6,833 research outputs found
Discussion on the progress and future of satellite communication (Japan)
The current status of communications satellite development in Japan is presented. It is shown that beginning with research on satellite communucations in the late 1950's, progress was made in the areas of communications, remote sensing, and technology experimentation. The current status of communication satellites is presented, stressing development in the areas of CFRP construction elements, the use of LSI and MIC circuits, advanced multibeam antenna systems, Ku and Ka band transmission systems, and the shift to small-scale earth stations. Methods for reducing costs and increasing transmission efficiency are shown. The technical specifications of all satellite projects currently under development are given. Users of Japanese communications satellite are presented
Analysis of (K^-,K^+) inclusive spectrum with semiclassical distorted wave model
The inclusive K^+ momentum spectrum in the 12C(K^-,K^+) reaction is
calculated by the semiclassical distorted wave (SCDW) model, including the
transition to the \Xi^- bound state. The calculated spectra with the strength
of the \Xi^--nucleus potential -50, -20, and +10 MeV are compared with the
experimental data measured at KEK with p_{K^-}=1.65 GeV/c. The shape of the
spectrum is reproduced by the calculation. Though the inclusive spectrum
changes systematically depending on the potential strength, it is not possible
to obtain a constraint on the potential from the present data. The calculated
spectrum is found to have strong emission-angle dependence. We also investigate
the incident K^- momentum dependence of the spectrum to see the effect of the
Fermi motion of the target nucleons which is explicitly treated in the SCDW
method.Comment: 7 pages, 5 figure
New Approach for Evaluating Incomplete and Complete Fusion Cross Sections with Continuum-Discretized Coupled-Channels Method
We propose a new method for evaluating incomplete and complete fusion cross
sections separately using the Continuum-Discretized Coupled-Channels method.
This method is applied to analysis of the deuteron induced reaction on a 7Li
target up to 50 MeV of the deuteron incident energy. Effects of deuteron
breakup on this reaction are explicitly taken into account. Results of the
method are compared with those of the Glauber model, and the difference between
the two is discussed. It is found that the energy dependence of the incomplete
fusion cross sections obtained by the present calculation is almost the same as
that obtained by the Glauber model, while for the complete fusion cross
section, the two models give markedly different energy dependence. We show also
that a prescription for evaluating incomplete fusion cross sections proposed in
a previous study gives much smaller result than an experimental value.Comment: 10 pages, 5 figure
Description of Four-Body Breakup Reaction with the Method of Continuum-Discretized Coupled-Channels
We present a method for smoothing discrete breakup -matrix elements
calculated by the method of continuum-discretized coupled-channels (CDCC). This
smoothing method makes it possible to apply CDCC to four-body breakup
reactions. The reliability of the smoothing method is confirmed for two cases,
Ni(, ) at 80 MeV and the transition of He. We apply
CDCC with the smoothing method to He breakup reaction at 22.5 MeV.
Multi-step breakup processes are found to be important.Comment: 19 pages, 7 figures, published in Progress of Theoretical Physic
Experimental band structure of the nearly half-metallic CuCrSe: An optical and magneto-optical study
Diagonal and off-diagonal optical conductivity spectra have been determined
form the measured reflectivity and magneto-optical Kerr effect (MOKE) over a
broad range of photon energy in the itinerant ferromagnetic phase of
CuCrSe at various temperatures down to T=10 K. Besides the low-energy
metallic contribution and the lower-lying charge transfer transition at
2 eV, a sharp and distinct optical transition was observed in the
mid-infrared region around 0.5 eV with huge magneto-optical activity.
This excitation is attributed to a parity allowed transition through the Se-Cr
hybridization-induced gap in the majority spin channel. The large off-diagonal
conductivity is explained by the high spin polarization in the vicinity of the
Fermi level and the strong spin-orbit interaction for the related charge
carriers. The results are discussed in connection with band structure
calculations
Spin-Gap Phase in the One-Dimensional t-J-J' Model
The spin-gap phase of the one-dimensional t-J-J' model is studied by the
level-crossing of the singlet and the triplet excitation spectra.
The phase boundary obtained between the Tomonaga-Luttinger and the spin-gap
phases is remarkably consistent with the analytical results at the
and the low-density limits discussed by Ogata et al.
The spin-gap phase has a single domain in the phase diagram even if the spin
gap opens at half-filling.
The phase boundary coincides with the line where the
Tomonaga-Luttinger liquid behaves as free electrons, in the low-density region.
The relation between our method and the solution of the two-electron problem
is also discussed.Comment: 4 pages(JPSJ.sty), 5 figures(EPS), to appear in J. Phys. Soc. Jpn.
67, No.3 (1998
- …