H. Nakagawa

Present Status of the J-PARC Control System

The present status of the design and construction of the control system for Japan Proton Accelerator Research Complex (J-PARC) is given. J-PARC is a 3-stage accelerator complex with a 200MeV Linac, a 3GeV Rapid Cycling Synchrotron (RCS) and a 50GeV Main Ring synchrotron (MR). The accelerators are under construction jointly by Japan Atomic Energy Research Institute (JAERI) and KEK, High Energy Accelerator Research Organization. Linac and RCS are being constructed mainly by JAERI and MR is mainly by KEK. [1,2] And the control systems for Linac and RCS [17] are constructed mainly by JAERI and that of MR is done mainly by KEK. [3] Commissioning of Linac, RCS and MR are scheduled in September 2006, May 2007, and January 2008, respectively. There are three control systems under construction corresponding to three accelerators. These three control systems will be operated from one central control room when each control system is completed construction. We chose Experimental Physics and Industrial System (EPICS) [4] as the software environment so that three control systems can be unified easily to single control system. J-PARC control system has the three-layer standard model architecture for accelerator controls that is very common in the EPICS world. We have chosen the standard network protocol TCP/IP and UDP/IP as the J-PARC standard field-bus used to connect interface units that links accelerator component to the control system.

Manufacturing and Operation of the Magnetic Septa for the Slow Beam Extraction From the J-PARC 50 GeV Proton Synchrotron

The magnetic septa have been developed for the slow beam extraction from the 50 GeV Proton Synchrotron to the Hadron Experimental Hall at J-PARC (Japan Proton Accelerator Research Complex). The magnetic septa consist of two thin magnetic septa, four medium thick magnetic septa and four thick magnetic septa. The typical operating current is 3000 A and the total kick angle is 77 mrad with the 30 GeV proton beam. All parts of the thin and of the medium thick septum magnets are made of inorganic materials to resist high radiation environment. The positions of the thin and medium thick septa can be aligned remotely in the horizontal range of ±5 mm, which enables us to minimize the beam loss at the magnetic septum section. The septa were installed in the synchrotron ring in December, 2008, after a test at KEK (High Energy Accelerator Research Organization), and were successfully operated in the beam time for the slow beam extraction in January and February, 2009, which resulted in the first 30 GeV slow extracted beam delivery to the Hadron Experimental Hall.

Enhancement of the characteristic X-ray yield from oriented crystal irradiated by high-energy electrons

Abstract In this report, results of a measurement of characteristic X-ray (CXR) yields from oriented tungsten crystal targets irradiated by 600–1000 MeV electrons are presented. Characteristic X-rays from tungsten are measured with a Si(Li) semiconductor detector placed at the backward direction with respect to the incident electron beam. We have observed an enhancement of the X-ray yield due to the K-shell ionization when the crystal axis 〈1 1 1〉 is oriented along the beam. The ratio of the K-line yield from the oriented crystal to the one from the disoriented crystal is about 1.6–1.9 for the target thickness of 1.2 mm at the electron energy of 1000 MeV. For L-line yields the enhancement is not appreciable. We demonstrated a possibility of using the orientation dependence of the CXR as a mean of aligning the crystal axis at the channeling condition to the beam.