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.
14514129
BEAM LOADING EFFECTS IN JHF SYNCHROTRON
Beam loading effects on the rf system of JHF proton synchrotrons have been investigated by both computer simulation and experiment using a low energy electron beam. From the simulation results, it is found that even under the heavy beam loading the beam acceleration becomes stable if applying the beam loading compensation, and the compensation experiment is succeeded on proto-type Magnetic Alloy loaded cavity.
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.
209358824
THE CHARACTERISTICS OF DIFFERENT MAGNETIC MATERIAL FOR RF CAVITY UNDER PERPENDICULAR MAGNETIZATION
In recent years, a technology of perpendicular magnetization for ferrite loaded cavities is developed. Yttrium Garnet ferrite is generally used for that case with higher frequency range from 30-60 MHz. An attempt is taken to measure the characteristics of different new materials such as FINEMET,METGLAS and NiZn ferrite under the condition of perpendicular magnetization. The results are summarized in this paper.
56351344
RF SYSTEMS FOR JHF SYNCHROTRONS
Based on the measurements of the magnetic cores and R&D works, MA(Magnetic Alloy)-loaded cavity will be adopted for the RF cavity of JHF 50 GeV Main Ring and 3 GeV Booster. Because of high stability at large RF amplitude, high gradient of acceleration voltage (>50 kV/m) is available. By a test cavity, 2.5 kV/core has been already achieved in the CW operation using one MA core of 2.5 cm thickness. For the pulse operation, 5.5 kV/core has been obtained. Another advantage is that the system does not require the tuning system because of the cavity band width is wide enough to cover the RF frequency. A stability analysis shows that the RF system without the tuning loop has wider stable region than high Q cavity system with the loop. A multi-particle simulation shows that the RF system is also stable for the periodic transient and the RF bucket distortion. However, the distortion should be corrected when the Q value of the cavity is low (Q<2).
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.
53960485
TECHNIQUES OF SC CAVITY PREPARATION FOR HIGH GRADIENT
High gradient of sc cavities was much improved in the past one decade. Today the accelerating field gradient >30 MV/m is produced routinely in single cell niobium cavities by electropolishing (EP). Recently, such a gradient has been achieved in TTF 9-cavities. In this paper, essential preparation techniques for the high gradient are introduced. Especially, EP is a breakthrough technique and its superiority will be resolved from recent new phenomena. In the last, recent results of multi-cell cavities with both β=1 and medium β are reviewed.
59129737
Development of a Superconducting Cavity for the High Intensity Proton Linac in JAERI
The R&D work of a superconducting (SC) cavity for the high intensity proton linac in JAERI has been started in collaboration with KEK. The RF field calculation and the structural analyses of the cavity have been made for the design in the proton energy range between 100 and 1500 MeV. The results indicate the feasibility of the SC proton linac, while more optimization is required. A vertical test stand with a cryostat, a clean room and a water rinsing system has been constructed. We present the preliminary cavity design and the overview of the test stand.
118654996
Analytic Formulae for the Off-Center CMB Anisotropy in a General Spherically Symmetric Universe
The local void model has recently attracted considerable attention because it can explain the apparent accelerated expansion of the present universe without introducing dark energy. However, in order to justify this model as an alternative to the standard ΛCDM cosmology, the model should be tested by various observations, such as the CMB temperature anisotropy, besides the distance-redshift relation of SNIa. For this purpose, we derive analytic formulae for the dipole and quadrupole moments of the CMB temperature anisotropy that hold for any spherically symmetric universe model and can be used to compare consequences of such a model with observations of the CMB temperature anisotropy rigorously. We check that our formulae are consistent with the numerical studies previously made for the CMB temperature anisotropy in the void model. We also update the constraints concerning the location of the observers in the void model by applying our analytic dipole formula with the latest WMAP data. Subject Index: 400, 401, 402, 403, 468
13952308
Meson mixing amplitudes in asymmetric nuclear matter
Abstract Using a purely hadronic model, we study the charge-symmetry-breaking ρ – ω , σ – δ , σ – ρ and δ – ω mixing amplitudes in isospin asymmetric nuclear matter. The basic assumption of the model is that the mixing amplitude is generated by nucleon and antinucleon loops and hence driven entirely by the difference between proton and neutron Fermi momenta and the proton–neutron mass difference. We find that the behavior of the mixing amplitude is very complicated in the spacelike region and quite sensitive to the proton fraction of nuclear medium and nuclear density. In particular, in neutron rich nuclei (like Pb) and/or neutron stars the mixing amplitudes become about 10∼100 times as large as those in typical mirror nuclei.
925890
The role of nucleon structure in finite nuclei
Abstract The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of σ, ω and ϱ mesons, is extended to investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation of motion for the nucleon, as well as the self-consistent equations for the meson mean fields. The model is first applied to nuclear matter, after which we show some initial results for finite nuclei.