The true cyclotron frequency for particles and ions in a Penning trap
The true cyclotron frequency for particles and ions in a Penning trap
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DOI：
10.1016/j.ijms.2008.10.015
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发表时间：
2009-01-15
影响因子：
1.8
通讯作者：
Gabrielse, G.
中科院分区：
文献类型：
--
作者：
Gabrielse, G.
粒子或离子的真实回旋频率是在彭宁陷阱中进行质谱分析和其他精确测量所需的，不能直接测量。它不是被捕获粒子的振荡频率之一。可以测量的三个振荡频率随陷阱电势的失调和谐波失真而变化。讨论了两种确定回旋频率的方法。首先，当捕获粒子的三个本征频率都可以测量时，由Brown-Gabrise不变性定理给出了真实的回旋频率。这一规定使得粒子、核物理和原子物理中数量惊人的最准确的测量成为可能，因为它准确地解释了最低阶的静电缺陷和磁失调。其次，当对精度要求较低时，比如测量不稳定核的质量时，通常只测量一个边带频率--这是一种驱动力的频率，它最佳地耦合了陷阱中离子的两个运动。使用相同不变性定理的扩展，为这种替代方法提供了缺失的理论证明。预测了系统测量误差的显著抑制，说明了为什么这些测量不确定度不大于报告的测量不确定度，尽管简单估计相反。(C)2008爱思唯尔B.V.保留所有权利。
The true cyclotron frequency of a particle or ion, needed for mass spectrometry and other accurate measurements in a Penning trap, cannot be measured directly. It is not one of the oscillation frequencies of the trapped particle. and the three oscillation frequencies that can be measured vary with the misalignment and the harmonic distortion of the trap potential. Two methods to determine the cyclotron frequency are discussed. First, when all three eigenfrequencies of a trapped particle can be measured, the true cyclotron frequency is given by the prescription of the Brown-Gabrielse invariance theorem. This prescription makes possible a surprising number of the most accurate measurements in particle, nuclear and atomic physics because it accounts exactly for the lowest order electrostatic imperfections and magnetic misalignments. Second, when less accuracy is required, as when the masses of unstable nuclei are measured, a single side-band frequency is often measured instead-the frequency of a driving force that optimally couples two of the motions of the ion in the trap. A missing theoretical justification for this alternate method is provided using an expansion of the same invariance theorem. A remarkable suppression of systematic measurement errors is predicted, showing why these are not larger than reported measurement uncertainties, despite the contrary indication of simple estimates. (C) 2008 Elsevier B.V. All rights reserved.