arXiv subjects

J. Chiba

Publications and source records attributed to J. Chiba.

77 records · Page 5Linked to original sources

arXiv2002

Implementation of the Epics Device Support for Network-Based Controllers

In the control system of the JAERI-KEK joint project (High Intensity Proton Accelerator Facility), it is planned to employ network-based controllers such as PLC's and measurement stations instead of using other field control networks, since the network hardware and software can be standardized and they have been successfully utilized in other accelerator control systems in KEK. EPICS software support for those controllers was designed paying special attention to robustness and has been implemented and applied for the accelerator test stand. Basic functionalities were confirmed and miscellaneous functions such as diagnosis of the software itself would be added. Since many kinds of network-based equipment such as oscilloscopes have become available recently, they are considered to be integrated as well. They may enable more manageable controllers.

physics.acc-ph↗

arXiv2001

A Control System of the Joint-Project Accelerator Complex

The current status of the control system for a new high intensity proton accelerator, the JAERI-KEK Joint Project, is presented. The Phase 1 of the Joint-Project has been approved and recently started its construction at JAERI site at Tokai. The first beam commissioning is scheduled in 2006. In parallel with it, a 60-MeV Linac is now being constructed at KEK site at Tsukuba for R&D purpose. Recently the Project has officially decided to use the Experimental Physics and Industrial Control System (EPICS). Under the EPICS environment, we are challenging to implement the Ethernet/IP network for all communication, even at the level of end-point controllers which are so far connected via a field bus. In order to realize such a system, three new controllers (PLCs, WE7000 stations and general-purpose Ethernet boards) are being developed. A prototype EPICS driver for the PLCs works fine and is used to control the ion-source at the KEK Linac.

physics.acc-ph↗

arXiv2000

Observation of $ρ/ ω$ Meson Modification in Nuclear Matter

We have measured invariant mass spectra of electron-positron pairs in the target rapidity region of 12GeV p+A reactions. We have observed a significant difference in the mass spectra below the $ω$ meson between p+C and p+Cu interactions. The difference is interpreted as a signature of the $ρ/ω$ modification at normal nuclear-matter density.

nucl-ex↗

arXiv2000

Physics of High-Mass Dimuon Production at the 50-GeV Proton Synchrotron

We discuss the physics interest and the experimental feasibility for detecting high-mass dimuon pairs using the planned 50-GeV Proton Synchrotron (PS) at the KEK/JHF and JAERI/NSP joint accelerator project. The Drell-Yan measurement of $p+d$ versus $p+p$ at 50 GeV will provide unique information on the flavor asymmetry of proton's up and down sea-quark distributions in the large-$x$ region. A study of the nuclear dependences of Drell-Yan cross sections can reveal the modification of antiquark distributions in nuclei. Furthermore, the effect of energy loss for fast partons traversing nuclear medium could also be sensitively measured. If polarized proton beam becomes available at the 50-GeV PS, unique information on the sea-quark polarization could be obtained. Study of heavy quarkonium production at the 50-GeV PS can set important constraints on the mechanism of vector meson productions. Using a prototype dimuon spectrometer, we have simulated the sensitivities for a variety of measurements.

hep-ph↗

arXiv1999

Effect of Coulomb blockade on STM current through a granular film

The electron transport through an array of tunnel junctions consisting of an STM tip and a granular film is studied both theoretically and experimentally. When the tunnel resistance between the tip and a granule on the surface is much larger than those between granules, a bottleneck of the tunneling current is created in the array. It is shown that the period of the Coulomb staircase(CS) is given by the capacitance at the bottleneck. Our STM experiments on Co-Al-O granular films show the CS with a single period at room temperature. This provides a new possibility for single-electron-spin-electronic devices at room temperature.

cond-mat.mes-hall↗