119242705
Equation of State for Neutron Stars: Hyperon Mixing in SU(3) Flavor Symmetry
Using various kinds of relativistic mean-field models as well as the quark-meson coupling model, we study in detail the properties of neutron stars. We find that the equation of state in SU(3) flavor symmetry can support a neutron star with mass of $(1.8 \sim 2.1) M_{\odot}$ even if hyperons exist inside the core of a neutron star.
10938062
Composite nucleons in scalar and vector mean fields.
We emphasize that the composite structure of the nucleon may play quite an important role in nuclear physics. It is shown that the momentum-dependent repulsive force of second order in the scalar field, which plays an important role in Dirac phenomenology, can be found in the quark-meson coupling (QMC) model, and that the properties of nuclear matter are well described through the quark-scalar density in a nucleon and a self-consistency condition for the scalar field. The difference between theories of pointlike nucleons and composite ones may be seen in the change of the {omega}-meson mass in nuclear matter if the composite nature of the nucleon suppresses contributions from nucleon-antinucleon pair creation.
121131573
New Scaling Phenomena in Nuclear Structure Functions
We consider the nuclear mass-number (A) dependence of the nuclear structure functions. We restrict ourselves to a two-component model, in which we assume the existence of an exotic component other than the normal nucleon component in nuclei. We find that there exist scaling phenomena and that the structure function of the exotic component should be independent of A. We also show that the A dependence of the nuclear structure function can be attributed to that of the surface-to-volume ratio which is incorporated in the probability of finding the exotic component in the nucleus.
15022310
A Deformable Bag Model of Hadrons. I
As a generalization of the MIT spherical bag model, we construct the spheroidal bag model of hadron with an arbitrary eccentricity. This generalization is made by slightly modifying the MIT linear boundary condition: The linear boundary condition is examined in detail. Our model always satisfies two necessary requirements of the MIT bag model --i. e., n-j=O, no quark colour flux leaves the bag, and ijq =0, the scalar density of quark should vanish on the bag surface-- and it reduces to the MIT spherical bag model in the limit of zero-eccentricity. Lagrangian formalism of our model is briefly described. The eigenfrequencies of a single massless quark confined in this spheroidal bag are numer­ ically calculated. We obtain the level-splitting of the excited quark orbits, which is just analogous to the well-known Nilsson's splitting of single particle orbits in deformed nuclei. By using the numerical results of the lowest orbit, the effect of the bag-deformation on the mass of low-lying hadrons is estimated. It is found that, although the spherical bag is stable, tbe quark bag is extremely soft against the quadrupole deformation. Brief discussions are added on the mechanisms which make the spherical bag more stable.
119162077
The quark-meson coupling model and chiral symmetry
We extend the quark‐meson coupling (QMC) model to incorporate chiral symmetry. The relationship between the QMC model and chiral perturbation theory is also discussed. The nuclear central potential is modified by the effect of internal structure of the nucleon.
119311709
A new molecular dynamics calculation and its application to the spectra of light and strange baryons
A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the many-body correlations. We applied it to the spectra of low-lying, light and strange baryons. The inclusion of the quark–quark correlation is important to predict the precise spectra, and the semi- relativistic kinematics is also vital to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.
16595187
Luminosity Dependence of the Electron Temperature in the Bright Hard State of the Black Hole Candidate GX 339–4
We have analyzed 200 Rossi X-ray Timing Explorer observations of the black hole candidate GX 339� 4, all from bright hard state periods between 1996 and 2005. The purpose of our study is to investigate the radiation mechanisms in the hard state of GX 339� 4. The broadband 3–200 keV spectra were successfully modeled by as imple analytic model, power-law with an exponential cut-off modified with a smeared edge. The obtained energy cut-off (Ecut )w as distributed over 50–200 keV, and the photon index over 1.4–1.7. We found a clear anti-correlation (Ecut / L � 0:70˙0:06 )b etween the X-ray luminosity (L )i n2–200 keV and Ecut ,w henL is larger than 7 � 10 37 erg s � 1 (assuming a distance of 8 kpc), while Ecut is roughly constant at around 200 keV when L is smaller than 7 � 10 37 erg s � 1 .T his anti-correlation remained unchanged by adopting a more physical thermal Comptonization model, which resulted in an anti-correlation that can be expressed as kTe / L � 0:24˙0:06 .T hese anti-correlations can be quantitatively explained by a picture in which the energy-flow rate from protons to electrons balances with inverse Compton cooling.
109241787
Test Operation of Ball Screw Type Tuner for Low Loss High Gradient Superconducting Cavity in a Cryomodule
135524505
A New type of RF cavity for high intensity proton synchrotron using high permeability magnetic alloy
A new type of rf accelerating cavity using a high-permeability magnetic alloy (MA) core is proposed for a highintensity hadron synchrotron. The prototype of a single-gap high gradient cavity whose total length is only 40cm is under development and a maximum rf voltage of 20kV has been obtained so far.
54701295
The first measurement of low-loss 9-cell cavity in a cryomodule at stf
We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of ILC accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) 9-cell cavity into a cryomodule (CM) at STF. We assembled the cavity with an input-coupler and peripherals in a clean room and the cavity package was dressed with thermal shields to be installed in a CM. At the room-temperature, we performed the processing of input-coupler up to the RF power of 350 kW. At the temperatures of 2 K, RF power was supplied from a klystron to the cavity. The lorentz force detuning of cavity was measured and the performance of the cavity packeage was tested. This article presents the results of the first test of the LL 9-cell cavity at 2 K in a CM.
55891691
Beam Loading Experiment with Short Bunched Electron Beams for New Type of Accelerating RF System of High Intensity Proton Synchrotron
Beam loading effects on rf system is one of the most difficult parts of high intensity proton synchrotrons. To investigate the effects, beam loading test experiment using an intense electron beam has been carried out. The wake voltages induced by an actual electron beam have been measured at an accelerating gap of an rf cavity. The electron beam used in the experiments was modulated with the frequency of about 3 MHz and the pulse width can be variable in due consideration of the circulating beam of the JHF synchrotrons. The maximum beam current is about 9 A. The beam loading compensation also has been tried.