Detection of the time variance of the mass ratio of electron to proton

为了测试电子与质子质量比的时间变化，我们提出了精确测量CaH+基电子态振动跃迁的方法。我们对Ca~+-H对势能进行了从头计算，估算了CaH~+在几个低激发态的跃迁频率和强度。我们用激光烧蚀氢气中的金属钙产生了含钙的等离子体，并测量了几个吸收谱带。虽然它们中的大多数被指定为中性CAH的跃迁，但仍有几个带有待指定，并且可能包含CAH+跃迁。我们还开发了中性极性分子的斯塔克指南，以将冷分子引入离子陷阱并产生冷CAH+。对几种分子(Nd3、NH3、CH3OH和CH3F)进行了引导，并测量了它们的速度分布。通过将喷嘴温度降低到210K，分子通量增加了两倍。

We have proposed the precise measurement of vibrational transition in the ground electronic state of CaH+ for the test of the temporal change of the mass ratio of electron to proton. We have carried out ab initio calculations of Ca+-H pair potential to evaluate the transition frequency and intensity of the CaH+ in the several low lying states. We have employed the laser ablation of Ca metal in the hydrogen gas to produce CaH+ containing plasma and measured several bands of absorption lines. Although most of them were assigned to the transitions of neutral CaH, several bands have been left to be assigned, and might contain the CaH+ transitions. We have also developed a Stark guide of neutral polar molecules to introduce cold molecule into the ion trap and to produce cold CaH+. Several molecules (ND3, NH3, CH3OH, and CH3F) have been guided and their velocity distributions have been measured. By lowering the nozzle temperature down to 210K, molecular flux has been increased up to twice.