We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at the RIKEN Radioactive Isotope Beam Factory by using the time-of-flight magnetic-rigidity technique. The atomic mass excesses of ^{55-57}Ca are determined for the first time to be -18650(160), -13510(250), and -7370(990)  keV, respectively. We examine the emergence of neutron magicity at N=34 based on the new atomic masses. The new masses provide experimental evidence for the appearance of a sizable energy gap between the neutron 2p_{1/2} and 1f_{5/2} orbitals in ^{54}Ca, comparable to the gap between the neutron 2p_{3/2} and 2p_{1/2} orbitals in ^{52}Ca. For the ^{56}Ca nucleus, an open-shell property in neutrons is suggested.

Strain effects and band parameters in MgO, ZnO, and CdO Appl. Phys. Lett. 101, 152105 (2012) Interaction of n-type dopants with oxygen in silicon and germanium J. Appl. Phys. 112, 073706 (2012) Structural, elastic, and polarization parameters and band structures of wurtzite ZnO and MgOSilicon is one of the most promising anode materials for future rechargeable batteries because of its high theoretical capacity. New crystalline Li 15 Si 4 was found as the fully electrochemical lithiated phase of crystalline Si or amorphous Si. Density functional theory was used to study the crystal and electronic structure of Li 15 Si 4 . Li 15 Si 4 is formed by the unit figure in which six Li atoms surround a Si atom with two different Li-Si bond lengths. The Li atom has negative charge of 0.56-0.63 in Li 15 Si 4 . The average intercalation voltage for the lithium intercalation reaction from crystalline Si to Li 15 Si 4 is 0.303 V, which is in good agreement with that predicted by the Coulometric titration experiment result for Li-Si alloys.

We report on the measurement of the first 2 + and 4 + states of 66 Cr and 70,72 Fe via in-beam γ-ray spectroscopy. The nuclei of interest were produced by (p, 2p) reactions at incident energies of 260 MeV/nucleon. The experiment was performed at the Radioactive Isotope Beam Factory, RIKEN using the DALI2 γ-ray detector array and the novel MINOS device, a thick liquid hydrogen target combined with a vertex tracker. A low-energy plateau of 2 + 1 and 4 + 1 energies as a function of neutron number was observed for N≥38 and N≥40 for even-even Cr and Fe isotopes, respectively. State-of-the-art shell model calculations with a modified LNPS interaction in the pf g 9/2 d 5/2 valence space reproduce the observations. Interpretation within the shell model shows an extension of the Island of Inversion at N=40 for more neutron-rich isotopes towards N=50. Atomic nuclei are the place of a complex interplay between single-particle configurations and correlations which strongly determine their quantum coherent wavefunctions. All over the nuclear chart, the so-called magic numbers of nucleons define boundaries of large areas of deformation. This picture, mainly established for stable nuclei and neighbors, is re-examined at the light of new available nuclei with an unbalanced proton-to-neutron ratio, with the underlying question of the persistence or evolution of magic numbers [1,2]. Specific terms of the nuclear interaction can induce the formation of shell gaps or the lowering of relative orbital energies which, combined with correlations, sometimes lead to energetically favored intruder states as the ground state configuration [3][4][5][6][7][8]. Regions where two-particle two-hole (2p2h) configurations are favored over normally-filled orbitals by quadrupole correlations have been termed as Islands of Inversion (IoI) [9][10][11]. The N=20 IoI in the vicinity of 32 Mg has provided unique information on shell evolution [12]. This IoI does not show any decrease in collectivity for Mg isotopes at N > 24 and merges with the N=28 deformation region [8,13]

Silicon is of special interest in lithium-ion batteries (LIBs) since it has large theoretical specific capacity or volumetric capacity. The crystal structure, charge distribution and density of states of LiSi as the Li-poorest side compound at the start of Li intercalation mechanism for Si anode in LIBs has been studied by using density functional theory (DFT) calculations. The triangular pyramids are formed by four Li atoms in LiSi. Compared to the charge density of crystalline Si, the Si Si covalent bonds in LiSi become weak due to Li intercalation. On the other hand, the electrons around the Li atoms in LiSi increase compared to those in metallic Li. The Li atoms in LiSi have negative charge of 0.83-0.84. These electrons, which are transferred from p electrons in the Si atoms, are mainly made of p electrons of the Li atoms. When considering the lithium intercalation reaction from crystalline Si to LiSi, the average intercalation voltage is about 0.4 V.