RIKEN Nishina Center, Wako
A highly sensitive beam current (position) monitor with a high Tc (Critical Temperature) SQUID (Superconducting QUantum Interference Device) and current sensor – the HTc-SQUID monitor – has been developed for the RIBF (RI Beam Factory) in RIKEN. In the present work, the HTc-SQUID monitor allows us to measure the DC of high-energy heavy-ion beams nondestructively in such a way that the beams are diagnosed in real time and the beam current extracted from the cyclotron can be recorded without interrupting the beam user's experiments. Both the HTc magnetic shield and the HTc current sensor were dip-coated with a thin layer of Bi-Sr-Ca-Cu-O (2223-phase, Tc 106 K) on 99.9 % MgO ceramic substrates. Unlike other existing facilities, all these HTS fabrications are cooled by a low-vibration pulse-tube refrigerator. These technologies enable us to downsize the system. Last year, aiming at the practical use, the HTc-SQUID monitor was installed in the RIBF. As a result, a 1 uA Xe beam intensity (50 MeV/u) was successfully measured with a 100 nA resolution. We will report the present status of the facility, the details of the monitor system and the results of the beam measurement.
