119182192
Clustering structure of nuclei in deep inelastic processes
A clustering aspect is explained for the 9Be nucleus in charged-lepton deep inelastic scattering. Nuclear modifications of the structure function F2 are studied by the ratio REMC = FA2/FD2, where A and D are a nucleus and the deuteron, respectively. In a JLab experiment, an unexpectedly large nuclear modification slope |dREMC/dx| was found for 9 Be, which could be related to its clustering structure. We investigated a mean conventional part of a nuclear structure function FA2 by a convolution description with nucleon momentum distributions calculated by antisymmetrized (or fermionic) molecular dynamics (AMD) and also by a simple shell model. We found that clustering effects are small in the conventional part, so that the JLab result could be associated with an internal nucleon modification or a short-range nuclear correlation which is caused by high densities due to cluster formation.
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.
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.
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.
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.
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.
109241787
Test Operation of Ball Screw Type Tuner for Low Loss High Gradient Superconducting Cavity in a Cryomodule
25242851
Test operation of ball-screw-type tuner for low-los high-gradient superconducting cavity at 77 K
Super-conducting Radio Frequency (SRF) 9-cell cavities have been developed in Low-Loss (LL) ICHIRO shape at KEK aiming at high-gradient operation for the International Linear Collider (ILC). One of the most important issues to realize high-gradient linac with SRF cavitiest in pulsed-mode operation is the compensation of the Lorentz detuning of cavities which amounts to 3 kHz at our goal of 45 MV/m acceleration field. None of tuners to date have achieved this specification. A coaxial ball- screw tuner was designed, fabricated and proven to reach this specification in room temperature. The performance was studied also at liquid-nitrogen temperature and the needed dynamic-range for 45 MV/m operation was proven at this temperature. The microphonic vibration was measured to be 100 Hz order in a test setup. In this paper, we describe these studies and evaluate the feasibility of ball-screw tuner operation at 2 K.
111051825
Cryomodule development for superconducting RF test facility (STF) at KEK
The Current status of cryomodule development for the superconducting RF test facility (STF) at KEK is described. An objective of this effort is to experience fabrication of 5-m long cryomodule and to perform high power testing of superconducting RF cavities towards ILC (International Linear Collider). The STF features two 5-m long cryomodules, each holding up to four 9-cell cavities. The cavities, about 1-m long each, will be cooled by saturated superfluid helium at 2.0 K
14114906
Clear anti-correlation between luminosity and high energy cutoff in the low/hard state of the black hole candidate GX339-4
We have analyzed the 171 RXTE data sets of the black hole candidate GX 339-4 in the low/hard state during its 1996--2005 outburst. All the broadband spectra were successfully modeled by a simple analytic model, power-law with an exponential cutoff. The obtained energy cutoff($E_{\rm{cut}}$) is distributed over 50--300 keV, and the photon index over 1.4-1.6. We found a clear correlation ($E_{\rm{cut}}$ is proportional to $L^{-0.75 \pm 0.04}$) between luminosity in 2-200 keV (L) and $E_{\rm{cut}}$ when L is larger than 5$\times 10^{37}$ erg $s^{-1}$, while $E_{\rm{cut}}$ is almost constant at 200 keV when L is smaller than 5$\times 10^{37}$ erg $s^{-1}$. This anti-correlation is unchanged by adopting the more physical model of thermal Comptonization by Sunyaev and Titarchuk, although a slightly different relation is obtained as the electron temperature is proportional to $L^{-0.23 \pm 0.02}$. These anti-correlations are qualitatively explained by a picture where the energy flow rate from protons to electrons balance with cooling due to inverse Compton scattering.
7147715
Design of a Low Loss SRF Cavity for the ILC
An international team comprising SLAC, KEK, FNAL, JLAB and DESY is collaborating on the design, fabrication and test of a low loss, 1.3 GHz 9-cell SRF structure as a potential improvement for the ILC main linac. The advantages of this structure over the TESLA structure include lower cryogenic loss, shorter rise time, and less stored energy. Among the issues to be addressed in this design are HOM damping, Lorentz force detuning and multipacting. We will report on HOM damping calculations using the parallel finite element eigenmode solver Omega3P and the progress made towards an optimized design. Studies on multipacting and estimates of the Lorentz force detuning will also be presented.