Elekes Z, Dombrádi Zs, Aoi N, Bishop S, Fülöp Zs, Gibelin J, Gomi T, Hashimoto Y, Imai N, Iwasa N, Iwasaki H, Kalinka G, Kondo Y, Korsheninnikov A A, Kurita K, Kurokawa M, Matsui N, Motobayashi T, Nakamura T, Nakao T, Nikolskii E Yu, Ohnishi T K, Okumura T, Ota S, Perera A, Saito A, Sakurai H, Satou Y, Sohler D, Sumikama T, Suzuki D, Suzuki M, Takeda H, Takeuchi S, Togano Y, Yanagisawa Y
Institute of Nuclear Research of the Hungarian Academy of Sciences, P.O. Box 51, Debrecen, H-4001, Hungary.
Phys Rev Lett. 2007 Mar 9;98(10):102502. doi: 10.1103/PhysRevLett.98.102502. Epub 2007 Mar 8.
Neutron single particle energies have been measured in 23O using the 22O(d,p)23O*-->22O+n process. The energies of the resonant states have been deduced to be 4.00(2) MeV and 5.30(4) MeV. The first excited state can be assigned to the nu d3/2 single particle state from a comparison with shell model calculations. The measured 4.0 MeV energy difference between the nu s1/2 and nu d3/2 states gives the size of the N=16 shell gap which is in agreement with the recent USD05 ("universal" sd from 2005) shell model calculation, and is large enough to explain the unbound nature of the oxygen isotopes heavier than A=24. The resonance detected at 5.3 MeV can be assigned to a state out of the sd shell model space. Its energy corresponds to a approximately 1.3 MeV sized N=20 shell gap, therefore, the N=20 shell closure disappears at Z=8 in agreement with Monte Carlo shell model calculations using SDPF-M interaction.
利用(^{22}O(d,p)^{23}O^*\to^{22}O + n)过程测量了(^{23}O)中的中子单粒子能量。已推断出共振态的能量为(4.00(2))兆电子伏和(5.30(4))兆电子伏。通过与壳模型计算进行比较，可将第一激发态归为(\nu d_{3/2})单粒子态。测量得到的(\nu s_{1/2})和(\nu d_{3/2})态之间(4.0)兆电子伏的能量差给出了(N = 16)壳层间隙的大小，这与最近的USD05（2005年的“通用”(sd)）壳模型计算结果一致，并且大到足以解释比(A = 24)更重的氧同位素的非束缚性质。在(5.3)兆电子伏处检测到的共振可归为(sd)壳模型空间之外的一个态。其能量对应于大约(1.3)兆电子伏大小的(N = 20)壳层间隙，因此，与使用SDPF - M相互作用的蒙特卡罗壳模型计算结果一致，(N = 20)壳层闭壳层在(Z = 8)时消失。
