Author: Kase, M.
Paper Title Page
TUPC105 Improvement of Beam Current Monitor with High Tc Current Sensor and SQUID at the RIBF 1260
 
  • T. Watanabe, N. Fukunishi, O. Kamigaito, M. Kase, Y. Sasaki
    RIKEN Nishina Center, Wako, Japan
 
  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.  
 
TUPS088 Charge Stripping of Uranium-238 Ion Beam with Low-Z Gas Stripper 1746
 
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
  • N. Fukunishi, A. Goto, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, T. Watanabe, Y. Yano, S. Yokouchi
    RIKEN Nishina Center, Wako, Japan
 
  One of the primary goals of the RIKEN RI beam factory is to generate unprecedented high-power uranium beams (up to tens kW), which yield an enormous breakthrough for exploring new domains of the nuclear chart. The development of reliable and efficient charge stripping scheme for such high-power beams is a key unsolved issue, affecting the overall performance of the heavy ion accelerations. A charge stripper using low-Z (low atomic number Z) gas is an important candidate. Because of the suppression of the electron capture process, the high equilibrium mean charge states for the low-Z gas stripper are expected in conjunction with the intrinsic robustness of the gas. There was, however, no direct experimental data of the charge evolution, because of the difficulty in making massive windowless low-Z gas targets. In the present work, the charge evolution of the 238U beams injected at 10.75 MeV/u were investigated using thick hydrogen and helium gas strippers with huge differential pumping system newly developed. In the energy region of interest, near 10 MeV/u, achievable mean charge states around 65+ with the low-Z gas strippers are far superior to those of the medium-Z ones around 55+.