(e,gamma,2e) Threshold Spectroscopy - A new method to study collisional excitation of atoms using combined laser and electron beams

(e,gamma,2e) 阈值光谱 - 一种使用激光和电子束组合来研究原子碰撞激发的新方法

• 批准号: EP/W003864/1
• 负责人: Andrew Murray
• 金额: $ 64.38万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FW003864%2F1
• 关键词: gamma; 2e; Threshold; Spectroscopy; new

Since the foundation of modern physics where Rutherford and collaborators discovered the structure of the atom in Manchester and Neils Bohr developed the first quantum theory, collision experiments between an incident particle and an atomic target have provided physicists with precise details on the nature of matter. Rutherford's experiments probed the nucleus and its size using alpha particles, leading to modern nuclear physics. The work of Franck and Hertz soon after used electron beams to probe the structure of the electrons surrounding the nucleus. This work lead to the development of modern quantum theory and atomic physics. Since that time our understanding of the atom and its structure (which has been learned through developing theories and more sophisticated experiments) has paved the way to the development of almost all technologies that we use today. Key to these successes and to the future development of new and emerging technologies is the close collaboration between experimentalists who measure the interactions to high precision and theoreticians who develop the quantum theories that describe these processes. By testing theory with experiment the models are refined and improved, allowing them to accurately predict what happens in many areas of modern science and industry. Processes where the models have direct application include the development of new lasers, in Tokomaks for the generation of fusion energy, in the earth's upper atmosphere (including the ozone layer and ionosphere) and in areas of astrophysical interest including for models of stellar atmospheres and in the atmosphere of exoplanets. Understanding excitation of atoms by electron impact hence plays an essential role in testing different models of the interaction. Results from experiment and theory have converged in recent years, with the models now agreeing well when compared to existing experimental data. The conventional experiments that are used are however limited due to the low efficiency of the detectors or due to limitations of the techniques that are adopted. They therefore cannot measure the excitation of a wide range of target states, including higher lying states that have long lifetimes and metastable states where the atom effectively 'stores' the energy imparted by the collision for a long time. Understanding excitation of these 'metastable' atoms hence is important in many different areas.The new technique that has been proposed here will allow these types of interactions to be studied for the first time. This will be carried out by using a very precise laser beam to further excite the atoms created by the collision to a highly excited Rydberg state that is very close to ionization. These 'Rydberg atoms' can be huge - we can make neutral atoms in our laboratory that have diameters around 1/10th that of a human hair. These enormous atoms can very easily be ionized by applying a small electric field that releases the electron from the atom, which we can then detect. By measuring the ensuing electron yield and by changing the polarization of the laser beam, we can then extract all information about the initial collision in a unique way and with high efficiency. The new experimental technique proposed here hence complements that of existing methods without suffering from the technological limitations that occur with them. The experiments will therefore provide new data to test the quantum models, allowing them to be further refined, enhanced and improved.

自从卢瑟福和合作者发现曼彻斯特和尼尔斯玻尔原子的结构的现代物理基础以来，鲍尔开发了第一个量子理论，因此事件粒子和原子靶标之间的碰撞实验为物理学家提供了有关物质本质的精确细节。卢瑟福的实验使用α颗粒探测了核及其大小，从而导致现代核物理学。弗兰克（Franck）和赫兹（Hertz）的工作不久后使用电子梁来探测核周围电子的结构。这项工作导致了现代量子理论和原子理的发展。从那时起，我们对原子及其结构的理解（通过开发理论和更复杂的实验已经学到了这一点）为我们今天使用的几乎所有技术的发展铺平了道路。这些成功以及新兴技术的未来发展的关键是实验者之间的紧密合作，他们衡量了与高精度的相互作用与发展描述这些过程的量子理论的理论家。通过通过实验测试理论，模型得到了完善和改进，从而可以准确预测现代科学和工业的许多领域。模型直接应用的过程包括新激光器的发展，在地球上层大气层（包括臭氧层和电离层）中以及天体物理兴趣领域的融合能量的发展，包括恒星大气的模型以及外部活动的大气层。因此，通过电子影响对原子的激发，因此在测试相互作用的不同模型中起着至关重要的作用。近年来，实验和理论的结果融合了，与现有的实验数据相比，这些模型现在吻合良好。但是，由于检测器的效率低或由于采用的技术的局限性，使用的常规实验受到限制。因此，他们无法衡量广泛的目标状态的激发，包括较长的寿命和亚稳态状态的较高的状态，在这些状态下，原子有效地“存储”了碰撞长期以来赋予的能量。因此，了解这些“亚稳定性”原子的激发在许多不同的领域都很重要。这里提出的新技术将允许首次研究这些类型的相互作用。这将通过使用非常精确的激光束进一步激发碰撞产生的原子到非常接近电离的高度激发的rydberg状态。这些“ rydberg原子”可能是巨大的 - 我们可以在实验室中制作中性原子，该原子的直径约为1/10，即人的头发的直径。通过应用一个从原子中释放电子的小电场，可以很容易地将这些巨大的原子电离化，然后我们可以检测到。通过测量随之而来的电子产量并改变激光束的极化，我们可以以独特的方式提取有关初始碰撞的所有信息，并以高效率。因此，这里提出的新实验技术可以补充现有方法，而不会遭受随之而来的技术限制。因此，实验将提供新的数据来测试量子模型，从而进一步完善，增强和改进。

项目成果

Measurement of argon ( e , 2 e ) differential cross sections in the perpendicular plane from 5 to 200 eV above the ionization threshold

在高于电离阈值 5 至 200 eV 的垂直平面内测量氩 ( e , 2 e ) 微分截面

• DOI: 10.1103/physreva.105.042815
• 发表时间: 2022
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Patel M

Laser-atom interaction simulator derived from quantum electrodynamics

基于量子电动力学的激光-原子相互作用模拟器

• DOI: 10.1103/physreva.105.053117
• 发表时间: 2022
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Patel M

Evolution of the xenon ( e , 2 e ) differential cross section from a coplanar geometry to the perpendicular plane in the intermediate-energy regime

中能状态下氙 ( e , 2 e ) 微分截面从共面几何到垂直平面的演化

• DOI: 10.1103/physreva.105.032818
• 发表时间: 2022
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Patel M

Measurements of the Kr (e, 2e) differential cross section in the perpendicular plane, from 2 eV to 120 eV above the ionization threshold

垂直平面中 Kr (e, 2e) 微分截面的测量，电离阈值以上 2 eV 至 120 eV

• DOI: 10.48550/arxiv.2304.00956
• 发表时间: 2023
• 作者: Murray A

Measurements of the Kr ( e , 2 e ) differential cross section in the perpendicular plane from 2 to 120 eV above the ionization threshold

在高于电离阈值 2 至 120 eV 的垂直平面内测量 Kr ( e , 2 e ) 微分截面

• DOI: 10.1103/physreva.107.062807
• 发表时间: 2023
• 期刊: Physical Review A
• 影响因子: 2.9
• 作者: Murray A