Collaborative Research: Neutron Interferometry Experiments for Nuclear Physics

中子干涉仪是一种利用自由中子的量子力学波动特性来非常精确地测量物质的某些特性的设备。它的功能很像光干涉仪，只是它检测的是中子物质波而不是光波的干涉。冷中子（运动速度小于2000 m/s）的量子波长与固体中原子的间距相当，因此它与这些原子相干地相互作用，即像物质波而不是粒子。当一个慢中子进入干涉仪时，它的物质波在一个完美的硅晶体中被衍射，并分裂成两个子波，每个子波采取不同的路径。这两个子波在另一个晶体中再次相遇，并可以相互干涉。干涉的程度决定了在放置在干涉仪后面的中子探测器中探测中子的概率。我们可以在干涉仪内放置一块物质，磁场或电场，甚至引力场，以使一个子波相对于另一个子波的相位发生偏移，并改变这种干涉。这给出了关于物质或场中中子相互作用的强度和性质的重要且通常是唯一的信息。我们使用中子干涉仪研究对核物理重要的现象，如中子的内部电荷分布和中子从轻核的散射。几个研究生和本科生参加了这个研究计划。除了学习中子干涉测量学的科学，他们在中子源的物理学和研究方法方面受到广泛的教育，这为他们在学术界和工业界从事与中子科学相关的广泛职业做好了准备。

Neutron Interferometry Experiments for Nuclear Physics:The neutron interferometer is a device that uses the quantum mechanical wave-like properties of free neutrons to measure certain properties of matter very precisely. It functions much like a light interferometer, except that it detects the interference of neutron matter waves rather than light waves. A cold neutron (moving less than 2000 m/s) has an associated quantum wavelength comparable in size to the spacing of atoms in a solid, so it interacts with these atoms coherently, i.e. like a matter wave rather than a particle. When a slow neutron enters the interferometer, its matter wave is diffracted in a perfect silicon crystal and splits into two sub-waves, each taking a different path. The two sub-waves meet again in a another crystal and can interfere with each other. The degree of interference determines the probability of detecting the neutron in a neutron detector placed behind the interferometer. We can place a piece of matter, a magnetic or electric field, or even a gravitational field inside the interferometer to shift the phase of one sub-wave relative to another and change this interference. This gives important and often unique information about the strength and nature of the neutron's interaction in the material or field. We use the neutron interferometer to study phenomena important for nuclear physics, such as the internal charge distribution of the neutron and the scattering of neutrons from light nuclei.Several graduate and undergraduate students participate in this research program. In addition to learning the science of neutron interferometry, they are educated broadly in the physics and methodology of research at neutron sources, which prepares them for a wide range of careers related to neutron science in academia and industry.