Development of a detection system for elastic electron scattering experimente at electron storage rings

提出了一种新的短寿命放射性同位素内部结构研究的电子散射实验方案。这个方案，SCRIT，是基于众所周知的离子捕获现象在电子存储环。在这种离子捕获的帮助下，SCRIT在储存环中的循环电子束上形成局部RI靶，并通过数值模拟发现其亮度超过10^<27>/cm^2/s。为了证明其可行性，我们在京都大学KSR电子储存环上建立了一个SCRIT原型，并将其安装在现有的电子储存环上。进行了一系列的试验测量。到目前为止所进行的测试实验已经表明，SCRIT原型对储存环的性能，如寿命和最大储存束流没有任何负面影响。 关于我们 从SCRIT中提取离子，我们清楚地证实了外部注入的Cs^1+离子在SCRIT中稳定地捕获了大约一秒钟，正如数值模拟中所预期的那样。SCRIT系统已被证明是一种新型的离子阱。捕获离子数为107个数量级，这也与预期吻合得很好。由于电子束内部的离子不断被电子束进一步电离，被探测离子的电荷态的增长强烈地表明，所有被捕获的离子都分布在电子束内部。在本研发实验中，亮度预计为102.5/cm 2/s，而在韧致辐射测量中还没有观察到这种亮度的直接证据。为了减小韧致辐射探测器的巨大本底，对束流输运进行了修正。此外，还将安装另一个探测系统，以获得捕获离子与电子束重叠的直接证据。少

We have been proposing a novel scheme to realize electron-scattering experiments for internal-structure studies of short-lived radioactive isotopes(RI). This scheme, SCRIT, is based on well-known ion-trapping phenomena at electron-storage rings. With a help of this ion trapping, SCRIT forms a localized RI target on a circulating electron beam in a storage ring, and is found by a numerical simulation to provide a luminosity of more than 10^<27>/cm^2/s. This luminosity is high enough to measure the elastic scattering cross section to determine the charge distribution.In order to demonstrate its feasibility, a SCRIT prototype has been constructed, and installed at an existing electron storage ring, KSR, Kyoto University. A series of test measurements has been done. The test experiments conducted so far have already revealed that the SCRIT prototype does not have any negative influence on the storage-ring performances, such as the lifetime and maximum storage beam current.By means of extra … More cting ions from SCRIT, we have clearly confirmed that externally injected Cs^<1+> ions were stably trapped in SCRIT about one second, as expected in a numerical simulation. The SCRIT system has been demonstrated to work as a new type of ion trap. The number of trapped ions were an order of 107, which is also in good agreement with the expectation. The growth of the charge states of detected ions strongly indicates that all trapped ions distribute inside the electron beam, since the ions inside the electron beam are continuously further ionized by the electron beam.In this R & D experiment, the luminosity is expected to be on the order of 102.5/cm2/s, whereas no direct evidence of this luminosity has yet been observed in the bremmstrahlung measurements. A modification of the beam transport is to be made in order to reduce the huge background for the bremsstrahlung detector. In addition, another detection system is to be installed to obtain direct evidence for the overlapping of trapped ions with the electron beam. Less