Searcharxiv⌕ Search

arXiv subjects

S. Suzuki

Publications and source records attributed to S. Suzuki.

86 records · Page 5Linked to original sources
arXiv2005

Photoproduction of $η$-mesons off C and Cu nuclei for photon energies below 1.1 GeV

The $η$-meson photoproduction cross sections have been measured on the C and Cu targets for the photon energies between 600 and 1100 MeV to investigate the behavior of the $S_{11}$(1535) resonance in a nucleus. The excitation functions of the cross section as well as the angular and momentum distributions of $η$-mesons are in quantitative agreement with the Quantum Molecular Dynamics (QMD) model calculations in which the $η$-meson emission processes other than the $S_{11}$(1535) resonance are also incorporated as proposed in the $η$-MAID model. It is shown that the excitation of the $D_{15}$(1675) resonance might play an important role for $E_γ>900$ MeV.

nucl-ex↗
arXiv2005

A search for deeply bound kaonic nuclear states

We have measured proton and neutron energy spectra by stopping negative kaons on liquid helium4. Two distinct peak structures were found on both spectra, which were assigned to the formation of new kinds of strange stribaryons. In this paper, we summarize both results.

nucl-ex↗
arXiv2004

Indication of a strange tribaryon S^+ from the ^4He(stopped K^-,n) reaction

We measured the neutron time-of-flight spectrum in the ^4He(stopped K^-, n) reaction by stopping negative kaons in a superfluid helium target. A clear enhancement was observed in the neutron spectrum, which indicates the formation of a strange tribaryon of charge +1 with a mass and width of M = 3141 +/- 3 (stat.) +4/-1 (sys.) MeV/c^2 and G < 23 MeV/c^2. This state, denoted as S^+(3140), is about 25 MeV/c^2 higher than the previously observed S^0(3115) T=1.

nucl-ex↗
arXiv2004

Absorption of Scintillation Light in a 100 $\ell$ Liquid Xenon$γ$ Ray Detector and Expected Detector Performance

An 800L liquid xenon scintillation $γ$ ray detector is being developed for the MEG experiment which will search for $μ^+\to\mathrm{e}^+γ$ decay at the Paul Scherrer Institut. Absorption of scintillation light of xenon by impurities might possibly limit the performance of such a detector. We used a 100L prototype with an active volume of 372x372x496 mm$^3$ to study the scintillation light absorption. We have developed a method to evaluate the light absorption, separately from elastic scattering of light, by measuring cosmic rays and $α$ sources. By using a suitable purification technique, an absorption length longer than 100 cm has been achieved. The effects of the light absorption on the energy resolution are estimated by Monte Carlo simulation.

physics.ins-det↗
arXiv2004

Liquid Xe scintillation calorimetry and Xe optical properties

The optical properties of LXe in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be used for deriving the LXe optical properties in the VUV. A comparison is made with the few direct measurements in LXe for VUV light resulting from the LXe excitation by ionizing particles. A useful relation is obtained which connects the Rayleigh scattering length to the refractive index in LXe.

physics.ins-det↗
arXiv2001

Upgrade of Linac Control System with New Vme Controllers at Spring-8

We integrated an injector linac control system to the SPring-8 standard system on September 2000. As a result of this integration, the SPring-8 accelerator complex was controlled by one unified system. Because the linac was continuously running as the electron beam injector not only for the SPring-8 storage ring but also for New SUBARU, we had to minimize the hardware modification to reduce the time for the development and testing of the new control system. The integration method was almost the same as that of the integration of the booster synchrotron. We report here on the integration of the linac control system with emphasis on the upgrade of the VMEbus controllers and software involving the operating system Solaris 7 as the real-time OS.

physics.acc-ph↗
arXiv2001

Two-Dimensional Sigma-Hole Systems in Boron Layers: A First-Principles Study on Mg_{1-x}Na_xB_2 and Mg_{1-x}Al_xB_2

We study two-dimensional sigma-hole systems in boron layers by calculating the electronic structures of Mg_{1-x}Na_xB_2 and Mg_{1-x}Al_xB_2. In Mg_{1-x}Na_xB_2, it is found that the concentration of sigma holes is approximately described by (0.8 + 0.8 x) * 10^{22} cm^{-3} and the largest attainable concentration is about 1.6 * 10^{22} cm^{-3} in NaB_2. In Mg_{1-x}Al_xB_2, on the other hand, it is found that the concentration of sigma holes is approximately described by (0.8 - 1.4 x) * 10^{22} cm^{-3} and sigma holes are disappeared at x of about 0.6. These relations can be used for experimental studies on the sigma-hole systems in these materials.

cond-mat.supr-con↗
arXiv1998

Metal Rich Plasma at the Center Portion of the Cygnus Loop

We observed the center portion of the Cygnus Loop supernova remnant with the ASCA observatory. The X-ray spectrum of the center portion was significantly different from that obtained at the North-East (NE) limb. The emission lines from Si and S were quite strong while those of O and the continuum emission were similar to those obtained at the NE limb. Based on the spectral analysis, Si and S emission lines originated from a high-kTe and low ionization plasma whereas O and most of the continuum emission arose from a low-kTe and high ionization plasma. We suppose that Si and S emitting gas are present at the interior of the Loop while O lines and continuum emission mainly arise from the shell region. Therefore, we subtracted the spectrum of the NE limb from that of the center. Obtained abundances of Si, S, and Fe were 4 $\pm$ 1, 6 $\pm$ 2, and ${1.3}^{+0.6}_{-0.3}$ times higher than those of the cosmic abundances, respectively, and are $\sim$40 times richer than those obtained at the NE limb. These facts strongly support that some of the crude ejecta must be left at the center portion of the Cygnus Loop. The low abundance of Fe relative to Si and S suggests a type II SN with a massive progenitor star as the origin of the Cygnus Loop.

astro-ph↗
arXiv1998

Numerical Renormalization Group Study of non-Fermi-liquid State on Dilute Uranium Systems

We investigate the non-Fermi-liquid (NFL) behavior of the impurity Anderson model (IAM) with non-Kramers doublet ground state of the f$^2$ configuration under the tetragonal crystalline electric field (CEF). The low energy spectrum is explained by a combination of the NFL and the local-Fermi-liquid parts which are independent with each other. The NFL part of the spectrum has the same form to that of two-channel-Kondo model (TCKM). We have a parameter range that the IAM shows the $- \ln T$ divergence of the magnetic susceptibility together with the positive magneto resistance. We point out a possibility that the anomalous properties of U$_x$Th$_{1-x}$Ru$_2$Si$_2$ including the decreasing resistivity with decreasing temperature can be explained by the NFL scenario of the TCKM type. We also investigate an effect of the lowering of the crystal symmetry. It breaks the NFL behavior at around the temperature, $δ/10$, where $δ$ is the orthorhombic CEF splitting. The NFL behavior is still expected above the temperature, $δ/10$.

cond-mat.str-el↗
arXiv1997

Examination of T/CP Invariance in the e+e- --> tau+ tau- Reaction

We propose a method to examine the T/CP invariance of the heaviest lepton, tau, by means of a triple-momentum correlation for the reaction e^+e^- -->tau^+tau^-, tau --> e/mu nu nubar during the course of the B-Factory experimental program. An unprecedented high sensitivity could be obtained without requiring a high integrated luminosity.

hep-ex↗
arXiv1996

Chaos in Static Axisymmetric Spacetimes I : Vacuum Case

We study the motion of test particle in static axisymmetric vacuum spacetimes and discuss two criteria for strong chaos to occur: (1) a local instability measured by the Weyl curvature, and (2) a tangle of a homoclinic orbit, which is closely related to an unstable periodic orbit in general relativity. We analyze several static axisymmetric spacetimes and find that the first criterion is a sufficient condition for chaos, at least qualitatively. Although some test particles which do not satisfy the first criterion show chaotic behavior in some spacetimes, these can be accounted for the second criterion.

gr-qc↗
arXiv1995

Modified Reconstruction of Standard Model in Non-Commutative Differential Geometry

Sogami recently proposed the new idea to express Higgs particle as a kind of gauge particle by prescribing the generalized covariant derivative with gauge and Higgs fields operating on quark and lepton fields. The field strengths for both the gauge and Higgs fields are defined by the commutators of the covariant derivative by which he could obtain the Yang-Mills Higgs Lagrangian in the standard model. Inspired by Sogami's work, we present a modification of our previous scheme to formulate the spontaneously broken gauge theory in non-commutative geometry on the discrete space; Minkowski space multiplied by two points space by introducing the generation mixing matrix in operation of the generalized derivative on the more fundamental fields a_i(x,y) which compose the gauge and Higgs fields. The standard model is reconstructed according to the modified scheme, which does not yields not only any special relations between the particle masses but also the special restriction on the Higgs potential.

hep-th↗