The first phase of the ISAC II project consists of the acceleration of radioactive ions by 20 superconducting DTL's with a total effective voltage of up to 20 MV. Each of these quarter-wave cavities will be powered at a frequency of 106.08 MHz to a maximum field gradient of 6 MV/m. A test area was built to clean and test each cavity before installation. With unloaded cavity Q's of ~10 9 , the RF control system of these superconducting cavities is based on self-excited feedback loop, with the self-excited frequency stabilized by an internal analogue Phase-Locked Loop, capable of operating in both CW and pulse mode. A digital phase/frequency detector and a quadrature combiner are used to provide phase locking to an external frequency reference. The demodulated amplitude, phase and frequency are feedback regulated with digital signal processors. This paper describes the RF control system and the experience in operating this system with a prototype cavity.

In this work, we present a theoretical model of a near-infrared sensitive refractive index biosensor based on the truncate 1D photonic crystal (1D PC) structure with Dirac semimetal. This highly sensitive near-infrared biosensor originates from the sharp reflectance peak caused by the excitation of Bloch surface wave (BSW) at the interface between the Dirac semimetal and 1D PC. The sensitivity of the biosensor model is sensitive to the Fermi energy of Dirac semimetal, the thickness of the truncate layer and the refractive index of the sensing medium. By optimizing the structural parameters, the maximum refractive index sensitivity of the biosensor model can surpass 17.4 × 103/RIU, which achieves a certain competitiveness compared to conventional surface plasmon resonance (SPR) or BSW sensors. Considering that bulk materials are easier to handle than two-dimensional materials in manufacturing facilities, we judge that 3D Dirac semimetal and its related devices will provide a strong competitor and alternative to graphene-based devices.

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Three almost-identical rebunchers have been designed for HIRFL-CSR. The first one B1 is going to be taken the off-line test and will be installed in place soon. The rebunchers B1 and B2 are in the BL1 beam line from the injector cyclotron SFC to the main cyclotron SSC, together for the longitudinal matching between the two cyclotrons. The rebuncher B3 is in the BL2 beam line from SSC to the main ring CSRm, either working at the stand-alone mode for the beam from SSC or at the combined mode together with B1 for the beam from SFC. They work at different harmonic modes depending on the beam energy to get the best matching effect. The rebunchers of 22~54MHz for B1 and B2 and 23.5~56MHz for B3 in frequency range and 20~120kV in amplitude use two tuning mechanisms, where the two movable capacitors are for low frequency end and the movable short-circuit panel is for high frequency end.