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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.
K. Tahara,Y. Fukuda,G. Wakabayashi,H. Ban,Y. Morimoto,M. Yoshioka,K. Kiyohara,Y. Koba,H. Iwamoto,Y. Uozumi,N. Matsufuji 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
We measured proton-production double differential cross sections (DDXs) by 290 MeV/u carbon beams on carbon, copper, lead targets at forward angles. The proton energies were measured with the spectrometer which consisted of GSO(Ce) crystals and plastic scintillators. The measured DDXs were compared with the calculated ones with PHITS code. The simulation results generally agreed with the measured ones. The measured results will be useful as the benchmark of existing simulation codes and for the future improvements.
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.
A. Mzhavia,M. Ueyama,Y. Uozumi,Y. Sawada,M. Yoshioka,G. Wakabayashi,H. Iwamoto,Y. Koba,Z. Tsamalaidze,P. Evtukhovitch,V. Kalinnikov,N. Khomutov,N. Kuchinskii,G. Macharashvili,A. Moiseenko,A. Molokanov 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Double-differential cross section (DDX) data of nucleon-actinide reactions is crucial for the study of nuclear waste transmutation by accelerator driven systems. Charged particle emission data is strongly required as well as the neutron data up to several Gev. In the present study, we measured double-differential cross sections of light charged particle productions for proton induced reactions on ^(232)Th at 360 Mev. The experiment was carried out at the PHASOTRON facility of the Joint Institute for Nuclear Research (JINR) in Dubna.The light charged particles (LCPs) emitted from nuclear reactions were detected by ΔE-E counter telescopes. Eight detector systems were used. Four of them were comprised of two plastic scintillator plates and BGO crystal. The other four consisted of two silicon semiconductor detectors and two scintillation counters, a cubic CsI(TI) (40 mm long) crystal and plate plastic scintillator. The four identical detectors on each side were placed at laboratory angles of 20˚. 40˚, 70˚ and 105˚ with respect to the beam axis. Resultant DDX spectra of protons and deuterons were compared with intranuclear cascade (INC) model.
Lattice Modulation in YMn2O5 and TbMn2O5 Studied by Using Synchrotron Radiation X-rays
Yukio Noda,H Kimura,H Sawa,K Kohn,N Ikeda,S Kobayashi,Y Ishikawa,Y Kamada,Y Wakabayashi 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
RMn2O5 (R = Y and rare earth) shows successive magnetic and ferroelectric phase transitions at about 45 K, 40 K, 39 K, 20 K and 10 K and is called a multiferroic compound. We have investigated the lattice modulation vectors (qL) of YMn2O5 and TbMn2O5 by using single crystal Synchrotron Radiation X-ray diraction and compared them with the magnetic propagation vectors (qM) studied by neutron diraction. The relation of the propagation vectors between magnetic materials and dielectrics is found to be qL = 2qM. A preliminary structure analysis of the atomic displacement pattern in the commensurate ferroelectric phase of TbMn2O5 is discussed.fb
Study on α-cluster levels in non-4n nuclei using low-energy RI beams
Yamaguchi, H,Kahl, D,Hayakawa, S,Sakaguchi, Y,Abe, K,Nakao, T,Suhara, T,Iwasa, N,Kim, A,Kim, D H,Cha, S M,Kwag, M S,Lee, J H,Lee, E J,Chae, K Y,Wakabayashi, Y,Imai, N,Kitamura, N,Lee, P,Moon, J Y,Lee, IOP Publishing 2017 Journal of physics. Conference series Vol.863 No.-
Experimental investigation of a linear-chain structure in the nucleus <sup>14</sup>C
Yamaguchi, H.,Kahl, D.,Hayakawa, S.,Sakaguchi, Y.,Abe, K.,Nakao, T.,Suhara, T.,Iwasa, N.,Kim, A.,Kim, D.H.,Cha, S.M.,Kwag, M.S.,Lee, J.H.,Lee, E.J.,Chae, K.Y.,Wakabayashi, Y.,Imai, N.,Kitamura, N.,Lee North-Holland Pub. Co 2017 Physics letters. Section B Vol.766 No.-
It is a well-known fact that a cluster of nucleons can be formed in the interior of an atomic nucleus, and such clusters may occupy molecular-like orbitals, showing characteristics similar to normal molecules consisting of atoms. Chemical molecules having a linear alignment are commonly seen in nature, such as carbon dioxide. A similar linear alignment of the nuclear clusters, referred to as linear-chain cluster state (LCCS), has been studied since the 1950s, however, up to now there is no clear experimental evidence demonstrating the existence of such a state. Recently, it was proposed that an excess of neutrons may offer just such a stabilizing mechanism, revitalizing interest in the nuclear LCCS, specifically with predictions for their emergence in neutron-rich carbon isotopes. Here we present the experimental observation of α-cluster states in the radioactive <SUP>14</SUP>C nucleus. Using the Be10+α resonant scattering method with a radioactive beam, we observed a series of levels which completely agree with theoretically predicted levels having an explicit linear-chain cluster configuration. We regard this as the first strong indication of the linear-chain clustered nucleus.
김아람,N. H. Lee,I. S. Hahn,J. S. Yoo,M. H. Han,S. Kubono,H. Yamaguchi,S. Hayakawa,Y. Wakabayashi,D. Binh,H. Hashimoto,T. Kawabata,D. Kahl,Y. Kurihara,Y. K. Kwon,T. Teranishi,S. Kato,T. Komatsubara,B. Gu 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.1
For the study of astrophysically important states in 18Ne, the 14O(α, α)14O cross section was measured in inverse kinematics using a radioactive 14O beam. This reaction was investigated for properties of resonant states of 18Ne for determining the 14O(α, p)17F reaction rate, which is one of the most important reactions for understanding the breakout mechanism from the Hot CNO cycle to the rp-process. Alpha-induced elastic scattering on 14O was performed using the lowenergy radioactive ion (RI) beam separator at the Center for Nuclear Study (CNS) in the RIKEN Accelerator Research Facility. The energy range Ex = 7.2 ∽ 13.1 MeV of 18Ne was scanned with the thick target method. Recoiled alpha particles were measured with Si dE-E telescopes. Spins and widths of three resonances at Ex = 8.6, 9.22, and 10.06 MeV were calculated using the R-matrix analysis, and a new state of 18Ne at Ex = 12.0 MeV was found in this experiment.
A single particle Hamiltonian for electro-magnetic properties of graphene nanoribbons
Lee, H.,Wakabayashi, K.,Son, Y.W.,Miyamoto, Y. Pergamon Press ; Elsevier Science Ltd 2012 Carbon Vol.50 No.10
Graphene zigzag edges are known to show the spin polarized ferromagnetic states, which are well described by the mean field treatment of Hubbard model. The parameter of onsite Coulomb interaction U is estimated to be comparable to the kinetic hopping parameter t so as to fit the electronic band structures obtained by the spin-polarized density functional theory (DFT). In this paper, we propose a simple way to transfer the electronic band structures obtained by DFT onto the mean-field Hubbard Hamiltonian by adopting site-dependent U parameter, which is taken as the decaying function from the edge. This approach is applicable to both anti-ferromagnetic and ferromagnetic states between two edges of graphene nanoribbons and will serve to perform the further large-scale simulation of electro-magnetic transport properties of graphene-based nanodevices.