Radon measurement method based on time stamp background deduction

Abstract

The invention discloses a radon measurement method based on time stamp background deduction, and the method comprises the steps: recording an average count value per second and an end moment when the last measurement is finished when the last measurement is finished; otherwise, recording the average count value per second from which the background is not deducted as 0, and taking the ending moment as the starting moment of the measurement; after the measurement is started, recording moments according to seconds, and calculating background counts needing to be deducted at each moment; after the measurement is finished, adding the background counts which need to be deducted and are calculated at each second moment in the measurement to obtain a total background count; subtracting the total background count of the previous step from the total count of the measurement to obtain a deducted total count; dividing the deducted total count by the second number of the measurement time, and multiplying by the calibrated efficiency coefficient of the instrument to obtain the deducted real radon concentration. According to the method, the next measurement is directly carried out under the condition of decay interference in the previous measurement, so that a real result can be restored, the purification waiting time is canceled, and the working efficiency is improved.

Description

Technical Field

[0001] The 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. Its common single substance form is radon gas, which is a colorless, odorless, tasteless inert gas with radioactivity. Radon is not chemically active and it is difficult for radon to react with other elements to form compounds. Radon has no known biological effects. Because radon is a radioactive gas, when people inhale it, the alpha particles produced by radon decay can cause radiation damage to the human respiratory system and cause lung cancer. Building materials are the main source of indoor radon. Materials such as granite, brick sand, cement and gypsum, especially natural stones containing radioactive elements, are most likely to release radon.

[0003] At present, the radon detector based on the semiconductor detector principle mainly measures the radon concentration by using the electrostatic collection principle. After radon gas (Rn222) enters the electrostatic collection chamber with high voltage, it continuously decays into radon progeny (Po218). The half-life of radon gas is 3.82 days. Radon progeny are positively charged and will be enriched on the surface of the semiconductor detector under the action of the high voltage electric field. The radon progeny decays on the surface of the detector. The half-life of the radon progeny is 3.05 minutes, and the energy of the alpha rays it emits is 6MeV. Because the half-life of radon gas and radon progeny is quite different, after a certain period of time, the two will reach a decay equilibrium, that is, the concentration of radon progeny can be linearly equivalent to the concentration of radon gas. The alpha rays emitted by the decay of the radon progeny collected on the detector surface penetrate into the detector, which can generate electric charges. The charges are collected and converted into electrical pulses through circuits. By measuring the number of pulses, the radon gas concentration can be indirectly measured.

[0004] The semiconductor radon detector currently used has an obvious problem. When the last measurement is completed, because the half-life of radon progeny is 3.05 minutes, the radon progeny enriched on the detector surface will continue to decay and generate counts when the measurement is finished. Generally, it takes at least 5 half-lives, or 15 minutes, to decay to 1 / 32 of the original count value. Therefore, after the last measurement is completed, especially when the last measurement was high in radon gas, it is necessary to flush the electrostatic collection chamber with air and wait for more than 15 minutes (called purification) to ensure that the background of the detector is reduced to a very low level before the next measurement can be carried out.

[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 passive waiting, and the available time of the instrument cannot be maximized. Summary of the invention

[0006] In order to solve the shortcomings of the prior art, 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. When the next measurement starts, the time is recorded at every second of the measurement, and the last residual background that needs to be subtracted for the second is calculated based on the end time of the last measurement and the time. After the current 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 the measurement efficiency.

[0007] The embodiment of the present invention provides the following solution:

[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, then record the average counts per second before background deduction and the end time at the end of the last measurement; if it is the first measurement, then 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 in 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 by the calibrated efficiency coefficient of the instrument to obtain the actual radon concentration after deduction.

[0014] In an optional embodiment, the average count value 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 T0 indicates the start time of the last measurement, and T1 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 at the nth second of this measurement, T n represents the current time, and T0 represents the time when the last measurement ended.

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

[0021]

[0022] Where D b Represents total background counts.

[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] Where D r Denotes 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 by 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 concentration of radon gas by the average counts per second measured by the instrument in a standard radon chamber.

[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 last measurement is completed, in the case of the decay interference of the last measurement. Through the correction of the method, the real result can be well restored, the currently commonly used purification waiting time is cancelled, 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 drawings required for use in the embodiments will be briefly introduced below. 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 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention belong to the scope of protection of the embodiments of the present invention.

[0035] Reference Figure 1 , is the semiconductor radon detector used in this embodiment. The device is composed of a dryer, a daughter filter, an air inlet, a pump, an electrostatic collection chamber, a semiconductor detector, a signal processing and main control, a display part, a printer and other modules. The radon high-voltage electrostatic collection chamber is added with positive high voltage, and the detector surface is ground level. Based on the high-voltage electrostatic adsorption α energy spectrum method, the radon-containing gas is sucked into the electrostatic collection chamber (metal chamber) by an air pump. Once the radon undergoes α decay, the radon atoms become positively charged polonium atoms (ions), which move to the detector surface under the action of the high-voltage electric field and are adsorbed on the detector. Subsequently, the polonium atoms on the surface undergo α decay, and the excitation of the α particles generates a current signal (electric pulse signal) on the detector surface. After the electric pulse signal passes through the instrument multi-channel pulse analyzer, the number and energy of the generated α particles are obtained, thereby indirectly calculating the concentration of radon in the air.

[0036] The steps of a radon measurement method based on time-stamped background subtraction provided by an embodiment of the present invention include:

[0037] Step 1: At the end of the last measurement, record the end time T0 of this 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 count value C0 without background count deduction as 2cps (in counts per second).

[0038] C0 is the average count 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 time when the last measurement started, 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 this time, 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 time 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, calculated using the formula:

[0054]

[0055] in:

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

[0057] C0 is the count rate measured last time, 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 in seconds 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 gas concentration value by the average counts per second measured by the instrument in the standard radon room.

[0066] If the subtraction method is not used and the total count without background subtraction 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 last measurement is completed, in the case of decay interference of the last measurement. Through the correction of the present invention, the real result can be well restored, the currently commonly used purification waiting time is cancelled, and the working efficiency of the instrument is improved.

[0067] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, 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 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, devices (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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 generate 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 flowchart and / or block diagram. 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 capable of directing a computer or other programmable data processing device to operate 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 A 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 operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0071] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other 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 can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

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, then record the average counts per second before background deduction and the end time at the end of the last measurement; if it is the first measurement, then record the average counts per second before background deduction as 0, and the end time as the start time of this measurement; Step 2: After the measurement starts, record the time in seconds and calculate the background count to be deducted at each moment; 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 of 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 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 C0 without background deduction in step 1 is calculated by the following formula: Where D represents the total count of the last measurement, T b T0 indicates the start time of the last measurement, and T1 indicates the end time of the last measurement.

3. The radon measurement method based on time-stamped background subtraction according to claim 2 is characterized in that: The background counts to be deducted at each moment in step 2 are calculated by the following formula: Among them C n Indicates the count that needs to be deducted at the nth second of this measurement, T n represents the current time, and T0 represents the time when the last measurement ended.

4. The radon measurement method based on time-stamped background subtraction according to claim 3 is characterized in that: The total background count described in step 3 is calculated by the following formula: Where D b Represents total background counts.

5. The radon measurement method based on time-stamped background subtraction according to claim 4 is characterized in that: The total count after deduction described in step 4 is calculated by the following formula: D r =D t -D b Where D r Denotes the total count after deduction, D t Indicates the total count of this measurement.

6. The radon measurement method based on time-stamped background subtraction according to claim 5, characterized in that: The actual radon concentration described in step 5 is calculated by the following formula: Where R represents the actual radon concentration and F represents the instrument calibration factor.

7. The radon measurement method based on time-stamped background subtraction according to claim 6, characterized in that: The instrument calibration coefficient is the data obtained by dividing the known radon gas concentration value of the instrument in the standard radon room by the average counts per second measured by the instrument.

Images