Adaptive purging low background device and method for high purity germanium gamma spectrometer

Abstract

The application discloses a kind of self-adapting purging low background device and method for high purity germanium gamma spectrometer, it is related to radioactive nuclide detection technical field.The device includes: gas source module, flow control module, inner cover, purification module, sensing module and main control module;Method includes: S1, start high purity germanium gamma spectrometer self-adapting purging low background system;S2, obtain the monitoring data of sensing module;S3, whether the pressure difference is more than air pressure difference threshold value is judged;S4, whether humidity or radon concentration is more than corresponding threshold value is judged;S5, nitrogen purging flow is obtained using box model;S6, nitrogen purging flow control is realized by flow control module;S7, end.The application is without needing to change high purity germanium gamma spectrometer ontology under the premise, using existing equipment, by introducing first-order linear box mass conservation model, by using real-time monitoring data dynamic calculation nitrogen purging flow, realizes the self-adapting regulation and control under low background condition.

Description

Technical Field

[0001] This invention relates to the field of radionuclide detection technology, specifically to an adaptive purge low-background device and method for a high-purity germanium gamma spectrometer. Background Technology

[0002] Soil erosion and deposition are among the most important geomorphic evolution and environmental processes in the Earth's surface system, directly affecting the stability of terrestrial ecosystems, water and soil resource utilization, and the sustainable development of human society. Accurately reconstructing erosion and deposition rates on a centennial scale is a core issue in environmental geosciences and soil and water conservation research. 210 Pb (half-life 22.3a) as 238 A naturally occurring radionuclide in the U decay series, it has become an important radioactive tracer for dating soil erosion and sedimentation on a centennial scale due to its suitable time window, well-defined source mechanism, and stable atmospheric deposition characteristics.

[0003] 210 Pb ex Dating methods are among the most mature techniques in environmental sedimentology research. Their basic principle is that surface sediments continuously acquire dating data. 210 Pb ex Input activity decreases exponentially with increasing burial time. This is achieved by establishing sedimentary profiles. 210 Pb ex The distribution of activity with depth or cumulative mass can be used to inversely determine the depositional age and rate. 210 Pb's half-life covers a period of nearly a century of human activity and climate change, providing... 137 Cs and 14 Key time information between C.

[0004] High-purity germanium HPGe gamma spectrometers are widely used for environmental nuclides due to their excellent energy resolution. 210 Pb, 137 Analysis of Cs, etc. However, in practical applications, 210 The measurement sensitivity of Pb at low energies (46.5 keV) is highly susceptible to radon. 222 The strong interference from Rn and its daughter products, as well as the effect of self-absorption, necessitate precise measurement. 210 To control the Pb content, a feasible method is needed to suppress the radon background. Common modification methods to reduce radon interference include: (1) Physical sealing: adding a plastic film or metal cover to the outside of the probe to restrict air exchange, but the sealing effect is limited and it is not conducive to sample replacement. (2) Environmental-level purification: such as overall nitrogen purification in low-background laboratories and deep underground laboratories, but the cost is extremely high and it is not suitable for promotion in general universities and research institutions. In addition, the humidity of the environment in which the instrument is located is an important factor affecting the stability of the instrument, but most existing systems rely on manual monitoring of humidity, and the degree of automation is low.

[0005] Currently, high-purity germanium gamma spectrometers primarily use quantitative nitrogen input, which suffers from high gas consumption, poor long-term operational economy, and a lack of dynamic adjustment, making it impossible to flexibly control based on actual humidity and radon levels. Therefore, existing technologies have the following shortcomings: lack of real-time monitoring and feedback of humidity, radon concentration, and pressure difference; fixed purge flow rate, unable to be adjusted as needed; excessive nitrogen consumption, detrimental to long-term operation; and lack of integration with database scheduling, preventing intelligent optimization based on long-term background data. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention aims to provide an adaptive purging low-background device and method for a high-purity germanium gamma spectrometer. Through multi-sensor fusion and intelligent control, the device achieves adaptive adjustment of nitrogen purging, maintaining a long-term low background while reducing gas consumption and improving laboratory operating efficiency and reliability.

[0007] Specifically, on one hand, the present invention provides an adaptive purge low-background device for a high-purity germanium gamma spectrometer, comprising: a gas source module, a flow control module, an inner shroud, a purification module, a sensing module, and a main control module; the inner shroud is located in the lead chamber of the high-purity germanium gamma spectrometer, and then the gas source module, flow control module, inner shroud, and purification module are connected in sequence to form an airflow path; the sensing module is located in the inner shroud and the lead chamber for receiving monitoring data, and the main control module is connected to the gas source module, flow control module, and sensing module respectively for receiving monitoring data or sending control parameters; specifically:

[0008] The gas source module is used to ensure that nitrogen gas enters the inlet of the flow control module stably at the pressure value set by the main control module;

[0009] The flow control module is connected to the gas source module, the inner cover and the main control module respectively. The flow control module receives nitrogen from the gas source module and inputs nitrogen into the inner cover through the air inlet of the lead chamber of the high-purity germanium gamma spectrometer according to the nitrogen output flow rate received from the main control module.

[0010] The inner cover is a cover installed inside the lead chamber of the high-purity germanium gamma spectrometer. The inner cover is made of transparent acrylic material and covers the sample area to form a local sealed space. There is an air inlet on the bottom side wall of the inner cover, which is connected to the air inlet of the lead chamber through the first pipeline. There is an exhaust hole on the top side wall of the inner cover, which is connected to the exhaust hole of the lead chamber through the second pipeline. A rubber sealing ring is used at the contact point between the inner cover and the lead chamber.

[0011] The purification module is used to remove radon gas from the exhaust port of the lead chamber of the high-purity germanium gamma spectrometer. The inlet of the purification module is connected to the exhaust port of the lead chamber. After removing the radon gas, the gas is directly discharged into the air.

[0012] The sensing module is used to measure temperature and humidity, radon concentration, and air pressure in the inner enclosure and lead chamber. The sensing module is connected to the main control module and sends the monitoring data to the main control module.

[0013] The main control module is connected to the gas source module, the sensor module, and the flow control module respectively. It is used to receive monitoring data from the sensor module and control the gas source module and the flow control module to adjust the flow rate by setting the equipment parameters.

[0014] Preferably, the main control module includes a control parameter submodule, a data acquisition submodule, a threshold judgment submodule, a flow regulation submodule, and a data storage submodule, specifically:

[0015] The data acquisition submodule is used to receive data collected by all sensors. The data acquisition submodule sends the collected data to the threshold judgment submodule, the flow regulation submodule and the data storage submodule.

[0016] The threshold judgment submodule is used to compare with the set threshold and give the corresponding control parameters of the device based on the comparison result, and send the control parameters to the control parameter submodule;

[0017] The flow regulation submodule is used to obtain the nitrogen purging flow rate based on the temperature and humidity values, radon concentration, inner cover pressure and lead chamber pressure obtained by the data acquisition submodule, and send the nitrogen purging flow rate as the control parameter of the flow control module to the control parameter submodule;

[0018] The control parameter submodule is used to send control parameters to the corresponding devices;

[0019] The data storage submodule is used to save the corresponding data and parameters to the database according to the settings.

[0020] Preferably, the sensing module includes a temperature and humidity sensor, a radon online monitor, a first pressure sensor, and a second pressure sensor; the temperature and humidity sensor is located on the upper part of the inner cover and is used to monitor the temperature and humidity inside the inner cover; the sampling port of the radon online monitor is located near the exhaust port at the top of the inner cover and is used to monitor the radon concentration inside the inner cover; the second pressure sensor is installed inside the inner cover and is used to monitor the air pressure inside the inner cover; the first pressure sensor is installed inside the lead chamber and is used to monitor the air pressure inside the lead chamber.

[0021] Preferably, the main control module also includes a linkage scheduling submodule;

[0022] When the daily or weekly background spectrum measurement plan is triggered, the linkage scheduling submodule automatically generates a background spectrum measurement task, sends control parameters to the control parameter submodule and the data storage submodule according to the background spectrum measurement task, starts the purging or monitoring task, and generates an operation log.

[0023] On the other hand, the present invention also provides a method of using the above-mentioned adaptive purge low-background device for a high-purity germanium gamma spectrometer, which includes the following steps:

[0024] S1, activate the adaptive purge low-background device for the high-purity germanium gamma spectrometer;

[0025] S2, acquire monitoring data from the sensor module;

[0026] The sensor module acquires the temperature, humidity, radon concentration, inner enclosure pressure, and lead chamber pressure.

[0027] S3, determine whether the pressure difference exceeds the air pressure difference threshold;

[0028] When the pressure difference between the inner casing and the lead chamber is less than the pressure difference threshold, a short-term flow boost is performed for a preset duration to ensure a positive pressure environment is maintained; when the pressure difference between the inner casing and the lead chamber exceeds or equals the pressure difference threshold, S4 is executed directly.

[0029] S4, determine whether the humidity or radon concentration exceeds the corresponding threshold;

[0030] If neither humidity nor radon concentration exceeds the corresponding threshold, return directly to S2; if either humidity or radon concentration exceeds the corresponding threshold, execute S5 to adjust the nitrogen purging flow rate.

[0031] S5, using the box model to obtain the nitrogen purging flow rate;

[0032] S51, obtained using a radon concentration chamber model. The first minimum steady-state demand flow rate at any given moment;

[0033] First minimum steady-state demand flow rate The calculation formula is as follows:

[0034] (6);

[0035] In the formula: for The first minimum steady-state demand flow rate at any given time, in m³. 3 / h, The target value for radon concentration inside the inner cover is set as the radon threshold value. for The rate at which radon enters at any given time. This is the fitted value of the equivalent ventilation rate when the radon concentration is not purged. Let be the decay constant of radon. The effective volume of the inner cover is obtained according to equation (6). First minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate;

[0036] S52, obtained using a humidity chamber model. The second minimum steady-state demand flow rate at time 1;

[0037] Second minimum steady-state demand flow rate at time t The formula is:

[0038] (15);

[0039] In the formula: for The second minimum steady-state demand flow rate at time 1. for Temperature at any time The target value for the actual absolute humidity inside the lower inner cover. for The rate at which water vapor enters at any given moment. The fitted value of the equivalent air exchange rate when the actual absolute humidity is not purged is obtained according to equation (15). Second minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate;

[0040] S53, determine the nitrogen purging flow rate;

[0041] exist First minimum steady-state demand flow at time step Choose the larger flow rate from the second minimum steady-state demand flow rate at time step 2. Nitrogen purge flow rate :

[0042] S6, nitrogen purging flow control is achieved through the flow control module;

[0043] After obtaining the nitrogen purging flow rate, the main control module sends the nitrogen purging flow rate to the flow control module, and then the flow control module outputs nitrogen to the inner shroud at the received nitrogen purging flow rate.

[0044] S7, End; The main control module records temperature, humidity, pressure difference and radon concentration data at preset time intervals and stores the data in the database. When the main control module receives a shutdown command, it shuts off the nitrogen output of the flow control module and ends the current control process.

[0045] Preferably, S1, activating the adaptive purge low-background device for the high-purity germanium gamma spectrometer specifically involves:

[0046] Upon receiving the start command, the adaptive purging low-background device for the high-purity germanium gamma spectrometer is initialized based on the received or pre-stored control parameters. During initialization, the communication status between the main control module, gas source module, flow control module, and sensor module is monitored, and the temperature, humidity, inner shroud pressure, and lead chamber pressure output by the sensor modules are read to determine whether the adaptive purging low-background device for the high-purity germanium gamma spectrometer is in an allowable operating state. If any module status is found to be inconsistent with the preset operating conditions, the main control module prohibits the purging process and outputs an alarm message. When all parameters meet the operating conditions, the adaptive purging low-background device for the high-purity germanium gamma spectrometer enters the operating state.

[0047] Preferably, in step S3, when the pressure difference between the inner shroud and the lead chamber exceeds a specified threshold, a short-term flow boost for a preset duration is performed to ensure a positive pressure environment is maintained. Specifically:

[0048] When the pressure difference between the inner shroud and the lead chamber is less than the specified threshold, a short-term flow boost will be performed at a preset flow boost rate within a preset time period. After the short-term flow boost is completed, the flow control module will restore the nitrogen purging flow rate to the nitrogen purging flow rate before the short-term flow boost and return to S2.

[0049] Preferably, in S51 The relationship with humidity and air pressure is shown in equation (4):

[0050] (4);

[0051] In the formula, For the inner cover Relative humidity at any given time For the inner cover air pressure at any moment The initial radon ingress rate. The initial relative humidity inside the inner cover. The initial air pressure inside the inner casing. As the first parameter, The second parameter can be obtained by least squares fitting. Fitted values ;

[0052] To determine the natural ventilation intensity without nitrogen purging, the radon attenuation method was used to determine the radon concentration inside the inner enclosure when nitrogen purging was not performed. The decay after the interval time satisfies:

[0053] (5);

[0054] In the formula, The interval time, Interval time The actual radon concentration was measured later. The initial radon concentration is obtained from the actual measured concentration using formula (5). Fitted values .

[0055] Preferably, in S52, the temperature and humidity monitor obtains the relative humidity. First, convert the relative humidity to the absolute humidity, specifically:

[0056] The saturated vapor pressure is calculated using the Magnus formula:

[0057] (7);

[0058] Actual water vapor pressure:

[0059] (8);

[0060] The formula for converting relative humidity to actual absolute humidity is:

[0061] (9);

[0062] In the formula: The current temperature is monitored by the temperature and humidity sensor. For temperature The saturated water vapor pressure at that time The relative humidity is monitored by a temperature and humidity sensor. This is the actual water vapor pressure. This refers to the actual absolute humidity.

[0063] The relationship with temperature and air pressure is shown in equation (13):

[0064] (13);

[0065] In the formula, It is the initial rate at which water vapor enters. For the inner cover Temperature at any moment The initial temperature inside the inner cover. For the inner cover air pressure at any moment The initial air pressure inside the inner casing. As the third parameter, The fourth parameter can be obtained by least squares fitting. Fitted values ;

[0066] The equivalent air exchange rate without purging is the actual absolute humidity. The calculation is performed by fitting the formula (14):

[0067] (14);

[0068] In the formula: The absolute humidity of the air inside the inner cover at the initial moment; time Absolute humidity of the air inside the inner cover; This refers to the absolute humidity of the ambient air in an outdoor lead laboratory.

[0069] Preferably, it also includes an automatic scheduling step.

[0070] The device will repeatedly execute S1-S7 during specified time periods, record radon concentration and humidity, and upload the data to the database for long-term analysis to optimize thresholds.

[0071] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0072] (1) This invention innovatively introduces a first-order linear box mass conservation model into the radon control process of a high-purity germanium lead chamber, and incorporates environmental factors such as humidity and air pressure into the radon source term modeling, thereby realizing a physical description of the radon concentration evolution process in the lead chamber.

[0073] (2) Based on the first-order linear box mass conservation model, the present invention uses real-time monitoring data to invert the radon source intensity and equivalent air leakage rate in the lead chamber, and dynamically calculates the nitrogen purging flow rate accordingly, thereby realizing an adaptive radon control strategy under low background conditions, breaking through the traditional method of relying on experience setting or fixed flow rate purging.

[0074] (3) The present invention constructs a closed-loop control mechanism that links multiple parameters such as humidity, radon concentration and pressure difference, which can automatically adjust the nitrogen purging intensity according to the environmental conditions, effectively reducing the background while reducing gas consumption.

[0075] (4) This invention, through adjustable nitrogen purging, can significantly reduce the accumulation of radon and its short-lived progeny in the lead chamber, suppressing the continuous background and scattering background in the low-energy region from the source, which is particularly beneficial. 210 High-precision measurement of low-energy environmental nuclides such as Pb.

[0076] (5) Based on existing instruments and equipment, the present invention can be modularly combined through standardized interfaces without modifying the detector body or building a dedicated low background laboratory, and has good feasibility and scalability.

[0077] (6) This invention can achieve long-term stable operation without human intervention through database linkage and automatic scheduling, and is suitable for low background environment control in conventional γ-ray spectroscopy laboratories. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to the present invention.

[0079] Figure 2 This is a schematic diagram of the main control module in this invention;

[0080] Figure 3 This is a flowchart illustrating the usage method of the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to the present invention.

[0081] Key reference numerals:

[0082] 1. Gas source module; 2. Flow control module; 3. Inner cover; 31. First pipeline; 32. Second pipeline; 4. Purification module; 5. Sensing module; 51. First pressure sensor; 52. Second pressure sensor; 53. Temperature and humidity sensor; 54. Radon online monitor; 6. Main control module; 61. Control parameter submodule; 62. Data acquisition submodule; 63. Threshold judgment submodule; 64. Flow regulation submodule; 65. Data storage submodule; 66. Linkage scheduling submodule; 7. Lead chamber; 8. Sample area. Detailed Implementation

[0083] To fully explain the technical content, objectives, and effects of this invention, the embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0084] This invention discloses an adaptive purge low-background device for a high-purity germanium gamma spectrometer, the overall structure of which is as follows: Figure 1 As shown, it mainly includes a gas source module 1, a flow control module 2, an inner cover 3, a purification module 4, a sensing module 5, and a main control module 6. Each module can be installed independently or modularly combined through standardized interfaces, facilitating rapid addition or upgrade under existing high-purity germanium gamma-ray spectrometer laboratory conditions.

[0085] The inner casing 3 is located inside the lead chamber 7 of the high-purity germanium gamma spectrometer. The gas source module 1, flow control module 2, inner casing 3, and purification module 4 are then connected sequentially to form the airflow path. The sensing module 5, located inside the inner casing 3 and lead chamber 7, receives monitoring data. The main control module 6 is connected to the gas source module 1, flow control module 2, and sensing module 5 respectively, and is used to receive monitoring data or send control parameters. Specifically:

[0086] The gas source module 1 is used to ensure that nitrogen gas enters the inlet of the flow control module 2 at a stable pressure. The gas source module 1 includes at least a high-purity nitrogen cylinder and a pressure reducing valve located on top of the high-purity nitrogen cylinder. The high-purity nitrogen cylinder provides nitrogen with a purity ≥99.999% and an internal pressure of 10-15 MPa. The pressure reducing valve is a high-precision pressure reducing valve. The pressure reducing valve controls the outlet pressure according to parameters set by the main control module 6. In this embodiment, the pressure reducing valve stabilizes the outlet pressure of the high-purity nitrogen cylinder within the range of 0.2-0.5 MPa. Furthermore, to ensure long-term operational safety, a cylinder pressure sensor can be optionally installed at the end of the high-purity nitrogen cylinder. The cylinder pressure sensor sends the real-time monitored residual pressure to the main control module 6. When the pressure is lower than the preset pressure, an alarm or switch to a backup cylinder can be triggered. The gas source module 1 is connected to the flow control module 2 via a high-pressure hose from the gas cylinder.

[0087] The flow control module 2 has a standard structure, including a mass flow controller (MFC), a needle valve, and a solenoid valve, to achieve baseline flow and pulsed flow boosting. The MFC is responsible for precise flow control, ranging from 0-1 L / min, with an accuracy better than ±1%. The needle valve is used for manually setting the baseline flow and provides physical flow limiting redundancy. The solenoid valve can be used for rapid cut-off or pulse control. In the prior art, the needle valve is a protective or fine-tuning element used to assist the MFC in operation. Therefore, the needle valve and the mass flow controller (MFC) can be connected in series or in parallel. The solenoid valve, as an electrically controlled safety switch, can be located upstream or downstream of the needle valve and the mass flow controller, or both upstream and downstream. The flow control module 2 is connected to the gas source module 1, the inner casing 3, and the main control module 6, respectively. The flow control module 2 obtains nitrogen from the gas source module 1, receives the nitrogen output flow from the main control module 6, and inputs a specified flow rate of nitrogen into the inner casing 3 through the inlet of the lead chamber 7 of the high-purity germanium gamma spectrometer according to the nitrogen output flow rate.

[0088] The inner cover 3 is a cover installed inside the lead chamber 7 of the high-purity germanium gamma spectrometer. The inner cover 3 is made of transparent acrylic material and covers the sample area 8 to form a partially sealed space. An air inlet is provided on the bottom side wall of the inner cover, connected to the air inlet of the lead chamber via a first pipe 31; an exhaust port is provided on the top side wall of the inner cover, connected to the exhaust port of the lead chamber via a second pipe 32. A rubber sealing ring is used at the contact point between the inner cover 3 and the lead chamber 7 to reduce air permeation. Based on the connection relationship between the inner cover 3 and the lead chamber 7, a gas flow path is formed from the air inlet of the lead chamber, the air inlet of the inner cover, the interior of the inner cover, the exhaust port of the inner cover, and back to the exhaust port of the lead chamber. In this embodiment, the inner cover is 3-5 mm thick and cylindrical in shape. The diameter of both the air inlet and exhaust port of the inner cover is 6 mm. The first and second pipes are preferably made of PTFE material.

[0089] Purification module 4 is used to remove radon gas from the exhaust port of the lead chamber of the high-purity germanium gamma spectrometer. Purification module 4 is connected to the exhaust port of lead chamber 7, and after removing radon, the gas is directly discharged into the air. In this embodiment, the purification module uses an activated carbon device for purification. The activated carbon device is a black cylinder filled with columnar activated carbon, with a volume of approximately 1-2L, capable of adsorbing more than 90% of radon progeny. To maintain the adsorption effect, the activated carbon needs to be replaced or regenerated by heating every 3-6 months.

[0090] Sensing module 5 is used to measure temperature, humidity, radon concentration, and air pressure in the inner enclosure and lead chamber. Sensing module 5 is connected to the main control module 6 and sends the monitoring data to the main control module 6. Sensing module 5 includes a first pressure sensor 51, a second pressure sensor 52, a temperature and humidity sensor 53, and an online radon monitor 54. The first pressure sensor 51 is installed inside the lead chamber 7 to monitor the air pressure inside the lead chamber. The second pressure sensor 52 is installed inside the inner enclosure 3 to monitor the air pressure inside the inner enclosure. The pressure difference between the inner enclosure and the lead chamber can also be obtained from the first and second pressure sensors. The temperature and humidity sensor 53 is located on the upper part of the inner cover 3 and is used to monitor the temperature and humidity inside the inner cover. The sampling port of the radon online monitor 54 is located near the exhaust hole at the top of the inner cover 3 and is used to monitor the radon concentration inside the inner cover. In this embodiment, the first pressure sensor 51 and the second pressure sensor 52 have an accuracy range of ±125Pa, the temperature accuracy of the temperature and humidity sensor is ±0.5℃, and the humidity accuracy is ±2%RH. The radon online monitor uses diffusion or pump-suction sampling, and each measurement lasts for 5-10 minutes.

[0091] The main control module 6 is connected to the sensor module 5, the gas source module 1, and the flow control module 2, respectively. It receives monitoring data from the sensor module 5 and controls the gas source module 1 and the flow control module 2 to regulate the flow rate based on equipment parameters. Figure 2 As shown, the main control module 6 includes a control parameter submodule 61, a data acquisition submodule 62, a threshold judgment submodule 63, a flow regulation submodule 64, a data storage submodule 65, and a linkage scheduling submodule 66, specifically as follows:

[0092] The data acquisition submodule 62 is used to receive data collected by all sensors, such as parameters like temperature and humidity, radon concentration, inner enclosure pressure, and lead chamber pressure; the data acquisition submodule 62 sends the collected data to the threshold judgment submodule 63, the flow regulation submodule 64, and the data storage submodule 65.

[0093] The threshold judgment submodule 63 is used to compare with the set threshold and give the corresponding control parameters of the device according to the comparison result, and send the control parameters to the control parameter submodule 61; for example, when the cylinder pressure sensor is lower than 0.5MPa, it will automatically alarm and send a backup gas cylinder switching signal to the gas source module, or when the MFC flow exceeds the specified threshold, it will quickly shut off the solenoid valve.

[0094] The flow regulation submodule 64 is used to obtain the nitrogen purging flow rate based on the temperature and humidity values, radon concentration, inner cover pressure and lead chamber pressure obtained by the data acquisition submodule 62, and send the nitrogen purging flow rate as the control parameter of the flow control module 2 to the control parameter submodule 61.

[0095] The control parameter submodule 61 is used to receive control parameters and send control parameters to the corresponding devices. For example, if the outlet pressure of the high-purity nitrogen cylinder is set to 0.2 MPa, the control parameter submodule needs to send this parameter to the pressure reducing valve of the gas source module.

[0096] The data storage submodule 65 is used to save specified data, control parameters and system parameters to the local database according to the settings, and preferably can also upload them to the server; the data storage submodule 65 is connected to the data acquisition submodule 62, the control parameter submodule 61 and the linkage scheduling submodule 66.

[0097] The linkage scheduling submodule 66, upon triggering the daily / weekly background measurement plan, automatically generates a background spectrum measurement task. Based on this task, it sends control parameters to the control parameter submodule 61 and the data storage submodule 65, initiates a purging or monitoring task, and generates an operation log. During operation, it automatically records parameter values ​​such as temperature, humidity, pressure difference, and radon concentration. For example, if the daily background spectrum measurement plan starts at 2:00 AM and runs for 2 hours, when the linkage scheduling submodule 66 detects 2:00 AM, it initiates the daily background spectrum measurement plan, causing the data storage submodule to automatically record temperature, humidity, pressure difference, and radon concentration data, and generates an operation log based on the equipment data monitored by the main control module. In this embodiment, recording is preferably performed every 10 minutes. Based on the multiple recorded operation logs and parameter values, thresholds and control parameters can be optimized according to background trends.

[0098] This invention also discloses a method for using an adaptive purge low-background device for a high-purity germanium gamma spectrometer, such as... Figure 3 As shown, the specific steps include:

[0099] S1, activate the adaptive purge low-background device for the high-purity germanium gamma spectrometer;

[0100] Upon receiving the start command, the adaptive purging low-background device for the high-purity germanium gamma spectrometer is initialized based on the received or pre-stored control parameters. During initialization, the communication status between the main control module, gas source module, flow control module, and sensor module is monitored, and the temperature, humidity, and inner chamber pressure and lead chamber pressure output by the sensor modules are read to determine whether the adaptive purging low-background device for the high-purity germanium gamma spectrometer is in a permissible operating state. If any module status is found to be unsatisfactory under the preset operating conditions, the main control module prohibits the purging process and outputs an alarm message. When all parameters meet the operating conditions, the adaptive purging low-background device for the high-purity germanium gamma spectrometer enters the operating state, including: opening the pressure reducing valve and solenoid valve, allowing nitrogen to enter the inner chamber through the flow control module, and then the gas inside the inner chamber flows into the purification module, is purified, and then discharged into the air; and activating the sensor module to detect the temperature, humidity, radon concentration, and inner chamber pressure and lead chamber pressure inside the inner chamber.

[0101] S2, acquire monitoring data from the sensor module;

[0102] The temperature, humidity, radon concentration, inner cover pressure, and lead chamber pressure are acquired from the sensor module. In this embodiment, the main control module acquires the sensor module monitoring results once every 5-10 minutes.

[0103] S3, determine whether the pressure difference exceeds the air pressure difference threshold;

[0104] To prevent outside air from infiltrating and maintain a stable low-radon environment, a slight positive pressure needs to be maintained between the inner enclosure and the lead chamber. If the pressure difference is too small or a negative pressure occurs, outside air may enter the inner enclosure, thereby introducing radon gas and increasing the background in the low-energy region.

[0105] Therefore, it is necessary to calculate the air pressure difference ΔP = P1-P2 between the inner cover and the lead chamber, where P1 is the air pressure of the inner cover monitored by the second air pressure sensor, and P2 is the air pressure of the lead chamber monitored by the first air pressure sensor.

[0106] When the pressure difference ΔP between the inner shroud and the lead chamber is less than the pressure difference threshold, a short-term flow boost for a preset duration is performed to ensure the inner shroud maintains a positive pressure environment. In this embodiment, the pressure difference threshold is set to 5 Pa, the preset duration is 15 minutes, and the flow boost rate is 0.1 L / min. Therefore, when the pressure difference is less than 5 Pa, the flow boost will continue for 15 minutes at a rate of 0.1 L / min. After the short-term flow boost is completed, the flow control module restores the nitrogen purging flow rate to the level before the short-term flow boost and returns to S2.

[0107] When the pressure difference between the inner cover and the lead chamber exceeds or equals the pressure difference threshold, execute S4 directly.

[0108] S4, determine whether the humidity or radon concentration exceeds the corresponding threshold;

[0109] If the humidity does not exceed the humidity threshold and the radon concentration does not exceed the radon threshold, return directly to S2; otherwise, execute S5 to adjust the nitrogen purging flow rate.

[0110] S5, using the box model to obtain the nitrogen purging flow rate;

[0111] The principle of the physics-statistics fusion discrete-time box model is to treat the inner casing as a volume. A thorough mixing chamber was constructed, treating radon and humidity (i.e., water vapor) as controlled variables to be purged and removed. Separate small chamber models were established for radon concentration and humidity. The minimum steady-state flow rate required for each model was calculated based on its respective target threshold, and the larger flow rate was selected as the nitrogen purging flow rate. A physics-statistical fusion discrete-time chamber model was used to calculate the minimum steady-state nitrogen purging flow rate that satisfies the target concentrations of radon and humidity. This approach meets the accuracy requirements of high-purity germanium instruments while reducing nitrogen consumption and saving costs.

[0112] S51, obtained using a radon concentration chamber model. The first minimum steady-state demand flow rate at any given moment;

[0113] Analysis shows that the radon concentration inside the inner enclosure is controlled by three factors: (1) the source, radon from the outside air entering during sample changing or through gaps (affected by humidity and air pressure); (2) the sink, the radioactive decay of radon itself; and (3) purging: nitrogen gas at a volumetric flow rate. (m) 3 ( / h) Continue purging to displace radon.

[0114] Therefore, the continuity equation for the radon concentration change and nitrogen purging flow rate in the radon concentration chamber model is as follows:

[0115] (1);

[0116] In the formula: for Radon concentration at any given time, in Bq / m³ 3 ; for The rate at which radon enters at any given time, it varies with... Humidity and air pressure changes over time, in Bq / h; The decay constant of radon is 0.00754 h. -1 This value is based on the decay constant formula and the half-life of radon-222, with the unit converted to hourly. The equivalent ventilation rate without purging is the radon concentration, expressed in hours. -1 ; The volume exchange rate caused by nitrogen purging, in h. -1 , The volumetric flow rate of nitrogen purging is expressed in cubic meters per second (m³). 3 / h, The effective volume of the inner cover is expressed in meters (m). 3 .

[0117] Based on equation (1), discretize to the sampling interval. The formula for calculating radon concentration is:

[0118] (2);

[0119] (3);

[0120] In the formula: The sampling interval, also known as the step size, is measured in hours (h). In order to be in Radon concentration inside the inner enclosure at any given time, in Bq / m³. 3 ; for The radon concentration inside the inner casing at any given time. for go through The decrease after time, in units of Bq / m 3 The reduction includes radon decay over time, and reductions due to leakage and purging. The total radon removal rate; for Nitrogen purging volumetric flow rate at any given time, in m³ 3 / h; for The rate at which radon enters at any given time. The volume of the inner casing is in meters (m). 3 ; Radon input rate per unit volume, in Bq / (m³). 3 ·h); To be in the sampling interval Within this framework, the source terms gradually approach equilibrium with exponential weights, with the overall unit being Bq / m. 3 ; The contribution to the source term, namely the radon newly entering the inner cavity. Contribution within the time limit; This is the random noise term, with units of Bq / m. 3 ;

[0121] The relationship with humidity and air pressure is shown in equation (4):

[0122] (4);

[0123] In the formula, for The rate at which radon enters at any given time. For the inner cover Relative humidity at any given time For the inner cover air pressure at any moment The initial radon ingress rate. The initial relative humidity inside the inner cover. The initial air pressure inside the inner casing. As the first parameter, This is the second parameter. It can be obtained using least-squares fitting based on actual observation data. Fitted values .

[0124] This represents the natural ventilation intensity of the inner cover due to gaps and incomplete sealing when nitrogen purging is not performed. The calculation utilizes the radon attenuation method (exponential fitting) under conditions of no nitrogen purging. When =0, the radon concentration inside the inner cover is at The decay after the interval time satisfies:

[0125] (5);

[0126] In the formula, The interval time, Interval time The actual radon concentration was measured later, in units of Bq / m³. 3 ; The initial radon concentration, measured in Bq / m³. 3 According to formula (5), we can obtain Fitted values .

[0127] In determining and After obtaining the fitted value, the current value can be obtained according to formula (4). The rate of radon entry at any given time Since the goal is to keep the radon concentration inside the inner enclosure below the radon threshold, the control strategy is to keep the flow rate as stable as possible. Therefore, according to formula (1), when the radon concentration... When it is the radon threshold, The derivative is 0, therefore according to formulas (1) and (2), we get:

[0128] When the box model is at a steady-state fixed point:

[0129] ;

[0130] ;

[0131] Thus solve First minimum steady-state demand flow rate The calculation formula is as follows:

[0132] (6);

[0133] In the formula: for The first minimum steady-state demand flow rate at any given time, in m³. 3 / h, The target value for radon concentration inside the inner cover is set as the radon threshold value. In this embodiment, the target radon concentration inside the inner cover is less than 5 Bq / m³. 3 That is, it is close to the detection lower limit, therefore set =5 Bq / m 3 , for The rate at which radon enters at any given time. This is the fitted value of the equivalent ventilation rate when the radon concentration is not purged. Let be the decay constant of radon. The effective volume of the inner cover is expressed in meters (m). 3 .

[0134] Using equation (4), the current measured values ​​are... , calculate Then use equation (6) to solve in real time to satisfy The minimum nitrogen flow rate is obtained. First minimum steady-state demand flow rate .

[0135] S52, obtained using a humidity chamber model. The second minimum steady-state demand flow rate at time 1;

[0136] The temperature and humidity monitor provides the relative humidity. Using % to represent relative humidity requires first converting relative humidity to absolute humidity. Given... Temperature of Time and relative humidity In this case, first obtain the saturated vapor pressure. Then obtain the actual water vapor pressure Finally, the actual absolute humidity is obtained using the gas law. That is, the mass concentration of water vapor in the air, specifically:

[0137] The saturated vapor pressure is calculated using the Magnus formula:

[0138] (7);

[0139] Actual water vapor pressure:

[0140] (8);

[0141] According to formulas (7)-(8), the conversion formulas between relative humidity and actual absolute humidity are as follows:

[0142] (9);

[0143] In the formula: The current temperature monitored by the temperature and humidity sensor, in °C; The relative humidity is monitored by the temperature and humidity sensor, and the unit is %; For temperature The saturated vapor pressure at that time, expressed in hPa; This is the actual water vapor pressure, in hPa. This represents the actual absolute humidity, expressed in g / m³. 3 .

[0144] The continuity equation for the humidity chamber model simulating actual absolute humidity changes and water vapor purge flow rate is as follows:

[0145] (10);

[0146] In the formula: for Real-time absolute humidity, in g / m³ 3 ; for The rate at which water vapor enters at any given moment, it varies with... Changes in temperature and air pressure over time The effective volume of the inner cover is expressed in meters (m). 3 , The equivalent air exchange rate without purging is the actual absolute humidity, expressed in hours. -1 ; The volumetric exchange rate caused by humidity purging, in h. -1 , The purge volumetric flow rate is the humidity, in cubic meters (m³). 3 / h.

[0147] The discrete recursion of actual absolute humidity follows the same principle as radon concentration, treating the inner cover as a volume. The fully mixed box, based on equation (10), is discretized to the sampling interval. The formula for calculating actual absolute humidity is:

[0148] (11);

[0149] (12);

[0150] In the formula: In order to be in The actual absolute humidity inside the inner cover at any given time. The total water vapor removal rate, for The rate at which water vapor enters the inner shroud is measured in g / h. The amount of water vapor entering the inner shroud usually comes from moisture release from the measured sample, instrument materials, etc., or seepage through gaps. The equivalent air exchange rate without purging is the actual absolute humidity, expressed in hours (h). -1 The ultrapure nitrogen gas used for purging is dry gas, so the removal rate is... , for The volumetric flow rate of water vapor being blown away at any given time.

[0151] The relationship with temperature and air pressure is shown in equation (13):

[0152] (13);

[0153] In the formula, It is the initial rate at which water vapor enters. For the inner cover Temperature at any moment The initial temperature inside the inner cover. For the inner cover air pressure at any moment The initial air pressure inside the inner casing. As the third parameter, This is the fourth parameter. It can be obtained using least-squares fitting based on actual observation data. Fitted values .

[0154] The equivalent air exchange rate is the actual absolute humidity without purging. The amount of water vapor entering the inner cover usually comes from moisture release from the measured sample, instrument materials, etc., and seepage through gaps.

[0155] The following formula is used for fitting and calculation:

[0156] (14);

[0157] In the formula: The absolute humidity of the air inside the inner cover at the initial moment; time Absolute humidity of the air inside the inner cover; This refers to the absolute humidity of the ambient air in an outdoor lead laboratory.

[0158] Sure , , and After obtaining the fitted value, the current value can be obtained according to formula (13). The rate of water vapor entering at any given time Since the target is for the relative humidity inside the enclosure to be less than the humidity threshold, and the humidity chamber model in formula (10) uses the actual absolute humidity, the relative humidity threshold is first converted into the actual absolute humidity target value according to formulas (7)-(9). The control strategy is to keep the flow rate as stable as possible, so according to formula (10), when When the actual absolute humidity target value is, The derivative is 0, therefore, according to formulas (10) and (11), we get... Second minimum steady-state demand flow rate The formula is:

[0159] (15);

[0160] In the formula: for The second minimum steady-state demand flow rate at time step (m³) is given. 3 / h, for Temperature at any time The target absolute humidity value inside the lower inner cover is, in this embodiment, set at less than a humidity threshold of 40%. for The rate at which water vapor enters at any given moment. This is the fitted value of the equivalent air exchange rate when the actual absolute humidity is not purged. Let be the decay constant of radon. The effective volume of the inner cover is expressed in meters (m). 3 .

[0161] Using equation (13), with the current measured values... , Calculated Then use equation (15) to solve in real time to satisfy The minimum nitrogen flow rate is obtained. Second minimum steady-state demand flow rate .

[0162] S53, determine the nitrogen purging flow rate;

[0163] exist First minimum steady-state demand flow at time step Choose the larger flow rate from the second minimum steady-state demand flow rate at time step 2. Nitrogen purge flow rate :

[0164] (16);

[0165] In the formula, for Nitrogen purging flow rate at all times.

[0166] S6, nitrogen purging flow control is achieved through the flow control module;

[0167] After obtaining the nitrogen purging flow rate, the main control module sends the nitrogen purging flow rate to the MFC in the flow control module, and then the MFC outputs nitrogen to the inner cover module with the received nitrogen purging flow rate.

[0168] S7, End;

[0169] The main control module records temperature, humidity, pressure difference, and radon concentration data at preset time intervals and stores the data in the database. When the main control module receives a shutdown command, it shuts off the nitrogen output of the flow control module, ending the current control process. The main control module can also generate an operation log during the purging process.

[0170] Furthermore, this method also includes:

[0171] The automatic scheduling process involves the device repeatedly executing S1-S7 during specified time periods, recording radon concentration and humidity, and uploading the data to a database for long-term analysis to optimize thresholds.

[0172] Verification of the effectiveness of this invention:

[0173] Verification Experiment 1: Laboratory Verification and Comparison Experiment;

[0174] 1. Experimental objective:

[0175] The performance of the adaptive purging low background device of the present invention was verified under different humidity and radon concentration conditions, and compared with that of conventional constant flow purging.

[0176] 2. Experimental conditions:

[0177] Location: Environmental laboratory, background radon concentration 80-250 Bq / m³ 3 Humidity 40-70%RH.

[0178] Instrument: ORTEC P-type HPGe spectrometer, equipped with a standard 10cm lead chamber.

[0179] Test nuclides: 210 Pb (46.5 keV), 214Pb (352keV) 214 Bi (609keV) 137 Cs (661keV).

[0180] 3. Contrast Design:

[0181] Option A is the traditional constant flow rate: continuous nitrogen purging at a flow rate of 0.4 L / min.

[0182] Option B is the present invention: an adaptive purging system with a baseline of 0.25 L / min, which automatically increases the flow rate when humidity / radon exceeds the standard.

[0183] 4. Experimental Results:

[0184] Radon progeny background: In scheme A, the peak area at 609 keV is about 350 cpm; in scheme B, it decreases to 120 cpm, a reduction of about 66%.

[0185] Low-energy signal-to-noise ratio: Under scheme A, 210 The peak signal-to-noise ratio of Pb46.5 keV is approximately 2:1; under scheme B, it is improved to 5:1.

[0186] Gas consumption: Under the same operating cycle, the nitrogen consumption of scheme B is 55% lower than that of scheme A.

[0187] 5. Conclusion:

[0188] The device of this invention significantly reduces nitrogen consumption while ensuring low background performance, making it suitable for long-term unattended operation.

[0189] Verification Experiment 2: In 210 Applications of Pb dating;

[0190] 1. Application Background:

[0191] 210 Pb dating is widely used in lake sedimentation rate studies and soil sedimentation process tracking. However, the low-energy 46.5 keV peak is susceptible to radon progeny interference, making background suppression crucial.

[0192] 2. Experimental conditions:

[0193] Sample: Lake sediment column, slice thickness 1 cm;

[0194] Measurement conditions: Comparison before and after the modification 210 Pb activity measurement.

[0195] 3. Experimental Results:

[0196] Before the modification: the signal-to-noise ratio of low-layer samples was low, and some slices could not be quantified;

[0197] After modification: all slices can be clearly measured, and the activity profile is smooth and continuous;

[0198] Dating results: Deposition rates were calculated using the CRS model, and the results after modification were compared with... 137 The Cs peak (1963) corresponds more consistently.

[0199] 4. Conclusion:

[0200] The system of this invention has significantly improved 210 The reliability of Pb dating makes deposition rate calculations more accurate.

[0201] Verification Experiment 3: Long-term operation and database management;

[0202] 1. Experimental objective:

[0203] Verify the stability of the system of this invention during long-term continuous operation and the value of data accumulation.

[0204] 2. Experimental Design:

[0205] Operating cycle: 6 months of continuous operation;

[0206] Data management: The database records humidity and pressure difference every 10 seconds, radon concentration every 10 minutes, and performs background data collection once every morning.

[0207] 3. Experimental Results:

[0208] Humidity is maintained at 30-45%RH for an extended period;

[0209] Radon concentration has been below 80 Bq / m³ for an extended period 3 It was significantly lower than the laboratory average concentration (180 Bq / m³). 3 );

[0210] 210 The detection limit for Pb remained stable at 35-40 Bq / kg;

[0211] The database has accumulated over 20GB of storage and supports long-term baseline trend analysis.

[0212] 4. Conclusion:

[0213] It can be seen that the radon progeny peak of this invention is reduced by 60-80%. 210 The detection limit of Pb is doubled, resulting in a significant effect of low background; nitrogen consumption is reduced by 40-60%, saving operating costs; this invention adopts multi-sensor closed-loop feedback and automatically switches operating modes to achieve intelligent operation; and database linkage and scheduling management enable unattended operation.

[0214] Therefore, the system of this invention has excellent long-term operating capability and can realize the construction of a laboratory-level baseline database, providing a low-cost, high-efficiency, and intelligent new technical solution for the precise measurement of environmental radionuclides. This invention is applicable to multiple fields such as sediment dating, soil erosion monitoring, environmental radioactivity analysis, and archaeological chronology, and has broad prospects for widespread application.

[0215] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An adaptive purge low-background device for a high-purity germanium gamma spectrometer, characterized in that: It includes: Gas source module, flow control module, inner cover, purification module, sensor module and main control module; The inner enclosure is located inside the lead chamber of the high-purity germanium gamma spectrometer. The gas source module, flow control module, inner enclosure, and purification module are then connected sequentially to form the airflow path. The sensing module, located within the inner enclosure and lead chamber, receives monitoring data. The main control module is connected to the gas source module, flow control module, and sensing module to receive monitoring data or send control parameters. Specifically: The gas source module is used to ensure that nitrogen gas enters the inlet of the flow control module stably at the pressure value set by the main control module; The flow control module is connected to the gas source module, the inner cover and the main control module respectively. The flow control module receives nitrogen from the gas source module and inputs nitrogen into the inner cover through the air inlet of the lead chamber of the high-purity germanium gamma spectrometer according to the nitrogen output flow rate received from the main control module. The inner cover is a cover installed inside the lead chamber of the high-purity germanium gamma spectrometer. The inner cover is made of transparent acrylic material and covers the sample area to form a local sealed space. There is an air inlet on the bottom side wall of the inner cover, which is connected to the air inlet of the lead chamber through the first pipeline. There is an exhaust hole on the top side wall of the inner cover, which is connected to the exhaust hole of the lead chamber through the second pipeline. A rubber sealing ring is used at the contact point between the inner cover and the lead chamber. The purification module is used to remove radon gas from the exhaust port of the lead chamber of the high-purity germanium gamma spectrometer. The inlet of the purification module is connected to the exhaust port of the lead chamber. After removing the radon gas, the gas is directly discharged into the air. The sensing module is used to measure temperature and humidity, radon concentration, and air pressure in the inner enclosure and lead chamber. The sensing module is connected to the main control module and sends the monitoring data to the main control module. The main control module is connected to the gas source module, sensor module, and flow control module respectively. It receives monitoring data from the sensor module and controls the gas source module and flow control module to regulate the flow rate by setting equipment parameters. The flow rate regulation includes obtaining the nitrogen purging flow rate using the chamber model, specifically including the following steps: S51, obtained using a radon concentration chamber model. The first minimum steady-state demand flow rate at any given moment; First minimum steady-state demand flow rate The calculation formula is as follows: （6）； In the formula: for The first minimum steady-state demand flow rate at any given time, in m³ / s. 3 / h, The target value for radon concentration inside the inner cover is set as the radon threshold value. for The rate at which radon enters at any given time. This is the fitted value of the equivalent ventilation rate when the radon concentration is not purged. Let be the decay constant of radon. The effective volume of the inner cover is obtained according to equation (6). First minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate; S51 The relationship with humidity and air pressure is shown in equation (4): （4）； In the formula, For the inner cover Relative humidity at any given time For the inner cover air pressure at any moment The initial radon ingress rate. The initial relative humidity inside the inner cover. This represents the initial air pressure inside the inner casing. As the first parameter, The second parameter can be obtained by least squares fitting. Fitted values ; To determine the natural ventilation intensity without nitrogen purging, the radon attenuation method was used to determine the radon concentration inside the inner enclosure without nitrogen purging. The decay after the interval time satisfies: （5）； In the formula, The interval time, Interval time The actual radon concentration was measured later. The initial radon concentration is obtained from the actual measured concentration using formula (5). Fitted values ; S52, obtained using a humidity chamber model. The second minimum steady-state demand flow rate at time 1; Second minimum steady-state demand flow rate The formula is: （15）； In the formula: for The second minimum steady-state demand flow rate at time 1. for Temperature at any time The target value for the actual absolute humidity inside the lower inner cover. for The rate at which water vapor enters at any given moment. The fitted value of the equivalent air exchange rate when the actual absolute humidity is not purged is obtained according to equation (15). Second minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate; In S52, the temperature and humidity monitor obtains the relative humidity. First, convert the relative humidity to the absolute humidity, specifically: The saturated vapor pressure is calculated using the Magnus formula: （7）； Actual water vapor pressure: (8) ； The formula for converting relative humidity to actual absolute humidity is: (9) ； In the formula: The current temperature is monitored by the temperature and humidity sensor. For temperature The saturated water vapor pressure at that time The relative humidity is monitored by a temperature and humidity sensor. This is the actual water vapor pressure. This refers to the actual absolute humidity. The relationship with temperature and air pressure is shown in equation (13): (13）； In the formula, It is the initial rate at which water vapor enters. For the inner cover Temperature at any moment The initial temperature inside the inner cover. For the inner cover air pressure at any moment This represents the initial air pressure inside the inner casing. As the third parameter, The fourth parameter can be obtained by least squares fitting. Fitted values ; The equivalent air exchange rate without purging is the actual absolute humidity. The calculation is performed by fitting the formula (14): （14）； In the formula: The absolute humidity of the air inside the inner cover at the initial moment; time Absolute humidity of the air inside the inner cover; The absolute humidity of the air in the outdoor lead laboratory environment; S53, determine the nitrogen purging flow rate; exist First minimum steady-state demand flow at time step Choose the larger flow rate from the second minimum steady-state demand flow rate at time step 2. Nitrogen purge flow rate .

2. The adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 1, characterized in that: The main control module includes a control parameter submodule, a data acquisition submodule, a threshold judgment submodule, a flow regulation submodule, and a data storage submodule, specifically: The data acquisition submodule is used to receive data collected by all sensors. The data acquisition submodule sends the collected data to the threshold judgment submodule, the flow regulation submodule and the data storage submodule. The threshold judgment submodule is used to compare with the set threshold and give the corresponding control parameters of the device based on the comparison result, and send the control parameters to the control parameter submodule; The flow regulation submodule is used to obtain the nitrogen purging flow rate based on the temperature and humidity values, radon concentration, inner cover pressure and lead chamber pressure obtained by the data acquisition submodule, and send the nitrogen purging flow rate as the control parameter of the flow control module to the control parameter submodule. The control parameter submodule is used to send control parameters to the corresponding devices; The data storage submodule is used to save the corresponding data and parameters to the database according to the settings.

3. The adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 1, characterized in that: The sensing module includes a temperature and humidity sensor, a radon online monitor, a first pressure sensor, and a second pressure sensor. The temperature and humidity sensor is located on the upper part of the inner cover and is used to monitor the temperature and humidity inside the inner cover. The sampling port of the radon online monitor is located near the exhaust port at the top of the inner cover and is used to monitor the radon concentration inside the inner cover. The second pressure sensor is installed inside the inner cover and is used to monitor the air pressure inside the inner cover. The first pressure sensor is installed inside the lead chamber to monitor the air pressure inside.

4. The adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 2, characterized in that: The main control module also includes a linkage scheduling submodule; When the daily or weekly background spectrum measurement plan is triggered, the linkage scheduling submodule automatically generates a background spectrum measurement task, sends control parameters to the control parameter submodule and the data storage submodule according to the background spectrum measurement task, starts the purging or monitoring task, and generates an operation log.

5. A method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer as described in claim 1, characterized in that: Specifically, the following steps are included: S1, activate the adaptive purge low-background device for the high-purity germanium gamma spectrometer; S2, acquire monitoring data from the sensor module; The sensor module acquires the temperature, humidity, radon concentration, inner enclosure pressure, and lead chamber pressure. S3, determine whether the pressure difference exceeds the air pressure difference threshold; When the pressure difference between the inner casing and the lead chamber is less than the pressure difference threshold, a short-term flow boost is performed for a preset duration to ensure a positive pressure environment is maintained; when the pressure difference between the inner casing and the lead chamber exceeds or equals the pressure difference threshold, S4 is executed directly. S4, determine whether the humidity or radon concentration exceeds the corresponding threshold; If neither humidity nor radon concentration exceeds the corresponding threshold, return directly to S2; if either humidity or radon concentration exceeds the corresponding threshold, execute S5 to adjust the nitrogen purging flow rate. S5, using the box model to obtain the nitrogen purging flow rate; S51, obtained using a radon concentration chamber model. The first minimum steady-state demand flow rate at any given moment; First minimum steady-state demand flow rate The calculation formula is as follows: （6）； In the formula: for The first minimum steady-state demand flow rate at any given time, in m³ / s. 3 / h, The target value for radon concentration inside the inner cover is set as the radon threshold value. for The rate at which radon enters at any given time. This is the fitted value of the equivalent ventilation rate when the radon concentration is not purged. Let be the decay constant of radon. The effective volume of the inner cover is obtained according to equation (6). First minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate; S52, obtained using a humidity chamber model. The second minimum steady-state demand flow rate at time 1; Second minimum steady-state demand flow rate The formula is: （15）； In the formula: for The second minimum steady-state demand flow rate at time 1. for Temperature at any time The target value for the actual absolute humidity inside the lower inner cover. for The rate at which water vapor enters at any given moment. The fitted value of the equivalent air exchange rate when the actual absolute humidity is not purged is obtained according to equation (15). Second minimum steady-state demand flow rate That is, satisfying Minimum nitrogen flow rate; S53, determine the nitrogen purging flow rate; exist First minimum steady-state demand flow at time step Choose the larger flow rate from the second minimum steady-state demand flow rate at time step 2. Nitrogen purge flow rate ; S6, nitrogen purging flow control is achieved through the flow control module; After obtaining the nitrogen purging flow rate, the main control module sends the nitrogen purging flow rate to the flow control module, and then the flow control module outputs nitrogen to the inner shroud at the received nitrogen purging flow rate. S7, End; The main control module records temperature, humidity, pressure difference, and radon concentration data at preset time intervals and stores the data in the database. When the main control module receives a shutdown command, it shuts off the nitrogen output of the flow control module and ends the current control process.

6. The method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 5, characterized in that: S1, activating the adaptive purge low-background device for the high-purity germanium gamma spectrometer specifically involves: Upon receiving the start command, the adaptive purging low-background device for the high-purity germanium gamma spectrometer is initialized based on the received or pre-stored control parameters. During initialization, the communication status between the main control module, gas source module, flow control module, and sensor module is monitored, and the temperature, humidity, inner shroud pressure, and lead chamber pressure output by the sensor modules are read to determine whether the adaptive purging low-background device for the high-purity germanium gamma spectrometer is in an allowable operating state. If any module status is found to be inconsistent with the preset operating conditions, the main control module prohibits the purging process and outputs an alarm message. When all parameters meet the operating conditions, the adaptive purging low-background device for the high-purity germanium gamma spectrometer enters the operating state.

7. The method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 5, characterized in that: In S3, when the pressure difference between the inner shroud and the lead chamber exceeds a specified threshold, a short-term flow boost for a preset duration is implemented to maintain a positive pressure environment. Specifically: When the pressure difference between the inner shroud and the lead chamber is less than the specified threshold, a short-term flow boost will be performed at a preset flow boost rate within a preset time period. After the short-term flow boost is completed, the flow control module will restore the nitrogen purging flow rate to the nitrogen purging flow rate before the short-term flow boost and return to S2.

8. The method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 5, characterized in that: S51 The relationship with humidity and air pressure is shown in equation (4): （4）； In the formula, For the inner cover Relative humidity at any given time For the inner cover air pressure at any moment The initial radon ingress rate. The initial relative humidity inside the inner cover. This represents the initial air pressure inside the inner casing. As the first parameter, The second parameter can be obtained by least squares fitting. Fitted values ; To determine the natural ventilation intensity without nitrogen purging, the radon attenuation method was used to determine the radon concentration inside the inner enclosure without nitrogen purging. The decay after the interval time satisfies: （5）； In the formula, The interval time, Interval time The actual radon concentration was measured later. The initial radon concentration is obtained from the actual measured concentration using formula (5). Fitted values .

9. The method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 5, characterized in that: In S52, the temperature and humidity monitor obtains the relative humidity. First, convert the relative humidity to the absolute humidity, specifically: The saturated vapor pressure is calculated using the Magnus formula: （7）； Actual water vapor pressure: (8) ； The formula for converting relative humidity to actual absolute humidity is: (9) ； In the formula: The current temperature is monitored by the temperature and humidity sensor. For temperature The saturated water vapor pressure at that time The relative humidity is monitored by a temperature and humidity sensor. This is the actual water vapor pressure. This refers to the actual absolute humidity. The relationship with temperature and air pressure is shown in equation (13): (13）； In the formula, It is the initial rate at which water vapor enters. For the inner cover Temperature at any moment The initial temperature inside the inner cover. For the inner cover air pressure at any moment This represents the initial air pressure inside the inner casing. As the third parameter, The fourth parameter can be obtained by least squares fitting. Fitted values ; The equivalent air exchange rate without purging is the actual absolute humidity. The calculation is performed by fitting the formula (14): （14）； In the formula: The absolute humidity of the air inside the inner cover at the initial moment; time Absolute humidity of the air inside the inner cover; This refers to the absolute humidity of the ambient air in an outdoor lead laboratory.

10. The method of using the adaptive purge low-background device for a high-purity germanium gamma spectrometer according to claim 5, characterized in that: It also includes automatic scheduling steps. The device will repeatedly execute S1-S7 during specified time periods, record radon concentration and humidity, and upload the data to the database for long-term analysis to optimize thresholds.

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