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.

The present status of the Photon Factory storage ring (PF-ring) and the Photon Factory advanced ring (PF-AR) at High Energy Accelerator Research Organization (KEK), including recent progress for the machine developments, are reported. The operation times of both PF-ring and PFAR were about 5000 hours and the failure time were about 50 hours in FY2008. Utilizing shutdown pariods of KEK B-factory (KEKB) from January to March 2009, a top-up operation with a continuous injection has been successfully carried out in multi-bunch mode at PF-ring.

* E-mail: m082182@hiroshima-u.ac.jp ** Current affiliation: High energy accelerator research organization, accelerator lab. *** Current affiliation: The graduate university for advanced studies Abstract The Beam Physics Laboratory of Hiroshima University has studied GaAs photo-cathode for a high brightness electron source. It aims to develop a cathode with the higher quantum efficiency and longer-lifetime. The Negative Electron Affinity (NEA) surface is essential for GaAs to activate as an electron source. By artificial treatments, NEA surface is made on GaAs cathode, so that electron beam can be extracted to vacuum with a laser pulse, whose energy corresponds to the band gap. NEA surface is made by Yo-Yo method, alternating deposition of Cs and O2 to a GaAs surface. In this article, we examine a lifetime of the GaAs cathode, as a function of temperature. We evaluated also a temperature rise on the cathode surface by laser, which generates the electron bunch train. Temperature rise depends on the laser spot size; it is 60K for 10mm. We observed a significant degradation on the lifetime by heating cathode. By considering expected temperature rise and this result, some active temperature control is necessary to obtain an enough operation lifetime for high brightness electron source, because of the small spot size (a few mm) and high power (several 10 W).

Aiming at the future X-ray source based on the energy recovery linac (ERL), we are making aggressive R&D efforts. Our efforts include the developments of a highbrilliance photo injector, 1.3-GHz superconducting cavities, and planned construction of the Compact ERL. We report the updated status of our ERL project.

A bunch-by-bunch feedback system has been developed to suppress longitudinal coupled-bunch instabilities at the KEK-PF. A longitudinal kicker based on a DAFNE-type overdamped cavity has been designed and installed in the ring, and a general purpose signal processor, called iGp, has been developed by the collaboration of the KEK, SLAC, and INFN-LNF. The entire feedback loop has been closed by the end of June 2007. and the feedback system has successfully suppressed the longitudinal dipole-mode instabilities up to 450 mA, which is a nominal operating beam current at the PF.

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. This reconstruction is the main pail 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, recovery of the beam lifetime has favorably progressed due to the vacuum scrubbing by the synchrotron radiation.

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.

The rapid cycling synchrotron (RCS) radio frequency accelerating systems have been prepared for the beam commissioning scheduled in the middle of September 2007. Installations of cavities, power supplies and amplifiers were carried out. And, the systems have been checked for the combined operations. For the main synchrotron (50GeV-MR) accelerating systems, the high power examinations and final adjustments are ongoing. And, installations are planned in September 2007. Here, we report on various issues that had been found and solved during the examination and installation period.

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.

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 bigh-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 two-bunch operation for the clinical application, a successful operation of a multi-bunch feedback system, and an installation of a test undulator which enables us to control polarization using a new arrangement of magnets.

The rapid cycling synchrotron (RCS) radio frequency accelerating systems have been prepared for the beam commissioning scheduled in the middle of September 2007. Installations of cavities, power supplies and amplifiers were carried out. Also, the systems have been checked for the combined operations. For the main synchrotron (50 GeV-MR) accelerating systems, the high power examinations and final adjustments are ongoing. Installations are planned for September 2007. Here, we report on various issues that had been found and solved during the examination and installation period.

At the 2.5-GeV ring of the Photon Factory, a large-scale reconstruction of its lattice is in progress. The objects of the reconstruction are an increase in number and extensions of the straight sections for insertion devices. Four new straight sections will be created and all existing straight sections will be largely extended. As a result, the number of straight sections for insertion devices will be increased from the currently available seven to thirteen. The newly created straight sections are short in length but will have low beta functions and will be suitable for housing short-period narrow-gap undulators. An invacuum undulator, which has a sufficiently high brilliance within a spectral range for the x-ray research field, is being developed and will be installled. The shutdown for the upgrade project is scheduled for the period from March to September, 2005.

In the Photon Factory 2.5 GeV electron storage ring at KEK, the upgrade project of its straight sections is underway. In the project, we improve the beam-position monitors (BPMs) and the global orbit feedback system. New BPMs are designed and installed in the straight sections and the orbit stabilization system is improved. The effect RF phase modulation to the beam position fluctuation is also observed with turn by turn BPM.

The Photon Factory Advanced Ring (PF-AR) is a synchrotron light source dedicated to X-ray research. Although the PF-AR is usually operated at a stored beam energy of 6.5 GeV, a 5.0 GeV mode is also available for medical application. In the 6.5 GeV mode, the beam current of 60 mA in a single-bunch and the typical lifetime of 15 hrs at the current have been archived. Single-bunch operation for pulsed X-ray and its relatively high beam energy characterize the PF-AR. However, the high-current in single-bunch causes several problems to be solved, such as the temperature rise of some of the vacuum components, a pressure increase in the ring, and a sudden drop of beam lifetime. In order to avoid these problems, developments of new methods have been continued. In this paper, the status and the recent developments of the PF-AR are presented. It concerns: the successful operation with a two-bunch high-current operation at 5.0 GeV; the vertical beam size control for the medical application; modulating the RF acceleration phase in order to elongate the bunch length; stabilizing temperature in the ring tunnel; the study for medium emittance operation with 160 nm · rad; transferring the RF cavities in order to install a new insertion device; an innovative injection scheme using a pulsed quadrupole magnet.

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.

The PF‐AR is a full‐time single‐bunch light source for SR experiments in the X‐ray region. Electrons are injected at 3.0 GeV and ramped up to the final energy of 6.5 GeV for normal user operation or 5.0 GeV for medical application. The typical initial beam current is 55 mA at 6.5 GeV and the beam lifetime is 15 h at 50 mA. The initial single‐bunch impurity better than 10−8 was achieved, however, degradation of the impurity during the users’ run has to be solved. Since the present emittance of 290nm⋅rad is not satisfactory, we are making an effort to realize the minimum attainable emittance of 160nm⋅rad. The high quality of pulse X‐ray has brought us abundant occasions to do time‐domain and/or time‐resolved measurements.

UVSOR, a 2nd generation synchrotron light source of 750 MeV, was converted to UVSOR‐II, which has eight straight sections and small emittance of 27 nm‐rad. The magnetic lattice was modified without changing the circumference of 53.2 m. All the magnets and their beam ducts except for the bending magnets were replaced. An undulator and a super‐conducting wiggler were replaced with two new in‐vacuum undulators. Some parts of the injector were replaced and upgraded. Some beam‐lines were reconstructed. All the reconstruction works were completed within three months, from April to June 2003. In July, UVSOR‐II was successfully commissioned. Some preliminary measurements on the beam parameters suggested that the design goal of the emittance, 27 nm‐rad, was likely achieved. Vacuum conditioning with beams are in progress. Users experiments will start in September.

Two synchrotron light sources, the 2.5-GeV Photon Factory (PF) storage ring and the 6.5-GeV PF-AR, are working at the High Energy Accelerator Research Organization (KEK). We first describe the PF storage ring on its present system, operations and the beam performance. We then report the current status of the PFAR and a future plan of the Photon Factory.

The transverse dynamic apertures for the high-brilliant optics were directly observed at two operating points of betatron tunes near 3 rd order coupling resonance at the Photon Factory storage ring (PF-ring). The measurements were made on the quarter of the transverse plane using the fast kicker magnets and the turn-by-turn monitor system. The dynamic apertures were preciously estimated through the fine control of kicker voltage and turn-by-turn observation of beam loss after the kick. The measured transverse dynamic apertures were quantitatively compared with the prediction of the computer simulation based on the realistic lattice model.