120862625
Masses of the Light Hadrons in the Chiral and Cloudy Bag Models
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.
20298579
Relativistic hydrodynamics of quark-gluon plasma and stability of scaling solutions.
The scaling solutions of the relativistic hydrodynamics are expected to play an important role in describing the expansion stage of a quark-gluon plasma which may be formed in nucleus-nucleus collisions at high energies. After summarizing some general properties of the scaling solutions, we study in detail their stability against small perturbations. In some typical cases of the two-dimensional scaling solution it is found that (i) the scaling solution is stable if the Reynolds number {ital R} defined in terms of the viscosity coefficients is larger than a critical value {ital R}{sub {ital c}} (=1), (ii) it is also stable for a long-wavelength perturbation if {ital R} is small enough, and (iii) it becomes unstable when {ital R} approaches {ital R}{sub {ital c}} from below. It is also shown that these results are related to the time dependence of the Reynolds number, the entropy density, and the temperature, and the point {ital R}={ital R}{sub {ital c}} corresponds to a critical instant when the heating due to the dissipative processes balances with the cooling due to the expansion of the fluid. The stability of the scaling solution of the quark-gluon plasma is examined for typical ranges of the relevant parameters.
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.
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.
14603783
A Measurement System Using Gp-Ib For A Magnetic Core Test Cavity
In the design of the RF system of the JHF (Japan Hadron Facilit y) proton synchrotrons, it is very important to find a magnetic core to which satisfies the required condition of the JHF accelerators[1]. Ferrite cores are usually used for the magnetic core of the proton synchrotron, however there are some problems. Generally, some ferrite cores have non-linear characteristics which depend on the RF magnetic field. And, there is a size-dependence of the characteristics. Thus, it is required to measure the characteristics of large size magnetic cores. To measure characteristics of the magnetic cores, we have developed a test cavity which is capable of measuring an actual size one, and measurement system using software ‘HP-VEE’[ 2,3] which is possible to control the measurement devices by using a GP-IB command directly. In this measuring system, the acquisition of data and calculation of the characteristics of the magnetic cores are automatically processed.
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.
114452760
The first cool-down test of the 6 meter-long-cryomodules for superconducting rf test facility (STF) at KEK
KEK has been constructing the STF as the center of the ILC-R&D in Asia from 2005. In this construction, KEK developed two 6-m cryomodules in order to get manufacturing and operational experiences of the superconducting RF cavity and cryomodule toward the ILC. Two cryomodules were designed to accommodate 4 nine-cell cavities in each cryostat. At the first step, the cryomodules with one cavity were assembled and their cold tests were performed. And in the following test, the cryomodule with four cavities was reassembled and the cold test of this module is being carried out now. In this paper, we will report the design of the cryomodules briefly and the thermal results of the cold tests.
33534124
Higher-Order-Mode Damping of L-Band Superconducting Cavity Using A Radial-Line HOM Damper
For the energy recovery linacs, strong damping of higher-order-modes (HOMs) is indispensable to avoid beam breakup instabilities. We studied a new HOM damping scheme using a radial-line HOM damper with a choke structure. Both models of the radial-line damper and the TESLA-type 9-cell cavity were prepared and the HOM characteristics of this scheme were experimentally investigated. Measurement results showed a promising performance of the radial-line HOM damper.
110462153
SERIES TESTS OF HIGH-GRADIENT SINGLE-CELL SUPERCONDUCTING CAVITY FOR THE ESTABLISHMENT OF KEK RECIPE
We have performed a series of vertical tests of single cell Nb superconducting cavities at 2 degrees Kelvin. These tests aimed at establishing the feasibility of reaching an accelerating gradient of 45 MV/m on a routine basis. The cavity profiles were all of the KEK low loss design and were fabricated from deep-drawn Nb half cups using electron beam welding. The cavity surface preparation followed an established KEK procedure of centrifugal barrel polishing, light chemical polishing, high temperature annealing, electro-polishing, and finally a high pressure water rinse. Of the six cavities tested, three exceeded 44 MV/m on the first test and the rest of three also exceeded 44 MV/m after additional electro-polishing. This clearly establishes the feasibility of this gradient.