123608885
Upgrading of TRISTAN by superconducting RF system
The energy upgrade of TRISTAN by a superconducting RF system is progressing. Sixteen five-cell 508 MHz cavities made of niobium have been installed and started to operate in November 1988. Superconducting cavities have raised the energy of e/sup -/e/sup +/ to 30.4 GeV from 28.5 GeV with a normal conducting RF system. Construction, vertical tests, horizontal tests and three months of operational experience are described.<<ETX>>
125432193
State-of-the-art and future prospects in rf superconductivity
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.
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.
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.
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.
123115010
The nuclear EMC effect
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.
17428438
Stability analysis using EMTP for JHF systems
The Stability analysis for JHF (Japan Hadron Facility) synchrotron has been performed by using a code for the stability analysis, EMTP(Electronic Magnetic Transient Program). We have examined two cases; a MA (Magnetic Alloy) loaded cavity and ordinary ferrite one. The MA loaded cavity has low Q value and does not require the tuning system for a frequency sweep. The result shows that the MA loaded cavity has larger stable area than the ordinary ferrite loaded cavity. The JHF RF system using the MA loaded cavity can be operated stably. Another simulation has been performed with a code, MC(Micro Cap). The results were consistent with the EMTP analysis.
123518493
Manifestation of Short-Range Few-Nucleon Correlations in Nuclear Structure Functions