Development of the Polarized Ultra Slow Muon

超慢µ子是在脉冲真空紫外光照射下，由热Muonium(Mu)原子共振电离而产生的，具有低发射度、低能量和极高时间分辨率等优良特性。在这个项目中，我们一直在探索具有更好的热Mu产额和Mu-(Mu负离子，m+e-e-)发射的材料。我们一直在开发一种实验装置，通过在材料表面涂覆钠或铯来研究材料表面的热蒸发。利用该实验装置，我们进行了从钨(W)和Ir到真空区的热蒸发实验。我们展示了来自W和Ir的美丽的热Mu发射，但我们在室温下没有观察到任何Mu发射。我们现在正试图通过降低表面功函数来观察更高温度下的Mu发射。

Ultra slow muons which has many excellent features such as low emittance,low energy,and very high time resolution,are generated by resonant ionization of thermal Muonium(Mu)atoms,synchronized with the pulsed VUV laser irradiation.Thermal Mu is known to be evaporated from the hot tungsten, silica powder, and silica aerogel. In this project, we have been exploring materials which have better thermal Mu yield as well as Mu-(Mu negative ion, m+e-e-)emission. We have been developing an experimental apparatus to investigate thermal Mu or Mu- evaporation from the materials surface, by coating surfaces with Na, or Cs. With use of the experimental apparatus, we performed experiments on thermal Mu or Mu- evaporation into vacuum region from the tungsten (W) and Ir. We demonstrated beautiful thermal Mu emissions from W and Ir, but we could not observe any Mu- emission at room temperature.We are now trying to observe Mu- emission at the higher temperatures by reducing work function on the surface.