Shinya Nagahashi

Commissioning of the PF Ring after the Reconstruction for the Straight‐sections Upgrade

At the 2.5‐GeV ring of the Photon Factory, a large reconstruction of the lattice around the straight sections has been accomplished in 2005. Thus reconstruction is the main part of the straight‐sections upgrade project to rebuild existing undulators and to increase the number of undulator beamlines. As a result of the reconstruction, four short straight sections have been newly created and the lengths of the existing straight sections have been much extended. To exploit the new straight sections, short‐period narrow‐gap undulators which have a sufficiently high brilliance in hard x‐ray range have been developed. The reconstruction work of the ring was completed in a seven‐month shutdown from March to September, 2005. In the area over two thirds of the storage ring, all the quadrupole magnets and all the beam ducts have been renewed and rearranged to construct the new lattice. Recommissioning of the storage ring was finished at the end of October, 2005. Though we made no in‐situ baking for the beam ducts, ...

Present status of Photon Factory Advanced Ring

The upgrade project of the pulse X-ray source PF-AR was successfully completed by the end of 2001. The initial beam current and the lifetime were largely improved. The injection energy was raised from 2.5 GeV to 3.0 GeV, the maximum beam current of 65 mA was achieved. With a new global orbit feedback system, orbit drifts were largely improved.

New Upgrade Project for the Photon Factory Storage Ring

A new project for upgrading the 2.5‐GeV Photon Factory (PF) storage ring is now being undertaken to create six new short‐straight sections and to lengthen the existing eight straight sections. The short‐straight sections will provide an opportunity to install short‐period narrow‐gap undulators, while the extensions of existing straight sections will be taken advantage of updating current insertion devices to the latest models in future. To this end, the lattice configuration around the straight sections is modified by replacing old quadrupole magnets with new shorter ones and placing them closer to the near‐by bending magnets. Necessary replacement of the vacuum ducts and the beamline front ends will be carried out together. This project will be completed by the end of September, 2005, after six months of shutdown.

Status of R&D efforts toward the ERL-based future light source in Japan

The energy recovery linac is a very promising synchrotron light source in future. We are contemplating to realize a ERL_based next generation light source in Japan, under a collaboration between KEK, JAEA, ISSP, and other SR institutes. To this end, we started R&D efforts on its key technologies, including a low-emittance photocathode gun and superconducting cavities. We also plan to assemble these technologies into a small test ERL, and to demonstrate their operations. We report our R&D status.

Upgrade of the Photon Factory Control System

The Photon Factory control system was originally developed more than 20 years ago and has been upgraded several times. As a part of the straight‐sections upgrade, which started in March, 2005, we renewed the control system incorporating modern technologies in both low‐level and high‐level control layers. In the low‐level layer, a PLC (Programmable Logic Controller) is now intensively used for title safety control system, for RF klystron control boards and for the vacuum control system. In the middle‐level and high‐level layers, the EPICS (Experimental Physics and Industrial Control System) software toolkit was adopted. We also replaced VME‐board computers with HP‐RT operating system by Linux‐based computers, which are now used as input/output controllers (IOCs) for the EPICS. The new system has been running without any serious problems since its commissioning in September, 2005.

PF-ring and PF-AR operational status

The present operational status of the Photon Factory storage ring (PF-ring) and the Photon Factory advanced ring (PF-AR) in KEK is reported. The scheduled user times of them were more than 4000 hours in FY2006. In the last summer shutdown, new undulators were installed in both of the rings and have been stably operated. A top-up operation in a single-bunch mode was demonstrated for six days in February 2007 druring the shutdown of KEKB at the PF-ring.

Pulse octupole magnet system at the Photon Factory storage ring

n order to study a dynamical property of a vertical instability, we have developed a pulse octupole magnet system. The magnet can be operated with magnetic field rise and fall time of around 1.2msec, respectively. The maximum integrated field strength reach up to 2600T/m2. We measured the dynamical behavior of the vertical instability using the pulse octupole magnet for a multi-bunch beam of 400mA. We found that the growth time of the instability was longer than the suppression time.

Operational Status of PF-Ring and PF-AR after the Earthquake

In 2011, two SR sources of KEK, PF-ring and PF-AR, needed to change the operation schedule because of the unprecedented earthquake on March 11. Though the injector linac and the storage rings suffered a serious damage, temporary recovery was accomplished quickly and the trial operation started in May. The regular user operation could be resumed in October 2011. In the restoration work after the earthquake, some old vacuum components were removed from PF-ring. This work fortunately brought an effect of settling the quadrupole-mode longitudinal instability. For the top-up injection of PF-ring, the pulsed sextupole magnet has been used instead of the conventional kicker magnets since 2011. The hybrid-fill mode in place of the single-bunch mode has become available. Recently, the 10-Hz orbit switching for the tandem circularly polarized undulators has been developed for the user operation.

Development of a pulsed sextupole magnet system for beam injection at the Photon Factory storage ring

We have developed a pulsed sextupole magnet (PSM) system to demonstrate a new scheme of a beam injection at the Photon Factory storage ring (PF-ring) in KEK. We are going to install the PSM in this winter shutdown. Since a sextupole magnet has a characteristic of the parabolic magnetic field with no field at the magnetic center, it can give an effective kick to the injected beam at a distant position from the magnetic center and suppress effects on the stored beam at the beam injection. This enables us to inject the beam using the single PSM without a conventional pulsed local bump. The new injection scheme has a great advantage to achieve the top- up injection for a synchrotron radiation light source because it is not necessary to prepare a long straight section for the pulsed local bump system. The designed PSM has a length of 0.3m, a field gradient of about 13T/m2 at a peak current of 3000 A, and a pulse full width of 1.2 musec in a half-sine waveform. In this paper, the current status of the development for the system is described.

Status of the 6.5‐GeV Photon Factory Advanced Ring

The Photon Factory Advanced Ring (PF‐AR) is a 6.5‐GeV synchrotron light source at the High Energy Accelerator Research Organization (KEK). It can provide high‐flux hard X‐rays for such research as the materials science, structural biology and medical applications. The PF‐AR has five insertion devices including four in‐vacuum undulators. It is operated with a single bunch which fits for time‐resolved experiments. A special 5‐GeV operation is partly provided for a clinical application. An initial beam current and a beam lifetime are 60 mA and approximately 14 hours, respectively. Recent developments include an installation of a new in‐vacuum undulator (U♯NW14‐36) to the west rf section, which was accompanied by transferring two rf cavities to other section. The undulator has been successfully operated at a minimum magnetic gap of 10 mm. We also carried out such accelerator studies as a successful test of beam injection using a pulsed quadrupole magnet, a study of low emittance optics, an establishment of tw...