An approach to determine the kinetic beam energy at the ${10}^{-5}$ level is presented, which corresponds to an improvement by more than one order of magnitude compared with conventional methods. Particularly, collinear fluorescence and resonance-ionization spectroscopy measurements on rare-isotope beams, where the beam energy is a major contribution to the uncertainty, can benefit from this method. The approach is based on collinear spectroscopy and requires no special equipment besides a wavelength meter, which is commonly available. Its advent is demonstrated in a proof-of-principle experiment on a Ni beam. In preparation for the energy measurement, the rest-frame transition frequencies of the $3d^{9}4s{}^3{D}_3\to 3d^{9}4p{}^3{P}_2$ transitions in neutral nickel isotopes have been identified to be ${\nu }_0{(}^{58}\mathrm{Ni})=850343678\left(20\right)$ MHz and ${\nu }_0{(}^{60}\mathrm{Ni})=850344183\left(20\right)$ MHz.

中文翻译：

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通过共线激光光谱确定束能量

一种确定在动轴处的动束能量的方法 ${10}^{-5}$提出了一种水平，与传统方法相比，这相当于提高了一个数量级以上。特别是，在稀有同位素束上的共线荧光和共振电离光谱测量中，束能量是不确定性的主要贡献，可以从该方法中受益。该方法基于共线光谱法，除了通常使用的波长仪外，不需要任何特殊设备。在镍离子束的原理验证实验中证明了它的出现。在准备能量测量时，$3d^{9}4s{}^3{d}_3\to 3d^{9}4p{}^3{P}_{\mathrm{2个}}$ 中性镍同位素的跃迁已被确定为 ${\nu }_0{（}^{58}你）=850343678（20）$ 兆赫和 ${\nu }_0{（}^{60}你）=850344183（20）$ 兆赫