Enhancement of muonium emission rate from silica aerogel with a laser ablated surface

Emission of muonium ($mu^+e^-$) atoms from a laser-processed aerogel surface into vacuum was studied for the first time. Laser ablation was used to create hole-like regions with diameter of about 270$~mu$m in a triangular pattern with hole separation in the range of 300--500$~mu$m. The emission probability for the laser-processed aerogel sample is at least eight times higher than for a uniform one.

Coupled Oscillator Model of the Business Cycle with Fluctuating Goods Markets

The sectoral synchronization observed for the Japanese business cycle in the Indices of Industrial Production data is an example of synchronization. The stability of this synchronization under a shock, e.g., fluctuation of supply or demand, is a matter of interest in physics and economics. We consider an economic system made up of industry sectors and goods markets in order to analyze the sectoral synchronization observed for the Japanese business cycle. A coupled oscillator model that exhibits synchronization is developed based on the Kuramoto model with inertia by adding goods markets, and analytic solutions of the stationary state and the coupling strength are obtained. We simulate the effects on synchronization of a sectoral shock for systems with different price elasticities and the coupling strengths. Synchronization is reproduced as an equilibrium solution in a nearest neighbor graph. Analysis of the order parameters shows that the synchronization is stable for a finite elasticity, whereas the synchronization is broken and the oscillators behave like a giant oscillator with a certain frequency additional to the common frequency for zero elasticity.

Temperature dependencies of the energy and time resolution of silicon drift detectors

The response of silicon drift detectors (SDDs), which were mounted together with their preamplifiers inside a vacuum chamber, was studied in a temperature range from 100 K to 200 K. In particular, the energy resolution could be stabilized to about 150 eV at 6 keV between 130 K and 200 K, while the time resolution shows a temperature dependence of T^3 in this temperature range. To keep a variation of the X-ray peak positions within 1 eV, it is necessary to operate the preamplifier within a stability of 1 K around 280 K. A detailed investigation of this temperature influences on SDDs and preamplifiers is presented.

A Paradigm Shift from Production Function to Production Copula: Statistical Description of Production Activity of Firms

Heterogeneity of economic agents is emphasized in a new trend of macroeconomics. Accordingly the new emerging discipline requires one to replace the production function, one of key ideas in the conventional economics, by an alternative which can take an explicit account of distribution of firms production activities. In this paper we propose a new idea referred to as production copula; a copula is an analytic means for modeling dependence among variables. Such a production copula predicts value added yielded by firms with given capital and labor in a probabilistic way. It is thereby in sharp contrast to the production function where the output of firms is completely deterministic. We demonstrate empirical construction of a production copula using financial data of listed firms in Japan. Analysis of the data shows that there are significant correlations among their capital, labor and value added and confirms that the values added are too widely scattered to be represented by a production function. We employ four models for the production copula, that is, trivaria

P-wave Lambda N - Sigma N coupling and the spin-orbit splitting of 9 Lambda Be

We reexamine the spin-orbit splitting of 9 Lambda Be excited states in terms of the SU_6 quark-model baryon-baryon interaction. The previous folding procedure to generate the Lambda alpha spin-orbit potential from the quark-model Lambda N LS interaction kernel predicted three to five times larger values for Delta E_{ell s}=E_x(3/2^+)-E_x(5/2^+) in the model FSS and fss2. This time, we calculate Lambda alpha LS Born kernel, starting from the LS components of the nuclear-matter G-matrix for the Lambda hyperon. This framework makes it possible to take full account of an important P-wave Lambda N - Sigma N coupling through the antisymmetric LS^{(-)} force involved in the Fermi-Breit interaction. We find that the experimental value, Delta E^{exp}_{ell s}=43 pm 5 keV, is reproduced by the quark-model G-matrix LS interaction with a Fermi-momentum around k_F=1.0 fm^{-1}, when the model FSS is used in the energy-independent renormalized RGM formalism.

n alpha Resonating-Group Calculation with a Quark-Model G-Matrix NN Interaction

We calculate n alpha phase-shifts and scattering observables in the resonating-group method, using the nuclear-matter G-matrix of an SU_6 quark-model NN interaction. The G-matrix is generated in the recent energy-independent procedure of the quark-model NN interaction with the continuous prescription for intermediate spectra, by assuming an appropriate Fermi momentum k_F=1.2 fm^-1. The n alpha RGM interaction kernels are evaluated with explicit treatments of the nonlocality and momentum dependence of partial-wave G-matrix components. The momentum dependence of the G-matrix components is different for each of the nucleon-exchange and interaction types. Without introducing any artificial parameters except for k_F, the central and spin-orbit components of the n alpha Born kernel are found to have reasonable strengths under the assumption of a rigid translationally invariant shell-model wave function of the alpha-cluster. The characteristic behaviors of three different exchange terms, corresponding to knockout, heavy-particle pickup and nucleon-rearrangement processes, are essentially the same between the case of previous local effective NN forces and the case of nonlocal G-matrix NN interactions.

Addendum: Triton and hypertriton binding energies calculated from SU_6 quark-model baryon-baryon interactions

Previously we calculated the binding energies of the triton and hypertriton, using an SU_6 quark-model interaction derived from a resonating-group method of two baryon clusters. In contrast to the previous calculations employing the energy-dependent interaction kernel, we present new results using a renormalized interaction, which is now energy independent and reserves all the two-baryon data. The new binding energies are slightly smaller than the previous values. In particular the triton binding energy turns out to be 8.14 MeV with a charge-dependence correction of the two-nucleon force, 190 keV, being included. This indicates that about 350 keV is left for the energy which is to be accounted for by three-body forces.