清華水池式反應器W-3 實驗站三維去極化中子束之建立

The setup of a 3-D neutron depolarization beamline at W-3 port of the Tsing-Hua Open Pool Reactor

張信豪(Hsin-Hao Chang)

指導教授 ： 李志浩

國立清華大學/原子科學院/工程與系統科學系/碩士(2009年)

https://doi.org/10.6843/NTHU.2009.00007

摘要

本論文的主題是在清華水池式反應器（THOR）W-3 實驗站建立 三維去極化中子束。三維去極化中子儀主要為觀察極化中子通過磁 性材料過程，受到內部磁區的擾動使得極化中子向量的方向和大小 改變，來進行分析後可以觀察出材料內部平均磁區大小、平均感應磁 場強度、磁區平均方向餘弦的平方。本論文將使用三維去極化中子儀 量測不同密度的鎳鐵氧磁體 (Ni-ferrite)的內部磁區大小和使用磁力 顯微鏡 (Magnetic Force Microscopy, MFM) 量測表面磁區的大小之 後，比較表面和內部磁區大小，實驗結果表面和內部磁區大小大致相 同大小約2 μm。此外，研究三維去極化中子儀的極化率無法提高的 原因，然後將影響極化率的原因解決之後，極化率提升到92 %。

關鍵字

三維去極化中子儀

並列摘要

A three-dimensional neutron depolarization beamline was commissioned in Tsing-Hua Open Pool Reactor (THOR). In this beamline, with the neutron depolarization technique, provides information of the mean domain size, the mean square direction cosine of the magnetic induction in the domains, and the mean magnetization of a magnetic sample. In this work, the surface magnetic domain and inner magnetic domain of Ni-ferrite samples with different densities are studied. The MFM results show the surface magnetic domain size is about 2 m, which is consistent with 2 m of inner magnetic domain size measured by depolarized neutron technique. In addition, the problems of improving the polarization ratio of neutron beamline were discussed. The final polarization factor of this beamline is 92%.

並列關鍵字

three-dimensional neutron depolarization

參考文獻

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