19387199
In-Line Control in T2K Proton Beam Line Magnet Safety System
Magnet Safety Systems (MSS) frequently use quench detection based on voltage measurement, in order to protect superconducting magnets. Disconnecting quench detection cables and using a voltage generator to simulate quench voltages is a good way to check the system. This paper describes another method, with a hardware and software in-line control system, used to periodically check the MSS of the 28 superconducting magnets of the T2K proton beam line, at J-PARC. With in-line control, an isolated simulation voltage is added to each real input voltage of the detectors, without disconnecting quench detection cables. In-line control can also check if quench detection cables are connected or not, and if a detection wire is broken. In-line control is realized with additional electronic hardware and software on the MSS electronic boards and with a connection to a PC with a specific software and Graphic User Interface running under Windows. Nevertheless, quench detection and safety actions are always based on hardware only. Extreme care is taken so that in-line control cannot prevent the MSS to protect the magnet system, even if software stops running. Other remote functions are also available with this system, like monitoring of analog and logical signals and setting of detection and electronic parameters, if needed.
113855195
Studies of Fabrication Procedure of 9-cell SRF Cavity for ILC Mass-production at KEK.
We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deepdrawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collier (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.
21013020
Conduction Cooling Test of a Splittable Quadrupole for ILC Cryomodules
A superconducting splittable quadrupole magnet was designed at Fermilab for use in ILC-style cryomodules, in which the magnet is to be assembled around the beam tube to avoid contaminating the ultraclean superconducting RF beam volume. This quadrupole was built and first tested in a liquid helium bath environment at Fermilab, where its quench and magnetic performance were characterized. The device is intended to be cooled by conduction when installed in cryomodules, so a separate test was made at KEK where an appropriate conduction cooling test facility exists. We present results of the thermal performance of the magnet in the conduction cooling mode, and discuss its excitation characteristics in this operating mode.
118392464
Relevant momentum components of gluons for confinement and chiral symmetry breaking
We investigate which momentum components of gluons induce color confinement and spontaneous chiral symmetry breaking in lattice QCD. For this purpose, we formulate a lattice framework to introduce the momentum cutoff of the gluon field. Using this framework, we calculate the quark-antiquark potential, the color flux tube, the chiral condensate, and the Dirac spectrum. Our results suggest that confinement and chiral symmetry breaking are induced by somehow different momentum components of gluons.
119220877
Lattice study of the chiral magnetic effect in a chirally imbalanced matter
We investigate the chiral magnetic effect by lattice QCD with a chiral chemical potential. In a chirally imbalanced matter, we obtain a finite induced current along an external magnetic field. We analyze the dependence on the lattice spacing, the temperature, the spatial volume, and the fermion mass. The present result indicates that the continuum limit is important for the quantitative argument of the strength of the induced current.
27061707
Lattice QCD in rotating frames.
We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD.