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NSR database version of April 11, 2024.

Search: Author = T.Niwase

Found 16 matches.

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2024XI06      Phys.Rev. C 109, 035804 (2024)

W.Xian, S.Chen, S.Nikas, M.Rosenbusch, M.Wada, H.Ishiyama, D.Hou, S.Iimura, S.Nishimura, P.Schury, A.Takamine, S.Yan, F.Browne, P.Doornenbal, F.Flavigny, Y.Hirayama, Y.Ito, S.Kimura, T.M.Kojima, J.Lee, J.Liu, H.Miyatake, S.Michimasa, J.Y.Moon, S.Naimi, T.Niwase, T.Sonoda, D.Suzuki, Y.X.Watanabe, V.Werner, K.Wimmer, H.Wollnik

Mass measurements of neutron-rich A ≈ 90 nuclei constrain element abundances

doi: 10.1103/PhysRevC.109.035804
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2023HO11      Phys.Rev. C 108, 054312 (2023)

D.S.Hou, A.Takamine, M.Rosenbusch, W.D.Xian, S.Iimura, S.D.Chen, M.Wada, H.Ishiyama, P.Schury, Z.M.Niu, H.Z.Liang, S.X.Yan, P.Doornenbal, Y.Hirayama, Y.Ito, S.Kimura, T.M.Kojima, W.Korten, J.Lee, J.J.Liu, Z.Liu, S.Michimasa, H.Miyatake, J.Y.Moon, S.Naimi, S.Nishimura, T.Niwase, T.Sonoda, D.Suzuki, Y.X.Watanabe, K.Wimmer, H.Wollnik

First direct mass measurement for neutron-rich 112Mo with the new ZD-MRTOF mass spectrograph system

doi: 10.1103/PhysRevC.108.054312
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2023II01      Phys.Rev.Lett. 130, 012501 (2023)

S.Iimura, M.Rosenbusch, A.Takamine, Y.Tsunoda, M.Wada, S.Chen, D.S.Hou, W.Xian, H.Ishiyama, S.Yan, P.Schury, H.Crawford, P.Doornenbal, Y.Hirayama, Y.Ito, S.Kimura, T.Koiwai, T.M.Kojima, H.Koura, J.Lee, J.Liu, S.Michimasa, H.Miyatake, J.Y.Moon, S.Naimi, S.Nishimura, T.Niwase, A.Odahara, T.Otsuka, S.Paschalis, M.Petri, N.Shimizu, T.Sonoda, D.Suzuki, Y.X.Watanabe, K.Wimmer, H.Wollnik

Study of the N=32 and N=34 Shell Gap for Ti and V by the First High-Precision Multireflection Time-of-Flight Mass Measurements at BigRIPS-SLOWRI

ATOMIC MASSES 55Sc, 56,58Ti, 56,57,58,59V; measured TOF; deduced masses, nonexistence of the N=34 empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap in Ca. Comparison with new Monte Carlo shell model calculations. RIKEN's Radioactive Isotope Beam Factory (RIBF).

doi: 10.1103/PhysRevLett.130.012501
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2023NI02      J.Nucl.Radiochem.Sci. 23, 1 (2023)

T.Niwase, P.Schury, M.Wada, for the SHE-Mass Collaboration

Accurate event assignment from the decay-correlated mass measurement of the superheavy nuclide 257Db

RADIOACTIVITY 257Db, 253Lr, 249Md, 245Es, 211Po(α); measured decay products, Eα, Iα, TOF; deduced α-decay-correlated masses, certainty of each decay-correlated event. The SHE-Mass-II facility, jointly operated under the auspices of RIKEN Nishina Center and KEK Wako Nuclear Science Center, the RIKEN RI Beam Factory.


2023NI04      Phys.Rev.Lett. 130, 132502 (2023)

T.Niwase, Y.X.Watanabe, Y.Hirayama, M.Mukai, P.Schury, A.N.Andreyev, T.Hashimoto, S.Iimura, H.Ishiyama, Y.Ito, S.C.Jeong, D.Kaji, S.Kimura, H.Miyatake, K.Morimoto, J.-Y.Moon, M.Oyaizu, M.Rosenbusch, A.Taniguchi, M.Wada

Discovery of New Isotope 241U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions

NUCLEAR REACTIONS 198Pt(238U, X)235U/236U/237U/238U/239U/240U/241U/242U/235Pa/236Pa/237Pa/239Np/240Np/241Np/239Pu/240Pu/241Pu/242Pu, E=10.75 MeV/nucleon; measured reaction products, TOF. 241U; deduced new isotope production. The KEK Isotope Separation System (KISS) for the nuclear spectroscopy of nuclides produced via MNT reactions, installed at the RIKEN Nishina Center.

ATOMIC MASSES 235,236,237,238,239,240,241,242U, 235,236,237Pa, 239,240,241Np, 239,240,241,242Pu; measured frequencies (the first excitation step laser wavelength), TOF; deduced mass excesses. Comparison with AME2020 evaluation.

doi: 10.1103/PhysRevLett.130.132502
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2022HI07      Phys.Rev. C 106, 034326 (2022)

Y.Hirayama, M.Mukai, Y.X.Watanabe, P.Schury, H.Nakada, J.Y.Moon, T.Hashimoto, S.Iimura, S.C.Jeong, M.Rosenbusch, M.Oyaizu, T.Niwase, M.Tajima, A.Taniguchi, M.Wada, H.Miyatake

In-gas-cell laser resonance ionization spectroscopy of 200, 201Pt

NUCLEAR MOMENTS 198,200,201Pt; measured time-of-flight (TOF) spectra for ions with mass-to-charge-ratios, laser resonance ionization spectra using Multireflection time-of-flight mass spectrograph (MRTOF-MS) at KEK Isotope Separation System (KISS) of RIKEN facility. 200,201Pt; deduced differential mean-square charge radii and isotope shifts relative to those of 198Pt, magnetic dipole and electric quadrupole moments of 201Pt, β2 deformation parameters Comparison with theoretical calculations using symmetry-conserving configuration-mixing (SCCM) with Gogny D1S energy density functionals (SCCM+Gogny D1S), finite-range droplet model (FRDM), and constrained-Hartree-Fock-Bogoliubov (CHFB) theory with five-dimensional collective Hamiltonian (5DCH) based on the Gogny D1 interaction. 201Pt; deduced most likely spin-parity of 5/2-. 198,200,201Pt produced in 198Pt(136Xe, X), E=10.75 MeV/nucleon multi-nucleon transfer reactions.

doi: 10.1103/PhysRevC.106.034326
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Data from this article have been entered in the XUNDL database. For more information, click here.


2022MU10      Phys.Rev. C 105, 034331 (2022)

M.Mukai, Y.Hirayama, Y.X.Watanabe, H.Watanabe, H.Koura, S.C.Jeong, H.Miyatake, M.Brunet, S.Ishizawa, F.G.Kondev, G.J.Lane, Yu.A.Litvinov, T.Niwase, M.Oyaizu, Zs.Podolyak, M.Rosenbusch, P.Schury, M.Wada, P.M.Walker

Ground-state β-decay spectroscopy of 187Ta

RADIOACTIVITY 187Ta(β-)[from W(136Xe, X), E=7.2 MeV/nucleon]; measured Eγ, Iγ, βγ-coin; deduced Iβ feedings, T1/2, logft, Iγ/β-decay. 187W; deduced Eγ, multipolarities, total conversion coefficients (BrIcc calculations). Comparison to KTUY+gross theory, FRDM+QRPA and RHB+pn-RQRPAKEK calculations. Isotope Separation System (KISS) at RIKEN, an argon-gas-cell-based laser ion source combined with an on-line isotope separator.

doi: 10.1103/PhysRevC.105.034331
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Data from this article have been entered in the XUNDL database. For more information, click here.


2021NI08      Phys.Rev. C 104, 044617 (2021)

T.Niwase, M.Wada, P.Schury, P.Brionnet, S.D.Chen, T.Hashimoto, H.Haba, Y.Hirayama, D.S.Hou, S.Iimura, H.Ishiyama, S.Ishizawa, Y.Ito, D.Kaji, S.Kimura, J.Liu, H.Miyatake, J.Y.Moon, K.Morimoto, K.Morita, D.Nagae, M.Rosenbusch, A.Takamine, T.Tanaka, Y.X.Watanabe, H.Wollnik, W.Xian, S.X.Yan

α-decay-correlated mass measurement of 206, 207g, mRa using an α-TOF detector equipped multireflection time-of-flight mass spectrograph system

ATOMIC MASSES 206,207,207mRa; measured time-of-flight spectra by α-decay-correlated mass spectroscopy using multireflection time-of-flight mass spectrograph (MRTOF-MS) system, with an α-TOF detector at SHE-Mass-II facility of RIBF-RIKEN; deduced mass excesses, and compared with evaluated data in AME2020. 207mRa; deduced excitation energy of the isomer, J, π. 206,207,207mRa isotopes produced in 159Tb(51V, X), E=306 MeV, followed by separation of evaporation residues using recoil ion separator GARIS-II at RIKEN.

RADIOACTIVITY 206,207mRa(α)[from 159Tb(51V, X), E=306 MeV at RIBF-RIKEN]; measured Eα, Iα, T1/2 of decays of 206Ra and 207mRa, excitation energy of the isomer; deduced α-reduced width, configuration. Systematics of spins, parities, Eα, T1/2, α-branching ratios, reduced α widths for 203,203m,205,205m,207,207mRa. 198,199Po, 202,203At, 202,203Rn, 206,207Fr, 207Ra; observed α spectra from decays.

doi: 10.1103/PhysRevC.104.044617
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Data from this article have been entered in the XUNDL database. For more information, click here.


2021SC14      Phys.Rev. C 104, L021304 (2021)

P.Schury, T.Niwase, M.Wada, P.Brionnet, S.Chen, T.Hashimoto, H.Haba, Y.Hirayama, D.S.Hou, S.Iimura, H.Ishiyama, S.Ishizawa, Y.Ito, D.Kaji, S.Kimura, H.Koura, J.J.Liu, H.Miyatake, J.-Y.Moon, K.Morimoto, K.Morita, D.Nagae, M.Rosenbusch, A.Takamine, Y.X.Watanabe, H.Wollnik, W.Xian, S.X.Yan

First high-precision direct determination of the atomic mass of a superheavy nuclide

ATOMIC MASSES 257Db; measured Eα, time-of flight, distribution of time-of-flight (ToF)-correlated α-decay events using multireflection time-of-flight mass spectrograph (MRTOF-MS) at RIKEN Ring Cyclotron facility; deduced A/q and mass excess for each of the 11 observed correlated events assigned to 257Db. Comparison with AME2016 evaluated data. 257Db isotope produced in 208Pb(51V, 2n), E=306 MeV reaction, followed by separation of fragments using GARIS-II separator.

doi: 10.1103/PhysRevC.104.L021304
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2021WA15      Phys.Lett. B 814, 136088 (2021)

H.Watanabe, Y.X.Watanabe, Y.Hirayama, A.N.Andreyev, T.Hashimoto, F.G.Kondev, G.J.Lane, Yu.A.Litvinov, J.J.Liu, H.Miyatake, J.Y.Moon, A.I.Morales, M.Mukai, S.Nishimura, T.Niwase, M.Rosenbusch, P.Schury, Y.Shi, M.Wada, P.M.Walker

Beta decay of the axially asymmetric ground state of 192Re

RADIOACTIVITY 192Re(β-) [from Pt(136Xe, X)192Re, E=10.75 MeV/nucleon]; measured decay products, Eγ, Iγ; deduced γ-ray energies and intensities, level scheme, J, π. Comparison with single-particle structure using the nuclear Skyrme-Hartree-Fock model. KEK Isotope Separation System (KISS) in RIKEN Nishina Center.

doi: 10.1016/j.physletb.2021.136088
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Data from this article have been entered in the XUNDL database. For more information, click here.


2021WA39      Phys.Rev. C 104, 024330 (2021)

Y.X.Watanabe, P.M.Walker, Y.Hirayama, M.Mukai, H.Watanabe, G.J.Lane, M.Ahmed, M.Brunet, T.Hashimoto, S.Ishizawa, S.Kimura, F.G.Kondev, Yu.A.Litvinov, H.Miyatake, J.Y.Moon, T.Niwase, M.Oyaizu, J.H.Park, Zs.Podolyak, M.Rosenbusch, P.Schury, M.Wada

First direct observation of isomeric decay in neutron-rich odd-odd 186Ta

RADIOACTIVITY 186Ta(β-), 186mTa(IT)[from W(136Xe, X), E=7.2 MeV/nucleon, followed by laser ionization and mass separation at the KEK Isotope Separation System (KISS) of RIBF-RIKEN facility]; measured Eγ, Iγ, (particle)γ-coin, half-lives of decays of 186Ta and neutral 186mTa from γ-decay curves. 186Ta; deduced levels, J, π, E3 multipolarity of the 161-keV isomeric transition from a comparison of measured half-life of the neutral isomer with previous measurements of the ionized isomeric state of 186Ta using the Experimental Storage Ring at GSI Darmstadt, no evidence found for the β decay mode of the 186Ta isomer.

doi: 10.1103/PhysRevC.104.024330
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Data from this article have been entered in the XUNDL database. For more information, click here.


2020CH33      Phys.Rev. C 102, 034309 (2020)

H.Choi, Y.Hirayama, S.Choi, T.Hashimoto, S.C.Jeong, H.Miyatake, J.Y.Moon, M.Mukai, T.Niwase, M.Oyaizu, M.Rosenbusch, P.Schury, A.Taniguchi, Y.X.Watanabe, M.Wada

In-gas-cell laser ionization spectroscopy of 194, 196Os isotopes by using a multireflection time-of-flight mass spectrograph

NUCLEAR MOMENTS 194,196Os; measured laser resonance spectra, time-of-flight spectra using the in-gas-cell laser ionization method and multireflection time-of-flight mass spectrograph (MRTOF-MS); deduced isotope shifts, change in mean-square charge radii and quadrupole deformation parameters. 194,196Os produced in 198Pt(136Xe, X), E=10.75 MeV/nucleon reaction at the KEK Isotope Separation System (KISS). 188,189,190,192,194,196Os; systematics of the change in mean-square charge radii and quadrupole deformation parameters, and their comparison with theoretical calculations.

doi: 10.1103/PhysRevC.102.034309
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Data from this article have been entered in the XUNDL database. For more information, click here.


2020TA02      Phys.Rev.Lett. 124, 052502 (2020)

T.Tanaka, K.Morita, K.Morimoto, D.Kaji, H.Haba, R.A.Boll, N.T.Brewer, S.Van Cleve, D.J.Dean, S.Ishizawa, Y.Ito, Y.Komori, K.Nishio, T.Niwase, B.C.Rasco, J.B.Roberto, K.P.Rykaczewski, H.Sakai, D.W.Stracener, K.Hagino

Study of Quasielastic Barrier Distributions as a Step towards the Synthesis of Superheavy Elements with Hot Fusion Reactions

NUCLEAR REACTIONS 248Cm(22Ne, X), (26Mg, X), 238U(48Ca, X), E(cm)=165.1, 203.7 MeV; measured reaction products; deduced σ. Comparison with available data.

doi: 10.1103/PhysRevLett.124.052502
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2020WA29      Phys.Rev.Lett. 125, 192505 (2020)

P.M.Walker, Y.Hirayama, G.J.Lane, H.Watanabe, G.D.Dracoulis, M.Ahmed, M.Brunet, T.Hashimoto, S.Ishizawa, F.G.Kondev, Y.A.Litvinov, H.Miyatake, J.Y.Moon, M.Mukai, T.Niwase, J.H.Park, Z.Podolyak, M.Rosenbusch, P.Schury, M.Wada, X.Y.Watanabe, W.Y.Liang, F.R.Xu

Properties of 187Ta Revealed through Isomeric Decay

RADIOACTIVITY 187Ta(IT) [from W(136Xe, X), E=7.2 MeV/nucleon]; measured decay products, Eγ, Iγ, Eβ, Iβ, γ-γ-, β-γ-coin.; deduced level energies, J, π, T1/2. Comparison with theoretical calculations.

doi: 10.1103/PhysRevLett.125.192505
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Data from this article have been entered in the XUNDL database. For more information, click here.


2018IT04      Phys.Rev.Lett. 120, 152501 (2018)

Y.Ito, P.Schury, M.Wada, F.Arai, H.Haba, Y.Hirayama, S.Ishizawa, D.Kaji, S.Kimura, H.Koura, M.MacCormick, H.Miyatake, J.Y.Moon, K.Morimoto, K.Morita, M.Mukai, I.Murray, T.Niwase, K.Okada, A.Ozawa, M.Rosenbusch, A.Takamine, T.Tanaka, Y.X.Watanabe, H.Wollnik, S.Yamaki

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph

NUCLEAR REACTIONS 232Th(19F, 5n)246Es, E=99.6, 103 MeV;238U(18O, 5n)251Fm, E=93.9 MeV; 203Tl(48Ca, 2n)249Md, E=215 MeV; 205Tl(48Ca, 3n)250Md, E=223 MeV; 205Tl(48Ca, 2n)251Md, E=215 MeV; 238U(19F, 5n)252md, E=98.6 MeV; 208Pb(48Ca, 2n)254No, E=219 MeV; measured reaction products, TOF; deduced mass excesses. Comparison with available data.

ATOMIC MASSES 253,254Lr, 257,258Db, 261,262Bh, 266Mt; analyzed available data; deduced mass excesses.

doi: 10.1103/PhysRevLett.120.152501
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2018RO14      Phys.Rev. C 97, 064306 (2018)

M.Rosenbusch, Y.Ito, P.Schury, M.Wada, D.Kaji, K.Morimoto, H.Haba, S.Kimura, H.Koura, M.MacCormick, H.Miyatake, J.Y.Moon, K.Morita, I.Murray, T.Niwase, A.Ozawa, M.Reponen, A.Takamine, T.Tanaka, H.Wollnik

New mass anchor points for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes

ATOMIC MASSES 210,211,212,214Ra, 210,211,212,213,214Ac; measured time of flight, and mass excess using multireflection time-of-flight mass spectrograph (MRTOF-MS) at superheavy element (SHE) mass facility of RIKEN-KEK, and using gas-filled recoil ion separator GARIS-II at RIKEN. Comparison with values from AME-2016. Ra and Ac isotopes produced in 169Tm(48Ca, X), E=5, 6 MeV/nucleon reaction at RIKEN. Z=82-92, N=121-129; systematics of S(2n) values.

doi: 10.1103/PhysRevC.97.064306
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