Neutron scattering experiment simulation method, device, equipment and product

Abstract

The invention discloses a neutron scattering experiment simulation method, device, equipment and product. The method comprises the following steps: constructing a scattering front-end model of a target scattering spectrometer; wherein the scattering front-end model comprises a neutron moderator and a slit; simulating the movement process of neutrons with different incident energies from the neutron moderator to the slit, and extracting neutron beam data in the movement process; constructing a sample environment model and a detector array model of the target scattering spectrometer; wherein a sample is arranged in the sample environment model; and performing a scattering experiment based on the neutron beam data of the selected incident energy, the sample environment model and the sample, intercepting neutrons after the scattering experiment by using the detector array model, and generating a scattering simulation result of the neutrons. The virtual scattering experiment method for the high-energy inelastic neutron scattering spectrometer is developed, so that the optimal setting of part of experiments can be cleared in a relatively low-time-cost manner before the real experiment is carried out, and the situation that the supply of the current spectrometer experiment machine is tense is relieved.

Description

Technical Field

[0001] This invention relates to the field of neutron scattering technology, specifically to a method, apparatus, equipment, and product for neutron scattering experimental simulation. Background Technology

[0002] Inelastic neutron scattering (INS) is a powerful technique for studying spin and lattice dynamics in various materials. Time-of-flight (TOF) spectrometers, equipped with large stereoscopic angle coverage detector arrays, have become standard equipment in INS spectrometers at major spallation neutron sources worldwide, as they can acquire dynamic information of the entire Brillouin zone of a sample in a single measurement. Due to the inherently weaker INS signal (three orders of magnitude weaker than elastic scattering), and factors such as reducing sample size to minimize multiple scattering and sacrificing beam intensity to improve incident energy resolution, it typically takes several hours to tens of hours to acquire analyzable data for a single sample in INS experiments. Therefore, the demand for experimental time for INS spectrometers remains high. However, research on quantum materials often requires extremely low temperatures (0.1–2 K) or strong magnetic fields (7–10 T) for sample environments, and the preparation and stabilization of the equipment consume considerable time, further reducing effective experimental time. Currently, there are only about 20 inelastic scattering spectrometers worldwide, leading to fierce competition among users. A single application typically yields only 3-5 days of testing time. Although the pressure on testing time is expected to ease in the future with improvements in neutron source brightness and advancements in detector technology, inelastic neutron scattering experimental testing time will remain in short supply for a considerable period.

[0003] As the first inelastic scattering spectrometer at the China Spallation Neutron Source (CSNS), the High Energy Direct Geometric Spectrometer (HD) in beamline 05 employs a 25Hz source frequency design. It primarily utilizes thermal neutrons to measure inelastic scattering signals such as magnetic excitations, phonons, and molecular vibrations in functional materials like high-temperature superconductors and multiferroic materials. Since its successful beam emergence in January 2023, HD has undertaken multiple tasks, including spectrometer parameter calibration, equipment upgrade testing, and sample experiments. The supply and scheduling of experimental opportunities have also consistently faced challenges. Summary of the Invention

[0004] The present invention aims to develop a virtual experiment method for high-energy inelastic neutron scattering spectrometers, so that the optimal settings for some experiments can be determined in a relatively low-time-cost manner before the actual experiment is carried out, thereby alleviating the current shortage of experimental time for spectrometers.

[0005] According to the first aspect, one embodiment provides a method for simulating a neutron scattering experiment, comprising:

[0006] Construct a scattering front-end model for the target scattering spectrometer; wherein the scattering front-end model includes a neutron moderator and a slit;

[0007] The motion process of neutrons with different incident energies from the neutron moderator to the slit is simulated, and neutron beam data during the motion process is extracted;

[0008] Construct a sample environment model and a detector array model for the target scattering spectrometer; wherein, the sample environment model includes a sample.

[0009] A scattering experiment is conducted based on the neutron beam data of the selected incident energy, the sample environment model, and the sample. The neutrons after the scattering experiment are intercepted using the detector array model, and the scattering simulation results of the neutrons are generated.

[0010] In some embodiments, the scattering front-end model further includes a neutron conduit, a disk chopper, and a Fermi chopper; the neutron moderator is constructed using the SNS_source component and preset parameters, including the surface dimensions of the neutron moderator, the distance between the neutron moderator and the entrance of the neutron conduit, and the neutron energy range of the target scattering spectrometer; the neutron conduit is constructed using the Guide component, and is divided into a first part and a second part, the first part being an elliptical neutron conduit and the second part being a conical neutron conduit; the disk chopper... Constructed using the DiskChopper component, the disk-shaped chopper is located at a predetermined distance from the center of the neutron moderator; the Fermi chopper, constructed using the FermiChopper component, includes a straight-channel absorber filled with Gd₂O₃ neutron-absorbing material; the slit, constructed using the Slit component, has a first slit and a second slit in the scattering front-end model, wherein the distance between the second slit and the surface of the neutron moderator is greater than the distance between the first slit and the surface of the neutron moderator.

[0011] In some embodiments, an MCPL_output component is provided at the exit position of the second slit; the simulation of the motion process of neutrons with different incident energies from the neutron moderator to the slit, and the extraction of neutron beam data during the motion process, includes:

[0012] The MCPL_output component acquires neutron beam data of neutrons with different incident energies during their motion from the neutron moderator to the second slit; wherein the neutron beam data includes the incident energy, position, velocity, flight time of the neutrons, and a first probability weight, the first probability weight being the ratio of the total number of neutrons reaching the second slit to the total number of neutrons emitted from the neutron moderator.

[0013] In some embodiments, constructing a sample environment model for the target scattering spectrometer includes:

[0014] The physical process of the sample environment material is defined by the NCrystal_process component, and the geometry of the sample environment is defined according to the preset geometry component to complete the construction of the sample environment model.

[0015] In some embodiments, the detector array model includes multiple detector modules, and the construction process of the detector modules includes:

[0016] The position and orientation of the detector module are defined based on the position and orientation of the Arm component and the actual detector corresponding to the detector module, and modeling is performed based on the module parameters of the PSD_monitor_TOF component and the actual detector to complete the construction of the detector module; wherein, the actual detector is the detector inside the target scattering spectrometer.

[0017] In some embodiments, after intercepting the neutrons after the scattering experiment using the detector array model and generating the scattering simulation results of the neutrons, the neutron scattering experiment simulation method further includes:

[0018] Obtain the second probability weights of all pixels in each detector module captured by neutrons during the target flight time in the scattering simulation results, and construct a first matrix based on the second probability weights; wherein the first matrix has the target flight time as the horizontal axis;

[0019] Obtain the instrument definition file of the target scattering spectrometer, and convert the first matrix into a second matrix according to the instrument definition file; wherein, the second matrix uses energy transfer as the abscissa;

[0020] The scattering angle of each pixel in the detector module is calculated based on the first matrix, and the momentum transfer of the neutrons captured on the pixel of the detector module is calculated based on the scattering angle.

[0021] Based on the energy transfer and momentum transfer in the second matrix, a momentum transfer-energy transfer diagram is constructed, and the scattering experiment is analyzed based on the momentum transfer-energy transfer diagram to obtain the experimental analysis results.

[0022] In some embodiments, the detector module includes multiple pixels, and the instrument positioning file includes the position of the sample and the position of the pixels in the detector module; the step of converting the first matrix into a second matrix according to the instrument definition file includes:

[0023] Calculate the displacement vector between the position of each pixel in the detector module and the position of the sample;

[0024] For each pixel of the detector module, the corresponding neutron velocity is calculated based on the pixel's displacement vector and neutron flight time.

[0025] The arrival energy of the neutron is calculated based on the neutron velocity and the preset energy calculation formula, and the corresponding energy transfer is calculated based on the arrival energy and the incident energy of the neutron.

[0026] The target flight time in the first matrix is ​​replaced with energy transfer to obtain the second matrix.

[0027] According to a second aspect, one embodiment provides a neutron scattering experiment simulation apparatus, comprising:

[0028] A scattering front-end model construction module is used to construct a scattering front-end model of the target scattering spectrometer; wherein, the scattering front-end model includes a neutron moderator and a slit;

[0029] The data acquisition module is used to simulate the motion process of neutrons with different incident energies from the neutron moderator to the slit, and to extract neutron beam data during the motion process;

[0030] The detector array model construction module is used to construct the sample environment model and detector array model of the target scattering spectrometer; wherein, the sample environment model includes a sample.

[0031] The experimental simulation module is used to conduct a scattering experiment based on the neutron beam data of the selected incident energy, the sample environment model, and the sample. It uses the detector array model to intercept the neutrons after the scattering experiment and generate the scattering simulation results of the neutrons.

[0032] According to a third aspect, one embodiment provides a neutron scattering experiment simulation apparatus, comprising:

[0033] Memory, used to store programs;

[0034] A processor for implementing the neutron scattering experiment simulation method by executing a program stored in the memory.

[0035] According to the fourth aspect, one embodiment provides a computer program product, including a computer program and / or instructions, which, when executed by a processor, implement the neutron scattering experiment simulation method described above.

[0036] The neutron scattering experiment simulation method, apparatus, equipment, and computer program products according to the above embodiments construct a scattering front-end model, a sample environment model, and a detector array model of the target scattering spectrometer, and simulate the motion process of neutrons with different incident energies from the neutron moderator to the slit, extracting neutron beam data during the motion process. Using the neutron beam data as the incident neutron data when the sample is scattered eliminates the need to repeatedly simulate the path of neutrons from the neutron moderator surface to the slit when conducting virtual scattering experiments with the same incident energy, reducing the computational load when conducting virtual scattering experiments with the same incident energy. Based on the selected incident energy neutron beam data, the sample environment model, and the sample, a scattering experiment is conducted. The detector array model intercepts the neutrons after the scattering experiment and generates the scattering simulation result of the neutrons. Before conducting real experiments, a relatively low-cost simulation experiment is used to conduct scattering experiments, alleviating the current shortage of spectrometer experimental opportunities, reducing the frequency of on-site experimental setup adjustments and the waste of valuable time, improving experimental efficiency, and providing evidence for the correctness of real experimental results. Attached Figure Description

[0037] Figure 1 This is a flowchart of the neutron scattering experiment simulation method in the embodiments of this application;

[0038] Figure 2 This is a list of neutron beam data in one embodiment;

[0039] Figure 3 This is a structural diagram of choppers T0, T1, and T2 in one embodiment;

[0040] Figure 4 This is a structural diagram of a Fermi chopper in one embodiment;

[0041] Figure 5 This is a flowchart of a neutron scattering experiment simulation method, which involves using a detector array model to intercept neutrons after a scattering experiment and generating neutron scattering simulation results.

[0042] Figure 6 This is a reference diagram of the first matrix in one embodiment;

[0043] Figure 7 This is a flowchart illustrating the conversion of a first matrix into a second matrix according to an instrument definition file in one embodiment.

[0044] Figure 8 This is a comparison of non-elastic scattering background simulations for a thinning scheme of the aluminum cover in the low-temperature sample environment of an HD spectrometer in one embodiment;

[0045] Figure 9This is a diagram illustrating the simulated diffraction rings of sub-scattering in an Al sample environment on a detector array constructed in Mantid software in one embodiment.

[0046] Figure 10 This is a simulated QE diagram of sub-scattering in an Al sample environment in one embodiment;

[0047] Figure 11 This is a QE diagram of an actual experimentally measured Al powder sample in one embodiment;

[0048] Figure 12 This is a schematic diagram of the structure of a neutron scattering experiment simulation device in one embodiment. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0050] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0051] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0052] The current non-explosive neutron scattering experiments face the following challenges: (1) Non-explosive neutron scattering experiments involve multiple complex experimental setup steps, including the selection and control of neutron sources, precise control of the sample environment (such as temperature, pressure, magnetic field, etc.), and the layout and parameter adjustment of detectors. Each step has multiple possible setup methods, and the steps affect each other, resulting in the need for a large number of trials to find the optimal combination of experimental conditions; (2) Non-explosive neutron scattering experiments usually rely on large neutron source facilities, such as reactor neutron sources or spallation neutron sources. The construction and operation costs of these facilities are extremely high. Therefore, the time available for using neutron beams is very precious and limited. Each experiment requires a certain amount of time. If the frequency of trials is too high, a large amount of time will be wasted on suboptimal experimental setups, while the time actually used to obtain effective scientific data will be reduced accordingly; (3) Spectrometer scientists play an important technical guidance role in non-explosive neutron scattering experiments. They need to assist experimental personnel in solving various technical problems encountered during the experiment, including the optimization of experimental setups and the troubleshooting of instrument malfunctions. Because of the high frequency of experimental exploration, researchers often consult with and seek help from spectrometer scientists, which requires spectrometer scientists to invest a lot of time and energy to deal with various technical problems, increasing their workload.

[0053] To reduce the frequency of on-site experimental setup adjustments, minimize the waste of valuable experimental time, improve experimental efficiency, and alleviate the workload of spectrometer scientists, this application provides a neutron scattering experiment simulation method. In this method, a scattering front-end model of the target scattering spectrometer is constructed. This model includes a neutron moderator and a slit. The motion of neutrons with different incident energies from the neutron moderator to the slit is simulated, and neutron beam data during this motion is extracted. A sample environment model and a detector array model of the target scattering spectrometer are constructed, with a sample included in the sample environment model. A scattering experiment is conducted based on the selected incident neutron beam data, the sample environment model, and the sample. The detector array model is used to intercept the neutrons after the scattering experiment and generate the scattering simulation results for those neutrons.

[0054] The neutron scattering experimental simulation method provided in the embodiments of this application is described below with reference to the accompanying drawings.

[0055] Figure 1 A flowchart of a neutron scattering experimental simulation method provided in an embodiment of this application is shown, which will be described in detail below.

[0056] Step S10: Construct the scattering front-end model of the target scattering spectrometer.

[0057] Specifically, the target scattering spectrometer is a high-resolution diffractometer (HD). The scattering front-end model of the target scattering spectrometer includes components such as a neutron moderator, a neutron conduit, a disk chopper, a Fermi chopper, and a slit. The neutron moderator model is constructed using the SNS_source component, combined with preset parameters as input. These preset parameters are actually measured neutron spectrum data from the moderator surface, including the surface dimensions of the neutron moderator, the distance between the neutron moderator and the entrance of the neutron conduit, and the neutron energy range of the target scattering spectrometer. The neutron conduit is constructed using the Guide component, and is divided into a first part and a second part. The first part is an elliptical neutron conduit, and the second part is a conical neutron conduit. Before the T0 chopper is an elliptical neutron conduit with a first parameter of 3. After the T0 chopper is a conical neutron conduit with a first parameter of 4. Its shape is a constriction with a large inlet and a small outlet. The first parameter of the conduit determines the critical angle at which the coating on its inner surface allows neutrons of different wavelengths to undergo total internal reflection. The formula for calculating the critical angle is θ. c =mθ0λ, where m is the first parameter, λ is the wavelength of the neutron, θ0≈0.1, and θ0 is the wavelength of the natural nickel pair. The critical angle for total internal reflection of neutrons. In reality, the elliptical neutron conduit of the HD spectrometer is approximated by piecing together 20 conical conduits. Therefore, this method is also used in modeling to approximate the elliptical conduit segment by segment, modeling each conical conduit segment according to its actual shape to reproduce the reality as closely as possible. The disk chopper is constructed using the DiskChopper component and is located at a predetermined distance from the center of the neutron moderator. The Fermi chopper is constructed using the FermiChopper component and includes a straight-channel absorber filled with Gd₂O₃ neutron absorbing material. The slits are constructed using the Slit component. The scattering front-end model has a first slit and a second slit, with the distance between the second slit and the neutron moderator surface being greater than the distance between the first slit and the neutron moderator surface.

[0058] For example, for the decoupled water moderator (DWM) used in the HD spectrometer, the DWM surface size is 10cm × 10cm, the distance between the DWM and the neutron conduit inlet is 2.3m, and the HD spectrometer is designed for a neutron energy range of 10-1500meV. Therefore, the following parameter settings are required for this neutron moderator component: Emin = 10, Emax = 1500, xwidth = 0.1, yheight = 0.1, dist = 2.3. The neutron moderator is defined as the origin. Disk chopper T0 is located 6.5m from the center of the neutron moderator, disk chopper T1 is located 7.3m from the center of the neutron moderator, and disk chopper T2 is located 10m from the center of the neutron moderator. The scattering front-end model has a first slit Slit1 and a second slit Slit2. The opening sizes of the two slits are 50mm×50mm and 30mm×30mm, respectively, and they are located 17.3m and 17.81m away from the center of the neutron moderator, respectively.

[0059] In this embodiment, by constructing a scattering front-end model of the target scattering spectrometer, the neutron transport and scattering process under different parameters can be simulated, and the behavior of neutrons in each component of the scattering front-end model can be intuitively displayed. Simulating a virtual neutron scattering experiment using the scattering front-end model allows for the evaluation and optimization of different experimental schemes before actual experiments, avoiding blindly conducting experiments and reducing unnecessary experimental attempts and wasted time.

[0060] Step S20: Simulate the motion of neutrons with different incident energies from the neutron moderator to the slit, and extract the neutron beam data during the motion process.

[0061] Specifically, the motion of neutrons with different incident energies from the neutron moderator to the slit in the scattering front-end model is simulated, and neutron beam data during the above motion process is extracted. The neutron beam data includes the incident energy, position, velocity, flight time of the neutrons, and a first probability weight, which is the ratio of the total number of neutrons reaching the second slit to the total number of neutrons emitted from the neutron moderator.

[0062] For example, please refer to Figure 2 This section extracts neutron beam data output by the scattering front-end model at the slit location. The list of this neutron beam data records the incident energy, position, velocity, time of flight, and first probability weight for each neutron. Here, pdgcode2112 indicates that the particle is a neutron.

[0063] In this embodiment, the extracted neutron beam data is used as the incident neutron data when the sample is scattered. This eliminates the need to repeatedly simulate the path of neutrons from the neutron moderator surface to the slit when performing virtual neutron scattering experiments with the same incident energy, thus greatly reducing the computational load of virtual neutron scattering experiments with the same incident energy.

[0064] Step S30: Construct the sample environment model and detector array model of the target scattering spectrometer.

[0065] Specifically, the sample environment typically consists of multiple cylindrical or square shields. To construct models of these shields and distinguish between geometric descriptions and scattering processes, the Union function in McStas software is required. Modeling the sample environment using the Union function follows a standard procedure, which includes defining the physical processes of the sample environment materials, constructing the materials, describing the geometry of the sample environment, and handling neutron scattering. Similarly, by defining the physical processes of the desired sample, the corresponding materials and geometry can be constructed and placed within the sample environment; that is, the sample is included in the sample environment model. After neutrons scatter with the sample environment and the sample itself, they need to be intercepted by detectors. Therefore, the actual positions and orientations of each detector module are measured, and a detector array model is constructed based on this.

[0066] In this embodiment, by constructing a sample environment model of the target scattering spectrometer, the various conditions under which the sample is located in the actual experiment can be reproduced with high precision. The detector array model allows for flexible adjustment of the position, angle, and number of detectors in virtual space. By simulating the reception of scattered neutrons by detectors under different layouts, the optimal detector arrangement can be found to maximize coverage of the scattering angle range and improve signal reception efficiency.

[0067] Step S40: Based on the neutron beam data of the selected incident energy, a scattering experiment is conducted with the sample environment model and the sample. The neutrons after the scattering experiment are intercepted using the detector array model, and the scattering simulation results of the neutrons are generated.

[0068] Specifically, based on the neutron beam data of the selected incident energy as the incident neutron data, scattering experiments are conducted with the sample environment model and the sample, respectively. The scattered neutron trajectory is extended to the detector array model, and the position, time and energy of the neutron reaching the detector array model are calculated. The neutron event is converted into a simulated detector signal, and the neutron scattering simulation results are obtained based on the simulated detector signal conversion.

[0069] In this embodiment of the application, simulating scattering experiments can reduce trial-and-error costs and optimize experimental design.

[0070] In this embodiment, a scattering front-end model, a sample environment model, and a detector array model of the target scattering spectrometer are constructed. The motion of neutrons with different incident energies from the neutron moderator to the slit is simulated, and neutron beam data during this motion is extracted. Using this neutron beam data as the incident neutron data during sample scattering eliminates the need to repeatedly simulate the neutron path from the neutron moderator surface to the slit when conducting virtual scattering experiments with the same incident energy, thus reducing the computational load for virtual scattering experiments with the same incident energy. Based on the selected incident energy neutron beam data, the sample environment model, and the sample, a scattering experiment is conducted. The detector array model intercepts the neutrons after the scattering experiment and generates the scattering simulation results. This allows for a relatively low-cost simulation experiment before actual experiments, alleviating the current shortage of spectrometer experimental opportunities, reducing the frequency of on-site experimental setup adjustments and the waste of valuable time, improving experimental efficiency, and providing evidence for the correctness of actual experimental results.

[0071] In some embodiments, please refer to Figure 3 The disk choppers in the scattering front-end model include T0 chopper, T1 chopper, and T2 chopper. The disk choppers are constructed using the DiskChopper component. Based on the actual chopper design of the HD spectrometer, the model setup code for T0 chopper, T1 chopper, and T2 chopper is as follows:

[0072] COMPONENT T0_Chopper=DiskChopper(

[0073] theta_0=340,yheight=0.081937,radius=0.3,

[0074] nu=25,nslit=1,phase=180)

[0075] AT(0,0,6.5)RELATIVE Origin

[0076] ROTATED(0,0,0)RELATIVE Origin

[0077] COMPONENT T1_Chopper=DiskChopper(

[0078] theta_0=53.7,yheight=0.080398,radius=0.3,

[0079] nu=25,nslit=1,phase=phase_T1)

[0080] AT(0,0,7.3)RELATIVE Origin

[0081] ROTATED(0,0,0)RELATIVE Origin

[0082] COMPONENT T2_Chopper_wide=DiskChopper(

[0083] theta_0=65.107,yheight=0.073011,radius=0.3,

[0084] nu=nu_T2,nslit=1,phase=phase_T2)

[0085] AT(0,0,10)RELATIVE Origin

[0086] ROTATED(0,0,0)RELATIVE Origin

[0087] GROUP T2_Chopper

[0088] COMPONENT T2_Chopper_narrow=DiskChopper(

[0089] theta_0=16.6,yheight=0.073011,radius=0.3,

[0090] nu=nu_T2,nslit=1,phase=phase_T2+180)

[0091] AT(0,0,10)RELATIVE Origin

[0092] ROTATED(0,0,0)RELATIVE Origin

[0093] GROUP T2_Chopper

[0094] Wherein, theta_0 represents the aperture angle range of the disk chopper in degrees, yheight represents the radial depth of the aperture in meters, radius represents the radius of the disk in meters, nu represents the rotation frequency of the disk in Hz, nslit represents the total number of channels in the chopper aperture, and phase represents the initial phase delay of the center position of the disk aperture relative to the positive y-axis in degrees. In the design of the HD spectrometer, the rotation frequencies of the T0 and T1 choppers are the same as those of the neutron moderator, both at 25 Hz, while the rotation frequency of the T2 chopper needs to be adjusted according to the actual experimental requirements. In addition, the design of the T2 chopper is relatively special, with two apertures on its disk with angle spans of 65.107° and 16.6° respectively, and a phase difference of 180°. To implement this design, two disks need to be created separately, with openings of 65.107° and 16.6° on each disk. Then, the two disks are linked together as a whole using the GROUP keyword, and a phase difference of 180° is set between the two disks. The three disk choppers are located at distances of 6.5m, 7.3m, and 10m from the center of the neutron moderator (defined as the origin), respectively, with a deflection angle of 0 from the center of the neutron moderator.

[0095] In some embodiments, the Fermi chopper is built using the FermiChopper component; please refer to [reference needed]. Figure 4 The Fermi chopper's absorber uses a straight-channel design, filled with Gd₂O₃ neutron absorbing material. The black portion within the yellow dashed ellipse represents the Fermi chopper's straight-channel absorber, its actual structure shown in the image indicated by the arrow. The white portion is the Al material neutron channel, the blue portion is the Gd₂O₃ neutron absorbing material, and the black portion is the edge absorbing material. The Fermi chopper's configuration code is as follows:

[0096] COMPONENT Fermi=FermiChopper(

[0097] radius=0.086, yheight=0.06, w=0.00023, nslit=246,

[0098] m=0,curvature=0,length=0.0115,

[0099] nu=nu_Fermi, phase=phase_Fermi)

[0100] AT(0,0,16)RELATIVE Origin

[0101] ROTATED(0,0,0)RELATIVE Origin

[0102] Wherein, radius represents the radius of the cylindrical vacuum cavity containing the absorber packet in meters (m), yheight represents the height of the absorber packet channel in meters (m), w represents the width of a single channel in meters (m), nslit represents the total number of channels on the absorber packet, m represents the channel's neutron reflection capability (ideally set to 0 to indicate that the neutron absorbing material completely absorbs neutrons with zero reflection), curvature represents the channel curvature (set to 0 to indicate that the channel is straight), length represents the channel length in meters (m), nu represents the absorber packet's rotation frequency in Hz, and phase represents the absorber packet's initial phase. Here, phase is positive, the opposite of phase delay in DiskChopper. Therefore, to set the phase delay of the Fermi chopper absorber packet, phase here must be set to a negative value. The distance between the Fermi chopper and the center of the neutron moderator is 16 meters.

[0103] In some embodiments, an MCPL_output component is provided at the exit position of the second slit Slit2. The MCPL_output component is used to acquire neutron beam data during the motion of neutrons with different incident energies from the neutron moderator to the second slit Slit2. The neutron beam data includes the incident energy, position, velocity, flight time, and a first probability weight. The first probability weight is the ratio of the total number of neutrons reaching the second slit Slit2 to the total number of neutrons emitted from the neutron moderator, i.e., the probability that a neutron reaches its current position. In subsequent data processing, this probability weight is multiplied by the measured total number of neutrons emitted from the neutron moderator, which gives the total number of neutrons that follow the same flight path as the simulated neutron.

[0104] Specifically, to facilitate numerical simulations, the HD spectrometer front-end (referring to the sample environment model, sample, and detector array model) and back-end are decoupled. To this end, an MCPL_output component is added at the exit position of the second slit (Slit2) to export the neutron beam data corresponding to that location. MCPL (Monte Carlo Particle List) is a binary file format used for particle physics simulations. This type of file is a list recording particle state information, which can be easily stored and cross-applied between different Monte Carlo simulation applications. By decoupling the HD spectrometer front-end and back-end, the neutron beam data of a specific energy exported from the second slit (Slit2) can be used as the incident neutron data during downstream and sample scattering. This eliminates the need to repeatedly simulate the path of neutrons from the neutron moderator surface to the second slit (Slit2) when performing virtual scattering experiments with the same incident energy, significantly reducing the computational burden of virtual scattering experiments with the same incident energy.

[0105] In some embodiments, constructing a sample environment model for the target scattering spectrometer includes:

[0106] The physical process of the sample environment material is defined by the NCrystal_process component, and the geometry of the sample environment is defined according to the preset geometry component to complete the construction of the sample environment model.

[0107] Specifically, the NCrystal_process component is used to define the physical processes of the sample environment material. While other components in McStas can be used to define physical processes, such as Incoherent_process, Single_crystal_process, and Powder_process, these typically only define a single physical process. In contrast, the NCrystal_process component integrates multiple physical processes, including coherent scattering, incoherent scattering, elastic scattering, and inelastic scattering, making it suitable for various materials such as crystalline powders, mosaic single crystals, layered single crystals, amorphous solids, and liquids. Furthermore, the NCrystal_process component also supports multiphase materials or isotope-enriched materials. When defining object properties using the NCrystal_process component, the multiple definable physical processes can be flexibly enabled and disabled, allowing users to eliminate other interferences and study specific combinations of physical processes. Currently, the sample environment enclosures on HD spectrometers are all composed of Al, with the corresponding material definition as follows:

[0108] COMPONENTAl_process=NCrystal_process(

[0109] cfg="Al_sg225.ncmat;density=1x;temp=25C;elas=1;inelas=auto")

[0110] AT(0,0,0)ABSOLUTE

[0111] Al_sg225.ncmat comes from the virtual material library included with the McStas software. It contains information on the crystal structure and lattice dynamics of Al materials. The density parameter defines the tightness of the material, the temp parameter defines the ambient temperature, elas=1 indicates that the elastic scattering process is enabled during the simulation, including elastic coherent scattering and elastic incoherent scattering processes, and inelas=auto indicates that the most suitable inelastic scattering process contained in the Al_sg225.ncmat file is automatically selected when performing a simulated neutron scattering experiment.

[0112] In some embodiments, after defining the physical processes of the material, the material is constructed using the following statement:

[0113] COMPONENTAl_material=Union_make_material(

[0114] process_string="Al_process_NCrystal")

[0115] AT(0,0,0)ABSOLUTE

[0116] In some embodiments, the sample environment and sample geometry need to be defined using geometric components such as Union_cylinder, Union_cone, Union_sphere, and Union_box. Taking a single-layer aluminum shield as an example, the geometry of the sample environment is defined using the following statement:

[0117] COMPONENT sampleCan_solid=Union_cylinder(

[0118] radius = 0.05, yheight = 0.1,

[0119] priority=1,material_string="Al_material")

[0120] AT(0,0,0)RELATIVE sample_position

[0121] COMPONENT sampleCan_vacuum=Union_cylinder(

[0122] radius = 0.049, yheight = 0.1,

[0123] priority=2,material_string="Vacuum")

[0124] AT(0,0,0)RELATIVE sample_position

[0125] In the above statement, a solid Al cylinder with a radius of 5cm and a height of 10cm is first defined at the sample location, with a geometry priority value of 1. Then, a vacuum cylinder with a radius of 4.9cm and a height of 10cm is defined at the same location, with a geometry priority value of 2. The object with the higher priority value will cover the overlapping portion of itself and the object with the lower priority value. In this way, a model of a hollow aluminum cover with an outer diameter of 5cm, a height of 10cm, and a wall thickness of 1mm is constructed. Other types of sample environment geometry can be modeled using a similar method. Similarly, by defining the physical processes of the desired sample, the corresponding materials and geometry can be constructed and placed in the sample environment.

[0126] In some embodiments, after the geometric modeling statements are written, a Union_master component needs to be placed at the sample location to inform the program that the simulation of neutron scattering with specific physical processes of the Union geometric model can begin at this location. It is worth noting that the ray tracing technology used in McStas software means that during the numerical simulation, whenever the program advances to a component, neutrons will immediately interact with that component (e.g., through penetration, scattering, absorption, reflection, etc.). However, when components from the Union function are used to build materials and geometry in the program, during the numerical simulation, when the program advances to such components, neutrons will not immediately interact with them. Instead, the material and geometry construction operations will continue until the program advances to the Union_master component, at which point neutrons will interact with the specific physical processes of the previously written (Union_master) geometric model. This is defined using the following statement:

[0127] COMPONENT sampleMantid=Union_master()

[0128] AT(0,0,0)RELATIVE sample_position

[0129] In some embodiments, the detector array model includes multiple detector modules, and the construction process of the detector modules includes:

[0130] The position and orientation of the detector module are defined based on the position and orientation of the actual detector corresponding to the Arm component and detector module. Modeling is then performed based on the module parameters of the PSD_monitor_TOF component and the actual detector to complete the construction of the detector module. The actual detector is the detector inside the target scattering spectrometer.

[0131] Specifically, after neutrons are scattered by the sample environment and the sample itself, a detector is needed to intercept the scattered neutrons and record the pixel number (id) and time of flight (TOF) of the detector module to which the neutrons arrive. This can be achieved in the McStas software using the PSD_monitor_TOF component. The detector inside the HD spectrometer's scattering cavity currently consists of 14 3He tube modules, each containing 8 vertically arranged 3He tubes. The 3He tubes in the modules above and below the beam dump are 1.2m long, while those in the remaining modules are 3m long. Each pixel is 1cm high vertically, with a time resolution of 8μs. The detector is positioned around the sample center at a radius of R = 2500mm, achieving a horizontal detection angle coverage of -30° to 60°. To reduce crosstalk between neutron signals in adjacent detection areas, modules are grouped into sets of three, with a 3m high, 10mm thick boron carbide ceramic partition installed between each two sets. In virtual neutron scattering experiments, neutron signals from different modules do not interfere with each other. However, to closely approximate reality, the positional spacing between modules to accommodate the boron carbide ceramic spacers is still considered when modeling the detector. Therefore, the actual positions and orientations of each detector module were measured. Furthermore, the aforementioned time resolution is explained as follows: time resolution refers to the resolvable time span, which can be understood as the accuracy of recording the time of an event. For example, the recording of historical event times can be accurate to the year, month, day, and hour; the recording of sports performance can be accurate to the minute, second, and microsecond. In this embodiment, the timestamps of neutron events are recorded with an accuracy of 8 μs. That is, the detector considers the neutron signals captured within each 8 μs time period as captured at the same moment, merges these neutron events into a single neutron event, and adds the probability weights of these neutron events. The higher the time resolution, the more accurate the timestamps of neutron events, but the higher the requirements for hardware data processing and storage capabilities.

[0132] In some embodiments, taking detector module 01 as an example, the displacement vector of its center position from the sample center is (1.33704, 0, 2.11444), in meters. The angle between the line connecting its center and the sample center and the z-axis is 30.19°. Therefore, its modeling statement is as follows:

[0133] COMPONENT module01_position=Arm()

[0134] AT(1.33704,0,2.11444)RELATIVE sample_position

[0135] ROTATED(0,30.19,0)RELATIVE sample_position

[0136] COMPONENT module01=PSD_monitor_TOF(

[0137] xwidth=0.2112,yheight=3,nx=8,ny=300,

[0138] tmin=0,tmax=40000,nt=5000,restore_neutron=1)

[0139] AT(0,0,0)RELATIVE module10101_position

[0140] The module center was modeled using the Arm component. After determining its position and orientation, the first detector module was modeled using the PSD_monitor_TOF component at its center. The overall width of the module is 0.2112m and the height is 3m. Since the module contains 8 vertically arranged 3He tubes, the number of pixels in the horizontal direction is nx = 8. Since each pixel in the vertical direction of the 3He tube is 1cm high, the number of pixels in the vertical direction is ny = 300. Because the China Spallation Neutron Source (CSNS) uses a 25Hz source frequency, each neutron pulse lasts for 40,000 μs. For the detector, the effective detection time period is tmin = 0 and tmax = 40,000. nt = 5000 corresponds to a time resolution of 8 μs. Here, nt is the number of times the detector pixel timestamps the captured neutron signal within the total time period. Since 40,000 μs / 5000 = 8 μs, nt = 5000 tells the detector module to timestamp the neutron signal every 8 μs. The modeling method for the remaining detector modules is similar to that of module 01, and will not be elaborated here.

[0141] In some embodiments, McStas software is used when constructing the scattering front-end model, sample environment model, and detector array model, while Mantid software is used when performing data reduction after obtaining the simulation experimental results. Since Mantid software can handle data in the NeXus format, which is commonly used for neutron, X-ray, and muon scientific research data, its underlying layer is an HDF (Hierarchical Data Format) binary data file format that supports cross-platform reading. All data from a single experiment are stored in the same file and are distinguished by different "groups" and "datasets". Since this embodiment combines two steps—performing a virtual neutron scattering experiment using McStas software and reducing the results of the scattering experiment using Mantid software—it is necessary to enable McStas software to output virtual scattering experiment results in NeXus format. Therefore, when running the virtual scattering experiment code, the `--format=NeXus` option is added: `mcrun myVertualExperiment.instr --format=NeXus`. In this way, the experimental simulation results can be obtained and saved in a file named `mccode.h5`.

[0142] In some embodiments, the geometric information of the HD spectrometer first needs to be written into an XML-formatted Instrument Definition File (IDF) before it can be read by the Mantid software to reduce the neutron scattering data. Therefore, the IDF needs to include the orientation and position of the neutron moderator, sample, and detector. It also needs to specify the size, number of pixels, and arrangement of the detector module. The modeling statement for the IDF is as follows:

[0143] First, the sample's position is typically defined as the origin. Taking the HD spectrometer as an example, the neutron moderator position is defined as -18m on the z-axis:

[0144] <componenttype="sourceMantid-type"name="sourceMantid">

[0145] <locationx="0"y="0"z="-18.0" / >

[0146]

[0147] <componenttype="sampleMantid-type"name="sampleMantid">

[0148] <location x="0"y="0"z="0" / >

[0149]

[0150] Regarding the definition of the detector, taking detector module 01 as an example, its definition statement is as follows:

[0151] <type is="rectangular_detector"name="panel"type="pixel"xpixels="8"xstep="0.0264"xstart="-0.1848"ypixels="300"ystep="0.01"ystart="0" / >

[0152] <componenttype="panel"idfillbyfirst="y"idstart="0"idstepbyrow=

[0153] 300

[0154] <location name="module01"x="1.33704"y="-1.495"z="2.11444">

[0155] <rot val="30.19"axis-x="0.0"axis-y="1.0"axis-z="0.0" / >

[0156]

[0157]

[0158] The above definition statement first defines a class named `panel`, which declares that the number of pixels in the detector module's pixel array in the x and y dimensions are 8 and 300 respectively, and that the size of each pixel is 2.64 × 1 cm². Then, based on the `panel` class, the geometric information of detector module 01 is defined, including the pixel arrangement, ID numbering method, position, and orientation. It can be seen that the detector module pixels are preferentially arranged and filled along the y-direction, with numbering starting from 0. The definition method of the remaining detector modules is similar to that of detector module 01, and will not be repeated here.

[0159] Please refer to Figure 5 In some embodiments, after step S40: using the detector array model to intercept the neutron after the scattering experiment and generating the scattering simulation result of the neutron, the neutron scattering experiment simulation method further includes steps S41 to S44, which are described in detail below.

[0160] Step S41: Obtain the second probability weights of all pixels of each detector module in the scattering simulation results for the neutrons captured during the target flight time, and construct the first matrix based on the second probability weights.

[0161] Specifically, the second probability weights of all pixels of each detector module captured neutrons during the target flight time are read from the scattering simulation results, and a first matrix workspace is created based on the second probability weights. The horizontal axis of the first matrix is ​​the target flight time, which is divided into time intervals. The target flight time after the time intervals are used as the horizontal axis, and the vertical axis is the ID of the pixel of each detector module. Then, each value in the first matrix represents the sum of the probability weights of all neutrons captured by the pixel of the detector module within a certain time interval.

[0162] Please refer to Figure 6The target flight time is 0-40000 μs, with an 8 μs time interval. Each value in the first matrix represents the sum of probability weights for all neutrons captured by a pixel of the detector module within a given 8 μs time interval. For example, when pixel ID is 24367, the sum of probability weights for all neutrons captured within a 5644 μs time interval is 0.0; when pixel ID is 24368, the sum of probability weights for all neutrons captured within a 5644 μs time interval is 1.22930258 × 10⁻⁶. -10 .

[0163] Step S42: Obtain the instrument definition file of the target scattering spectrometer, and convert the first matrix into the second matrix according to the instrument definition file.

[0164] Specifically, the LoadInstrument function is called to read the instrument definition file of the target scattering spectrometer. Simultaneously, the ConvertUnits function is called to convert the first matrix, in units of target time-of-flight, into a second matrix, in units of energy transfer. The detector module contains multiple pixels, and the instrument positioning file includes the location of the sample and the pixel positions of the detector module. Please refer to [reference needed]. Figure 7 Step S42: Convert the first matrix into the second matrix according to the instrument definition file, including steps S421 to S424, which are explained in detail below.

[0165] Step S421: Calculate the displacement vector between the position of the pixel of each detector module and the position of the sample.

[0166] Specifically, since the position of the sample and the position of the pixels in each detector module are defined in the instrument definition file, the displacement vector between the position of the pixels in each detector module and the position of the sample can be calculated. The displacement vector contains two key pieces of information: distance and pointing angle.

[0167] Step S422: For each pixel of the detector module, calculate the corresponding neutron velocity based on the pixel's displacement vector and neutron flight time.

[0168] Specifically, for each pixel of the detector module, the velocity of the neutron can be obtained by dividing the distance length of its corresponding displacement vector by the recorded flight time of the neutron.

[0169] Step S423: Calculate the arrival energy of the neutron based on the neutron velocity and the preset energy calculation formula, and calculate the corresponding energy transfer based on the arrival energy and the incident energy of the neutron.

[0170] Specifically, according to the preset energy calculation formula E f =m n v 2The arrival energy E of the neutron when it reaches a pixel in the detector module is calculated. f m n This represents the neutron mass, with a value of 1.675 × 10⁻⁶. -24 g and v represent the neutron velocity. Energy transfer E = E i -E f E i This represents the incident energy, E. i Given the energy of the monoenergetic neutron obtained by the combination of T0, T1, T2 and the Fermi chopper, it can be known that the energy transfer E is the energy exchange between the neutron and the sample when the neutron is scattered.

[0171] Step S424: Replace the target flight time in the first matrix with energy transfer to obtain the second matrix.

[0172] Specifically, the target flight time, which serves as the horizontal axis in the first matrix, is replaced with energy transfer to obtain a second matrix with energy transfer E as the horizontal axis.

[0173] Step S43: Calculate the scattering angle of each pixel in the detector module based on the first matrix, and calculate the momentum transfer of the neutrons captured on the pixels of the detector module according to the scattering angle.

[0174] Specifically, the `CorrectKiKf` function is called, and the pixel IDs of the detector modules in the first matrix are used to calculate the scattering angle θ of each detector module's pixel location relative to the sample location. Then, the momentum transfer of the neutron is calculated based on the scattering angle θ and the momentum transfer formula. The momentum transfer formula is |Q|=√(k i 2 +k f 2 -2k i k f cosθ), where k i and k f These are the wave vectors of the incident neutron (before scattering from the sample) and the emitted neutron (after scattering from the sample), respectively. v i and v f Let be the velocity vectors of the incident neutron and the emitted neutron. is the reduced Planck constant.

[0175] Step S44: Construct a momentum transfer-energy transfer diagram based on the energy transfer and momentum transfer in the second matrix, and perform experimental analysis on the scattering experiment based on the momentum transfer-energy transfer diagram to obtain the experimental analysis results.

[0176] Specifically, the SaveNXSPE function is called to output the energy transfer E and momentum transfer Q from the second matrix as dynamic structure factor data format, which can be used by neutron scattering experiment data analysis software to plot Q (momentum transfer)-E (energy transfer) diagrams. The output file records the neutron intensities corresponding to different (Q,E) coordinates in ASCII text format. Further, based on the recorded data, momentum transfer-energy transfer diagrams are plotted to perform experimental analysis on the scattering experiment, yielding the experimental analysis results.

[0177] In some embodiments, an example is shown to demonstrate the feasibility of the numerical simulation and data reduction methods described above, which is explained in detail below.

[0178] When upgrading the cryogenic sample environment of the HD spectrometer, it is necessary to estimate the effect of reducing the aluminum shield thickness on background reduction. The aluminum shield has an inner diameter of 100 mm and a height of 120 mm, with an original wall thickness of 0.89 mm. To reduce the background, the sample environment team proposed reducing the aluminum wall thickness of the two regions projected onto the cylinder from the 60×60 mm² square window at the beam center to 0.2 mm. To simulate the effect of this design on background reduction, the sample environment was modeled using the method described in step S30, simulating four scenarios: 1) the original design, i.e., a wall thickness of 0.89 mm; 2) a case where the wall thickness of the aluminum shield at the beam window position on one side was reduced to 0.2 mm, serving as a control group; 3) the improved design proposed by the sample environment team, i.e., a case where the wall thickness of the aluminum shield at both the front and rear beam window positions was reduced to 0.2 mm; 4) a design where the wall thickness of the entire aluminum shield was reduced to 0.2 mm, serving as a control group. In the simulation, the most commonly used neutron incident conditions for HD spectrometers were first selected: a Slit2 aperture size of 30mm × 30mm, an incident neutron energy of 70.4meV, and a Fermi chopper rotation frequency of 400Hz. Then, the elas option in NCrystal_process was set to 0, allowing neutrons to undergo only inelastic scattering on the aluminum material, and the ambient temperature was set to 300K. The simulation results are as follows. Figure 8 As shown, the inelastic scattering background of the single-sided beam window thinning scheme (condition 2) is 37.76% lower than the original design (condition 1); while when both the front and rear beam windows of the aluminum cover are thinned (condition 3), the inelastic scattering background is 78.39% lower than that of condition 1, which is a very significant effect; in contrast, the effect of the scheme of completely thinning the thickness of the entire aluminum cover (condition 4) is the same as that of condition 3, indicating that thinning the 60×60mm2 projection area of ​​the beam center of the aluminum cover can achieve the best effect without risking a reduction in structural strength by reducing the thickness of the entire aluminum cover.

[0179] In the above simulation, the only material used is Al. Therefore, the simulation results can be reduced using Mantid software, and then a QE plot can be plotted and compared with the actual experimental results. The elas option in NCrystal_process is set to 1 (inelas is left at auto) so that Al in the model includes both elastic and inelastic scattering processes, and Case 1 is simulated again. Then, using the methods described in steps S41 to S44, the simulation data is imported into Mantid software to obtain the diffraction ring distribution of the simulation data on the detector (e.g., Figure 9 (As shown). In Figure 9 In the image, each long, thin rectangle represents a detector module. As mentioned earlier, the HD spectrometer detectors are actually installed in groups of three, with a 3m high, 10mm thick boron carbide ceramic partition separating each two groups. This is reflected in... Figure 9 The relatively large gaps between every three detector modules indicate that our model construction is close to reality. The data was then reduced in Mantid software, exported in NXSPE format, and QE plots were generated using DAVE software, with comparisons made to the measured data. Please refer to [link / reference]. Figure 10 This represents the simulated QE plot of sub-scattering in the Al sample environment. Please refer to [reference needed]. Figure 11 The figure represents the QE diagram of an actual experimentally measured Al powder sample. It can be seen that the simulated elastic and inelastic scattering peak positions precisely match the measured results. Figure 11 Traces of phonon dispersive spectra can be seen in the inelastic scattering signal, while Figure 10 No similar dispersion relation appears in the non-elastic scattering signal.

[0180] This application aims to propose a method for simulating and determining the physical conditions required for inelastic neutron scattering experiments in advance, based on the physical design of a high-energy inelastic neutron scattering spectrometer. This reduces the frequency of on-site experimental setup adjustments, minimizes the waste of valuable time, improves experimental efficiency, and alleviates the workload of spectrometer scientists. After conducting the virtual neutron scattering experiment, data reduction can be performed on the experimental results. The virtual neutron scattering experiment is implemented using the McStas Monte Carlo neutron ray tracing software package, while data reduction is achieved using the Mantid instrument data manipulation and analysis toolkit. By combining neutron scattering numerical simulation methods and data reduction methods, a virtual experiment and its analysis method for high-energy inelastic neutron scattering spectrometers are developed. This allows the optimal settings for some experiments to be determined in a relatively low-time-cost manner before the actual experiment, alleviating the current shortage of spectrometer experimental time. Simultaneously, the results of the virtual experiment can also serve as a reference for the actual experimental results, providing corroboration for the correctness of the actual experimental results. In summary, by combining virtual neutron scattering experiments and data reduction based on a high-energy inelastic neutron scattering spectrometer, it is possible to know in advance whether the experimental design (incident energy, temperature, magnetic field strength) on the high-energy inelastic neutron scattering spectrometer is suitable, thus reducing the wasted time in actual experiments. Furthermore, the equipment and software required for the virtual scattering experiment method and data reduction method proposed in this application are readily available. The equipment consists of a computer with at least 16GB of memory, and the software consists of the open-source software McStas and Mantid. The method is relatively simple to implement and can save a significant amount of experimental exploration time.

[0181] Please refer to Figure 12 In some embodiments, this application provides a neutron scattering experiment simulation device, including a scattering front-end model construction module 10, a data acquisition module 20, a detector array model construction module 30, and an experiment simulation module 40, which are described in detail below.

[0182] The scattering front-end model construction module 10 is used to construct the scattering front-end model of the target scattering spectrometer; wherein, the scattering front-end model includes a neutron moderator and a slit.

[0183] The data acquisition module 20 is used to simulate the motion of neutrons with different incident energies from the neutron moderator to the slit, and to extract neutron beam data during the motion process.

[0184] The detector array model construction module 30 is used to construct the sample environment model and detector array model of the target scattering spectrometer; wherein, the sample environment model contains a sample.

[0185] The experimental simulation module 40 is used to conduct scattering experiments based on neutron beam data with selected incident energy, sample environment model, and sample. It uses a detector array model to intercept neutrons after the scattering experiment and generate scattering simulation results for the neutrons.

[0186] In some embodiments, the scattering front-end model further includes a neutron conduit, a disk chopper, and a Fermi chopper; the neutron moderator is constructed using the SNS_source component and preset parameters, including the surface size of the neutron moderator, the distance between the neutron moderator and the entrance of the neutron conduit, and the neutron energy range of the target scattering spectrometer; the neutron conduit is constructed using the Guide component, and is divided into a first part and a second part, the first part being an elliptical neutron conduit and the second part a conical neutron conduit; the disk chopper is constructed using the DiskChopper component, and is located at a preset distance from the center of the neutron moderator; the Fermi chopper is constructed using the FermiChopper component, and includes a straight-channel absorber filled with Gd2O3 neutron absorbing material; the slit is constructed using the Slit component, and the scattering front-end model has a first slit and a second slit, the distance between the second slit and the surface of the neutron moderator being greater than the distance between the first slit and the surface of the neutron moderator.

[0187] In some embodiments, an MCPL_output component is provided at the exit position of the second slit; the data acquisition module 20 is also used to simulate the motion process of neutrons with different incident energies from the neutron moderator to the slit, and to extract neutron beam data during the motion process, including:

[0188] The MCPL_output component is used to acquire neutron beam data of neutrons with different incident energies during their motion from the neutron moderator to the second slit. The neutron beam data includes the incident energy, position, velocity, flight time, and first probability weight of the neutrons. The first probability weight is the ratio of the total number of neutrons reaching the second slit to the total number of neutrons emitted from the neutron moderator.

[0189] In some embodiments, the detector array model building module 30 is used to build a sample environment model of the target scattering spectrometer, including:

[0190] The physical process of the sample environment material is defined by the NCrystal_process component, and the geometry of the sample environment is defined according to the preset geometry component to complete the construction of the sample environment model.

[0191] In some embodiments, the detector array model includes multiple detector modules, and the detector array model construction module 30 is further used to construct the detector modules. The construction process of the detector modules includes:

[0192] The position and orientation of the detector module are defined based on the position and orientation of the actual detector corresponding to the Arm component and the detector module. The model is then built based on the module parameters of the PSD_monitor_TOF component and the actual detector to complete the construction of the detector module. The actual detector is the detector inside the target scattering spectrometer.

[0193] This application provides a neutron scattering experiment simulation device, including:

[0194] Memory, used to store programs;

[0195] A processor is used to implement a neutron scattering experiment simulation method by executing a program stored in memory.

[0196] This application provides a computer program product, including a computer program and / or instructions, which, when executed by a processor, implement a method for simulating neutron scattering experiments.

[0197] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0198] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A method for simulating neutron scattering experiments, characterized in that, include: Construct a scattering front-end model for the target scattering spectrometer; wherein the scattering front-end model includes a neutron moderator and a slit; The motion process of neutrons with different incident energies from the neutron moderator to the slit is simulated, and neutron beam data during the motion process is extracted; Construct a sample environment model and a detector array model for the target scattering spectrometer; wherein, the sample environment model includes a sample. A scattering experiment is conducted based on the neutron beam data of the selected incident energy, the sample environment model, and the sample. The neutrons after the scattering experiment are intercepted using the detector array model, and the scattering simulation results of the neutrons are generated.

2. The neutron scattering experiment simulation method as described in claim 1, characterized in that, The scattering front-end model further includes a neutron conduit, a disk chopper, and a Fermi chopper. The neutron moderator is constructed using the SNS_source component and preset parameters, including the surface size of the neutron moderator, the distance between the neutron moderator and the entrance of the neutron conduit, and the neutron energy range of the target scattering spectrometer. The neutron conduit is constructed using the Guide component, and is divided into a first part and a second part. The first part is an elliptical neutron conduit, and the second part is a conical neutron conduit. The disk chopper is constructed using the DiskChopper component, and is located at a preset distance from the center of the neutron moderator. The Fermi chopper is constructed using the FermiChopper component, and includes a straight-channel absorber filled with Gd₂O₃ neutron absorbing material. The slit is constructed using the Slit component, and the scattering front-end model has a first slit and a second slit, with the distance between the second slit and the surface of the neutron moderator being greater than the distance between the first slit and the surface of the neutron moderator.

3. The neutron scattering experimental simulation method as described in claim 2, characterized in that, An MCPL_output component is provided at the exit position of the second slit; the simulation of the motion process of neutrons with different incident energies from the neutron moderator to the slit, and the extraction of neutron beam data during the motion process, includes: The MCPL_output component acquires neutron beam data of neutrons with different incident energies during their motion from the neutron moderator to the second slit; wherein the neutron beam data includes the incident energy, position, velocity, flight time of the neutrons, and a first probability weight, the first probability weight being the ratio of the total number of neutrons reaching the second slit to the total number of neutrons emitted from the neutron moderator.

4. The neutron scattering experimental simulation method as described in claim 1, characterized in that, Constructing the sample environment model of the target scattering spectrometer includes: The physical process of the sample environment material is defined by the NCrystal_process component, and the geometry of the sample environment is defined according to the preset geometry component to complete the construction of the sample environment model.

5. The neutron scattering experimental simulation method as described in claim 1, characterized in that, The detector array model includes multiple detector modules, and the construction process of the detector modules includes: The position and orientation of the detector module are defined based on the position and orientation of the Arm component and the actual detector corresponding to the detector module, and modeling is performed based on the module parameters of the PSD_monitor_TOF component and the actual detector to complete the construction of the detector module; wherein, the actual detector is the detector inside the target scattering spectrometer.

6. The neutron scattering experimental simulation method as described in claim 5, characterized in that, After intercepting the neutrons after the scattering experiment using the detector array model and generating the scattering simulation results of the neutrons, the neutron scattering experiment simulation method further includes: Obtain the second probability weights of all pixels in each detector module captured by neutrons during the target flight time in the scattering simulation results, and construct a first matrix based on the second probability weights; wherein the first matrix has the target flight time as the horizontal axis; Obtain the instrument definition file of the target scattering spectrometer, and convert the first matrix into a second matrix according to the instrument definition file; wherein, the second matrix uses energy transfer as the abscissa; The scattering angle of each pixel in the detector module is calculated based on the first matrix, and the momentum transfer of the neutrons captured on the pixel of the detector module is calculated based on the scattering angle. Based on the energy transfer and momentum transfer in the second matrix, a momentum transfer-energy transfer diagram is constructed, and the scattering experiment is analyzed based on the momentum transfer-energy transfer diagram to obtain the experimental analysis results.

7. The neutron scattering experimental simulation method as described in claim 6, characterized in that, The detector module contains multiple pixels, and the instrument positioning file includes the position of the sample and the position of the pixels of the detector module; The step of converting the first matrix into a second matrix according to the instrument definition file includes: Calculate the displacement vector between the position of each pixel in the detector module and the position of the sample; For each pixel of the detector module, the corresponding neutron velocity is calculated based on the pixel's displacement vector and neutron flight time. The arrival energy of the neutron is calculated based on the neutron velocity and the preset energy calculation formula, and the corresponding energy transfer is calculated based on the arrival energy and the incident energy of the neutron. The target flight time in the first matrix is ​​replaced with energy transfer to obtain the second matrix.

8. A neutron scattering experimental simulation device, characterized in that, include: A scattering front-end model construction module is used to construct a scattering front-end model of the target scattering spectrometer; wherein, the scattering front-end model includes a neutron moderator and a slit; The data acquisition module is used to simulate the motion process of neutrons with different incident energies from the neutron moderator to the slit, and to extract neutron beam data during the motion process; The detector array model construction module is used to construct the sample environment model and detector array model of the target scattering spectrometer; wherein, the sample environment model includes a sample. The experimental simulation module is used to conduct a scattering experiment based on the neutron beam data of the selected incident energy, the sample environment model, and the sample. It uses the detector array model to intercept the neutrons after the scattering experiment and generate the scattering simulation results of the neutrons.

9. A neutron scattering experimental simulation device, characterized in that, include: Memory, used to store programs; A processor for implementing the neutron scattering experiment simulation method as described in any one of claims 1-7 by executing a program stored in the memory.

10. A computer program product comprising a computer program and / or instructions, characterized in that, When the computer program and / or instructions are executed by the processor, they implement the neutron scattering experimental simulation method as described in any one of claims 1-7.

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