论文标题

向热波长延伸露丝光谱

Extending MIEZE spectroscopy towards thermal wavelengths

论文作者

Jochum, Johanna K., Franz, Christian, Keller, Thomas, Pfleiderer, Christian

论文摘要

我们提出了对高分辨率中子光谱的零努力(Mieze)设置的强度调节,最高可转移3Å$^{ - 1} $,能量转移高达〜20 MeV,并且使用热中子和冷中子都可以在$μ$ eV-Range中进行能量分辨率。与经典的中子旋转回声相比,Mieze具有两个突出的优势。第一个是可能在强磁场中研究自旋 - 污染样品或样品,而不会丧失信号振幅和强度。这允许研究铁磁体中的自旋波动,并促进了具有强旋转散射的样品的研究。第二个优点是可以以相对较小的努力来实现多分析仪设置。热中子的使用增加了自旋回波近似值对较短的自旋回波时间的有效性范围。反过来,用于更大范围(老虎)的热晕选项封闭了经典中子自旋回声光谱和常规高分辨率中子光谱技术(例如三轴,飞行时间和背部造成)之间的差距。为了说明老虎的可行性,我们通过额外的速度选择器,偏振器和分析仪在FRM II的Beamine Reseda上介绍了实现的详细信息。

We propose a Modulation of intensity with zero effort (MIEZE) set-up for high-resolution neutron spectroscopy at momentum transfers up to 3Å$^{-1}$,energy transfers up to ~ 20 meV, and an energy resolution in the $μ$eV-range using both thermal and cold neutrons. MIEZE has two prominent advantages compared to classical neutron spin-echo. The first one is the possibility to investigate spin-depolarizing samples or samples in strong magnetic fields without loss of signal amplitude and intensity. This allows for the study of spin fluctuations in ferromagnets, and facilitates the study of samples with strong spin-incoherent scattering. The second advantage is that multi-analyzer setups can be implemented with comparatively small effort. The use of thermal neutrons increases the range of validity of the spin-echo approximation towards shorter spin-echo times. In turn, the thermal MIEZE option for greater ranges (TIGER) closes the gap between classical neutron spin-echo spectroscopy and conventional high-resolution neutron spectroscopy techniques such as triple-axis, time-of-flight, and back-scattering. To illustrate the feasibility of TIGER we present the details of an implementation at the beamline RESEDA at FRM II by means of an additional velocity selector, polarizer and analyzer.

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