DYNAMICS OF LATTICE STRAIN FIELD NEAR PHASE TRANSITION

该项目的目标是过渡期前晶格动力学的详细研究的热中子自旋回波光谱学的发展。由于这个目的是在ISSP-PONTA光谱仪上开发的热中子自旋回波选项得到了改进。（1） Spin echo test experiment using neutron wave length λ=1.609 has been performed。该波的长度将动态时间范围降低到7个picosec的最低限度，然后将7个到155个picosec的动态范围从两者使用1.609和2.35个波的长度中子。（2） Spin echo experiment at large Q=2.9. D1-1 D1 has been successfully performed。（3）梯度线圈的组合已被设计成构造和测试。这些线圈创建额外的中子自旋精密场整体组件依赖于中子光束内部的分裂中的中子飞行路径，并允许匹配自旋回波线的斜率到兴奋分化的斜率进行研究（自旋回波聚焦） ... More （g）2. Spin echo experiment at finite energy transfer and especially the use of above mented gradient coils demand the introduction of spin echo simulation program to plan and analyse the experiments。（1） Spin echo simulation program has been developed and is being tested。（2） The Phonononline width measurement in SrTiO3 has been analysed using the simulation program. 3.少数几个准热中子自旋回波实验已经被执行。（1）2-D中的慢自旋动力学，三角晶格系统CuFe D20.95型D2 Al型D20.05型D2 O型D22型D2已经研究，展示时刻在低T的时间尺度上的静态性质。（2） Larmor自旋精密相位的移位，靠近发射几何峰值的Ho在第一次观测到。（3）聚丁二烯的缓慢动力学在大Q=2.9铜铜D1-1已开始研究。在这个大Q的动力学中发现了T-依赖性比小Q沙发研究中的不同。Possible candidates to study the lattice distortions near phase transition with spin echo spectroscopy have been studied， especially the spin and lattice dynamics in the spin-Peierls system CuGeOイイD23イイD2 and the charge ordering system NaVイD22イD25イD2 have been studied。Less（低）

The aim of this project is the development of the thermal neutron spin echo spectroscopy for the detailed study of lattice dynamics near phase transition.1. For this purpose the newly developed thermal neutron spin echo option on ISSP-PONTA spectrometer has been improved.(1) Spin echo test experiment using neutron wave length λ=1.609Å has been performed. The use of this wave length pushes the lower limit of the dynamical time range down to 7 picosec, thus covering the dynamical range of 7 to 155 picosec by using both 1.609Å and 2.35Å wave length neutrons.(2) Spin echo experiment at large Q=2.9ÅィイD1-1ィエD1 has been successfully performed.(3) Pairs of gradient coils have been designed constructed and tested. These coils create additional neutron spin precession field integral component depending on the neutron flight paths within the divergence of the neutron beam and allow to match the slope of the spin echo line to the slope of the excitation dispersion to be studied (spin echo focussin … More g).2. Spin echo experiment at finite energy transfer and especially the use of above mentioned gradient coils demand the introduction of spin echo simulation program to plan and analyse the experiments.(1) Spin echo simulation program has been developed and is being tested.(2) The phonon line width measurement in SrTiO3 has been analysed using the simulation program.3. Few quasielastic thermal neutron spin echo experiments have been performed.(1) Slow spin dynamics in 2-D, triangular lattice system CuFeィイD20.95ィエD2AlィイD20.05ィエD2OィイD22ィエD2 has been studied, showing the static nature of the moment at low T in the time scale of 140 picosec.(2) Larmor spin precession phase shift near the magnetic satellite peak of Ho in transmission geometry has been observed for the first time.(3) Slow dynamics in Polybutadiene towards its glass transition at large Q=2.9ÅィイD1-1ィエD1 has been studied for the first time. The T-dependence of the dynamics at this large Q is found to be different than that of small Q sofar studied.4. Possible candidates to study the lattice distortions near phase transition with spin echo spectroscopy have been studied, especially the spin and lattice dynamics in the spin-Peierls system CuGeOィイD23ィエD2 and the charge ordering system NaVィイD22ィエD2OィイD25ィエD2 have been studied. Less