival time of the first pulse in two adjacent pulses of the rapid prototyping pulse series as the starting point, at T W +T th During the time period, the value of the anti-stacking logic level will be set to 0;

[0023] If T W >T th Then the value of the anti-stacking logic level will not be changed;

[0024] 3.4. Identify the pulse signals in the slow forming pulse series according to the values ​​of the anti-stacking logic levels to obtain the number of valid pulse signals in the slow forming pulse series.

[0025] Further, in step 3.4, the step of identifying the pulse signals in the slow forming pulse series based on the value of the de-stacking logic level specifically involves:

[0026] When the anti-stacking logic level is 0, the corresponding pulse signal within the same time period in the slow forming pulse series is marked as an invalid pulse signal; when the anti-stacking logic level is 1, the corresponding pulse signal within the same time period in the slow forming pulse series is marked as a valid pulse signal.

[0027] The present invention also provides a particle detection method, which is characterized by including the above-mentioned method for calculating the relative dead time in particle detection.

[0028] Furthermore, the particles are high input count rate particles.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] 1. The present invention provides a method for calculating the relative dead time in particle detection. Based on the probability distribution principle of the particle detection process, the relative dead time is calculated by the ratio of the effective pulse signal count to the total pulse signal count. The method is simple and the measurement uncertainty of the relative dead time will decrease with the increase of the measurement time. It has significant technical advantages in high input count rate measurement and can also take into account particle detection application scenarios with high and low input count rates.

[0031] 2. In the method for calculating relative dead time in particle detection provided by the present invention, the counting of identifiable pulse signals is used instead of the accumulation of absolute dead time, making the measurement object more convenient and accurate, and the relative dead time obtained is also more accurate.

[0032] 3. In the method for calculating relative dead time in particle detection provided by the present invention, the number of effective pulse signals in the slow-forming pulse series is corrected by using an independent pulse width, which can further improve the accuracy of the calculation of relative dead time. Attached Figure Description

[0033] Figure 1 This is a logic diagram for determining the de-stacking logic level and valid signal in an embodiment of the present invention, wherein A is the original digital signal series, B is the fast forming pulse series, C is the de-stacking logic level, and D is the slow forming pulse series. Detailed Implementation

[0034] To make the objectives, advantages and features of the present invention clearer, the following describes in further detail a method for calculating relative dead time in particle detection proposed by the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0035] A method for calculating relative dead time in particle detection includes the following steps:

[0036] Step 1: Perform fast prototyping and slow prototyping on the original digital signal series obtained from particle detection to obtain fast prototyping pulse series and slow prototyping pulse series.

[0037] Step 2: Calculate the total number of pulse signals N in the rapid prototyping pulse series based on the number of identifiable pulse signals and the time width of the identifiable pulse signals. f Specifically:

[0038] 2.1 Count the number of identifiable pulse signals and the time width of the identifiable pulse signals in the rapid prototyping pulse series;

[0039] 2.2 Calculate the total number of pulse signals N in the rapid prototyping pulse series according to the following formula. f :

[0040]

[0041] Among them, T R N represents the total measurement time. fR T represents the number of identifiable pulse signals in a rapid prototyping pulse series. i Let i be the time width of the i-th identifiable pulse signal, where i is an integer and 1 ≤ i ≤ N. fR .

[0042] Step 3: Identify the pulse signals of the slow forming pulse series based on the time interval between every two adjacent pulses in the fast forming pulse series, and obtain the number N of effective pulse signals in the slow forming pulse series. S .

[0043] Specifically:

[0044] 3.1 Define the de-stacking logic level and time threshold T th The initial value of the de-stacking logic level is 1, and the time threshold T th The value is the sum of the rise time and flat-top time of the independent pulses in the slow forming pulse series;

[0045] 3.2 Statistical analysis of the time interval T between every two adjacent pulses in the rapid prototyping pulse series. W ;

[0046] 3.3 Compare the time interval T between two adjacent pulses in the fast prototyping pulse series. W With time threshold T th Size;

[0047] like Figure 1 As shown, if T W ≤T th Then, taking the arrival time of the first pulse in two adjacent pulses in the rapid prototyping pulse series as the starting point, at T W +T th During the time period, the value of the anti-stacking logic level will be set to 0;

[0048] If T W >T th Then the value of the anti-stacking logic level will not be changed;

[0049] 3.4 When the de-stacking logic level is 0, the corresponding pulse signals within the same time period in the slow forming pulse series are marked as invalid signals; when the de-stacking logic level is 1, the corresponding pulse signals within the same time period in the slow forming pulse series are marked as valid signals, and then the number N of valid pulse signals in the slow forming pulse series is counted. S .

[0050] Step 4: Calculate the relative dead time R of particle detection according to the following formula. d :

[0051]

[0052] This embodiment obtains fast-forming pulse series B and slow-forming pulse series D by performing fast-forming and slow-forming on the original digital signal series A. First, based on fast-forming pulse series B, the number and time width of identifiable pulse signals are directly counted to calculate the total number of pulse signals in fast-forming pulse series B. Then, an anti-stacking logic level C with an initial value of 1 and a time threshold equal to the sum of the rise time and flat-top time of independent pulses in the slow-forming pulse series are defined. Based on fast-forming pulse series B, the anti-stacking logic level C is assigned a value. Then, the pulse signals in the slow-forming pulse series D are identified according to the value of the anti-stacking logic level C, thus obtaining the number of effective pulse signals in the slow-forming pulse series D. Finally, based on the total number of pulse signals in fast-forming pulse series B and the number of effective pulse signals in slow-forming pulse series D, the relative dead time in particle detection is calculated.

[0053] Based on the probability distribution principle of particle detection process, this invention proposes a method to calculate the relative dead time by the ratio of effective pulse signal count to total pulse signal count. This method is simple, and the measurement uncertainty of the relative dead time will decrease with the measurement time, which has significant technical advantages in high input count rate measurement.

[0054] This embodiment also provides a particle detection method, including the aforementioned method for calculating the relative dead time in particle detection, wherein the particles are high input count rate particles.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A method for calculating relative dead time in particle detection, characterized in that, Includes the following steps: Step 1: Perform fast prototyping and slow prototyping on the original digital signal series obtained from particle detection to obtain fast prototyping pulse series and slow prototyping pulse series respectively; Step 2: Calculate the total number of pulse signals in the rapid prototyping pulse series based on the number of identifiable pulse signals and the time width of the identifiable pulse signals. N f Specifically: 2.1 Count the number of identifiable pulse signals and the time width of the identifiable pulse signals in the rapid prototyping pulse series; 2.2 Calculate the total number of pulse signals in the rapid prototyping pulse series using the following formula: in, T R Total measurement time N fR This refers to the number of identifiable pulse signals in the rapid prototyping pulse series. T i For the first i The time width of a recognizable pulse signal i It is an integer, and 1 ≤ i ≤ N fR ; Step 3: Identify the pulse signals in the slow forming pulse series based on the time interval between every two adjacent pulses in the fast forming pulse series, thus obtaining the number of effective pulse signals in the slow forming pulse series. N S Specifically: 3.1 Define the de-stacking logic level and time threshold. T th The initial value of the de-stacking logic level is 1, and the time threshold is... T th The value is the sum of the rise time and flat-top time of the independent pulses in the slow forming pulse series; 3.2 Statistical analysis of the time interval between every two adjacent pulses in the rapid prototyping pulse series. T W ; 3.3 Compare the time intervals between two adjacent pulses in the rapid prototyping pulse series. T W With time threshold T th The size between; like T W ≤ T th Then, taking the arrival time of the first pulse in two adjacent pulses of the rapid prototyping pulse series as the starting point, in T W + T th During the time period, the value of the anti-stacking logic level will be set to 0; like T W > T th Then the value of the anti-stacking logic level will not be changed; 3.

4. Identify the pulse signals in the slow forming pulse series according to the values ​​of the anti-stacking logic levels to obtain the number of valid pulse signals in the slow forming pulse series; Step 4: Calculate the relative dead time of particle detection using the following formula. R d : 。 2. The method for calculating relative dead time in particle detection according to claim 1, characterized in that, In step 3.4, the step of identifying the pulse signals in the slow forming pulse series based on the value of the de-stacking logic level specifically involves: When the anti-stacking logic level is 0, the pulse signals corresponding to the same time period in the slow forming pulse series are marked as invalid pulse signals; When the anti-stacking logic level is 1, the pulse signal corresponding to the same time period in the slow forming pulse series is marked as a valid pulse signal.

3. A particle detection method, characterized in that: This includes a method for calculating relative dead time in particle detection as described in claim 1 or 2.

4. The particle detection method according to claim 3, characterized in that: The particles are high input count rate particles.

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