Studies of In Flight Annihilation of High Energy Channeled Positrons in Single Crystals

单晶中高能引导正电子的飞行湮灭研究

• 批准号: 9623610
• 负责人: Jene Golovchenko
• 金额: $ 35.45万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-10-01 至 2000-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9623610&HistoricalAwards=false
• 关键词: Studies; Flight; Annihilation; Energy; Channeled

9623610 Golovchenko This experimental condensed matter physics project will explore experimentally the basic interaction of positrons with crystalline matter. The main focus will be on the process of in-flight annihilation of channeled MeV positrons with crystal valence electrons. The annihilation yields should be proportional to the electron density along the positron path, and should also be very sensitive to the spin polarization of the electrons. The experiments are expected to demonstrate that positron channeling can be developed into a sensitive probe of the electronic and magnetic structures of crystals on the atomic scale. This is a fundamental research project, but the results should lead to new instrumentation having broad technological applications in a range of materials research areas. %%% Positrons and electrons are antimatter-matter twins, with the consequence that when brought very close together, they annihilate - converting their energies, of mass and momentum, into energetic photons called gamma rays. It has recently become possible to obtain accelerated beams of mono- energetic positrons with sufficient intensities to develop the annihilation interaction as a sensitive atomic scale probe of the electronic and magnetic properties of crystals. In this research, energetic positrons will be focused (channeled) by the atomic potential of a crystal. The data will provide information about the density of the electrons that determine the atomic scale electronic and magnetic properties of the materials. This is a fundamental research project, but the results should lead to new instrumentation having broad technological applications in a range of materials research areas. **

9623610 Golovchenko这个实验凝聚态物理项目将通过实验探索正电子与晶体物质的基本相互作用。 主要的焦点将是在飞行过程中的通道MeV的正电子与晶体价电子湮灭。 湮灭产额应该与沿着正电子路径的电子密度成比例，并且还应该对电子的自旋极化非常敏感。 这些实验有望证明正电子沟道效应可以发展成为在原子尺度上探测晶体电子结构和磁性结构的灵敏探针。 这是一个基础研究项目，但其结果应该导致新的仪器在一系列材料研究领域具有广泛的技术应用。 正电子和电子是反物质的孪生子，当它们非常接近时，它们会湮灭-将它们的能量（质量和动量）转化为称为伽马射线的高能光子。 近年来，人们已经有可能获得具有足够强度的单能正电子加速束，以发展湮灭相互作用，作为晶体电子和磁性的灵敏原子尺度探针。 在这项研究中，高能正电子将被晶体的原子势聚焦（引导）。 这些数据将提供有关电子密度的信息，这些信息决定了材料的原子尺度电子和磁性。 这是一个基础研究项目，但其结果应该导致新的仪器在一系列材料研究领域具有广泛的技术应用。 **