Fine collimator debugging method for neutron time-of-flight spectrometer

Abstract

The invention discloses a fine collimator debugging method for a neutron time-of-flight spectrometer, which is applied to the field of neutron scattering science and technology, and comprises the following steps: acquiring diffraction intensity corresponding to left and right fine collimators at different positions when a first diffraction sample moves along a beam direction at a first preset step length, coarse debugging is carried out based on the deviation between the peak value corresponding position and the beam center position; obtaining diffraction intensity corresponding to the left fine collimator and the right fine collimator at different positions when the second diffraction sample moves at a second preset step length along the beam direction, and performing fine debugging based on the deviation between the peak value corresponding position and the beam center position; and acquiring the diffraction intensity of the third diffraction sample moving at a third preset step length along the beam direction and corresponding to the left and right fine collimators at different positions, and performing rotation debugging and synchronously correcting the residual tiny translation deviation based on the symmetrical distribution condition of the diffraction intensity relative to the beam center. According to the invention, the debugging precision of the fine collimator is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of neutron scattering science and technology, and more specifically to a method for fine collimator adjustment for a neutron time-of-flight spectrometer. Background Technology

[0002] In neutron science research experiments, to reduce or eliminate stray noise from the spectrometer's ambient equipment, a fine collimator is typically placed between the detector and the sample to absorb neutrons scattered by the ambient equipment. The use of fine collimators in neutron diffraction experiments not only reduces background noise from the ambient equipment but also significantly improves the quality of neutron diffraction data, facilitating subsequent data analysis.

[0003] In existing technologies, the adjustment of fine collimators is rarely addressed, especially the assessment of the accuracy of their positioning after installation, which has not been reported. Several patents exist regarding the mechanical adjustment and diaphragm measurement of fine collimators, such as an invention patent concerning the mechanical positioning adjustment of fine collimators after installation (publication number: CN117233185A). Although limited to attitude adjustment after mechanical installation, this electrically operated adjustment device still provides convenience for the adjustment of fine collimators. With the development of neutron-related research and the successive construction of neutron sources and neutron spectrometers in China, the demand for fine collimators has greatly increased, especially placing higher demands on the adjustment methods of fine collimators, making the accuracy of their installation and positioning particularly important.

[0004] Therefore, how to provide a precise collimator calibration method for neutron time-of-flight spectrometers is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for fine collimator adjustment for a neutron time-of-flight spectrometer.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for fine collimator calibration in a neutron time-of-flight spectrometer includes: Step 1: Obtain the diffraction intensity of the left and right fine collimators at different positions when the first diffraction sample moves along the beam direction with a first preset step size, and perform coarse translation adjustment of the position of the left and right fine collimators in the beam direction based on the deviation between the peak position of the diffraction intensity and the position of the beam center. Step 2: Obtain the diffraction intensity of the left and right fine collimators at different positions when the second diffraction sample moves along the beam direction with a second preset step size. Based on the deviation between the peak position of the diffraction intensity and the position of the beam center, finely adjust the position of the left and right fine collimators in the beam direction by translation. The diameter of the second diffraction sample is smaller than that of the first diffraction sample. The second preset step size is smaller than the first preset step size. Step 3: Obtain the diffraction intensity corresponding to the left and right fine collimators at different positions when the third diffraction sample moves along the beam direction with a third preset step size. Based on the symmetrical distribution of the diffraction intensity relative to the beam center, rotate and adjust the left and right fine collimators, and simultaneously correct residual small translational deviations. Repeat the measurement and adjustment process based on the third diffraction sample until the center of the left and right fine collimators completely coincides with the center of the sample, and the left and right fine collimators are completely symmetrical with respect to the center of the sample. The diameter of the third diffraction sample is smaller than that of the second diffraction sample, and the third preset step size is smaller than the second preset step size.

[0007] Optionally, based on the symmetrical distribution of diffraction intensity relative to the beam center, the left and right fine collimators are rotated and adjusted, specifically as follows: For the left fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, rotate it clockwise by 0.1°, and vice versa. For the right fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, it is rotated 0.1° counterclockwise, and vice versa.

[0008] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for fine collimator adjustment for a neutron time-of-flight spectrometer. This method can not only be used to evaluate the accuracy of the fine collimator's installation and positioning, but also provides guidance for its adjustment. Secondly, the adjustment method described in this invention greatly improves the data quality of neutron diffraction experiments, facilitating subsequent data processing. Finally, the adjustment method described in this invention has significant applications in specific fields. For example, when measuring the residual stress of engineering components, the adjustment of the left and right fine collimators further improves the accuracy of residual stress testing, contributing to addressing the strategic needs of the national industrial sector. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the method flow provided by the present invention.

[0011] Figure 2 This is a schematic diagram of the fine collimator provided by the present invention under ideal conditions.

[0012] Figure 3 This is a schematic diagram of the fine collimator provided by the present invention in the state of being to be adjusted.

[0013] Figure 4 This is a schematic diagram showing the diffraction intensity of the first diffraction sample provided by the present invention at different positions corresponding to the left and right fine collimators.

[0014] Figure 5 This is a schematic diagram showing the diffraction intensity of the second diffraction sample provided by the present invention at different positions corresponding to the left and right fine collimators.

[0015] Figure 6 This is a schematic diagram showing the diffraction intensity of the third diffraction sample provided by the present invention at different positions corresponding to the left and right fine collimators. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: Embodiment 1 of this invention discloses a method for fine collimator adjustment in a neutron time-of-flight spectrometer, such as... Figure 1 As shown, it includes: Step 1: Obtain the diffraction intensity of the left and right fine collimators at different positions when the first diffraction sample moves along the beam direction with a first preset step size, and perform coarse translation adjustment of the positions of the left and right fine collimators in the beam direction based on the deviation between the peak position of the diffraction intensity and the position of the beam center.

[0018] like Figure 2 As shown, ideally, after the fine collimators are installed, the left and right fine collimators should be perfectly symmetrical, and their centers should completely coincide with the sample center. However, current mechanical collimation positioning usually cannot meet this requirement. Not only is there a deviation between the center of the fine collimator and the sample center, but the left and right fine collimators are also asymmetrical, such as... Figure 3 As shown. Therefore, it is necessary to verify the positioning accuracy of the fine collimator.

[0019] The first diffraction sample (e.g., 2 mm in diameter) is placed at the center of the sample and moved along the beam direction with a first preset step size (e.g., 2 mm step size). It remains at each position for the same amount of time (15 minutes in this embodiment). The diffraction intensity corresponding to the left and right fine collimators at different positions is recorded. The accuracy of the fine collimator installation and positioning can be preliminarily determined by the diffraction intensity. Figure 4 As shown, based on the diffraction intensities corresponding to the left and right fine collimators at different positions of the first diffracted sample, it can be concluded that neither the left nor right fine collimators are aligned with the sample center. According to the deviation between the peak position of the diffraction intensity and the beam center position, the left fine collimator should be translated 0.8 mm against the beam direction, and the right fine collimator should be translated 0.5 mm along the beam direction (the bottom of the fine collimator is equipped with a four-dimensional motion system, including three-axis translation and rotation around the Z-axis). This completes the coarse adjustment of the translation of the left and right fine collimators.

[0020] Step 2: Obtain the diffraction intensity of the left and right fine collimators at different positions when the second diffraction sample moves along the beam direction with a second preset step size, and adjust the position of the left and right fine collimators in the beam direction based on the deviation between the peak position of the diffraction intensity and the position of the beam center.

[0021] After coarse adjustment, fine adjustment begins. A second diffraction sample (its diameter is smaller than that of the first diffraction sample, here taken as 1 mm) is placed at the center of the sample and moved along the beam direction at a second preset step size (the second preset step size is smaller than the first preset step size, here taken as 0.5 mm). The sample is held at each position for the same amount of time (20 minutes in this embodiment). The diffraction intensity corresponding to the left and right fine collimators at different positions of the second diffraction sample is recorded. The accuracy of the fine collimator installation and positioning is then determined again based on the diffraction intensity. Figure 5 As shown, based on the diffraction intensities corresponding to the left and right fine collimators at different positions of the second diffraction sample, it can be concluded that the left fine collimator should be translated 0.05 mm along the beam direction, and the right fine collimator should be translated 0.1 mm along the beam direction. This completes the fine-tuning of the translation of the left and right fine collimators.

[0022] Step 3: Obtain the diffraction intensity of the left and right fine collimators at different positions when the third diffraction sample moves along the beam direction with a third preset step size. Based on the symmetrical distribution of the diffraction intensity relative to the beam center, rotate and adjust the left and right fine collimators, and simultaneously correct residual small translational deviations. Repeat the measurement and adjustment process based on the third diffraction sample until the center of the left and right fine collimators completely coincides with the center of the sample, and the left and right fine collimators are completely symmetrical with respect to the center of the sample.

[0023] After coarse and fine adjustments, the centers of the left and right fine collimators are basically aligned with the sample center. However, the intensity distribution of the right fine collimator is asymmetrical relative to the sample center, meaning the left and right fine collimators are asymmetrical, and the right fine collimator needs to be rotated. At this point, a third diffraction sample (the diameter of the third diffraction sample is smaller than that of the second diffraction sample, here taken as 0.5 mm) is placed at the sample center and moved along the beam direction at a second preset step size (the third preset step size is smaller than the second preset step size, here taken as 0.1 mm). The sample is held at each position for the same amount of time (30 minutes in this embodiment), and the diffraction intensities corresponding to the left and right fine collimators at different positions are recorded. Figure 6 As shown, the left and right fine collimators are rotated and adjusted based on the symmetrical distribution of diffraction intensity relative to the beam center.

[0024] Based on the symmetrical distribution of diffraction intensity relative to the beam center, the left and right fine collimators are rotated and adjusted, specifically as follows: For the left fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, rotate it clockwise by 0.1°, and vice versa. For the right fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, it is rotated 0.1° counterclockwise, and vice versa.

[0025] Depend on Figure 5 The diffraction intensity distribution shows that the right fine collimator needs to be rotated counterclockwise by 0.1°, and residual minor translational deviations should be corrected simultaneously (after rotation and adjustment, some minor translational deviations may be exposed). Repeat the measurement and adjustment process based on the third diffraction sample until the centers of the left and right fine collimators completely coincide with the sample center, and the left and right fine collimators are completely symmetrical with respect to the sample center. At this point, all adjustments are complete.

[0026] When replacing a fine collimator of a different specification, the above steps can be used to reposition and adjust the fine collimator.

[0027] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0028] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fine collimator adjustment in a neutron time-of-flight spectrometer, characterized in that, include: Step 1: Obtain the diffraction intensity of the left and right fine collimators at different positions when the first diffraction sample moves along the beam direction with a first preset step size, and perform coarse translation adjustment of the position of the left and right fine collimators in the beam direction based on the deviation between the peak position of the diffraction intensity and the position of the beam center. Step 2: Obtain the diffraction intensity corresponding to the left and right fine collimators at different positions when the second diffraction sample moves along the beam direction with a second preset step size. Based on the deviation between the peak position of the diffraction intensity and the beam center position, perform fine translation adjustments on the positions of the left and right fine collimators in the beam direction. Wherein, the diameter of the second diffraction sample is smaller than that of the first diffraction sample; the second preset step size is smaller than the first preset step size. Step 3: Obtain the diffraction intensity corresponding to the left and right fine collimators at different positions when the third diffraction sample moves along the beam direction with a third preset step size. Based on the symmetrical distribution of the diffraction intensity relative to the beam center, rotate and adjust the left and right fine collimators, and simultaneously correct residual small translational deviations. Repeat the measurement and adjustment process based on the third diffraction sample until the center of the left and right fine collimators completely coincides with the center of the sample, and the left and right fine collimators are completely symmetrical with respect to the center of the sample. The diameter of the third diffraction sample is smaller than that of the second diffraction sample, and the third preset step size is smaller than the second preset step size.

2. The method for fine collimator adjustment for a neutron time-of-flight spectrometer according to claim 1, characterized in that, Based on the symmetrical distribution of the diffraction intensity relative to the beam center, the left and right fine collimators are rotated and adjusted, specifically as follows: For the left fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, it is rotated 0.1° clockwise, and vice versa. For the right fine collimator, when the diffraction intensity in the negative direction of the beam center is greater than the diffraction intensity in the positive direction of the beam center, it is rotated counterclockwise by 0.1°, and vice versa.

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