TY - JOUR
T1 - Low-Lying Structure of Ar 50 and the N=32 Subshell Closure
AU - Steppenbeck, D.
AU - Takeuchi, S.
AU - Aoi, N.
AU - Doornenbal, P.
AU - Matsushita, M.
AU - Wang, H.
AU - Utsuno, Y.
AU - Baba, H.
AU - Go, S.
AU - Lee, J.
AU - Matsui, K.
AU - Michimasa, S.
AU - Motobayashi, T.
AU - Nishimura, D.
AU - Otsuka, T.
AU - Sakurai, H.
AU - Shiga, Y.
AU - Shimizu, N.
AU - Söderström, P. A.
AU - Sumikama, T.
AU - Taniuchi, R.
AU - Valiente-Dobón, J. J.
AU - Yoneda, K.
N1 - Publisher Copyright:
© 2015 American Physical Society.
PY - 2015/6/25
Y1 - 2015/6/25
N2 - The low-lying structure of the neutron-rich nucleus Ar50 has been investigated at the Radioactive Isotope Beam Factory using in-beam γ-ray spectroscopy with Be9(Ca54,Ar50+γ)X, Be9(Sc55,Ar50+γ)X, and Be9(Ti56,Ar50+γ)X multinucleon removal reactions at ∼220MeV/u. A γ-ray peak at 1178(18) keV is reported and assigned as the transition from the first 2+ state to the 0+ ground state. A weaker, tentative line at 1582(38) keV is suggested as the 41+→21+ transition. The experimental results are compared to large-scale shell-model calculations performed in the sdpf model space using the SDPF-MU effective interaction with modifications based on recent experimental data for exotic calcium and potassium isotopes. The modified Hamiltonian provides a satisfactory description of the new experimental results for Ar50 and, more generally, reproduces the energy systematics of low-lying states in neutron-rich Ar isotopes rather well. The shell-model calculations indicate that the N=32 subshell gap in Ar50 is similar in magnitude to those in Ca52 and Ti54 and, notably, predict an N=34 subshell closure in Ar52 that is larger than the one recently reported in Ca54.
AB - The low-lying structure of the neutron-rich nucleus Ar50 has been investigated at the Radioactive Isotope Beam Factory using in-beam γ-ray spectroscopy with Be9(Ca54,Ar50+γ)X, Be9(Sc55,Ar50+γ)X, and Be9(Ti56,Ar50+γ)X multinucleon removal reactions at ∼220MeV/u. A γ-ray peak at 1178(18) keV is reported and assigned as the transition from the first 2+ state to the 0+ ground state. A weaker, tentative line at 1582(38) keV is suggested as the 41+→21+ transition. The experimental results are compared to large-scale shell-model calculations performed in the sdpf model space using the SDPF-MU effective interaction with modifications based on recent experimental data for exotic calcium and potassium isotopes. The modified Hamiltonian provides a satisfactory description of the new experimental results for Ar50 and, more generally, reproduces the energy systematics of low-lying states in neutron-rich Ar isotopes rather well. The shell-model calculations indicate that the N=32 subshell gap in Ar50 is similar in magnitude to those in Ca52 and Ti54 and, notably, predict an N=34 subshell closure in Ar52 that is larger than the one recently reported in Ca54.
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U2 - 10.1103/PhysRevLett.114.252501
DO - 10.1103/PhysRevLett.114.252501
M3 - Article
AN - SCOPUS:84936976982
VL - 114
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 25
M1 - 252501
ER -