We report a measurement of the annihilation decay rate of positronium (Ps) atoms, . Ground state atoms optically excited to radiatively metastable states were quenched via Stark mixing by the application of a time-delayed electric field. Rapid radiative decay of the Stark mixed states to the ground state, followed by self-annihilation, was observed via the annihilation radiation time spectrum, and used to determine the number of excited state atoms remaining at different times, and hence the decay rate. We obtain , in broad agreement with the Zeeman-shifted theoretical value of .

中文翻译：

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2 ³ S _1的an灭衰减率的测量 

我们报告了对posit（Ps）原子the灭衰减率的测量。通过施加时间延迟电场，通过斯塔克混合，将光学激发成辐射亚稳态的基态原子淬灭。通过an没辐射时间谱观察到斯塔克混合态快速辐射衰变到基态，然后自self灭，并用于确定在不同时间剩余的激发态原子数，从而确定衰变率。我们得到与的塞曼位移的理论值大致一致的。