55610926
EVALUATION OF MAGNETIC ALLOYS FOR JHF RF CAVITY
A new type of rf accelerating cavity using a high permeability magnetic alloy (MA) has been developed for the high intensity JHF proton synchrotrons. Compared with ordinary ferrites, the MA cores are very stable at high rf magnetic field and thus very high accelerating gradient (=accelerating voltage per cavity length) is available. We have measured several magnetic alloys in order to find a proper material for the cavity. In this paper, the test results are summarized and the evaluation of these materials is presented.
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.
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.
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.
118625081
Effects of Fock term, tensor coupling and baryon structure variation on a neutron star
Abstract The equation of state for neutron matter is calculated within relativistic Hartree–Fock approximation. The tensor couplings of vector mesons to baryons are included, and the change of baryon internal structure in matter is also considered using the quark–meson coupling model. We obtain the maximum neutron-star mass of ∼ 2.0 M ⊙ , which is consistent with the recently observed, precise mass, 1.97 ± 0.04 M ⊙ . The Fock contribution is very important and, in particular, the inclusion of tensor coupling is vital to obtain such large mass. The baryon structure variation in matter also enhances the mass of a neutron star.
55857127
PROMISING PERFORMANCE OF THE Nb/Cu CLAD SEAMLESS SUPERCONDUCTING RF CAVITIES
For future large applications of superconducting RF cavities, one has to fabricate cost-effective cavities with high electric-field gradients. We have proposed the fabrication of L-band seamless cavities from Nb/Cu clad material in order to eliminate the electron beam welding process. A feasibility study on the fabrication of 1.3 GHz Nb/Cu Clad single cell cavities from the clad sheet material was done. Three single cell Nb/Cu clad seamless cavities were fabricated by the collaboration with INFNLNL in Italy. In this paper, cold test results of seamless type cavities obtained by the spinning method are presented. The best performance of the cavities was Eacc = 25.1 MV/m with Qo=2.5X10 10 at a temperature of 1.4 K, which is very promising.
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.