Yuichi Hatsukawa - Academia.edu (original) (raw)
Papers by Yuichi Hatsukawa
Physical Review C, 2009
High spin states of ¹Dy have been studied through in-beam -ray spectroscopy by using the reaction... more High spin states of ¹Dy have been studied through in-beam -ray spectroscopy by using the reaction ²Mo(Fe,2p2n). It has been found that the continuation of the ground-state band forks into three I=2 bands above the 8{sup +} state. This forking has been attributed to the alignments of h² or h² configurations with the help of the systematics in neighboring nuclei. Additionally a negative-parity sideband of I=2 cascades has been observed to start from the 5{sup (-)} state and continue to a dipole band above the (13) state through another negative-parity sideband of I=2 cascades in between. These structures have been discussed from the viewpoint of a competition between ''Magnetic Rotation'' and ''Anti-magnetic Rotation'' based on a classical particles-plus-rotor model.
Journal of the Physical Society of Japan, 2015
Geochmica et Cosmochimica Acta
Journal of Radioanalytical and Nuclear Chemistry, 2014
ABSTRACT The astrophysical origin of a p-nucleus 115Sn has remained still an open question. The n... more ABSTRACT The astrophysical origin of a p-nucleus 115Sn has remained still an open question. The nucleus 115Sn may be produced by a weak branch of the s-process through a beta-unstable isomer in 113Cd. However, a neutron capture cross-section to this isomer has not been measured with high accuracy at any energy. A neutron capture cross-section for the 112Cd(n,gamma)113Cdm reaction has been measured with neutrons provided from a nuclear reactor. The nucleus 115Sn may be produced by a nucleosynthesis flow through 113Cdm in the s-process. We have obtained the thermal neutron capture cross-section of 0.028+/-0.009 [b] and the resonance integral of 1.1+/-0.3 [b] using a cadmium difference method. The cross-section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E
International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes, 1986
Built-up films of 57Co-labelled cobalt(H) stearate and arachidate were prepared from the tracer c... more Built-up films of 57Co-labelled cobalt(H) stearate and arachidate were prepared from the tracer concentration, 1 x 10-5mol/L, of cobalt(I1) with a specially designed small volume trough. The 57Co activity adsorbed on a film of seven layers was as much as 2.8 DCi/cm*. Chemical states of s7Fe formed through the EC-decay of s7Co were &died by observing emission Miissbauer spectra at 78 K. The absorption area of 57Fe(III)-species relative to the sum of the 57Fe(III) and 57Fe(IJ) was found to be influenced by the types of built-up films, namely, X-and Y-types.
Science China Physics, Mechanics and Astronomy, 2011
ABSTRACT A new rotational band has been identified and assigned to 188Au for the first time using... more ABSTRACT A new rotational band has been identified and assigned to 188Au for the first time using the 173Yb(19F,4nγ) reaction at the beam energies of 86 and 90 MeV. This band is proposed to be built on the πh 9/2 ⊗ νi 13/2 configuration by comparing the band properties with known bands in neighboring nuclei. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188Au for the ηh 9/2 ⊗ νi 13/2 bands in odd-odd Au isotopes on the basis of total Routhian surface (TRS) calculations. Keywordshigh-spin states–shape evolution–triaxial shape–signature inversion
a b s t r a c t A new measurement system to determine the neutron-capture cross-sections of a nuc... more a b s t r a c t A new measurement system to determine the neutron-capture cross-sections of a nucleus at 0.008 r E n o 20 MeV has been installed at the 4 MV Pelletron accelerator laboratory at the facility of radiation standards at Japan Atomic Energy Agency. The performance of the new system was studied by measuring the neutron-capture reaction cross-section of nat Pb using pulsed neutrons from 7 Li(p,n) 7 Be at 12 rE n r 103 keV. Prompt g-rays from the reaction were detected by means of a highly sensitive anti-Compton NaI(Tl) spectrometer combined with a time-of-flight method. The obtained result demonstrated good sensitivity of the new system to determine the neutron-capture cross-sections of a nucleus at kiloelectron volt neutron energy.
Motivated by the recent progress in the RI-beam physics and the discovery of the island of invers... more Motivated by the recent progress in the RI-beam physics and the discovery of the island of inversion, a systematic investigation of the medium to high spin excited states in neutron-rich A = 30 ˜ 40 region has been underway as a cooperative study at the JAEA tandem accelerator facility. Since the evolution of shell structure is a function of nuclear deformation and rotation as well as the isospin, systematic understanding of the levels in this neutron-rich region is of great interest. Especially, the systematic identification of the high-spin levels involving the sd to fp cross-shell excitation could be a key to clarify the evolution of N = 20 neutron shell gap. We will present recent results on some neutron rich nuclei in this mass region and disscuss their shell structure.
ABSTRACT The high-spin level structure of Au188 has been investigated via the Yb173(F19,4nγ) reac... more ABSTRACT The high-spin level structure of Au188 has been investigated via the Yb173(F19,4nγ) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new Iπ=20+ state associated with πh11/2-1⊗νi13/2-2h9/2-1 configuration and two new rotational bands, one of which is built on the πh9/2⊗νi13/2 configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around Au188 for the πh9/2⊗νi13/2 bands in odd-odd Au isotopes. Evidence for πh11/2-1⊗νi13/2-1 structure of nonaxial shape with γ<-70° has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.
The quadrupole shape evolution in heaviest stable Mo isotopes is studied in terms of the shape co... more The quadrupole shape evolution in heaviest stable Mo isotopes is studied in terms of the shape coexistence phenomenon occurrence in this region of nuclear chart. Quadrupole deformation parameters of the 96,98,100 Mo isotopes in the low-lying (ground and excited) 0 + states were deduced using Coulomb excitation method. In all cases rich sets of electromagnetic reduced matrix elements were determined using the GOSIA code and then analysed using the Quadrupole Sum Rules formalism. Discussion of the experimental results in comparison with the predictions of microscopic calculations within the general quadrupole collective Bohr Hamiltonian model is presented for 100 Mo. 443 Int. J. Mod. Phys. E 2011.20:443-450. Downloaded from www.worldscientific.com by UNIVERSITY OF WARSAW INSTITUTE OF THEORETICAL PHYSICS -LIBRARY on 08/23/12. For personal use only. 444 K. Wrzosek-Lipska et al.
The Astrophysical Journal, 2009
A neutron capture cross section for the 112 Cd(n, γ ) 113 Cd m reaction has been measured with ne... more A neutron capture cross section for the 112 Cd(n, γ ) 113 Cd m reaction has been measured with neutrons provided from a nuclear reactor in order to study the astrophysical origin of a rare p-process isotope 115 Sn, which may be produced by a nucleosynthesis flow through 113 Cd m in the s-process. We have obtained the thermal neutron capture cross section of 0.028 ± 0.009 [b] and the resonance integral of 1.1 ± 0.3 [b] using a cadmium difference method. The cross section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E < 100 keV. We have evaluated the s-process contribution to the solar abundance of 115 Sn using the classical steady-flow model with various astrophysical parameters. This calculated result has shown that the production through 113 Cd m may give minor contribution to 115 Sn.
Scientia Sinica Physica, Mechanica & Astronomica, 2012
Physics Letters B, 2010
A rotational band with five γ-ray transitions ranging from 2 + to 12 + states was identified in 4... more A rotational band with five γ-ray transitions ranging from 2 + to 12 + states was identified in 40 Ar. This band is linked through γ transitions from the excited 2 + , 4 + and 6 + levels to the low-lying states; this determines the excitation energy and the spin-parity of the band. The deduced transition quadrupole moment of 1.45 +0.49 −0.31 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartree-Fock-Bogoliubov calculations and a multiparticle-multihole configuration is assigned to the band.
Physical Review C, 2013
ABSTRACT High-spin states of 99Rh were studied through in-beam γ-ray spectroscopy by using the re... more ABSTRACT High-spin states of 99Rh were studied through in-beam γ-ray spectroscopy by using the reaction 68Zn(37Cl, α2n). The upper part of the band based on the g9/2 proton orbital was rearranged in four parallel cascades. Negative parity was tentatively assigned for the side-band that previously had no parity assignment. This negative-parity band was interpreted as having the configuration of π(g9/2)5ν[(d5/2g7/2)3(h11/2)] and extended up to 51/2(−), which is possibly a terminating state. The band based on the p1/2 proton orbital was observed up to 29/2− and its property was compared with those of neighboring odd-Z nuclei from the two different viewpoints, one of which is a weakly deformed soft rotor with spin alignments and the other is vibrational to rotational evolution along the band.
Physical Review C, 1991
ABSTRACT Mass yield curves in low-energy proton-induced fission of 233U, 235U, 236U, 237Np, 239Pu... more ABSTRACT Mass yield curves in low-energy proton-induced fission of 233U, 235U, 236U, 237Np, 239Pu, 242Pu, 244Pu, 241Am, and 243Am were investigated in the energy range of 8-32 MeV. The gross features of mass yield curves were compared either at the same excitation energy or for the same charge of the compound nucleus with different neutron number. The results are briefly discussed in terms of (1) the weighted mean mass number of the light and heavy asymmetric peak, (2) the FWHM of the heavier asymmetric peak, and (3) the peak-to-valley ratio.
Physical Review C, 2012
ABSTRACT High-spin states in the odd-odd 174Re have been investigated via the 152Sm(27 Al, 5nγ)17... more ABSTRACT High-spin states in the odd-odd 174Re have been investigated via the 152Sm(27 Al, 5nγ)174Re reaction with the help of excitation function, x-γ, and γ-γ coincidence measurements. Five rotational bands have been observed and their configurations were assigned based on alignments, band crossing frequencies, electromagnetic properties, and the estimated bandhead excitation energies. Low-spin signature inversion has been identified in the two-quasiparticle bands built on πh11/2⊗νi13/2, πh9/2⊗νi13/2, and π1/2−[541]⊗ν5/2−[512] configurations. E2 interband transitions were analyzed with band-mixing calculations giving information on shapes and shape driving effects for the bands of interest.
Physical Review C, 2010
The high-spin level structure of 188 Au has been investigated via the 173 Yb( 19 F,4nγ ) reaction... more The high-spin level structure of 188 Au has been investigated via the 173 Yb( 19 F,4nγ ) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new I π = 20 + state associated with πh −1 11/2 νi −2 13/2 h −1 9/2 configuration and two new rotational bands, one of which is built on the πh 9/2 νi 13/2 configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188 Au for the πh 9/2 νi 13/2 bands in odd-odd Au isotopes. Evidence for πh −1 11/2 νi −1 13/2 structure of nonaxial shape with γ < −70 • has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.
Physical Review C, 2009
High spin states of ¹Dy have been studied through in-beam -ray spectroscopy by using the reaction... more High spin states of ¹Dy have been studied through in-beam -ray spectroscopy by using the reaction ²Mo(Fe,2p2n). It has been found that the continuation of the ground-state band forks into three I=2 bands above the 8{sup +} state. This forking has been attributed to the alignments of h² or h² configurations with the help of the systematics in neighboring nuclei. Additionally a negative-parity sideband of I=2 cascades has been observed to start from the 5{sup (-)} state and continue to a dipole band above the (13) state through another negative-parity sideband of I=2 cascades in between. These structures have been discussed from the viewpoint of a competition between ''Magnetic Rotation'' and ''Anti-magnetic Rotation'' based on a classical particles-plus-rotor model.
Journal of the Physical Society of Japan, 2015
Geochmica et Cosmochimica Acta
Journal of Radioanalytical and Nuclear Chemistry, 2014
ABSTRACT The astrophysical origin of a p-nucleus 115Sn has remained still an open question. The n... more ABSTRACT The astrophysical origin of a p-nucleus 115Sn has remained still an open question. The nucleus 115Sn may be produced by a weak branch of the s-process through a beta-unstable isomer in 113Cd. However, a neutron capture cross-section to this isomer has not been measured with high accuracy at any energy. A neutron capture cross-section for the 112Cd(n,gamma)113Cdm reaction has been measured with neutrons provided from a nuclear reactor. The nucleus 115Sn may be produced by a nucleosynthesis flow through 113Cdm in the s-process. We have obtained the thermal neutron capture cross-section of 0.028+/-0.009 [b] and the resonance integral of 1.1+/-0.3 [b] using a cadmium difference method. The cross-section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E
International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes, 1986
Built-up films of 57Co-labelled cobalt(H) stearate and arachidate were prepared from the tracer c... more Built-up films of 57Co-labelled cobalt(H) stearate and arachidate were prepared from the tracer concentration, 1 x 10-5mol/L, of cobalt(I1) with a specially designed small volume trough. The 57Co activity adsorbed on a film of seven layers was as much as 2.8 DCi/cm*. Chemical states of s7Fe formed through the EC-decay of s7Co were &died by observing emission Miissbauer spectra at 78 K. The absorption area of 57Fe(III)-species relative to the sum of the 57Fe(III) and 57Fe(IJ) was found to be influenced by the types of built-up films, namely, X-and Y-types.
Science China Physics, Mechanics and Astronomy, 2011
ABSTRACT A new rotational band has been identified and assigned to 188Au for the first time using... more ABSTRACT A new rotational band has been identified and assigned to 188Au for the first time using the 173Yb(19F,4nγ) reaction at the beam energies of 86 and 90 MeV. This band is proposed to be built on the πh 9/2 ⊗ νi 13/2 configuration by comparing the band properties with known bands in neighboring nuclei. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188Au for the ηh 9/2 ⊗ νi 13/2 bands in odd-odd Au isotopes on the basis of total Routhian surface (TRS) calculations. Keywordshigh-spin states–shape evolution–triaxial shape–signature inversion
a b s t r a c t A new measurement system to determine the neutron-capture cross-sections of a nuc... more a b s t r a c t A new measurement system to determine the neutron-capture cross-sections of a nucleus at 0.008 r E n o 20 MeV has been installed at the 4 MV Pelletron accelerator laboratory at the facility of radiation standards at Japan Atomic Energy Agency. The performance of the new system was studied by measuring the neutron-capture reaction cross-section of nat Pb using pulsed neutrons from 7 Li(p,n) 7 Be at 12 rE n r 103 keV. Prompt g-rays from the reaction were detected by means of a highly sensitive anti-Compton NaI(Tl) spectrometer combined with a time-of-flight method. The obtained result demonstrated good sensitivity of the new system to determine the neutron-capture cross-sections of a nucleus at kiloelectron volt neutron energy.
Motivated by the recent progress in the RI-beam physics and the discovery of the island of invers... more Motivated by the recent progress in the RI-beam physics and the discovery of the island of inversion, a systematic investigation of the medium to high spin excited states in neutron-rich A = 30 ˜ 40 region has been underway as a cooperative study at the JAEA tandem accelerator facility. Since the evolution of shell structure is a function of nuclear deformation and rotation as well as the isospin, systematic understanding of the levels in this neutron-rich region is of great interest. Especially, the systematic identification of the high-spin levels involving the sd to fp cross-shell excitation could be a key to clarify the evolution of N = 20 neutron shell gap. We will present recent results on some neutron rich nuclei in this mass region and disscuss their shell structure.
ABSTRACT The high-spin level structure of Au188 has been investigated via the Yb173(F19,4nγ) reac... more ABSTRACT The high-spin level structure of Au188 has been investigated via the Yb173(F19,4nγ) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new Iπ=20+ state associated with πh11/2-1⊗νi13/2-2h9/2-1 configuration and two new rotational bands, one of which is built on the πh9/2⊗νi13/2 configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around Au188 for the πh9/2⊗νi13/2 bands in odd-odd Au isotopes. Evidence for πh11/2-1⊗νi13/2-1 structure of nonaxial shape with γ<-70° has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.
The quadrupole shape evolution in heaviest stable Mo isotopes is studied in terms of the shape co... more The quadrupole shape evolution in heaviest stable Mo isotopes is studied in terms of the shape coexistence phenomenon occurrence in this region of nuclear chart. Quadrupole deformation parameters of the 96,98,100 Mo isotopes in the low-lying (ground and excited) 0 + states were deduced using Coulomb excitation method. In all cases rich sets of electromagnetic reduced matrix elements were determined using the GOSIA code and then analysed using the Quadrupole Sum Rules formalism. Discussion of the experimental results in comparison with the predictions of microscopic calculations within the general quadrupole collective Bohr Hamiltonian model is presented for 100 Mo. 443 Int. J. Mod. Phys. E 2011.20:443-450. Downloaded from www.worldscientific.com by UNIVERSITY OF WARSAW INSTITUTE OF THEORETICAL PHYSICS -LIBRARY on 08/23/12. For personal use only. 444 K. Wrzosek-Lipska et al.
The Astrophysical Journal, 2009
A neutron capture cross section for the 112 Cd(n, γ ) 113 Cd m reaction has been measured with ne... more A neutron capture cross section for the 112 Cd(n, γ ) 113 Cd m reaction has been measured with neutrons provided from a nuclear reactor in order to study the astrophysical origin of a rare p-process isotope 115 Sn, which may be produced by a nucleosynthesis flow through 113 Cd m in the s-process. We have obtained the thermal neutron capture cross section of 0.028 ± 0.009 [b] and the resonance integral of 1.1 ± 0.3 [b] using a cadmium difference method. The cross section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E < 100 keV. We have evaluated the s-process contribution to the solar abundance of 115 Sn using the classical steady-flow model with various astrophysical parameters. This calculated result has shown that the production through 113 Cd m may give minor contribution to 115 Sn.
Scientia Sinica Physica, Mechanica & Astronomica, 2012
Physics Letters B, 2010
A rotational band with five γ-ray transitions ranging from 2 + to 12 + states was identified in 4... more A rotational band with five γ-ray transitions ranging from 2 + to 12 + states was identified in 40 Ar. This band is linked through γ transitions from the excited 2 + , 4 + and 6 + levels to the low-lying states; this determines the excitation energy and the spin-parity of the band. The deduced transition quadrupole moment of 1.45 +0.49 −0.31 eb indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartree-Fock-Bogoliubov calculations and a multiparticle-multihole configuration is assigned to the band.
Physical Review C, 2013
ABSTRACT High-spin states of 99Rh were studied through in-beam γ-ray spectroscopy by using the re... more ABSTRACT High-spin states of 99Rh were studied through in-beam γ-ray spectroscopy by using the reaction 68Zn(37Cl, α2n). The upper part of the band based on the g9/2 proton orbital was rearranged in four parallel cascades. Negative parity was tentatively assigned for the side-band that previously had no parity assignment. This negative-parity band was interpreted as having the configuration of π(g9/2)5ν[(d5/2g7/2)3(h11/2)] and extended up to 51/2(−), which is possibly a terminating state. The band based on the p1/2 proton orbital was observed up to 29/2− and its property was compared with those of neighboring odd-Z nuclei from the two different viewpoints, one of which is a weakly deformed soft rotor with spin alignments and the other is vibrational to rotational evolution along the band.
Physical Review C, 1991
ABSTRACT Mass yield curves in low-energy proton-induced fission of 233U, 235U, 236U, 237Np, 239Pu... more ABSTRACT Mass yield curves in low-energy proton-induced fission of 233U, 235U, 236U, 237Np, 239Pu, 242Pu, 244Pu, 241Am, and 243Am were investigated in the energy range of 8-32 MeV. The gross features of mass yield curves were compared either at the same excitation energy or for the same charge of the compound nucleus with different neutron number. The results are briefly discussed in terms of (1) the weighted mean mass number of the light and heavy asymmetric peak, (2) the FWHM of the heavier asymmetric peak, and (3) the peak-to-valley ratio.
Physical Review C, 2012
ABSTRACT High-spin states in the odd-odd 174Re have been investigated via the 152Sm(27 Al, 5nγ)17... more ABSTRACT High-spin states in the odd-odd 174Re have been investigated via the 152Sm(27 Al, 5nγ)174Re reaction with the help of excitation function, x-γ, and γ-γ coincidence measurements. Five rotational bands have been observed and their configurations were assigned based on alignments, band crossing frequencies, electromagnetic properties, and the estimated bandhead excitation energies. Low-spin signature inversion has been identified in the two-quasiparticle bands built on πh11/2⊗νi13/2, πh9/2⊗νi13/2, and π1/2−[541]⊗ν5/2−[512] configurations. E2 interband transitions were analyzed with band-mixing calculations giving information on shapes and shape driving effects for the bands of interest.
Physical Review C, 2010
The high-spin level structure of 188 Au has been investigated via the 173 Yb( 19 F,4nγ ) reaction... more The high-spin level structure of 188 Au has been investigated via the 173 Yb( 19 F,4nγ ) reaction at beam energies of 86 and 90 MeV. The previously reported level scheme has been modified and extended significantly. A new I π = 20 + state associated with πh −1 11/2 νi −2 13/2 h −1 9/2 configuration and two new rotational bands, one of which is built on the πh 9/2 νi 13/2 configuration, have been identified. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188 Au for the πh 9/2 νi 13/2 bands in odd-odd Au isotopes. Evidence for πh −1 11/2 νi −1 13/2 structure of nonaxial shape with γ < −70 • has been obtained by comparison with total Routhian surface and cranked-shell-model calculations.