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The cyclotron-like storage ring dedicated to Rare-RI Ring project consists of 6 magnetic sectors and 6 straight sections, having a circumference of 56.13 m. The magnetic sector works for both bending and focusing. The total circulation is assumed to be 1,000 turns. Over the momentum range from -1% to +1% in ∆p/p, the required isochronisity is 10-6 while the beam emittance is sevaral tens of π mm-mrad. To examine the design of cyclotron-like storage ring and fix its parameters, we have developed a high precision beam optics simulation. To achieve the precision as high as possible within a feasible computational time, we have adopted a geometrical tracking assuming a circular orbit for a small spatial segment. For that purpose, it is enough that the magnetic sector is divided into 150 sub-sectors in calculation. In each sub-sector, the magnetic field is given as a function of radial position but uniform around the vicinity of beam trajectory. The beam trajectory is evaluated in 4th order Runge-Kutta algorithm. Finally, we have achieved a precision of 10-9 in ∆T/T and a computational time of 1.8 sec on a typical PC server for ray tracing of single particle undergoing a circulation of 1,000 turns. [ABSTRACT FROM AUTHOR]

RIKEN Nishina Center for Accelerator-Based Science in RIKEN is constructing the Radioactive Isotope Beam Factory (RIBF), which is capable of providing the world's most intense RI beams over the whole range of atomic masses. The world's first superconducting ring cyclotron (SRC) is the final booster in the RIBF accelerator complex which is able to accelerate all-element heavy ions to a speed of about 70% of the velocity of light. Assembling of six superconducting sector magnets in the SRC vault was completed in August 2005. This paper describes results of their cool-down and excitation tests, which were performed to check the magnet system from the various points of views: magnetic force, coil protection, magnetic field and operation of their cryogenic cooling system. [ABSTRACT FROM AUTHOR]

The sector magnets of the K2500-MeV Superconducting Ring Cyclotron (SRC), which is under construction for the RIKEN RI Beam Factory, are described. The SRC consists of six sector magnets, four rf resonators, etc. Each sector magnet is 7.2 m in length and 6 m in height and 800 t (metric ton) in weight; the sector angle is 25 deg. The required maximum magnetic field is 3.8 T. The superconductor for the main and trim coil has a rectangular shape (8 mm by 15 mm) consisting of a Rutherford-type NbTi cable located at the center of an Al-alloy stabilizer housing. The main coil is bath-cooled and the trim coil is indirectly cooled. Each component of the sector magnet as well as the cryogenic cooling system was completed in the spring of 2003. [ABSTRACT FROM AUTHOR]

Discusses the fabrication of superconducting bending magnet applied as an energy cyclotron boosters for a ring cyclotron. Beam injection; Radius of curvature of the coil; Design of the bending magnet.

Studies the design of the magnetic channels of the injection and extraction systems of the RIKEN superconducting ring cyclotron. Insertion of the magnetic channels between upper and lower coils of the sector magnets; Maximum magnetic rigidity of the injected or extracted beams; Superimposition of additional magnetic fields on the base fields for injection or extraction.

Describes a trim coil system design of a superconducting ring cyclotron. Components; Correction for isochroninization of the magnetic field; Numerical procedure developed to generate isochronous fields; Correction schemes for presumed error fields.

We measured the beam oscillation of RIKEN 18 GHz electron cyclotron resonance ion source for various conditions. In this experiment, the frequency of the beam oscillation increases with increasing the gas pressure and decreases with increasing rf power. The oscillation frequency is strongly dependent on the negative voltage of biased disk, i.e., the frequency increases with increasing the negative voltage. We observed that the frequency is strongly dependent on the mass of ionized gas. [ABSTRACT FROM AUTHOR]

Abstract: The charge-state distributions of 238U and 136Xe ions at 11MeV/nucleon were measured using a gas charge stripper to test whether the charge states in gaseous media were acceptable for acceleration at the RIKEN RI-Beam Factory (RIBF). A differential pumping system facilitated the increase of the N2 gas thickness to 1.3mg/cm2; this is sufficient for the most probable charge state to attain equilibrium. The charge states of 238U attain equilibrium at 56.0, 56.6, and 55.7 in N2, Ar, and CO2 media with thicknesses of 125, 79, and , respectively, whereas those of 136Xe attain equilibrium at 40.5, 40.1, and 40.3 in N2, Ar, CO2 media with thicknesses of 163, 95, and , respectively. The equilibrium charge states of 136Xe are acceptable for acceleration by the subsequent cyclotron, whereas those of 238U are not acceptable for acceleration without a major remodeling of the accelerator. [Copyright &y& Elsevier]

A flattop acceleration system has been developed and installed in the RIKEN Azimuthally Varying Field (AVF) cyclotron in order to improve the transmission efficiency and energy spread of beams. The flattop accelerating voltage is generated by a superposition of voltages of the fundamental and third harmonics on the dee, by attaching an additional resonator capacitively coupled to the main resonator. The flattop voltage could be generated from 36 to 63 MHz corresponding to the third harmonic of the operating frequency range of 12–21 MHz. A beam acceleration test was carried out and beam emittance in the longitudinal phase space was measured using a spectrometer. With this flattop system, the single-turn extraction was achieved more easily and the momentum spread was reduced to one-third. The beam transmission efficiency through the AVF cyclotron as well as the RIKEN Ring Cyclotron (RRC) has also been improved. [Copyright &y& Elsevier]