Coherence Effects and Few-Body Dynamics in Atomic Fragmentation Processes

原子碎片过程中的相干效应和少体动力学

• 批准号: 1401586
• 负责人: Michael Schulz
• 金额: $ 50.74万
• 依托单位: Missouri University of Science and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1401586&HistoricalAwards=false
• 关键词: Coherence; Effects; Few; Body; Dynamics

This work seeks to address the following basic questions. What are the forces acting in nature and what are their properties? How do systems consisting of several objects develop under the influence of these forces? The second question represents one of the most fundamental, unsolved problems in science. The motion of two objects can often be predicted with virtual certainty. For example, if the solar system consisted of only the sun and the earth, one could predict the position and the velocity of the earth relative to the sun for all times in the future. But if only one more object is added to the system (say the moon in the above example) no analytic solution (one that is given in terms of equations) within our mathematical framework exists. This dilemma is known as the few-body problem (FBP). It has very broad impacts in all of the natural sciences because most of modern research deals with systems containing more than 2 objects. The project outlined in this proposal experimentally studies the FBP for atomic systems. For such systems of microscopic scale the FBP is further complicated by the characteristics of quantum-mechanics, the theory that was designed to describe such tiny systems. In the long term, this work may influence not only the understanding of isolated atoms, but also the interaction of beams of atoms (or ions or molecules) with surfaces, something which is a key technology underpinning the manufacturing of portable electronic devices and computers.In this project the few-body problem will be studied by performing kinematically complete experiments on ionization of simple targets by ion impact. The momentum vectors of the scattered projectiles and of the recoiling target ions are measured directly and the momentum of the ejected electron is deduced from the kinematic conservation laws. From the data, fully differential cross sections (FDCS) will be extracted. The coherence properties of the projectile can be varied by changing the geometry of a collimating slit placed before the target. Only relatively recently it was discovered that the FDCS can be sensitive to the projectile coherence length. This, in turn, can explain very puzzling discrepancies between theory and experiment, which were vividly debated for the last decade. The proposed work aims at systematically exploring the role of the projectile coherence properties in atomic few-body systems. It is anticipated that the results from these studies will represent an important step forward towards a thorough understanding of the few-body problem.

这项工作旨在解决以下基本问题。自然界的作用是什么？它们的特性是什么？在这些力的影响下，由几个物体组成的系统如何形成？第二个问题代表了科学中最基本，未解决的问题之一。通常可以通过虚拟确定性预测两个对象的运动。例如，如果太阳系仅由太阳和地球组成，则可以预测地球相对于太阳的地位和速度在将来的任何时候。但是，如果在我们的数学框架中只有另外一个对象添加到系统中（例如上述示例中的月球），则不存在分析解决方案（一个以方程式给出的解决方案）。这个困境被称为几个体型问题（FBP）。它在所有自然科学方面都具有非常广泛的影响，因为大多数现代研究都涉及包含2个以上对象的系统。该提案中概述的项目实验研究了原子系统的FBP。对于这种微观量表的系统，FBP因量子力学的特征而变得更加复杂，量子力学的特征旨在描述这种微小的系统。 In the long term, this work may influence not only the understanding of isolated atoms, but also the interaction of beams of atoms (or ions or molecules) with surfaces, something which is a key technology underpinning the manufacturing of portable electronic devices and computers.In this project the few-body problem will be studied by performing kinematically complete experiments on ionization of simple targets by ion impact.直接测量散射弹丸和后退靶离子的动量向量，并根据运动学保护定律推导出喷射电子的动量。从数据中，将提取完全差异的横截面（FDC）。可以通过更改位于目标面前的准直缝的几何形状来改变弹丸的相干性能。直到最近，才发现FDC可以对弹丸相干长度敏感。反过来，这可以解释理论与实验之间非常令人困惑的差异，这些差异在过去十年中一直在辩论。 拟议的工作旨在系统地探索弹丸相干性能在原子少体系统中的作用。可以预料，这些研究的结果将代表着对几个身体问题的彻底理解的重要一步。

项目成果

Fully Differential Study of Capture with Vibrational Dissociation in p + H2 Collisions

p H2 碰撞中振动解离捕获的全微分研究

• 发表时间: 2017
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: B.R. Lamichhane, T. Arthanayaka