A radon measurement method based on time-stamped background subtraction

Abstract

The present invention discloses a radon measurement method based on time-stamped background subtraction, comprising: if there is a previous measurement, then at the end of the previous measurement, the average count per second value before background subtraction and the end time are recorded; otherwise, the average count per second value before background subtraction is recorded as 0, and the end time is the start time of the current measurement; after the current measurement starts, the time is recorded in seconds, and the background count to be subtracted at each time is calculated; after the current measurement ends, the background count to be subtracted calculated at each second of the current measurement is added to obtain a total background count; the total background count of the previous step is subtracted from the total count of the current measurement to obtain a total count after subtraction; the total count after subtraction is divided by the number of seconds of the measurement time, and multiplied by the efficiency coefficient calibrated by the instrument to obtain the actual radon concentration after subtraction. The present invention can directly perform the next measurement in the case of decay interference from the previous measurement, thereby restoring the true result, eliminating the purification waiting time, and improving work efficiency.

Description

Technical Field

[0001] The present invention relates to the field of radioactive material measurement, and in particular to a radon measurement method based on time-stamped background subtraction. Background Art

[0002] Radon is a chemical element, usually found in its elemental form as radon gas. It is a colorless, odorless, and tasteless inert gas that is radioactive. Radon is chemically inactive and rarely reacts with other elements to form compounds. Radon has no known biological effects. However, because radon is radioactive, when inhaled, the alpha particles it decays into can cause radiation damage to the respiratory system and lead to lung cancer. Building materials are the primary source of indoor radon. Materials such as granite, brick sand, cement, and gypsum, especially natural stone containing radioactive elements, are most likely to release radon.

[0003] Current radon detectors based on semiconductor detectors primarily measure radon concentrations using the electrostatic collection principle. Radon gas (Rn222) enters a high-voltage electrostatic collection chamber and continuously decays into radon progeny (Po218). Radon gas has a half-life of 3.82 days. These positively charged progeny accumulate on the surface of the semiconductor detector under the influence of a high-voltage electric field. The progeny decay on the detector surface with a half-life of 3.05 minutes, and the alpha radiation they emit has an energy of 6 MeV. Because the half-lives of radon gas and progeny differ significantly, after a certain period of time, they reach decay equilibrium, meaning that the radon progeny concentration can be linearly correlated with the radon gas concentration. The alpha radiation emitted by the decaying progeny collected on the detector surface then enters the detector, generating an electrical charge. This charge is then collected and converted into electrical pulses by a circuit. Measuring the number of these pulses indirectly measures the radon concentration.

[0004] Current semiconductor radon detectors have a significant problem. Because the half-life of radon progeny is 3.05 minutes, radon progeny accumulated on the detector surface continue to decay and generate counts after the last measurement. It typically takes at least five half-lives, or 15 minutes, for the counts to decay to 1 / 32 of the original value. Therefore, after the last measurement, especially if high radon concentrations were detected, the electrostatic collection chamber must be flushed with air and allowed to wait for at least 15 minutes (called a purge) to ensure that the detector background is very low before the next measurement can be taken.

[0005] This undoubtedly reduces work efficiency. Taking the general measurement time of 15 minutes as a benchmark, the measurement time is equal to the waiting time. Almost half of the working time is spent passively waiting, and the available time of the instrument cannot be maximized. Summary of the Invention

[0006] In order to address the shortcomings of the existing technology, the present invention provides a radon measurement method based on time-stamped background subtraction. After the last measurement is completed, the end time of the measurement and the average counting rate are recorded. At the beginning of the next measurement, the time is recorded at each second of the measurement, and the last residual background that needs to be subtracted for that second is calculated based on the end time of the last measurement and the time. After the measurement is completed, the background of each second is added up and subtracted from the total count of this measurement. There is no need to wait for 15 minutes, which greatly improves the effective use time of the instrument and improves the measurement efficiency.

[0007] The embodiments of the present invention provide the following solutions:

[0008] An embodiment of the present invention provides a radon measurement method based on time-stamped background subtraction, the method comprising:

[0009] Step 1: If there is a previous measurement, record the average counts per second before background deduction and the end time of the previous measurement; if it is the first measurement, record the average counts per second before background deduction as 0, and the end time as the start time of this measurement;

[0010] Step 2: After the measurement starts, record the time in seconds and calculate the background count to be deducted at each moment;

[0011] Step 3: After the measurement is completed, add the background counts calculated at each second of the measurement to obtain the total background counts;

[0012] Step 4: Subtract the total background count from the previous step from the total count of this measurement to obtain the total count after deduction;

[0013] Step 5: Divide the total count after deduction by the measurement time in seconds, and multiply it by the calibrated efficiency coefficient of the instrument to obtain the actual radon concentration after deduction.

[0014] In an optional embodiment, the average counts per second C0 without background deduction in step 1 is calculated by the following formula:

[0015]

[0016] Where D represents the total count of the last measurement, T b Indicates the start time of the last measurement, and T0 indicates the end time of the last measurement.

[0017] In an optional embodiment, the background count to be deducted at each moment in step 2 is calculated by the following formula:

[0018]

[0019] Among them C nIndicates the count that needs to be deducted in the nth second of this measurement, T n Indicates the current time, and T0 indicates the end time of the last measurement.

[0020] In an optional embodiment, the total background count in step 3 is calculated by the following formula:

[0021]

[0022] Among them D b Indicates the total background count.

[0023] In an optional embodiment, the total count after deduction in step 4 is calculated by the following formula:

[0024] D r =D t -D b

[0025] Among them D r Indicates the total count after deduction, D t Indicates the total count of this measurement.

[0026] In an optional embodiment, the actual radon concentration in step 5 is calculated using the following formula:

[0027]

[0028] Where R represents the actual radon concentration and F represents the instrument calibration factor.

[0029] In an optional embodiment, the instrument calibration coefficient is a data obtained by dividing the known radon concentration value of the instrument in a standard radon chamber by the average counts per second measured by the instrument.

[0030] The beneficial effects of the present invention based on its technical solution are:

[0031] The radon measurement method based on time-stamped background subtraction provided by the present invention can directly carry out the next measurement after the end of the previous measurement, even if there is decay interference from the previous measurement. Through the correction of the method, the real result can be well restored, the currently commonly used purification waiting time is eliminated, and the working efficiency of the instrument is improved. At the same time, there is no need to consider the time interval between the end time of the last measurement and the start time of this measurement. As the time interval lengthens, the background count that needs to be deducted will continue to decrease according to the decay law, no error will be generated, and the measurement accuracy can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 This is a schematic diagram of the measurement principle of the semiconductor radon detector. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the embodiments of the present invention.

[0035] Reference Figure 1 The semiconductor radon detector used in this embodiment consists of a dryer, daughter filter, air inlet, pump, electrostatic collection chamber, semiconductor detector, signal processing and main control, display unit, printer, and other modules. A positive high voltage is applied to the radon high-voltage electrostatic collection chamber, and the detector surface is at ground level. Based on high-voltage electrostatic adsorption alpha spectroscopy, an air pump is used to draw radon-containing gas into the electrostatic collection chamber (metal chamber). Once radon undergoes alpha decay, the radon atoms become positively charged polonium atoms (ions), which migrate to the detector surface under the action of the high-voltage electric field and are adsorbed on the detector. The polonium atoms on the surface then undergo alpha decay, and the excitation of the alpha particles generates a current signal (electrical pulse signal) on the detector surface. This electrical pulse signal passes through the instrument's multi-channel pulse analyzer to obtain the number and energy of the generated alpha particles, thereby indirectly calculating the radon concentration in the air.

[0036] The embodiment of the present invention provides a radon measurement method based on time-stamped background subtraction, comprising the following steps:

[0037] Step 1: At the end of the last measurement, record the end time T0 of the measurement as 12:00:00 on June 20, 2024, and the start time of the measurement as 11:50:00 on June 20, 2024. The total count D of the last measurement without background deduction is 1200. According to the formula Calculate and record the average counts per second (C0) without background count deduction as 2 cps (in counts per second).

[0038] C0 is the average counting rate of the last measurement, cps, counts per second;

[0039] D is the total count of the last measurement, counts, count;

[0040] T b The start time of the last measurement, the minimum unit is second;

[0041] T0 is the end time of the last measurement, with the minimum unit being seconds.

[0042] Step 2: After the measurement starts, record the time of each second: T1 is 12:03:01 on June 20, 2024, T2 is 12:03:02 on June 20, 2024, T3 is 12:03:03 on June 20, 2024, etc. until T120 is 12:05:00 on June 20, 2024, and calculate the time according to the formula Calculate the background count to be deducted at that moment, where:

[0043] C n The counts that need to be deducted at the nth second of this measurement, counts, counts;

[0044] C0 is the count rate measured last time, i.e. cps, counts per second;

[0045] T n is the current moment of the nth second;

[0046] T0 is the end time of the last measurement.

[0047] The background counts to be deducted at each moment are shown in Table 1:

[0048]

[0049]

[0050]

[0051]

[0052] Table 1 Background counts to be deducted at each time

[0053] Step 3: After the measurement is completed, add the background counts calculated at each second of the measurement to obtain a total background count Db of 97.35. The calculation formula is:

[0054]

[0055] in:

[0056] D b The total background counts should be deducted for this measurement, counts, counts;

[0057] C0 is the count rate last measured, cps, counts per second.

[0058] Step 4: Total count D of this measurement t =300, minus the total background number D in the previous step b is 97.35, and the total count after deduction is D r It is 202.65.

[0059] Step 5: Divide the total count after deduction Dr by the measurement time t, which is 120 seconds, and multiply it by the calibrated efficiency coefficient F of the instrument, which is 600 Bq / m 3 / cps, the actual radon concentration R after deduction is 1013.25Bq / m 3 , the calculation formula is:

[0060]

[0061] in:

[0062] R is the actual radon concentration, Bq / m 3 ;

[0063] F is the instrument calibration factor, Bq / m 3 / cps;

[0064] Dr is the total count after deducting the background in this measurement, counts, counts.

[0065] The instrument calibration coefficient is the data obtained by dividing the known radon concentration value of the instrument by the average counts per second measured by the instrument in a standard radon chamber.

[0066] If the subtraction method is not used and the total count without background deduction is used directly, the result is 1500 Bq / m 3 , this result has been seriously distorted. It can be seen that the radon measurement method based on time-stamped background subtraction provided by the present invention can directly perform the next measurement after the previous measurement is completed, even if there is decay interference from the previous measurement. Through the correction of the present invention, the true result can be well restored, the currently commonly used purification waiting time is eliminated, and the working efficiency of the instrument is improved.

[0067] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0068] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatus (modules, systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0069] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0070] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0071] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0072] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A radon measurement method based on time-stamped background subtraction, characterized in that: The method comprises: Step 1: If there is a previous measurement, record the average counts per second before background deduction and the end time of the last measurement; if it is the first measurement, record the average counts per second before background deduction C 0 is 0, and the end time is the start time of this measurement; Step 2: After the measurement begins, record the time in seconds and calculate the background count to be deducted at each moment using the following formula: ， in C n Indicates the count that needs to be deducted at the nth second of this measurement. T n Indicates the current moment, T 0 indicates the end time of the last measurement; Step 3: After the measurement is completed, add the background counts calculated at each second of the measurement to obtain the total background counts; Step 4: Subtract the total background count from the previous step from the total count of this measurement to obtain the total count after deduction; Step 5: Divide the total count after deduction by the measurement time in seconds, and multiply it by the calibrated efficiency coefficient of the instrument to obtain the actual radon concentration after deduction.

2. The radon measurement method based on time-stamped background subtraction according to claim 1, characterized in that: The average counts per second value without background subtraction described in step 1 C 0 is calculated by the following formula: ， in D Indicates the total count of the last measurement. T b Indicates the start time of the last measurement. T 0 indicates the last measurement end time.

3. The radon measurement method based on time-stamped background subtraction according to claim 1, characterized in that: The efficiency coefficient is the data obtained by dividing the known radon concentration value by the average counts per second measured by the instrument in a standard radon chamber.

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