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A highly sensitive beam current (position) monitor with a high Tc (Critical Temperature) current sensor and a SQUID (Superconducting QUantum Interference Device), that is the HTc-SQUID monitor, has been developed for the RIBF (RI Beam Factory) in RIKEN. The purpose of our work is 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 by 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. As a result, 1 uA Xe beam intensity (50 MeV/u) was successfully measured with a 100 nA resolution. From last year, aiming at the higher resolution, improvement of the new HTc current sensor with two turn coils has been started. We will report the present status and the measurement results of the HTc-SQUID monitor.
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