Method and device for measuring and calibrating vacuum degree by using ultra-cold atom loading characteristic

Abstract

The invention relates to a method and a device for measuring and calibrating vacuum degree by using ultra-cold atom loading characteristics. The method comprises the steps that a vacuum chamber is vacuumized to the ultimate vacuum degree, and cold atoms are loaded into the vacuum chamber in a standard three-dimensional magneto-optical trap atom trapping mode; fitting parameters of ultra-cold atom loading characteristic measurement and calibration vacuum degree are obtained according to the atom source excitation current and the multiple vacuum degrees; measuring the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas of the ultra-cold atom loading characteristic measurement and calibration vacuum degree; and determining an ionization vacuum gauge correction factor of the ultra-cold atom loading characteristic measurement and calibration vacuum degree according to the test gas vacuum degree and the ionization vacuum gauge actual measurement gas vacuum degree. The method has the advantages that the dynamic measurement range is wide, the vacuum measurement lower limit is low, the measurement uncertainty is small, and the cold atom measurement result does not need to be calibrated.

Description

Technical Field

[0001] The present invention relates to the field of quantum vacuum measurement technology, and more specifically, to a method and device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics. Background Art

[0002] With the development of vacuum frontier science and technology and interdisciplinary disciplines, vacuum measurement based on cold atom effect represents the forefront of the current development of vacuum science and technology. Cold atom vacuum measurement and calibration is based on the quantum intrinsic characteristics of microscopic particle systems. The basic measurement feature is that the collision scattering cross section between trapped ultracold atoms and the measured neutral gas molecules is a constant physical constant. Therefore, ultra-precise and high-precision vacuum measurement can be achieved.

[0003] The ionization vacuum gauge is the most widely used vacuum measuring instrument in the fields of space science exploration, semiconductor industry, ultra-precision measurement and high-end equipment manufacturing. However, there are two problems with the instrument during use: First, the ionization vacuum gauge itself has inherent characteristics such as high-temperature filament thermal radiation effect, gas absorption and degassing effect, and catalytic chemical reaction, which will change the measured vacuum environment and make it difficult to truly reflect the actual vacuum characteristics; second, in order to achieve value traceability, the ionization vacuum gauge must be calibrated by a multi-stage vacuum standard device, and the existing highest performance vacuum standard device has a large measurement uncertainty, and the calibrated ionization vacuum gauge is difficult to meet the actual application requirements. Therefore, it is very necessary to express the physical quantity of vacuum degree based on the quantized characteristics between microscopic particles and use it as an absolute standard to achieve accurate vacuum measurement. Summary of the invention

[0004] The embodiments of the present application provide a method and apparatus for measuring and calibrating vacuum using ultracold atomic loading characteristics. In order to have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0005] In a first aspect, the present application provides a method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics, the method comprising:

[0006] The vacuum chamber is evacuated to the ultimate vacuum degree, and cold atoms are loaded into the vacuum chamber using a standard three-dimensional magneto-optical trap atom trapping method;

[0007] According to the atomic source excitation current and multiple vacuum degrees, the fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree are obtained;

[0008] The vacuum degree of the test gas is measured according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0009] According to the test gas vacuum and the gas vacuum actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and calibration vacuum is determined.

[0010] According to a preferred embodiment, obtaining fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees includes:

[0011] Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0012] A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

[0013] According to a preferred embodiment, obtaining fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees includes:

[0014] Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0015] Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0016] The first fitting parameter and the second fitting parameter are used as the fitting parameters.

[0017] According to a preferred embodiment, the vacuum degree of the test gas is measured according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree, including:

[0018] p s =(G'-G0-bR') / a

[0019] In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

[0020] According to a preferred embodiment, the method of determining the ionization vacuum gauge correction factor for measuring the ultracold atom loading characteristics and calibrating the vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge comprises:

[0021] According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

[0022] In a second aspect, the present application provides a device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics, the device comprising:

[0023] A loading module, used to evacuate the vacuum chamber to the ultimate vacuum degree and load the cold atoms into the vacuum chamber using a standard three-dimensional magneto-optical trap atom capture method;

[0024] A fitting parameter determination module is used to obtain fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees;

[0025] A gas vacuum degree determination module is used to measure the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0026] The correction factor determination module is used to determine the ionization vacuum gauge correction factor for measuring the ultracold atom loading characteristics and calibrating the vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge.

[0027] According to a preferred embodiment, the fitting parameter determination module is specifically used for:

[0028] Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0029] A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

[0030] According to a preferred embodiment, the fitting parameter determination module is further used for:

[0031] Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0032] Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0033] The first fitting parameter and the second fitting parameter are used as the fitting parameters.

[0034] According to a preferred embodiment, the gas vacuum degree determination module comprises:

[0035] p s =(G'-G0-bR') / a

[0036] In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

[0037] According to a preferred embodiment, the correction factor determination module is specifically used to:

[0038] According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

[0039] In a third aspect, the present application provides a computer storage medium, which stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the above-mentioned method steps.

[0040] In a fourth aspect, the present application provides a terminal, which may include: a processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the above-mentioned method steps.

[0041] The technical solution provided by this application may have the following beneficial effects:

[0042] In the present application, a method for measuring and calibrating the vacuum degree of ultracold atom loading characteristics is used to evacuate the vacuum chamber to the ultimate vacuum degree, and a standard three-dimensional magneto-optical trap atom capture method is used to load cold atoms into the vacuum chamber; fitting parameters for measuring and calibrating the vacuum degree of ultracold atom loading characteristics are obtained based on the atomic source excitation current and multiple vacuum degrees; the vacuum degree of the test gas is measured based on the fitting parameters to obtain the vacuum degree of the test gas for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics; and the ionization vacuum gauge correction factor for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics is determined based on the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge. In view of the deficiencies of the prior art, the present application can achieve 10 -10 Pa ultra-high vacuum measurement has the characteristics of low vacuum measurement lower limit; the cold atom loading of this application can be completed within a few seconds, which has the characteristics of fast measurement speed; the measurement range of this application is from 10 -10 Pa~10-5 Pa covers 6 orders of magnitude and has the characteristics of a wide dynamic range of measurement; the cold atom-neutral gas collision cross section of this application is a physical constant, and has the characteristics that the cold atom measurement results do not need to be calibrated; it is the direction of the evolution and development of the next generation of high-precision vacuum measurement technology. This application can overcome the defects of changing the real environment of the measured vacuum system caused by the absorption and degassing effect, high-temperature thermal radiation effect, and catalytic chemical reaction effect in the measurement process of traditional ionization vacuum gauges, and realize accurate measurement of vacuum degree.

[0043] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0045] Figure 1 It is a flow chart of a method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics provided in an embodiment of the present application;

[0046] Figure 2 It is a schematic diagram of the system structure of measuring and calibrating the vacuum degree of a method for measuring and calibrating the vacuum degree using ultracold atomic loading characteristics provided in an embodiment of the present application;

[0047] Figure 3 It is a schematic diagram of a third cold atom dynamic loading curve of a method for measuring and calibrating vacuum degree using ultracold atom loading characteristics provided in an embodiment of the present application;

[0048] Figure 4 It is a schematic diagram of a loss rate variation curve corresponding to multiple vacuum degrees of a method for measuring and calibrating vacuum degree using ultracold atom loading characteristics provided in an embodiment of the present application;

[0049] Figure 5 It is a schematic diagram of a loss rate variation curve corresponding to different loading rates of a method for measuring and calibrating vacuum degree using ultracold atom loading characteristics provided in an embodiment of the present application;

[0050] Figure 6 It is a schematic diagram of the structure of a device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics provided in an embodiment of the present application;

[0051] Figure 7 It is a structural diagram of a terminal provided in an embodiment of the present application.

[0052] Reference numerals:

[0053] 1. Sputtering ion pump, 2. Titanium sublimation pump, 3. Atomic source, 4. Vacuum chamber, 5. Ultracold atoms, 6. Ionization vacuum gauge, 7. All-metal plug valve, 8. Molecular pump, 9. All-metal conductance variable fine-tuning valve, 10. Voltage stabilizing chamber, 11. 1000Torr capacitance film vacuum gauge, 12. Pressure reducing valve, 13. Dry pump, 14. High-purity gas cylinder, 15. Focusing lens, 16. Photomultiplier tube;

[0054] 10000, loading module, 20000, fitting parameter determination module, 30000, gas vacuum degree determination module, 40000, correction factor determination module;

[0055] 1001. Processor, 1002. Communication bus, 1003. User interface, 1004. Network interface, 1005. Memory. DETAILED DESCRIPTION

[0056] The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them.

[0057] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples of systems and methods consistent with some aspects of the present invention as detailed in the attached claims.

[0059] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the previously associated objects are in an "or" relationship.

[0060] The following will be combined with the attached Figure 1 -Attached Figure 5 , a method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics provided in an embodiment of the present application is introduced in detail.

[0061] See also Figure 1-5 The method of the embodiment of the present application may include the following steps:

[0062] The present application provides a method for measuring and calibrating the vacuum degree using the ultracold atomic loading characteristics, which is a method for measuring and calibrating the vacuum degree based on the magneto-optical capture of ultracold lithium atoms, and belongs to the frontier technology of quantum vacuum measurement. Figure 2 As shown, the system for measuring and calibrating vacuum degree corresponding to the method mainly includes: a high-purity gas cylinder 14, a vacuum pump, an atomic source 3, an ionization vacuum gauge 6, a focusing lens 15, ultracold atoms 5, a vacuum chamber 4, a pressure stabilizing chamber 10, a photomultiplier tube 16, a pressure reducing valve 12, a metal valve and a pipeline; the atomic source 3 can be 7 Li atomic source, the cold atoms are ultracold atoms 5, the vacuum unit includes a dry pump 13, a molecular pump 8, a sputtering ion pump 1 and a titanium sublimation pump 2, the molecular pump 8 is a magnetically suspended turbomolecular pump, the metal valve includes: an all-metal plug valve 7 and an all-metal flow conductance variable fine-tuning valve 9, the pressure reducing valve 12 is used to control the gas pressure of the high-purity gas flowing out of the high-purity gas cylinder 14, the focusing lens 15 is used to focus the fluorescence signal radiated by the cold atomic group and then measure it by the photomultiplier tube 16, and the pipeline is used to introduce the high-purity gas flowing out of the high-purity gas cylinder 14 into the vacuum chamber 4 for measurement. The method measures the ultracold gas by regulating the vacuum degree of the neutral gas molecules in the vacuum measuring chamber and the atomic source excitation current of the cold atom system. 7 The cold atom loss rate and cold atom loading rate during the dynamic loading of Li atoms can achieve ultra-high / ultra-high vacuum (≤10 -5 The rapid, real-time and accurate measurement of the vacuum degree of the vacuum measuring chamber can be used to directly measure the vacuum degree of the vacuum measuring chamber and to accurately calibrate the ionization vacuum gauge 6. Compared with the traditional method, this method belongs to the category of quantum vacuum metrology and has the advantages of wide measurement dynamic range, low measurement limit, small measurement uncertainty and no need for calibration.

[0063] Ultracold atoms 5 select low saturated vapor pressure alkali metals 7 Li atoms can achieve 10 -10 Pa extremely high vacuum degree measurement. The ionization vacuum gauge 6 selects a 100Torr capacitance film vacuum gauge 11. When introducing the gas to be tested, a combination structure of a stabilizing chamber 10 and a conductance variable fine-tuning valve is designed. The volume of the stabilizing chamber 10 is designed to be 5L. The vacuum degree of the stabilizing chamber 10 is measured by a 100Torr capacitance film vacuum gauge, and the vacuum degree is maintained at 1000Pa; the conductance variable fine-tuning valve combination structure includes an all-metal conductance variable fine-tuning valve 9 and an all-metal plug valve 7. The conductance of the all-metal conductance variable fine-tuning valve 9 is 10 -9 m 3 / s~10 -12 m 3 / s range, can generate 10 -9 Pa~10 -5 The pumping speed of the sputtering ion pump 1 is designed to be 50 l / s, the pumping speed of the molecular pump 8 is designed to be 100 l / s, the working current of the titanium sublimation pump 2 is set to 48A, the metal valve can be a plug-in valve, the flange interface size of the plug-in valve is designed to be CF100, and the degassing rate of the vacuum measurement chamber is designed to be 10Pa.m 3 / s-11Pa.m 3 / s level, can be obtained in the vacuum measurement chamber 10 -10 When cold atoms are loaded using the standard three-dimensional magneto-optical trap atomic trapping method, the magnetic field gradient of the four-stage magneto-optical trap is set to 20G / cm in the axial direction and 10G / cm in the horizontal direction. 7 The temperature of the Li cold atom is below 300μK. When collecting the fluorescence signal radiated by the cold atom during the measurement, the solid angle of the fluorescence collection space of the photomultiplier tube 16 is designed to be 9×10 -2 srad, the photoelectric conversion factor was set to 5.7A / W, and the control voltage was set to 0.7V. During the cold atom loading and signal measurement, the laser detuning was set to -18MHz and the light intensity was set to 17.2mW / cm 2 .

[0064] This application is mainly based on supercooling 7 The quantum properties of the collision system between Li atoms and background neutral gas molecules are measured by 7 The cold atom loading rate and cold atom loss rate during the dynamic loading of Li cold atoms can achieve accurate measurement and calibration of vacuum degree. The specific measurement and calibration process is as follows:

[0065] S100, evacuate the vacuum chamber 4 to the ultimate vacuum degree, and load the cold atoms into the vacuum chamber 4 using a standard three-dimensional magneto-optical trap atom capture method.

[0066] In the embodiment of the present application, the all-metal gate valve 7 is first opened, the dry pump 13 and the molecular pump 8 of the vacuum unit are turned on, and the vacuum chamber 4 is evacuated to the ultimate vacuum degree 10 -7 Then, the sputtering ion pump 1 and the titanium sublimation pump 2 are turned on, and the vacuum chamber 4 is continuously evacuated until the ultimate vacuum degree reaches 10 -10 Pa. The vacuum chamber 4 is a vacuum measurement chamber.

[0067] S200, based on the atomic source excitation current and multiple vacuum levels, obtains the fitting parameters for ultracold atomic loading characteristic measurement and calibration vacuum level, including:

[0068] At the plurality of vacuum degrees p iUnder the condition, the collected first cold atom dynamic loading curve is fitted to determine the multiple vacuum degrees p for measuring the ultracold atom loading characteristics and calibrating the vacuum degree. i The corresponding loss rate G i For the plurality of vacuum degrees p i The corresponding loss rate G i Perform linear fitting to obtain the first fitting parameter of the ultracold atom loading characteristic measurement and calibration vacuum degree; when the atomic source excitation current I is increased i Under the condition of fitting the collected second cold atom dynamic loading curve, multiple loading rates R for measuring the ultracold atom loading characteristics and calibrating the vacuum degree are determined. i The corresponding loss rate G i -ap' i ; For the multiple loading rates R i The corresponding loss rate G i -ap' i Perform linear fitting to obtain the second fitting parameters for measuring the ultracold atom loading characteristics and calibrating the vacuum degree; and use the first fitting parameters and the second fitting parameters as the fitting parameters.

[0069] At a specific atomic source excitation current I i Under the condition, the cold atoms are loaded into the vacuum chamber 4 by using the standard three-dimensional magneto-optical trap atom capture method. After loading is completed, the third cold atom dynamic loading curve is obtained by data acquisition. The third cold atom dynamic loading curve is the three-dimensional magneto-optical trap. 7 The dynamic loading curve of Li cold atoms, such as Figure 3 As shown, the horizontal axis represents the cold atom loading time, and the vertical axis represents the number of cold atoms N obtained from the voltage signal after the cold atom fluorescence is measured by the photomultiplier tube 16. In the embodiment of the present application, the third cold atom dynamic loading curve obtained by measurement is used as follows: After fitting, the cold atom loading rate R and the cold atom loss rate G are obtained. This section describes the method for obtaining the cold atom loading rate R and the cold atom loss rate G, which is specifically applied to this application as follows:

[0070] In the embodiment of the present application, first, the all-metal gate valve 7 is closed, and the all-metal conductance variable fine-tuning valve 9 is opened to introduce the high-purity gas in the high-purity gas cylinder 14 as the high-purity gas source into the vacuum chamber 4; by adjusting the all-metal conductance variable fine-tuning valve 9, test gases with different vacuum degrees are generated in the vacuum chamber 4, so that the vacuum degree in the vacuum chamber 4 varies within a range of 1×10 -9 Pa~1×10 -6 Pa, the vacuum degree p in the vacuum chamber 4 during the introduction of the test gas i The vacuum is measured by the ionization vacuum gauge 6. Then, at multiple vacuum degrees p i Each vacuum degree pi The standard three-dimensional magneto-optical trap atomic trapping method was used to load cold atoms, and the loading rate R corresponding to each vacuum degree was fitted according to the first cold atom dynamic loading curve. i and loss rate G i ; Obtain multiple vacuum degrees p through data processing i The corresponding loss rate G i The change curve is Figure 4 It can be known that multiple vacuum degrees p i The corresponding loss rate G i Finally, we can Figure 3 The data in is linearly fitted using the linear fitting formula G=G'0+ap to obtain the first fitting parameter a, where Γ'0 refers to the loss rate, is a constant in the linear fitting formula, and is Figure 4 The constant in is 0.037; the first fitting parameter a is the coefficient in the linear fitting formula, which is Figure 4 The coefficient in is 284286.

[0071] In the embodiment of the present application, first, the all-metal conductance variable fine-tuning valve 9 is closed, the all-metal gate valve 7 is opened, and the vacuum chamber 4 is evacuated to the ultimate vacuum degree 10 by using the exhaust unit. -10 Pa; close the all-metal gate valve 7, open the all-metal conductance variable fine-tuning valve 9, adjust the all-metal conductance variable fine-tuning valve 9, and generate 5×10 -8 Then, the atomic source excitation current I was increased in steps of 0.5 A. i , in each atomic source excitation current I i Under the condition of 3D magneto-optical trapping, cold atoms are loaded by standard 3D magneto-optical trapping method, and the excitation current I of each atom source is fitted according to the dynamic loading curve of the second cold atom. i The corresponding loading rate R i and loss rate G i -ap' i . Through data processing, different loading rates R are obtained i The corresponding loss rate G i -ap' i The change curve is Figure 5 It can be seen that multiple loading rates R i The corresponding loss rate G i -ap' i ; where each atomic source excitation current I i The corresponding vacuum degree p' i Measured by ionization vacuum gauge 6. Finally, Figure 5 The data in are linearly fitted using the formula G-ap'=G0+bR to obtain the second fitting parameters b and G0. Among them, p refers to the specific 5×10 -8The vacuum degree of Pa; the second fitting parameter b is the coefficient, corresponding to Figure 5 9×10 -10 , the second fitting parameter G0 is 5×10 -8 The loss rate corresponding to the vacuum degree of Pa corresponds to Figure 5 0.033 of .

[0072] S300, measuring the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree, including:

[0073] After obtaining the second fitting parameters and the first fitting parameters of the cold atom system, test gases of different gas types and different vacuum degrees can be introduced into the vacuum chamber 4, and the test gas vacuum degree of the gas to be tested is accurately calculated by the following formula:

[0074] p s =(G'-G0-bR') / a

[0075] In the formula, p s is the vacuum degree of the test gas; G' and R' are obtained by fitting the above formula according to the actual cold atom dynamic loading curve after the actual test gas is introduced; R' and G' are respectively the cold atom loading rate and cold atom loss rate obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

[0076] S400, determining an ionization vacuum gauge correction factor for measuring the ultracold atom loading characteristics and calibrating the vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge, including:

[0077] According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

[0078] In the embodiment of the present application, it is assumed that the vacuum degree of a certain gas measured by the ionization vacuum gauge 6, that is, the vacuum degree of the gas actually measured by the ionization vacuum gauge, is p g , then the ionization vacuum gauge correction factor of the ionization vacuum gauge 6 for this gas is:

[0079] F=p s / p g =(G'-G0-bR') / ap g

[0080] Where F is the ionization vacuum gauge correction factor.

[0081] The ionization vacuum gauge 6 is accurately calibrated according to the ionization vacuum gauge correction factor.

[0082] The basic principle of the method for measuring and calibrating the vacuum degree using ultracold atomic loading characteristics described in the embodiment of the present application is:

[0083] The cooling and trapping of atoms adopts the method of magneto-optical trap cooling and trapping. The kinetic equation of cold atom loading and loss is expressed by the following equation:

[0084]

[0085] Where N is the number of cold atoms, t is the cold atom loading time; R is the cold atom loading rate; α represents the loss rate coefficient caused by the collision between cold atoms and background gas; is the average density of atoms in steady state; β is the loss rate coefficient caused by inelastic two-body collision between cold atoms. The method of magneto-optical trap cooling capture is the above-mentioned standard three-dimensional magneto-optical trap atom capture method.

[0086] The dynamic process of loading and dissipation of cold atom clusters is observed simultaneously. As the number of cold atoms increases, the solution of the following formula is:

[0087]

[0088] in, e is a natural constant.

[0089] Through atomic fluorescence photoelectric conversion measurement, the number of cold atoms N can be calculated according to the voltage signal output by the photomultiplier tube 16 using the following formula:

[0090]

[0091] Where W is the solid angle of fluorescence collection space, W = 9 × 10 -2 srad; λ is the wavelength of the fluorescence signal radiated by the cold atom, λ = 671nm; h is Planck's constant, h = 6.626×10 -34 Js; c is the speed of light, c = 3.0 × 10 8 m / s; X is the natural line width of the Li atomic spectrum, X = 5.87 × 2πMHz; I is the light intensity, I = 17.2mW / cm 2 ;I s is the saturation light intensity, I s =2.54mW / cm 2 ; Δ is the laser detuning, D = -18MHz; D is the resistance of the photomultiplier tube 16, D = 10 6 W; G is the photoelectric conversion factor, G=5.7A / W; U is the voltage signal output by the photomultiplier tube 16, the unit is V.

[0092] In the present application, the method of ultracold atom loading characteristic measurement and calibration of vacuum is used to evacuate the vacuum chamber 4 to the ultimate vacuum degree, and the cold atoms are loaded into the vacuum chamber 4 by using the standard three-dimensional magneto-optical trap atom capture method; the fitting parameters of ultracold atom loading characteristic measurement and calibration of vacuum degree are obtained according to the atomic source excitation current and multiple vacuum degrees; the vacuum degree of the test gas is measured according to the fitting parameters to obtain the test gas vacuum degree of the ultracold atom loading characteristic measurement and calibration of vacuum degree; the ionization vacuum gauge correction factor of the ultracold atom loading characteristic measurement and calibration of vacuum degree is determined according to the test gas vacuum degree and the gas vacuum degree measured by the ionization vacuum gauge. The present application adopts a new technology for realizing macroscopic vacuum degree measurement based on the intrinsic quantum characteristics of microscopic particle systems, and measures the basic properties of vacuum degree based on the intrinsic quantum characteristics. It has the inherent advantages of high measurement accuracy, low vacuum measurement lower limit, and small measurement uncertainty. It can replace the traditional vacuum measurement standard device to accurately calibrate the ionization vacuum gauge 6 and realize accurate value transfer.

[0093] The following are embodiments of the device of the present invention, which can be used to implement the method embodiments of the present invention. For details not disclosed in the device embodiments of the present invention, please refer to the method embodiments of the present invention.

[0094] See also Figure 6 , which shows a schematic diagram of a structure of a device for measuring and calibrating vacuum degree using ultracold atom loading characteristics provided by an exemplary embodiment of the present invention. The device includes: a loading module 10000, a fitting parameter determination module 20000, a gas vacuum degree determination module 30000 and a correction factor determination module 40000.

[0095] The loading module 10000 is used to evacuate the vacuum chamber to the ultimate vacuum degree and load the cold atoms into the vacuum chamber by using a standard three-dimensional magneto-optical trap atom capture method;

[0096] A fitting parameter determination module 20000 is used to obtain fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees;

[0097] A gas vacuum degree determination module 30000 is used to measure the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0098] The correction factor determination module 40000 is used to determine the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and calibration vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge.

[0099] According to a preferred embodiment, the fitting parameter determination module 20000 is specifically used for:

[0100] Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0101] A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

[0102] According to a preferred embodiment, the fitting parameter determination module 20000 is further used for:

[0103] Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0104] Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0105] The first fitting parameter and the second fitting parameter are used as the fitting parameters.

[0106] According to a preferred embodiment, the gas vacuum degree determination module 30000 comprises:

[0107] p s =(G'-G0-bR') / a

[0108] In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

[0109] According to a preferred implementation, the correction factor determination module 40000 is specifically used to:

[0110] According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

[0111] It should be noted that the device for measuring and calibrating the vacuum degree using the ultracold atom loading characteristics provided in the above embodiment only uses the division of the above functional modules as an example when executing the method for measuring and calibrating the vacuum degree using the ultracold atom loading characteristics. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device for measuring and calibrating the vacuum degree using the ultracold atom loading characteristics provided in the above embodiment and the method embodiment for measuring and calibrating the vacuum degree using the ultracold atom loading characteristics belong to the same concept. The implementation process is detailed in the method embodiment, which will not be repeated here.

[0112] In the present application, a device for measuring and calibrating the vacuum degree of ultracold atom loading characteristics is used to evacuate the vacuum chamber to the ultimate vacuum degree, and the cold atoms are loaded into the vacuum chamber using a standard three-dimensional magneto-optical trap atom capture method; fitting parameters for measuring and calibrating the vacuum degree of ultracold atom loading characteristics are obtained based on the atomic source excitation current and multiple vacuum degrees; the vacuum degree of the test gas is measured based on the fitting parameters to obtain the vacuum degree of the test gas for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics; and the ionization vacuum gauge correction factor for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics is determined based on the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge. In view of the deficiencies of the prior art, the present application can achieve 10 -10 Pa ultra-high vacuum measurement has the characteristics of low vacuum measurement lower limit; the cold atom loading of this application can be completed within a few seconds, which has the characteristics of fast measurement speed; the measurement range of this application is from 10 -10 Pa~10 -5 Pa covers 6 orders of magnitude and has the characteristics of a wide dynamic range of measurement; the cold atom-neutral gas collision cross section of this application is a physical constant, and has the characteristics that the cold atom measurement results do not need to be calibrated; it is the direction of the evolution and development of the next generation of high-precision vacuum measurement technology. This application can overcome the defects of changing the real environment of the measured vacuum system caused by the absorption and degassing effect, high-temperature thermal radiation effect, and catalytic chemical reaction effect in the measurement process of traditional ionization vacuum gauges, and realize accurate measurement of vacuum degree.

[0113] The present invention also provides a computer-readable medium having program instructions stored thereon, which, when executed by a processor, implement the method for measuring and calibrating the vacuum degree using ultracold atomic loading characteristics provided in the above-mentioned various method embodiments.

[0114] The present invention also provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the method of measuring and calibrating the vacuum degree using ultracold atomic loading characteristics in each of the above-mentioned method embodiments.

[0115] See also Figure 7, which is a schematic diagram of the structure of a terminal according to an embodiment of the present application. The terminal may include: at least one processor 1001, at least one network interface 1004, a user interface 1003, a memory 1005, and at least one communication bus 1002.

[0116] The communication bus 1002 is used to realize the connection and communication between these components.

[0117] The user interface 1003 may include a display screen (Display) and a camera (Camera), and the optional user interface 1003 may also include a standard wired interface and a wireless interface.

[0118] The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a WI-FI interface).

[0119] Among them, the processor 1001 may include one or more processing cores. The processor 1001 uses various interfaces and lines to connect various parts in the entire terminal, and executes various functions of the terminal and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 1005, and calling data stored in the memory 1005. Optionally, the processor 1001 can be implemented in at least one hardware form of digital signal processing (Digital Signal Processing, DSP), field programmable gate array (Field-Programmable Gate Array, FPGA), and programmable logic array (Programmable Logic Array, PLA). The processor 1001 can integrate one or a combination of a central processing unit (Central Processing Unit, CPU), a graphics processing unit (Graphics Processing Unit, GPU) and a modem. Among them, the CPU mainly processes the operating system, user interface and application programs; the GPU is responsible for rendering and drawing the content to be displayed on the display screen; the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor 1001, and it can be implemented separately through a chip.

[0120] Among them, the memory 1005 may include a random access memory (Random Access Memory, RAM) and may also include a read-only memory (Read-Only Memory). Optionally, the memory 1005 includes a non-transitory computer-readable storage medium. The memory 1005 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 1005 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 1005 may optionally be at least one storage device located away from the aforementioned processor 1001. As Figure 7 As shown, the memory 1005 as a computer storage medium may include an operating system, a network communication module, a user interface module, and an application program for measuring and calibrating the vacuum degree using ultracold atomic loading characteristics.

[0121] exist Figure 7 In the terminal shown, the user interface 1003 is mainly used to provide an input interface for the user and obtain the data input by the user; and the processor 1001 can be used to call the application program for measuring and calibrating the vacuum degree using the ultracold atomic loading characteristics stored in the memory 1005, and specifically perform the following operations:

[0122] The vacuum chamber is evacuated to the ultimate vacuum degree, and cold atoms are loaded into the vacuum chamber using a standard three-dimensional magneto-optical trap atom trapping method;

[0123] According to the atomic source excitation current and multiple vacuum degrees, the fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree are obtained;

[0124] The vacuum degree of the test gas is measured according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0125] According to the test gas vacuum and the gas vacuum actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and calibration vacuum is determined.

[0126] In one embodiment, when the processor 1001 executes the method of obtaining fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees, the processor 1001 specifically performs the following operations:

[0127] Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0128] A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

[0129] In one embodiment, when the processor 1001 executes the method of obtaining fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees, the processor 1001 specifically performs the following operations:

[0130] Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree;

[0131] Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree;

[0132] The first fitting parameter and the second fitting parameter are used as the fitting parameters.

[0133] In one embodiment, when the processor 1001 performs the measurement of the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree, the following operations are specifically performed:

[0134] p s =(G'-G0-bR') / a

[0135] In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

[0136] In one embodiment, when the processor 1001 determines the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and calibration vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge, the processor 1001 specifically performs the following operations:

[0137] According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

[0138] In the present application, a method and device for measuring and calibrating the vacuum degree of ultracold atom loading characteristics is used to evacuate the vacuum chamber to the ultimate vacuum degree, and the cold atoms are loaded into the vacuum chamber using a standard three-dimensional magneto-optical trap atom capture method; fitting parameters for measuring and calibrating the vacuum degree of ultracold atom loading characteristics are obtained based on the atomic source excitation current and multiple vacuum degrees; the vacuum degree of the test gas is measured based on the fitting parameters to obtain the test gas vacuum degree for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics; and the ionization vacuum gauge correction factor for measuring and calibrating the vacuum degree of the ultracold atom loading characteristics is determined based on the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge. In view of the deficiencies of the prior art, the present application can achieve 10 -10 Pa ultra-high vacuum measurement has the characteristics of low vacuum measurement lower limit; the cold atom loading of this application can be completed within a few seconds, which has the characteristics of fast measurement speed; the measurement range of this application is from 10 -10 Pa~10 -5 Pa covers 6 orders of magnitude and has the characteristics of a wide dynamic range of measurement; the cold atom-neutral gas collision cross section of this application is a physical constant, and has the characteristics that the cold atom measurement results do not need to be calibrated; it is the direction of the evolution and development of the next generation of high-precision vacuum measurement technology. This application can overcome the defects of changing the real environment of the measured vacuum system caused by the absorption and degassing effect, high-temperature thermal radiation effect, and catalytic chemical reaction effect in the measurement process of traditional ionization vacuum gauges, and realize accurate measurement of vacuum degree.

[0139] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0140] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics, characterized in that: The following steps are involved: The vacuum chamber is evacuated to the ultimate vacuum degree, and cold atoms are loaded into the vacuum chamber using a standard three-dimensional magneto-optical trap atom trapping method; According to the atomic source excitation current and multiple vacuum degrees, the fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree are obtained; The vacuum degree of the test gas is measured according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree; According to the test gas vacuum and the gas vacuum actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and calibration vacuum is determined.

2. The method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 1, characterized in that: The method of obtaining fitting parameters for measuring ultracold atom loading characteristics and calibrating vacuum degrees according to the atomic source excitation current and multiple vacuum degrees includes: Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree; A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

3. The method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 2, characterized in that: The method of obtaining fitting parameters for measuring ultracold atom loading characteristics and calibrating vacuum degrees according to the atomic source excitation current and multiple vacuum degrees includes: Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree; Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree; The first fitting parameter and the second fitting parameter are used as the fitting parameters.

4. The method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 1, characterized in that: The step of measuring the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree comprises: p s =(G'-G0-bR') / a In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

5. The method for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 1, characterized in that: The method of determining the ionization vacuum gauge correction factor for measuring the ultracold atom loading characteristics and calibrating the vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge comprises: According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

6. A device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics, characterized in that: include: A loading module, used to evacuate the vacuum chamber to the ultimate vacuum degree and load the cold atoms into the vacuum chamber using a standard three-dimensional magneto-optical trap atom capture method; A fitting parameter determination module is used to obtain fitting parameters for ultracold atom loading characteristic measurement and calibration vacuum degree according to the atomic source excitation current and multiple vacuum degrees; A gas vacuum degree determination module is used to measure the vacuum degree of the test gas according to the fitting parameters to obtain the vacuum degree of the test gas for measuring the ultracold atom loading characteristics and calibrating the vacuum degree; The correction factor determination module is used to determine the ionization vacuum gauge correction factor for measuring the ultracold atom loading characteristics and calibrating the vacuum degree according to the test gas vacuum degree and the gas vacuum degree actually measured by the ionization vacuum gauge.

7. The device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 6, characterized in that: The fitting parameter determination module is specifically used for: Under the multiple vacuum degrees, fitting the collected first cold atom dynamic loading curve to determine the loss rate corresponding to the multiple vacuum degrees of the ultracold atom loading characteristic measurement and the calibration vacuum degree; A linear fit is performed on the loss rates corresponding to the multiple vacuum degrees to obtain a first fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree.

8. The device for measuring and calibrating vacuum degree using ultracold atom loading characteristics according to claim 7, characterized in that: The fitting parameter determination module is further used for: Under the increased excitation current of the atom source, fitting the collected second cold atom dynamic loading curve to determine the loss rate corresponding to the multiple loading rates of the ultracold atom loading characteristic measurement and the calibration vacuum degree; Performing linear fitting on the loss rates corresponding to the multiple loading rates to obtain a second fitting parameter for measuring the ultracold atom loading characteristics and calibrating the vacuum degree; The first fitting parameter and the second fitting parameter are used as the fitting parameters.

9. The device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 6, characterized in that: The gas vacuum degree determination module comprises: p s =(G'-G0-bR') / a In the formula, p s is the vacuum degree of the test gas; R' and G' are the cold atom loading rate and cold atom loss rate respectively obtained by fitting the actual cold atom dynamic loading curve when measuring the test gas; a is the first fitting parameter; b and G0 are the second fitting parameters.

10. The device for measuring and calibrating vacuum degree using ultracold atomic loading characteristics according to claim 6, characterized in that: The correction factor determination module is specifically used for: According to the ratio of the test gas vacuum degree to the gas vacuum degree actually measured by the ionization vacuum gauge, the ionization vacuum gauge correction factor for the ultracold atom loading characteristic measurement and the calibration vacuum degree is determined.

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