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Experimental Approach to Explosive Nucloeosynthesis with RI Beams
S. Kubono,Y. Yamaguchi,G. Amadio,S. Hayakawa,Y. Wakabayashi,Y. Kurihara,J. J. He,A. Saito,H. Fujikawa,Le Hong Khiem,M. Niikura,T. Teranishi,N. Iwasa,S. Kato,S. Nishimura,C. S. Lee,Y. K. Kwon,I. S. Hah 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
Experimental efforts to investigate stellar reactions under high-temperature and high density conditions have been made as a major program using the RI beams from the Center for Nuclear Study (CNS) low-energy in-flight RI beam separator (CRIB) at University of Tokyo in order to understand the evolution of the universe, as well as various stellar phenomena. Specically, two subjects of hydrogen burning are discussed here. One is a reaction study of the pp-chain and the second is of the explosive hydrogen burning, the rp-process. Some s-wave resonances have been identified by the thick target method in the crucial reaction processes in the hydrogen burning. The resonant scattering with the thick target method also succeeded in identifying inelastic resonant scattering, giving proton widths for the first excited state of the target nucleus. This provided very efficiently the reaction rate estimate for the process under high-temperature equilibrium conditions. Possibilities of the CRIB facility in near future are also briey discussed. Experimental efforts to investigate stellar reactions under high-temperature and high density conditions have been made as a major program using the RI beams from the Center for Nuclear Study (CNS) low-energy in-flight RI beam separator (CRIB) at University of Tokyo in order to understand the evolution of the universe, as well as various stellar phenomena. Specically, two subjects of hydrogen burning are discussed here. One is a reaction study of the pp-chain and the second is of the explosive hydrogen burning, the rp-process. Some s-wave resonances have been identified by the thick target method in the crucial reaction processes in the hydrogen burning. The resonant scattering with the thick target method also succeeded in identifying inelastic resonant scattering, giving proton widths for the first excited state of the target nucleus. This provided very efficiently the reaction rate estimate for the process under high-temperature equilibrium conditions. Possibilities of the CRIB facility in near future are also briey discussed.
Astrophysically Important 26Si States Studied with the 28Si(4He,6He)26Si Reaction
Y. K. Kwon,이춘식,J. Y. Moon,J. H. Lee,J. Y. Kim,M. K. Cheoun,S. Kubono,H. Yamaguchi,J. J. He,A. Saito,Y. Wakabayashi,H. Fujikawa,G. Amadio,N. Iwasa,K. Inafuku,L. H. Khiem,M. Tanaka,Y. Fuchi,A. A. Chen,S 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
The emission of a 1.809-MeV γ-ray from the first excited state of 26Mg, followed by β-decay of 26Al in its ground state (denoted as 26Alg.s.), has been identied by several gamma-ray telescopes. To resolve the controversy over the possible sources of the observational 1.809-MeV γ-rays, one needs accurate knowledge of the production rate of 26Alg.s.. The 25Al(p,γ)26Si reaction is one of the most important astrophysical reactions to be investigated, but its rate is uncertain due to the lack of level information on 26Si above the proton threshold (Qpγ = 5.518 MeV). Illiadis et al. suggested that the 25Al(p,γ)26Si reaction should be dominated by a 3+ unnatural parity state at Ex = 5970 keV. Recent studies proposed several states as candidates for the 3+ states. However, the spin-parity assignments for these states are still uncertain. In the present work, we measured the 28Si(4He,6He)26Si reaction at 120 MeV to confirm the unnatural parity states just above the proton threshold. The measurement was performed with the high-resolution particle analyzer at the Center for Nuclear Study, University of Tokyo. We observed a total of 22 excited states in 26Si. The 7018-keV level, which was only observed by Bardayan et al. with the 28Si(p; t)26Si reaction, was confirmed in our measurement. Among the candidates of unnatural parity states at Ex = 5678, 5916, and 5945 keV, the 5918-keV state was only observed within the error of the excitation energy. A new state at Ex = 6101 keV was also identified.
Configuration Dependence of Toroidal Current in Heliotron J
gen Motojima,F. Sano,H. Yabutani,H. Okada,H. Nakamura,H. Arimoto,H. Kitagawa,H. Yamazaki,K. Kondo,K. Nagasaki,K. Hanatani,K.Y. Watanabe,M. Kaneko,M. Uno,S. Fujikawa,S. Watanabe,S. Yamamoto,S. Kobayash 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
A change of toroidal current by controlling the magnetic configuration has been observed in Heliotron J. The effect of the magnetic configuration on the neoclassical bootstrap current has been theoretically investigated for Heliotron J. It is found that the bumpy field component (B04) plays an important role in changing both the value and the direction of the bootstrap current in Heliotron J. The bootstrap current density is reversed at the small minor radius first, and then the net bootstrap current changes its direction from a positive value to a negative value as B04 decreases.
T. Muranaka,A. Nisii,T. Uehara,T. Sakano,Y. Nabetani,T. Akitsu,T. Kato and T. Matsumoto,T. Matsumoto,S. Hagihara,O. Abe,S. Hiraki,Y. Fujikawa 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Ga-doped zinc-oxide (GZO) films grown under various Ga/Zn supply ratios were carefully characterized by using Hall measurements and optical transmittance measurements to investigate the electrical and the optical properties of the GZO films on glass, polyethylene terephthalate (PET), and polycarbonate (PC) substrates. The resistivity of the GZO films grown at 290 ℃ on glass substrates ranged from 4 × 10-2 cm to 3 × 10-4 cm for Ga/Zn supply ratios from 0 % to 0.5 %. The growth of the GZO films at a low temperature of 90 ℃ was also performed on glass, PET, and PC substrates. When the Ga/Zn supply ratios were 0.05 - 0.1 %, the 90 ℃-grown GZO films on glass substrates showed resistivities similar to those of 290 ℃-grown GZO films. The 90 ℃-grown GZO films on PET and PC substrates showed resistivities of 1 × 10-3 cm and 4 × 10-4 cm, respectively. The Hall carrier density was 8 × 1020 cm-3, which was almost the same value as that of the 90 ℃-grown GZO films on glass substrates. The GZO films on PET and PC substrates also showed visible transparency as good as that of the GZO films on glass substrates, and the average transmittance in the visible region was higher than 85 %.
T. Muranaka,T. Uehara,T. Sakano,Y. Nabetani,T. Akitsu,T. Kato,T. Matsumoto,S. Hagihara,O. Abe,S. Hiraki,Y. Fujikawa 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Ga-doped zinc-oxide (GZO) films grown at various Ga/Zn supply ratios were prepared on glass substrates by using plasma-assisted molecular beam deposition. The films were carefully characterized by using Hall, X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. At low Ga/Zn supply ratios, the carrier density systematically increased with increasing Ga/Zn supply ratio. However, a saturation of the carrier density near 4 − 6 × 1020 cm−3 was observed when the Ga/Zn supply ratio was in the range from 5 × 10−5 % to 0.5 %. From TEM observations, uniform crystal grains were observed to grow with low-angle tilt grain boundaries in GZO films with low doping. On the other hand, high-angle tilt grain boundaries were observed in the highly-doped GZO films. A detailed selected area electron diffraction (SAED) analysis revealed that such non-uniformity in the highly-doped GZO films appears during the initial growth stage.