Hiroyuki Okamura

Development of an 18 GHz superconducting electron cyclotron resonance ion source at RCNP

An 18 GHz superconducting electron cyclotron resonance ion source has recently been developed and installed in order to extend the variety and the intensity of ions at the RCNP coupled cyclotron facility. Production of several ions such as O, N, Ar, Kr, etc., is now under development and some of them have already been used for user experiments. For example, highly charged heavy ion beams like (86)Kr(21+,23+) and intense (16)O(5+,6+) and (15)N(6+) ion beams have been provided for experiments. The metal ion from volatile compounds method for boron ions has been developed as well.

Production of highly charged heavy ions by 18 GHz superconducting electron cyclotron resonance at Research Center for Nuclear Physics

An 18 GHz superconducting electron cyclotron resonance ion source has been installed as a subject of the azimuthally varying field cyclotron upgrade project (K. Hatanaka et al., in Proceedings of the 17th International Conference on Cyclotrons and Their Applications, Tokyo, Japan, 18-22 October 2004, pp. 115-117), in order to increase beam currents and to extend the variety of ions. The production development of several ions has been performed since 2006 and some of them have already been used for user experiments [T. Yorita et al., Rev. Sci. Instrum. 79, 02A311 (2008)]. Further optimizations for each component such as the material of plasma electrode, material, and shape of bias probe and mirror field have been continued and more intense ion beams have been obtained for O, N, and Ar. For the purpose of obtaining highly charged Xe with several microamperes, the optimization of position and shape of plasma electrode and bias disk has also been done and highly charged Xe(32+) beam has been obtained successfully.

Complete set of polarization transfer observables for the ^ O(p^^→, n^^→)^ F reaction at 296 MeV and 0 degrees

We report measurements of the cross section and a complete set of polarization transfer observables for the {sup 16}O(p-vector, n-vector){sup 16}F reaction at a bombarding energy of T{sub p} = 296 MeV and a reaction angle of {theta}{sub lab} = 0 deg. The data are compared with distorted-wave impulse approximation calculations employing the large configuration-space shell-model (SM) wave functions. The well-known Gamow-Teller and spin-dipole (SD) states at excitation energies of E{sub x} < or approx. 8 MeV have been reasonably reproduced by the calculations except for the spin-parity J{sup {pi}} = 2{sup -} state at E{sub x} = 5.86 MeV. The SD resonance at E{sub x} {approx_equal} 9.5 MeV appears to have more J{sup {pi}} = 2{sup -} strength than J{sup {pi}} = 1{sup -} strength, consistent with the calculations. The data show significant strength in the spin-longitudinal polarized cross section ID{sub L}(0 deg.) at E{sub x} {approx_equal} 15 MeV, which indicates the existence of the J{sup {pi}} = 0{sup -} SD resonance as predicted in the SM calculations.

Total Spin Transfer in Continuum for 90Zr(p,n) Reaction at 295 MeV

A complete set of polarization transfer observables has been measured for the 90 Zr( p , n ) reaction at T p = 295 MeV and θ lab = 0°. The measurement can yield the total spin transfer Σ(0°) which is independent of nuclear reaction mechanisms such as the effective nucleon–nucleon interaction or distortions. The deduced Σ(0°) values indicate the strong spin-flip characteristics of the continuum up to 50 MeV excitation. A predominance of unnatural-parity transitions in the continuum is also observed from polarization transfer observables.

Study of Three-Nucleon Force Effect via Few-Nucleon Scattering

A complete set of deuteron analyzing powers for elastic deuteron-proton(dp) scattering at 250 and 294 MeV/nucleon has been measured. The obtained data are compared with the Faddeev calculations based on the modern nucleon-nucleon forces together with three-nucleon forces.