| Spin echo small angle neutron scattering(SESANS)technology has extracted extensive attention by the major neutron centers around the world,benefiting from its characters of wide scale range,high intensity,and free of multiple scattering.However,there is no such spectrometer and relative technology in China yet.SESANS can detect structures with size scale from nanometer to micron in real space.Moreover,it can avoid the limitation of small angle scattering technology(SANS)and ultra-small Angle scattering(USANS),such as the upper limit of the detection,the weak beam flux,and to decouple the resolution and flux.Recently,three major neutron sources have been developed in China.The standards of the three neutron centers are improved continuously,they played an increasingly important role in multi-disciplines.In order to enhance the influence of neutron science in China,new technologies such as SESANS are urgently needed.China Mianyang Research Reactor(CMRR)was officially operated in 2014,which has the advantage with technical of spectrometer instruction and polarization technology,etc.This thesis mainly introduces the construction of SESANS spectrometer at CMRR.On the one hand,the overall design of the spectrometer,which including how to optimize the design under the limitations of the of current objective conditions.How to reach the advanced level on the aspect of overall performance of the SESANS in the CMRR scattering hall.on the other hand,in order to achieve high standard of key spectrometer such as high neutron intensity and wide scale range,endeavors need to be conducted on the research and design of key parameters(size,uniformity,scale range)of key devices(magnetic field,permalloy film ? spin filliper)and the development of supporting technologies.Current thesis conducted the overall design of the spectrometer,the development of the key components such as the high uniformity magnetic field system and the high efficiency spin flippers.The main contents and conclusions are as follows:By investigating and comparing the main design parameters of the SESANS spectrometers around the world,as well as based on the characteristics and spectrum of the neutron source at CMRR,the structure of SESANS spectrometer is designed as with soft magnetic film as the spin flippers.It can achieve a spin echo length of no less than 20 ?m,which is better than that of the existing SESANS spectrometer.We established the model of SESANS spectrometer at CMRR with McStas.In order to obtain a higher neutron flux at the sample position and a smaller beam divergence,parameters such as the focusing radius of focusing monochromator,as well as the length,bending radius,and supermirror factor of the neutron polarizer were chosen carefully.The bending radius of the focusing monochromator was determined to be 2.7 m.Compromise parameters,namely,the length and radius of curvature of S-Bender were chosen as 300 mm and 2.0 m,respectively.The magnetic field system of SESANS spectrometer was designed and developed.The finite element simulation software was used to simulate the structure and size of the electromagnet and the distribution of magnetic field.In the process of the preparation for prototype device,optimization such as forced water cooling,multi-layer insulation at contact points,high-precision grinding machine,etc.were used to ensure that the magnetic field uniformity of the prototype could meet the requirements.The performance of the magnetic field of the prototype was tested.The results showed that within the range of 120 mm×20 mm×60 mm,the magnetic field homogeneity of the center area of the main magnetic field can reach 7×10-4 when the magnetic field intensity reached 2500 Gs.The performances meet the design indexes,exceeding the level of the same type of similar devices around the word(1800 Gs,while 1000 Gs for practice use).This thesis reports the first time the attempting to apply a multilayer structure metal film to a neutron spin flipper,which can be used under a main magnetic field of up to 2500 Gs.The magnetic properties and flatness were optimized from the aspects of parameter design and sample preparation.Magnetic films which meet the requirement were prepared.The feasibility of the metal multilayer films as spin flippers was verified by theoretical calculation.A test prototype for the film flippers was built and the neutron measurement were conducted,utilizing the TPNR spectrometer.The key component spin flipper is obtained.Moreover,the corresponding tests were also completed.The thickness of the soft magnetic film is 2.2 ?m.The effective size of the film is 140 mm×70 mm,which meets the requirements for the beam size of the SESANS.The thickness error of the soft magnetic film within the effective size is within 1%,and the saturation magnetic induction intensity of the film is 1.3 T.The experimental data shows that the efficiency of the spin flipper reaches 98%.During the construction of the spectrometer,we also developed a program(MyNeutronDAQ)for the spectrometer control,data acquisition,and analysis program.It provides technical guarantee for the SESANS spectrometer after the completion of the installation.The software is a graphical user interface(GUI)data acquisition and analysis program for parameter entry,batch mode management,and online analysis.MyNeutronDAQ has been successfully applied to several spectrometers at CMRR.Moreover,we also demonstrated the in-situ device and techniques for the existing spectrometer.All of these will provide solid technical support,both software and hardware,which guarantee the application of the SESANS spectrometer after its completion.In this thesis,the design and optimization of the SESANS spectrometer,the magnetic field system,and the spin flipper are introduced in detail.The conclusions will play a key role in the construction and later debugging of the spectrometer.The investigation on the corresponding instrument control,data analysis,and the in-situ sample environment device provides a strong guarantee for the later operation of the SESANS spectrometer. |
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