54770944
Degassing effect in water: sterilizing effect
Present ultrapure water making system requires a very high maintenance cost. One reason is its design philosophy with bacteria propagation in the system: kill bacteria in the system and filter the dead bodies. Filters in the system block frequently by the dead bodies and have to be exchanged so often. Deoxidization of water eliminates the condition for bacteria to be alive. Using this method, the maintenance should become very simple and cheap. In this paper we investigated quantitatively the effect of deoxidization of water on sterilizing and TOC level.
6846765
HIGHER HARMONICS BEAM LOADING COMPENSATION FOR A BROAD BAND MA-LOADED RF CAVITY
A broad band RF cavity loaded with magnetic alloy cores has been developed for the Japanese Hadron Facility synchrotrons. Its Q-value can be chosen at between 0.5 and 5. To reduce transient beam loading effects, a small Qvalue (< 3) is preferable to shorten the transient period. However, the circulating beam current of up to 7 A will induce a spurious voltage at the accelerating gap, which deforms the gap voltage due to higher harmonics components, if the Q-value is less than 3. The resulting RFbucket distortion may cause the beam loss. Therefore we have designed a beam loading compensation system to suppress the higher harmonics components.
137182571
A New Material Evaluation Method on Niobium by Magnetization Measurement
As a new evaluation method for the material defects or surface contamination of niobium, we have tried magnetization measurement using very small niobium samples. We could see the hyst~resis curve varied depending on the sample's history. This method has a high sensitivity. Th~ m.f1uence ?y surface treatments was observed on the hysteresis curve; annealing, chemical p~hshmg, Q-dlsease due to hydrogen etc .. In this paper we will report several study results by this method.
125432193
State-of-the-art and future prospects in rf superconductivity
94312812
High Field Studies on L-band Superconducting Cavities at KEK
Several 1.3 GHz single-cell and nine-cell niobium cavities were fabricated to attain a higher maximum accelerating gradient and to understand the phenomena limiting it. Vertical cold tests at {approx}1.8 K for the 4 single-cell cavities prepared by various surface treatments have been conducted 15 times. In eight of the tests, maximum accelerating gradients (E{sub acc}, max) of more than 14 MV/m were obtained with no field emission. Furthermore, E{sub acc}, max values of higher than 20 MV/m with a high Q{sub 0} value of {approx}10{sup 10} were achieved repeatedly after heat treatment at 1400 degrees C. Once quenching was observed at E{sub acc}, max (14 {approx} 20 MV/m), however, a common phenomenon resulting in Q{sub 0}-deterioration occurred in every test. The cavity performances and the phenomenon at high fields are reported in this paper.
55249742
Activities on Superconducting Cavities at TOSHIBA
Abstructs R&D activities on superconducting cavities at TOSHIBA are presented. Two L-band single-cell niobium cavities and an L-band three-cell structure were fabricated in our company and measured at KEK. The maximum field gradient of Eacc,max>30MV/m in both single-cell cavities and Eacc,max =18MV/m in the three-cell structure were attained respectively. An optimization study on the annealing temperature for the hydrogen Q-disease is reported. R&D of hydroforming to fabricate seamless cavities is also 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.
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.
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).
118377380
Neutron Star Properties in the Chiral Quark–Meson Coupling Model
We study the properties of neutron stars using the chiral quark–meson coupling model, in which the quark–quark hyperfine interaction due to the exchanges of gluon and pion based on chiral symmetry is considered. We also examine the effects of hyperons and Δ-isobars in a neutron star. Extending the SU(6) spin-flavor symmetry to more general SU(3) flavor symmetry in the vector–meson couplings to baryons, the maximum mass of neutron star can reach the recently observed massive pulsar mass, $${1.97 \pm 0.04 M_{\odot}}$$. In this calculation, Λ and Ξ are generated in a neutron star, while Σ and Δ-isobars do not appear.
118876588
Properties of dense, asymmetric nuclear matter in Dirac-Brueckner-Hartree-Fock approach
Within the Dirac-Brueckner-Hartree-Fock approach, using the Bonn potentials, we investigate the properties of dense, asymmetric nuclear matter and apply it to neutron stars. In the actual calculations of the nucleon self-energies and the energy density of matter, we study in detail the validity of an angle-averaged approximation and an averaging of the total momentum squared of interacting two-nucleons in nuclear matter. For practical use, we provide convenient parametrizations for the equation of state for symmetric nuclear matter and pure neutron matter. We also parametrize the nucleon self-energies in terms of polynomials of nucleon momenta. Those parametrizations can accurately reproduce the numerical results up to high densities.