Development of Thermal Neutron Spin-Echo Spectroscopy

热中子自旋回波光谱学的发展

• 批准号: 06452053
• 负责人: KAKURAI Kazuhisa
• 金额: $ 4.22万
• 依托单位: Institute for Solid State Physics(ISSP), The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06452053/
• 关键词: Inelastic neutron scattering; Spin-echo spectroscopy; Phase transition; Collective excitations; ダイナミックス; 中性子散乱; スピンエコー実験法; 集団励起寿命

The aim of this development is to improve the energy resolution of a conventional thermal neutron triple axis spectrometer to relative values of 10^<-4> of the incident neutron energy E_i or better by means of the Neutron Spin Echo method.For this purpose special Larmor precession magnets with "Optimal Field Shape" (OFS) have been developed and constructed.Following the analytical solution of the variational field-inteqral homogeneity problem, such magnets are the best compromise for homogeneous line integrals and low fringe-fields, The residual line integral inhomogeneities of the magnets and the path length effects due to the relatively large beam divergence are corrected by in-beam spiral coils, spark-erosion cut from Aluminum plates.The OFS coils are designed to reach a maximum field integral of 0.06Tm corresponding to a Fourier time of 0.16 nanosec at an incident neutron energy of 14.7meV.Apectral resolution of -0.2 mueV is obtained, to be compared to 2.2 meV for the same TAS conf … More iguration without Spin Echo.This Triple Axis Spectrometer with Spin Echo (TASSE) option can be installed on the conventional triple axis instrument in one and half day time.The spin echo polarisation is fully maintained when the momentum transfer is changed up to the maximum spectrometer values of Q-3.6 *^<-1>.The intensity loss factor of 50 due to the introduction of polarisers and increased distances is to be compared with the resolution gain factor of approximately 10^4.The performance of this new, high resolution TASSE option is demonstrated using the experimental data obtained on the quasielastic diffuse scattering near the order-disorder phase transition in KDCO_3.Here the first evidence for a dynamical Huang scattering has been obtained which may be viewed as a characteristic of a strain field mediated order-disorder phase transition.Furthermore the spin density wave in Chromium have been investigated as an example of antiferromagnetic spin echo experiment.The experiment on SrTiO_3 has been performed, where the problem of the central component' is reinvestigated using the thermal neutron spin echo spectroscopy.Preliminary results on finite energy transfer spin echo at DELTAE-6meV phonon mode in SrTiO_3 have been also obtained. Less

本文旨在利用中子自旋回波方法，将常规热中子三轴谱仪的能量分辨率提高到入射中子能量E_i的10%或更高。为此，我们研制了具有“最佳场形”（OFS）的特殊Larmor旋进磁体。根据变场-积分均匀性问题的解析解，这种磁体是均匀线积分和低边缘场的最佳折衷<-4>。磁体的剩余线积分不均匀性和由于相对大的束发散引起的路径长度效应通过束内螺旋线圈来校正，火花-OFS线圈被设计为达到0.06Tm的最大场积分，对应于0.16纳秒的傅立叶时间，入射中子能量为14.7meV，谱分辨率为-0.2 μ eV，与相同TAS条件下的2.2meV谱分辨率相比 ...更多信息 无自旋回波的三轴光谱仪。这种带自旋回波的三轴光谱仪（TASSE）选件可以在一天半的时间内安装在传统的三轴仪器上。当动量传递改变到最大光谱仪值Q-3.6 *^时，自旋回波偏振完全保持不变<-1>。由于引入偏振器和增加距离而导致的强度损失因子为50，将与分辨率增益因子约为10^4。这种新的，利用KDCO_3中有序-无序相变附近的准弹性漫散射实验数据，证明了高分辨率TASSE方案。作为反铁磁自旋回波实验的一个例子，我们还研究了Cr中的自旋密度波，并对SrTiO_3进行了实验，用热中子自旋回波谱重新研究了中心分量的问题，并对有限能量转移自旋回波谱的初步结果进行了讨论在SrTiO_3中也得到了Δ E-6 meV声子模。少

项目成果

C.M.E.Zeyen et al.: "Spin-echo three-axis spechomefer : A reality" J.of Neuhm Research. (発表予定).

C.M.E.Zeyen 等人：“自旋回波三轴光谱仪：现实”J.of Neuhm Research（待出版）。

C.M.E.Zeyen et al.: "Therrnal neudron spin echo three-axis spechaneten with μeV resolution" Neuhon News. (発表予定).

C.M.E.Zeyen 等人：“具有 μeV 分辨率的热中子自旋回波三轴光谱”Neuhon News（即将出版）。

K.Kakurai et al.: "Dynamics of the strain-mediated phase frausltion in KDCO_3 : A thermal neutron spin-echo study" Phys.Rev.B.Rapid Comm.

K.Kakurai 等人：“KDCO_3 中应变介导的相位断裂的动力学：热中子自旋回波研究”Phys.Rev.B.Rapid Comm。

R.Kanao et al.: "Deuferon self-trapped state and the skain-wediaked stuctmal phase fransition in KDCO_3" S.Phys.Soc.Japan.Lett.64. 2286-2289 (1995)

R.Kanao 等人：“KDCO_3 中的 Deuferon 自陷态和 skain-wediaked 结构相变”S.Phys.Soc.Japan.Lett.64。

C.M.E.Zeyen, K.Kakurai, M.Nishi, K.Nakajima, T.Sakaguchi, Y.Kawamura, S.Watanabe, M.Berneron, K.Sasaki and Y.Endoh: ""Thermal neutron spin echo three-axis, spectrometer with mueV resolution"" (In preparation for Neutron News.).

C.M.E.Zeyen、K.Kakurai、M.Nishi、K.Nakajima、T.Sakaguchi、Y.Kawamura、S.Watanabe、M.Berneron、K.Sasaki 和 Y.Endoh：“”热中子自旋回波三轴、能谱仪