Cremer J T, Williams D L, Fuller M J, Gary C K, Piestrup M A, Pantell R H, Feinstein J, Flocchini R G, Boussoufi M, Egbert H P, Kloh M D, Walker R B
Adelphi Technology, Inc., 2003 East Bayshore Rd., Redwood City, California 94063, USA.
Rev Sci Instrum. 2010 Jan;81(1):013902. doi: 10.1063/1.3274512.
A novel periodic magnetic field (PMF) optic is shown to act as a prism, lens, and polarizer for neutrons and particles with a magnetic dipole moment. The PMF has a two-dimensional field in the axial direction of neutron propagation. The PMF alternating magnetic field polarity provides strong gradients that cause separation of neutrons by wavelength axially and by spin state transversely. The spin-up neutrons exit the PMF with their magnetic spins aligned parallel to the PMF magnetic field, and are deflected upward and line focus at a fixed vertical height, proportional to the PMF period, at a downstream focal distance that increases with neutron energy. The PMF has no attenuation by absorption or scatter, as with material prisms or crystal monochromators. Embodiments of the PMF include neutron spectrometer or monochromator, and applications include neutron small angle scattering, crystallography, residual stress analysis, cross section measurements, and reflectometry. Presented are theory, experimental results, computer simulation, applications of the PMF, and comparison of its performance to Stern-Gerlach gradient devices and compound material and magnetic refractive prisms.
一种新型的周期性磁场（PMF）光学器件被证明可作为中子和具有磁偶极矩的粒子的棱镜、透镜和偏振器。PMF在中子传播的轴向上具有二维场。PMF交变磁场极性提供了强大的梯度，导致中子按波长在轴向分离，按自旋态在横向分离。自旋向上的中子离开PMF时，其磁自旋与PMF磁场平行排列，并向上偏转，在与PMF周期成正比的固定垂直高度处线聚焦，在下游焦距处，该焦距随中子能量增加。与材料棱镜或晶体单色仪不同，PMF不会因吸收或散射而衰减。PMF的实施例包括中子光谱仪或单色仪，其应用包括中子小角散射、晶体学、残余应力分析、截面测量和反射测量。本文介绍了PMF的理论、实验结果、计算机模拟、应用，以及其性能与斯特恩-盖拉赫梯度装置、复合材料和磁折射棱镜的比较。
