Tokyo Laboratory

About: Tokyo Laboratory is a based out in . It is known for research contribution in the topics: Cluster (physics) & Ion. The organization has 208 authors who have published 200 publications receiving 3519 citations.

Optical pumping by a laser pulse traveling in a cavity

Abstract: We have developed a general method to perform optical pumping by a pulsed laser with the aid of an optical cavity (cavity-assisted optical pumping). Optical pumping is achieved by repetitive interaction of a single laser pulse with a target material in the cavity. This method is demonstrated for manganese ions, ${\text{Mn}}^{+}$, stored in a linear radio-frequency ion trap; about ${10}^{8}$ ions are spin polarized by a 5-ns laser pulse via ${^{7}P}_{J}\ensuremath{\leftarrow}{^{7}S}_{3}$ ($J=3$ or 4) transition in the ultraviolet region. The linewidth of the pulsed light source is broad enough to transfer the populations of lower hyperfine levels to the highest one $(F=11/2)$ in the ${^{7}S}_{3}$ ground state; the nuclear spin is polarized as well.

Charge-state analysis of small barium-oxide clusters by x-ray absorption spectroscopy.

Abstract: Small barium-oxide clusters [Formula: see text] are studied by mass spectrometry and x-ray absorption spectroscopy (XAS) to discuss stability of the clusters and oxidation state of constituent atoms. It is found that clusters with bulk composition, n = m, are stable, which can accommodate one or two excess oxygen atoms additionally as manifested by n = m + 1 and m + 2 species in the mass spectrum. XAS spectra of [Formula: see text] and [Formula: see text] reveal that the oxidation state of barium atoms stays at +2 (the bulk BaO value) even after binding excess oxygen, whereas spectral features originating from oxygen exhibit composition dependence. The present finding suggests that stoichiometric small barium-oxide clusters bind less-negatively-charged oxygen atoms without change in the charge state of barium.

FEM Analysis on Mechanical Stress of 2.5D Package Interposers

Abstract: As data transmission rate increases, flip chip plastic ball grid array (FCPBGA) utilizing an interposer for multiple chips is gaining prominence because of high performance. The authors assessed interposer configurations with a set of chip and package assumptions and obtained key parameters for mechanical analysis. The authors studied warpage of interposer, first principal stress in the dielectric layer under the controlled collapse chip connection (C4) bump pad, and von Mises stress at the solder joint between interposer and organic substrate with Si, glass, and organic interposers. The analysis results indicate that the stress under the C4 bump is very low with Si or glass interposer compared to conventional FCPBGA. Also, the results indicate that glass interposer with coefficient of thermal expansion (CTE) of 6 ppm/°C has approximately 30% lower stress than Si interposer at the solder joint between the interposer and the organic substrate.

Lattice modes of polyethylene

Abstract: The lattice modes of polyethylene with the phase differences (θ andΦ along theα-axis and theb-axis were calculated at intervals of 30‡ for the phase differences. They wereT x, Ty, T′x, T′y, R′z andR′ z, and some special conditions of the phase differences separated the six modes. To know the reliability of the intermolecular force constants used in this calculation, the elastic moduli of polyethylene crystal along thea-axis and theb-axis were calculated with the modified potential functions and compared with the observed values.