久保 毅幸

I am Takayuki Kubo (久保毅幸), a physicist at KEK, trying to understand the physics of superconducting cavity (SRF cavity or 3D cavity) for particle accelerators, quantum computing and detectors.
　　The SRF cavity is one of the key components of modern particle accelerators. Its performance is described by the peak surface magnetic field, Bp, and the quality factor, Q0. The former is proportional to the average electric field that the charged particles see during transit, which determines the necessary accelerator length to achieve a target particle energy. The latter is the ratio of stored energy to dissipation per RF cycle. Improvements of both the parameters are vital challenges for a future high-energy accelerator, such as the International Linear Collider (ILC) 1TeV upgrades.
　　The study of SRF cavity has a half-century of history, but its theory leaves many fundamental questions unanswered: the fundamental limitation of Bp of cavity made of the traditional and alternative materials, the behavior of Q0 as a function of Bp, and its surface treatment dependences, the fundamental limitation of Q at very low temperatures etc. Understanding physics behind these phenomena must be clues to improving the performance of SRF cavity for particle accelerators, quantum computing and detectors.