High density mapping systems for SRF cavities

20th International Conference on RF Superconductivity (SRF 2021)In order to evaluate the performance of a superconducting cavity, we are developing a mapping system to measure the distribution of cavity temperature, field emission X-rays, and trapped magnetic flux with high positional resolution. In order to construct a system with high positional resolution, a large number of sensors are required. However, as the number of sensors increases, so does the amount of wiring, which increases the complexity of the wiring in the cryogenic apparatus, and also increases the heat transfer through the wiring, which disturb efficient operation of cavity tests. We are developing an efficient mapping system with a multiplexer that scans the readout signal on the same circuit as the sensor in the cryogenic dewar where the cavity test is conducted. In this presentation, we report the outline and test results of the mapping system under developmen

Possible observation of transverse laser cooled ultimate cold ion beam in S-LSR

Transverse laser cooling is pursued at an ion storage/cooler ring, S-LSR, Kyoto University. An RF bunched Mg+ beam was cooled transversely through synchro-betatron resonance coupling by a co-propagating laser. We investigated peaks of synchrotron oscillation spectroscopically so that we can observe them stably. Oscillation signals from a parallel-plate pickup were observed by a spectrum analyzer. We also observed the coherent synchrotron modes. As the beam temperature decreases, the ion beam would be in space charge limited region. According to the computer simulation, in the case the beam turns to be space charge limited, the disappearance of peaks of synchrotron oscillation is expected. We would like to propose a capability of detecting space charge limited region by observing such a frozen synchrotron oscillation

Progress in the R&D Experiments About a Novel Method of Electron Scattering off Short-lived Nuclei

A novel method has been established to realize the experiment of electron scattering off short-lived nuclei. The method was based on the well known "ion trapping" phenomenon in electron storage rings. In the R&D experiments at Kyoto University, stable nucleus, 133Cs, was employed as the target nucleus. The luminosity of scattering experiment was nearly 1026 cm−2s−1 at electron beam current around 75 mA. The angular distribution of elastically scattered electrons from trapped Cs ions was measured and the result was well fitted by theoretical calculation. It was indicated that higher luminosity can be reached with larger electron beam current