Development of the windowless solid para hydrogen target

iris实验采用无窗固体氢（氘核）靶，在加拿大的TRIUMF进行。固体氢靶的厚度为50-100微米。用GM-Cryocooler在真空中冷却，温度低于4 K，将室温下的氢气喷在纯银箔（t=5微米）表面，形成固体氢薄膜。在实验过程中，测量了光束在目标中的能量损失，并对目标的厚度进行了实时监测。由于目标厚度在8-24小时内减半，因此重新创建了氢目标。在固体氘的情况下，用能量损失法无法观察到靶厚度的减小。

The IRIS-experiment using the windowless solid hydrogen (deuteron) target was conducted at TRIUMF in Canada. The thickness of the solid hydrogen target was 50-100 micron. Hydrogen gas at room temperature was sprayed on the surface of pure silver foil (t=5 micron) at lower than 4 K cooled by the GM-Cryocooler in the vacuum, and the solid hydrogen thin film was created. During this experiment, the beam energy loss in the target was measured and the target thickness was always monitored. Since the target thickness was halved in 8-24 hours, the hydrogen target was re-created. In the case of solid deuterium, the reduction of target thickness could not be observed by the energy loss method.