臺灣博碩士論文加值系統

本論文的目的是在清華水池式反應器（簡稱THOR）W3 實驗站建置去極化中子束(Neutron depolarization beamline)，用來進行磁性塊材內部磁特性之研究。實驗上，主要為觀察極化中子通過磁性材料後，其極化向量的變化來進行分析；從量測到的去極化因子(depolarization factor)及進動角度(precession angle)這兩個變數，可以觀察到材料內部平均磁區大小(mean domain size)、以及平均磁化感應強度(mean magnetic induction)。目前W3上的設備僅能進行一維中子極化之研究，未來將發展成為可進行三維研究的中子束線。

The purpose of this thesis is to construct a neutron depolarization (ND) beamline in the Tsing-Hua Open Pool Reactor (THOR) in order to measure the magnetic characteristics in the interior of magnetic materials. The ND experiments were carried out at W3 port of THOR (2 MW). The neutron beam with wavelength λ0 = 2.37 Å is chosen by graphite monochromator, and then polarized and analyzed by Heusler Cu2MnAl (111) crystals. The neutron polarization ratio of the beamline is about 82%. The depolarized neutrons were collected by a 3He detector. Four hundred neutron counts per second was achieved. A Ni75Fe25 sample was used to test the performance of this beamline. The measured depolarization factor is 0.789 and the procession angle is 2.61 rad, which imply the mean magnetic domain size is 34±7 μm and mean magnetic induction is 236.6 Oe has been investigated by ND technique in Ni75Fe25.

第一章 前 言 1
1.1介紹 1
第二章 研究動機 3
2.1目的 3
2.2緣起 3
第三章 實驗原理 6
3.1中子簡介及特性 6
3.2中子束分光原理 8
3.3 中子去極化原理 9
3.4其他量測磁區方式 11
3.4.1畢德法(Bitter Method) 11
3.4.2磁力顯微鏡(Magnetic Force Micoroscopy,MFM) 13
第四章 實驗元件原理及特性 16
4.1中子濾過器 17
4.2中子極化器 18
4.2.1穿透式極化過濾器 18
4.2.2磁性鏡面全反射方式 21
4.2.3磁單晶布拉格反射方式 21
4.3 中子磁矩翻轉器 23
4.4偵檢器 25
4.5導磁盒 26
第五章 儀器架設及實驗步驟 29
第六章 實驗數據及討論 32
6.1 初步測試 32
6.1.1直射光設定 32
6.1.2 極化中子測試 33
6.2 Ni75Fe25去極化中子實驗 34
6.2.1 磁滯曲線量測 35
6.2.2 去極化中子實驗 36
6.3 畢德法磁區量測實驗 42
6.4 實驗結果討論 44
第七章 展望與建議 48
7.1 THOR-W3目前實驗狀況 48
7.2 展望與建議 49
第八章 結 論 51
參考文獻
附錄 A

[1] O. Halpern, and T. Holstein, Phys. Rev. 59 (1941) 960.
[2] F. Bloch, M. Hamermesh, and H. Staub, Phys. Rev. 64(1943) 47
[3] R. Rosman and M. Th. Rekveldt, Phys. Rev. B 43 (1991) 8437
[4] S. J. Blundell and J. A. C. Bland, Phys. Rev. B 46 (1992) 3391
[5] I. E. Stamatelatos et al., Rev. Sci. Instrum. 71 (2000) 70.
[6] H. F. Nieman et al., Rev. Sci. Instrum. 51 (1980) 1299.
[7] S. Holmryd et al., Rev. Sci. Instrum. 40 (1969) 49.
[8] A. K. Freund et al., Nucl. Instrum. & Meth. Phys. Res. A 234 (1985) 116.
[9] L. Dobrzynski et al., Neutrons and Solid State Physics, Ellis Horwood (1994) 75.
[10] L. Dobrzynski et al., Neutrons and Solid State Physics, Ellis Horwood (1994) 14.
[11] W. Heil et al., Physica B 267&268 (1999) 328.
[12] P. Boni, Physica B 276 (2000) 6.
[13] P. Courtois, Physica B 267 (1999) 363.
[14] A. Delapalme et al., Nucl. Instrum. & Meth. 95 (1971) 589.
[15] L. Dobrzynski et al., Neutrons and Solid State Physics, Ellis Horwood (1994) 21.
[16] A. Schreyer’s speech contents in INER on Feb. (2001).
[17] E. Fermi et al., Phys. Rev. 71 (1947) 666.
[18] J. B. Hayter et al., J. Phys. E: Sci. Instrum. 11 (1978) 454.
[19] F. Mezei, Commun. Phys. 1 (1976) 81.
[20] G. P. Felcher, Phys. Rev. B 24 (1981) 1995.
[21] J. Penfold et al., J. Phys.: Condens. Matter 2 (1990) 1369.
[22] B. Farnoux, Proc. Conf. Neutron Scattering in the Nineties 1985 (Vienna:IAEA).
[23] G. P. Felcher, J. Appl. Phys. 87 (2000) 1.
[24] M. Born et al., Principles of Optics (1970) (Oxford: Pergamon).
[25] O. S. Heavens, Optical Properties of Thin Films (1955) (London:Butterworth).
[26] J. Lekner, Theory of Reflection (1987) (Dordrecht: Martinus Nijhoff).
[27] L. Dobrzynski et al., Neutrons and Solid State Physics, Ellis Horwood (1994) .
[28] J. R. Lamarsh, Intruduction to Nuclear Engineering 2nd Edition,中央圖書出版社 (1987) 32.
[29] T. Riste et al., Nucl. Instru. & Meth. 75 (1969) 197.
[30] A. Gibaud et al., Acta Cryst. A 49 (1993) 642.
[31] W. G. Bouwman et al., J. Appl. Cryst. 29 (1996) 152.
[32] W. G. Williams, “Polarized neutron”, (Clarendon Press, Oxford, 1988).
[33] 金重勳主編, “磁性技術手冊”, 中華民國磁性技術協會
[34]游振良”圓形化鎳鐵磁性薄膜的磁性翻轉” , 國立東華大學應用物理研究所碩士論文
[35] WWW site http://my.nthu.edu.tw/~reactor/
[36] I. E. Stamatelatos et al., Rev. Sci. Instrum. 71 (2000) 70.
[37] H. F. Nieman et al., Rev. Sci. Instrum. 51 (1980) 1299.
[38] S. Holmryd et al., Rev. Sci. Instrum. 40 (1969) 49.
[39] A. K. Freund et al., Nucl. Instrum. & Meth. Phys. Res. A 234 (1985) 116.
[40] W. Heil et al., Physica B 267&268 (1999) 328.
[41] P. Boni, Physica B 276 (2000) 6.
[42] P. Courtois, Physica B 267 (1999) 363.
[43] A. Delapalme et al., Nucl. Instrum. & Meth. 95 (1971) 589.
[44] C.G Hwang et al., “Conceptual design for iner vertical focusing reflectometer ”,(TRR-II project,40)
[45] 蘇暉家,”清華大學水池反應器W-3中子反射儀之建立”, 國立清華大學碩士論文