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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.
Sankar Ganesh, R.,Sharma, Sanjeev K.,Abinnas, N.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, Deuk Young Elsevier Sequoia S.A 2017 Materials chemistry and physics Vol.192 No.-
<P><B>Abstract</B></P> <P>Nanostructured bismuth titanate (Bi<SUB>4</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB>) or BTO powders were synthesized by the combustion method. The crystalline phase of BTO nanopowders was evaluated from X-ray diffraction (XRD) and further confirmed by selected area electron diffraction (SAED) pattern. The SEM and TEM micrographic images clearly showed the nanosheets like morphology of BTO nanopowder. The EDS spectrum of BTO nanopowder showed the elemental peaks of O, Bi and Ti at 0.53 keV, 2.41 keV and 4.49 keV, respectively. FTIR band peaks were observed at 815 and 595 cm<SUP>−1</SUP> corresponding to the stretching vibrations of BiO and TiO. The red shift in optical absorption of BTO was observed and the bandgap decreased from 3.18 to 3.08 eV as the calcined temperature increased from 600 to 800 °C. The sandwich structure, called the nanogenerator, Graphene/BTO-PDMS/Graphene (G/BTO/G), was fabricated on graphene coated polymethyl methacrylate (PMMA) substrates, which produced a peak voltage (10 mV) by applying the pressure from human's finger. The switching mechanism of BTO nanosheets was observed to be dependent on the polarity and intrinsic dipole formation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bi<SUB>4</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (BTO) nanosheets synthesized from a simple combustion method. </LI> <LI> SEM & TEM images confirmed the nanosheets structure with a hexagonal shape. </LI> <LI> XRD and SAED pattern of BTO nanosheets confirmed the orthorhombic crystal structure. </LI> <LI> Flexible G/BTO/G nanogenerator fabricated by sol-gel method. </LI> <LI> Peak voltage was observed to be 10 mV by applying pressure from human's finger. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Sankar Ganesh, R.,Sharma, S.K.,Sankar, S.,Divyapriya, B.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, D.Y. ELSEVIER 2017 Current Applied Physics Vol.17 No.3
<P>Nanocrystalline BiFeO3 (BFO) powder was synthesized by sol-gel method and subsequent annealed at 100-500 degrees C. The microstructural analysis of BFO nanopowder confirmed the perovskite like structure of spherical nanoparticles annealed at 500 degrees C. The Raman spectrum of BFO nanoparticles showed the rhombohedrally structure with the space group of R3c. The XPS spectrum of BFO nanopowder showed the peaks of Bi, Fe, and O at the binding energy of 158.8, 711.75 and 529.2 eV, respectively. The piezoelectric properties of BFO nanoparticles were evaluated by making the sandwiched structure of graphene/BiFeO3-PDMS/graphene. The fabricated piezoelectric device demonstrated an output voltage of 0.4 V by applying the normal pressure from human finger on the device. (C) 2016 Elsevier B.V. All rights reserved.</P>
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.
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.-
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.
Study of a-cluster Structure in 22Mg Using a Radioactive Ion Beam
차수미,K. Y. Chae,김민주,M. S. Kwag,E. J. Lee,K. Abe,S. Hayakawa,H. Shimizu,H. Yamaguchi,L. Yang,S. H. Bae,S. H. Choi,D. N. Binh,N. N. Duy,Z. Ge,V. H. Phong,K. I. Hahn,B. Hong,B. Moon,N. Iwasa,D. Kahl,L. H. 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.8
The ff-clusterization of an atomic nucleus has been studied for a long time, even from the earliest days of nuclear physics. Our understanding of the ff-cluster structure is, however, mainly limited to the self-conjugate A = 4n (n = 2; 3; 4; ) light nuclei and some of the neutron-rich radionuclides such as 10Be, 11B, and 14C. In order to study the ff-cluster structure of a neutron-deficient 22Mg nucleus, we have measured the 18Ne(ff, ff)18Ne scattering in inverse kinematics by using radioactive 18Ne beams and the 4He gas target at the Center for Nuclear Study radioactive ion beam separator of the University of Tokyo. Recoiling ff particles from the scattering were detected by using silicon strip detectors, which constitute E-E telescopes for particle identification. By adopting a thick target method, we were able to investigate a wide range of excitation energies Ex = 9:9 - 16.5 MeV in 22Mg in this work.
Study of 19F Levels with Ex = 6.7 - 7.7 MeV by the 15N+α Scattering Experiment
D. Kim,G. W. Kim,S. Y. Park,A. Kim,한인식,K. Abe,O. Beliuskina,S. Hayakawa,N. Imai,N. Kitamura,Y. Sakaguchi,H. Yamaguchi,S. M. Cha,K. Y. Chae,M. S. Kwag,S. W. Hong,E. J. Lee,J. H. Lee,E. K. Lee,J. Y. Moo 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.3
The intense γ-rays from classical novae are emitted due to the β-decay of 18F which is produced by the Hot-CNO cycle. The reaction rate of 18F(p,α)15O affects the prediction of the abundance of 18F. The main contribution to this reaction rate is from the resonances in 19Ne near and above the proton threshold. Hence, many experiments and theoretical works have been performed on the low-lying 18F+p resonances. One of the methods for investigating 19Ne parameters is studying the mirror nucleus 19F. α elastic scattering experiment was performed with a 7 MeV/u 15N beam for investigating the resonance parameters in 19F using the thick target method in inverse kinematics at the radioactive beam facility CRIB of the Center for Nuclear Study, the University of Tokyo. The excitation function of 19F was obtained for the excitation energy Ex = 6.7 - 7.7 MeV, and the parameters of the resonance states in 19F were determined using an R-matrix analysis.
Beam production of <sup>18</sup>Ne with in-flight method for alpha scattering at CRIB
Duy, N.N.,Chae, K.Y.,Cha, S.M.,Yamaguchi, H.,Abe, K.,Bae, S.H.,Binh, D.N.,Choi, S.H.,Hahn, K.I.,Hayakawa, S.,Hong, B.,Iwasa, N.,Kahl, D.,Khiem, L.H.,Kim, A.,Kim, D.H.,Kim, E.J.,Kim, G.W.,Kim, M.J.,Kwa Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.897 No.-
<P><B>Abstract</B></P> <P>We conducted a measurement of <SUP>18</SUP>Ne + α scattering in inverse kinematics, in order to search for experimental evidence of α -cluster structure in <SUP>22</SUP>Mg above the alpha threshold ( <SUB> E thr </SUB> = 8 . 14 MeV ) and determine the astrophysical rates of the <SUP>18</SUP>Ne( α , p)<SUP>21</SUP>Na reaction under the conditions of break-out from the Hot-CNO cycle. A high intensity <SUP>18</SUP>Ne beam at 2.54 AMeV was successfully produced at CRIB (CNS Radioactive Ion Beam separator) of the Center for Nuclear Study, the University of Tokyo. This paper presents the in-flight production of the radioactive <SUP>18</SUP>Ne beam by using the production reaction <SUP>3</SUP>He(<SUP>16</SUP>O, <SUP>18</SUP>Ne)n with a windowed cryogenic gas target, which was employed in the mentioned resonant α -scattering experiment.</P>