Generation and Investigation of radium muonic atoms in thin solid hydrogen films

在这项研究中，我们提出了在固体氢膜中注入镭同位素以形成具有不稳定核的μ子原子，并进行μ子X射线光谱以确定转移率，同位素位移和核电荷半径。这种方法的独创性是基于μ子转移反应机制到固体氢中的更高Z原子核，以有效地产生μ子原子，因为只需要非常小的原子核浓度（ppm水平）来进行μ子X射线光谱实验。该项目的目标是开发一种新的离子源，可以产生长寿命的放射性镭同位素离子，以便植入固体氢膜并产生具有放射性核的μ子原子。这种新的离子源需要设计成能够与现有的实验装置（μA^*）一起使用，以便在安装在RIKEN-RAL μ子设施的固体氢膜中注入离子进行μ子原子光谱学。本项目历时3年，主要成果如下： ...更多信息 作为一种新的表面电离离子源的建设，其目的是在未来使用放射性同位素。选择表面电离型离子源是因为它能够以高效率从碱金属和碱土金属产生离子，这对于产生镭同位素离子是理想的，而且对于产生用于优化和调谐目的的许多其他稳定的离子束也是理想的。在镭的情况下，因为没有稳定的同位素，所以选择钡元素，因为它在同一组中并且具有相似的电离能。因此，通过混合稳定的钡同位素作为标记物，可以首先有效地调整和优化使用稳定核的实验条件，然后容易地切换到不稳定核以进行使用镭离子的实验。这种新的表面电离离子源去年在KURRI（京都大学研究反应堆研究所）进行了测试。成功地电离了钡离子，产生了数μA的钡离子束。还检查了离子源的稳定性，并且在操作几个小时后没有观察到显著的束劣化。2006年1月，它被运往英国卢瑟福阿普尔顿实验室，并安装在RIKEN-RAL端口4区的μA^* 实验装置上。安装进行得很顺利，现在几乎完成了。第一次使用新离子源的实验计划在今年秋天的某个时候进行。钡束将被产生并注入到固体氢膜中，以进行μ子X射线光谱实验。第一个实验结果将在以后的出版物中报道。然而，在任何镭放射性同位素可以用于该系统之前，需要对现有的μA^* 装置进行几次修改和改进，以安全地处理放射性材料。特别是，泵送系统将需要升级，并安装排气管。在离子源周围也需要局部辐射屏蔽。少

In this research, we proposed to implant radium isotopes in solid hydrogen films to form muonic atoms with unstable nuclei, and conduct muonic X-ray spectroscopy to determine transfer rates, isotope shifts and nuclear charge radii. The originality of this method was based on the muon transfer reaction mechanism to higher Z nuclei in solid hydrogen to efficiently produce muonic atoms, since only a very small concentration of nuclei (ppm level) is required to perform muonic X-ray spectroscopy experiments. The goal of this project was to develop a new ion source that can produce long-lived radioactive radium isotope ions, in order to be implanted in solid hydrogen films and produce muonic atoms with radioactive nuclei. This new ion source needed to be designed so that it can be used with the existing experimental apparatus (μA^*) for muonic atom spectroscopy with implanted ions in solid hydrogen films installed at the RIKEN-RAL Muon Facility. The main achievement of this 3 years project w … More as the construction of a new surface ionization ion source with the aim of using in the future radioactive isotopes. A surface ionization type ion source was selected because it is capable of producing ions from alkali and alkaline-earth metals with high efficiency, which is ideal to produce radium isotope ions, but also to produce many other stable ion beams for optimization and tuning purposes. In the case of radium, since there are no stable isotopes, the element barium is selected because it is in the same group and has similar ionization energy. Therefore, by mixing stable barium isotope as a marker, it is possible to first adjust and optimize efficiently the experimental conditions using stable nucleus, and then switch easily to unstable nucleus to perform the experiment with radium ions. This new surface ionization ion source was tested last year at KURRI (Research Reactor Institute, Kyoto University). Barium ions were successfully ionized and barium beams of several μA were produced. The stability of the ion source was also examined, and no significant beam deterioration was observed after several hours of operation. In January 2006, it was shipped to the Rutherford Appleton Laboratory in the UK, and installed on the μA^* experimental apparatus at RIKEN-RAL port 4 area. The installation went smoothly, and is now almost completed. The first experiment using the new ion source is scheduled sometime this autumn. Barium beams will be produced and implanted in solid hydrogen films to conduct muonic X-ray spectroscopy experiments. The first experimental results will be reported in a later publication. However, before any radium radioactive isotopes can be used in this system, several modifications and improvements to the existing μA^* apparatus will be required to handle radioactive materials safely. In particular, the pumping system will need to be upgraded and an exhaust stack installed. Local radiation shielding will also be needed around the ion source. Less