Small accelerator mass spectrum measurement device and method for 41Ca

Abstract

The invention belongs to the technical field of isotope detection, and particularly relates to a 41Ca small accelerator mass spectrometry measurement device and method.The device comprises an ion source, an injection magnet, a serial accelerator, an analysis magnet, a secondary stripper, an electrostatic analyzer, a measurement magnet and a detector, negative ions are led out through the ion source, 41Ca molecular negative ions are selected through the injection magnet, and the serial accelerator is connected with the analysis magnet; according to the method, 41Ca molecular positive ions enter a serial accelerator, are accelerated to required energy and are stripped into 41Ca molecular positive ions, the 41Ca molecular positive ions are selected by an analysis magnet, the 41Ca molecular positive ions are stripped into 41Ca + by a secondary stripper, then energy and momentum selection is carried out on the 41Ca + by utilizing an electrostatic analyzer and a measurement magnet respectively, and finally, the 41Ca + is measured by utilizing a detector. A high-sensitivity analysis technology of 41Ca on a small-sized accelerator mass spectrometry (AMS) device is established, so that the equipment cost, the operation cost and the maintenance cost are reduced; the problem that 41Ca cannot be popularized and measured is solved, a good foundation is provided for application of 41Ca in multiple fields, and development of related subjects can be promoted.

Description

Technical Field

[0001] This invention belongs to the field of isotope detection technology, specifically relating to a... 41 A small accelerator mass spectrometry device and method for measuring Ca. Background Technology

[0002] 41 Ca is a long-lived radioactive nuclide with a half-life of 9.9 × 10⁻⁶. 4 Year. It has significant research value in geology, biomedicine, and nuclear facility environment research; however, due to... 41 The long half-life of Ca and its extremely low concentration mean that it can only be measured using accelerator mass spectrometry. However, accelerator mass spectrometry measurements are subject to limitations... 41 Isotopic interference of K makes in 41 Ca measurements can only be performed using large-scale accelerator mass spectrometry (accelerator terminal voltage greater than 10 mV). After accelerating the particles to approximately 2 MeV / nucleus using this large-scale accelerator mass spectrometry, a gas multi-anode ionization chamber is then used... 41 Ca and 41 The energy loss of K in the gas ionization chamber varies, thus achieving the desired effect. 41 Ca and 41 The identification of K is thus achieved. 41 High-sensitivity determination of Ca. Although accelerator mass spectrometry (AMS) with a terminal voltage of 3MV is also used. 41 It can measure Ca, but its sensitivity is several orders of magnitude lower than that of a large accelerator mass spectrometer (AMS) device with a capacity of 10 MV, which cannot meet the actual measurement needs.

[0003] As can be seen from the above introduction, to achieve 41 Currently, both domestically and internationally, large-scale accelerator mass spectrometry facilities are used for Ca measurement. However, these facilities are expensive and have high operating costs. 41 The measurement of Ca is greatly limited, which also limits... 41 Research on the relevant applications of Ca. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to establish a feasible method using innovative technology. 41 A small-scale accelerator mass spectrometry device (terminal voltage 0.3 MV) and method for high-sensitivity Ca analysis are developed, overcoming the disadvantages of large accelerator mass spectrometry devices and paving the way for the development of Ca analysis. 41 Ca provides convenient and efficient analytical equipment and methods for applications in various fields.

[0005] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0006] A sort of 41The device for measuring Ca by small accelerator mass spectrometry comprises an ion source, an injection magnet, a tandem accelerator, an analyzing magnet, a secondary stripper, an electrostatic analyzer, a measuring magnet and a detector. The device selects 41 Ca molecular negative ions from the ion source, selects 41 Ca molecular negative ions by the injection magnet, accelerates 41 Ca molecular negative ions by the tandem accelerator, and strips 41 Ca molecular negative ions into 41 Ca + , respectively, selects 41 Ca + by the electrostatic analyzer and the measuring magnet, respectively, and measures 41 Ca + by the detector.

[0007] Further, the ion source is a cesium sputtering negative ion source, and the sample in the target cone is a mixture of CaF2 and PbF2 in a certain proportion.

[0008] Further, the mass ratio of CaF2 to PbF2 is 1:3.

[0009] Further, the 41 Ca molecular negative ions selected by the injection magnet are 41 CaF3 - .

[0010] Further, the 41 Ca molecular positive ions selected by the analyzing magnet are 41 CaF + .

[0011] Further, the secondary stripper strips 41 CaF + into 41 Ca + .

[0012] Further, the detector is a thin-window Bragg-like detector.

[0013] A method for measuring Ca by small accelerator mass spectrometry using the device comprises the following steps: 41

[0014] Step 1: The ion source emits negative ions.

[0015] Step 2: The injection magnet selects 41 Ca molecular negative ions.

[0016] Step 3: The tandem accelerator accelerates 41 Ca molecular negative ions and strips them into​41 Ca molecular positive ion;

[0017] Step 4, analysis of magnet pair 41 Ca molecular positive ion is selected;

[0018] Step 5, secondary stripper 41 Ca molecular positive ion is stripped into 41 Ca + ;

[0019] Step 6, electrostatic analyzer 41 Ca + is energy-selected;

[0020] Step 7, measurement magnet pair 41 Ca + is momentum-selected;

[0021] Step 8, detector 41 Ca + is measured.

[0022] Further, in step 1, the ion source is a cesium sputtering negative ion source, and the sample in the target cone is a mixture of CaF2 and PbF2 in a mass ratio of 1:3.

[0023] Further, in step 3, the terminal voltage of the tandem accelerator is set between 0.2-0.3 MV.

[0024] Further, in step 3, helium gas is used as the stripping medium to strip 41 CaF3 - into 41 CaF + .

[0025] Further, in step 5, the secondary stripper uses nitrogen gas as the stripping medium to strip 41 CaF + into 41 Ca + .

[0026] The beneficial effects of the present application are as follows:

[0027] 1. A high-sensitivity analysis technique for 41 Ca on a small accelerator mass spectrometry (AMS) device is established, greatly reducing equipment costs, operation and maintenance costs, etc.

[0028] 2. The problem of 41 Ca cannot be measured universally is solved, providing a good foundation for the application of 41 Ca in multiple fields and promoting the development of related disciplines. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 For 41 A schematic diagram of a small accelerator mass spectrometry device of Ca. DETAILED DESCRIPTION

[0030] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0031] A 41 The small accelerator mass spectrometry device of Ca includes an ion source, an injection magnet, a tandem accelerator, an analyzing magnet, a secondary stripper, an electrostatic analyzer, a measuring magnet, and a detector, negative ions are extracted from the ion source, selected by the injection magnet, and introduced into the tandem accelerator to accelerate to a required energy and stripped into 41 Ca molecular positive ions, the 41 Ca molecular positive ions are selected by the analyzing magnet, the 41 Ca molecular positive ions are stripped into 41 Ca molecular positive ions by the secondary stripper, the 41 Ca + , and the 41 Ca + are selected in energy and momentum by the electrostatic analyzer and the measuring magnet, respectively, and finally the 41 Ca + is measured by the detector.

[0032] The specific technical solutions are as follows:

[0033] The present application adopts a small accelerator mass spectrometry (AMS) system as shown in Figure 1 . Consistent with the traditional accelerator mass spectrometry (AMS) structure, it also includes an ion source, an injection magnet, a 0.3 MV tandem accelerator, an analyzing magnet, an electrostatic analyzer, a measuring magnet, and a detector, etc. components, in which two gas strippers are used. One is a gas stripper arranged in the middle of the 0.3 MV tandem accelerator, which is the structure adopted by the tandem accelerator; the second stripper is a second gas stripper (secondary stripper) arranged after the analyzing magnet and before the electrostatic analyzer, which is a gas stripper specially designed to meet the 41 Ca measurement. The main innovations of the present application on the device are: (1) a 0.3 MV tandem accelerator is adopted to carry out the measurement of 41 Ca; (2) a second gas stripper (secondary stripper) is adopted to disintegrate the molecular ions.

[0034] In order to realize the high-sensitivity measurement of 41 Ca, the following technical solutions are adopted by using the device as shown in Figure 1 .

[0035] 1. Ion Source Extraction: The sample CaF2 and PbF2 are mixed at a mass ratio of 1:3 and pressed into the target cone. A cesium sputtering negative ion source is then placed inside to extract negative ions. The extraction is then selected using an injection magnet. 41 CaF3 - Negative ions, this process can 41 Isotope interference of K excluded 10 6 This method is currently the best way to measure... times. 41 Ca is an internationally recognized technology.

[0036] 2. Acceleration and Stripping: Set the terminal voltage of the tandem accelerator to a suitable value between 0.2-0.3 MV (the specific terminal voltage value needs to be optimized based on the accelerator mass spectrometry (AMS) system). 41 CaF3 - After acceleration, the gas enters the gas stripper, where helium is used as the stripping medium. After stripping, an analytical magnet is used for selection. 41 CaF + After stripping, analytical magnets were used for selection. 41 CaF + This is the key core of the invention. Traditional accelerator mass spectrometry (AMS) systems select single-atom positive ions after gas stripping from a tandem accelerator, while the present invention selects... 41 CaF + Molecular positive ions were chosen because 41 CaF + This is because research found that KF was not present after stripping. + Ions, and 41 CaF + The transmission efficiency can still reach about 20%, so this stripping process can be used to... 41 The interference of isotopes of K is eliminated by 4-5 orders of magnitude, thereby achieving 41 Elimination of K-interference background. Additionally, the reason the tandem accelerator terminal voltage is set at 0.2-0.3 MV is because only within this energy range... 41 CaF + The optimal transmission efficiency is achieved by setting the voltage at the tandem accelerator terminals to 0.2-0.3 mV. 41 Another key technology employed in miniaturizing Ca measurements.

[0037] 3. Secondary stripping: Because the analytical magnet selected is... 41 CaF + Molecular positive ions, at this time in order to exclude and 41 CaF + Ions with the same mass number (e.g.) 60 Interference from Ni (etc.) requires a secondary stripper, which uses helium as the stripping medium. 41CaF + molecular ions are stripped into 41 Ca + monatomic ions, and the secondary stripping technique is another key core technology of the present application.

[0038] 4. 41 Ca measurement: the energy and momentum of the secondary stripped ions are selected by the electrostatic analyzer and the measuring magnet, respectively, at this time only 41 Ca + ions pass through the selection of the electrostatic analyzer and the measuring magnet, and other ions are all excluded, and finally the measurement of 41 Ca can be realized by using a thin window type Bragg-like detector.

[0039] The above technologies are combined to realize high sensitivity measurement of 41 Ca below 0.3 MV by the tandem accelerator.

[0040] The present application realizes 41 Ca small accelerator mass spectrometry measurement method, comprising the following steps:

[0041] Step 1, the ion source draws negative ions;

[0042] Step 2, the injection magnet selects 41 Ca molecular negative ions;

[0043] Step 3, the tandem accelerator accelerates and strips 41 Ca molecular negative ions into 41 Ca molecular positive ions;

[0044] Step 4, the analyzing magnet selects 41 Ca molecular positive ions;

[0045] Step 5, the secondary stripper strips 41 Ca molecular positive ions into 41 Ca + ;

[0046] Step 6, the electrostatic analyzer selects the energy of 41 Ca + ;

[0047] Step 7, the measuring magnet selects the momentum of 41 Ca + ;

[0048] Step 8, the detector measures 41 Ca + .

[0049] Embodiment

[0050] The present application is41 Ca small accelerator mass spectrometry device, such as Figure 1 shown.

[0051] 1. The ion source uses a multi-target high-current negative ion source, the accelerator uses a tandem accelerator with an end voltage of 0.3 MV, the injection magnet, analysis magnet, and electrostatic analyzer all use a double-focusing design mode, with a deflection radius of 50-60 cm, and the detector uses a thin-window type Bragg-like detector.

[0052] 2. The sample CaF2 and PbF2 are mixed in a mass ratio of 1:3, then pressed into a target cone, and placed in a cesium sputtering negative ion source to extract negative ions, and the injection magnet is used to select 41 CaF3 - negative ions.

[0053] 3. The tandem accelerator end voltage is set to a suitable voltage between 0.2-0.3 MV, and 41 CaF3 - is accelerated and enters the gas stripper, using helium as the stripping gas, and adjusting the stripping gas pressure, using the analysis magnet to select 41 CaF + to achieve the best transmission efficiency.

[0054] 4. The 41 CaF + molecular ions selected by the analysis magnet are transmitted to the secondary gas stripper, using nitrogen as the stripping medium, and 41 CaF + molecular ions are stripped into 41 Ca + single atom ions.

[0055] 5. The stripped 41 Ca + ions are energy and momentum selected by the electrostatic analyzer and measurement magnet, excluding other interfering isotopes, and finally 41 Ca + is sent to the detector for measurement, thereby achieving high sensitivity determination of 41 Ca by the tandem accelerator below 0.3 MV.

[0056] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as illustrative only of the preferred embodiments of the application, and that other embodiments of the application falling within the scope of the application are contemplated. Thus, if there is any conflict between what is described in the disclosure and the claims, the claim interpretation should prevail.

[0057] The above-described embodiments are merely illustrative of the application and should not be considered limiting in any respect. The scope of the application is defined by the claims and any variations that come within the meaning of equivalents of the claims are to be embraced.

Claims

1. A kind 41 A small accelerator mass spectrometry device for Ca, characterized in that: It includes an ion source, an injection magnet, a tandem accelerator, an analytical magnet, a secondary stripper, an electrostatic analyzer, a measuring magnet, and a detector. Negative ions are extracted by the ion source and selected by the injection magnet. 41 Ca molecules and negative ions enter a tandem accelerator, are accelerated to the required energy, and then stripped into... 41 Ca molecules are positive ions, and analysis of the magnet pair 41 Ca molecules are selected by positive ions and then separated by a secondary stripper. 41 Ca molecules are stripped of positive ions. 41 Ca + Then, using an electrostatic analyzer and a measuring magnet respectively, the electrostatic analysis was performed on the electrostatic analysis. 41 Ca + Energy and momentum selection are performed, and finally, a detector is used to... 41 Ca + Take measurements.

2. The one described in claim 1 41 A small accelerator mass spectrometry device for Ca, characterized in that: The ion source is a cesium sputtering negative ion source, and the sample in the target cone is a mixture of CaF2 and PbF2 in a specific ratio.

3. The one described in claim 2 41 A small accelerator mass spectrometry device for Ca, characterized in that: The mass ratio of CaF2 to PbF2 is 1:

3.

4. The one described in claim 1 41 A small accelerator mass spectrometry device for Ca, characterized in that: The injection magnet selected 41 Ca molecular anions 41 CaF3 - .

5. The one described in claim 1 41 A small accelerator mass spectrometry device for Ca, characterized in that: The analytical magnet is selected 41 Ca molecular positive ion is 41 CaF + .

6. The one described in claim 1 41 A small accelerator mass spectrometry device for Ca, characterized in that: The secondary stripper will 41 CaF + Peeled into 41 Ca + .

7. The one described in claim 1 41 A small accelerator mass spectrometry device for Ca, characterized in that: The detector is a thin-window type Bragg detector.

8. A device implemented using any one of claims 1-7 41 A method for measuring Ca using small accelerator mass spectrometry, characterized in that... Includes the following steps: Step 1: The ion source draws out negative ions; Step 2, inject magnets 41 Ca molecules are selected by negative ions; Step 3, serial accelerator pair 41 Ca molecules and negative ions are accelerated and stripped away. 41 Ca molecules are positive ions; Step 4, analyze the magnet pair 41 Ca molecules are selected by positive ions; Step 5, the secondary peeler will 41 Ca molecular positive ion stripping is 41 Ca + ; Step 6, the electrostatic analyzer... 41 Ca + Perform energy selection; Step 7, Measure the magnet pair 41 Ca + Momentum selection; Step 8, the detector... 41 Ca + Take measurements.

9. The one described in claim 8 41 A method for measuring Ca using a small accelerator mass spectrometry, characterized by: In step 1, the ion source is a cesium sputtering negative ion source, and the sample in the target cone is a mixture of CaF2 and PbF2 in a mass ratio of 1:

3.

10. The one described in claim 8 41 A method for measuring Ca using a small accelerator mass spectrometry, characterized by: In step 3, the terminal voltage of the tandem accelerator is set between 0.2 and 0.3 MV.

11. The one described in claim 8 41 A method for measuring Ca using a small accelerator mass spectrometry, characterized by: In step 3, helium is used as the gas stripping medium. 41 CaF3 - Stripped into 41 CaF + .

12. The one described in claim 8 41 A method for measuring Ca using a small accelerator mass spectrometry, characterized by: In step 5, the secondary stripper uses nitrogen as the stripping medium to... 41 CaF + Peeled into 41 Ca + .

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