Laser excitation of the n=3 level of positronium for antihydrogen production
Laser excitation of the n=3 level of positronium for antihydrogen production
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DOI：
10.1103/physreva.94.012507
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发表时间：
2016-07-07
影响因子：
2.9
通讯作者：
Zurlo, N.
中科院分区：
文献类型：
--
作者：
Aghion, S.;Amsler, C.;Zurlo, N.
我们证明了真空中正电子态（Ps）的激光激发。采用一种特殊设计的脉冲慢速正电子束和高效转换靶相结合的方式产生Ps，用单次正电子湮灭寿命谱法记录了Ps的湮灭过程。利用第二强激光脉冲在λ = 1064 nm处诱导的Ps光电离，监测了波长λ约为205 nm处n = 3能级的脉冲激光激发。发射到真空中的全部正电子中约有15%被激发到n = 3并光电离。用一个简单的速率方程模型观察并解释了n = 3激发和随后的光电离的饱和。通过测量多普勒加宽吸收谱线的宽度提取正电子的横向温度。此外，还观察到以n = 3为中间能级激发到Rydberg态n = 15和16，从而独立证实了激发到3p -3态。
We demonstrate the laser excitation of the n = 3 state of positronium (Ps) in vacuum. A combination of a specially designed pulsed slow positron beam and a high-efficiency converter target was used to produce Ps. Its annihilation was recorded by single-shot positronium annihilation lifetime spectroscopy. Pulsed laser excitation of the n = 3 level at a wavelength lambda approximate to 205 nm was monitored via Ps photoionization induced by a second intense laser pulse at lambda = 1064 nm. About 15% of the overall positronium emitted into vacuum was excited to n = 3 and photoionized. Saturation of both the n = 3 excitation and the following photoionization was observed and explained by a simple rate equation model. The positronium's transverse temperature was extracted by measuring the width of the Doppler-broadened absorption line. Moreover, excitation to Rydberg states n = 15 and 16 using n = 3 as the intermediate level was observed, giving an independent confirmation of excitation to the 3 P-3 state.