Tatsuro Shioya

Developing 100 ps-resolved X-ray structural analysis capabilities on beamline NW14A at the Photon Factory Advanced Ring

NW14A is a newly constructed undulator beamline for 100 ps time-resolved X-ray experiments at the Photon Factory Advanced Ring. This beamline was designed to conduct a wide variety of time-resolved X-ray measurements, such as time-resolved diffraction, scattering and X-ray absorption fine structure. Its versatility is allowed by various instruments, including two undulators, three diffractometers, two pulse laser systems and an X-ray chopper. The potential for the detection of structural changes on the 100 ps time scale at NW14A is demonstrated by two examples of photo-induced structural changes in an organic crystal and photodissociation in solution.

Construction of insertion devices for elliptically polarized synchrotron radiation

Two new insertion devices for the generation of elliptically polarized synchrotron radiation have been constructed to be installed in two electron storage rings, the Accumulation Ring for the TRISTAN project and the Photon Factory ring at KEK, National Laboratory for High Energy Physics. These new light sources are designed to produce (1) intense radiation with a degree of circular polarization (Pc) between 0.5 and 0.9 in hard x‐ray region, and (2) quasimonochromatic radiation with Pc>0.7 in vacuum ultraviolet region.

Construction of an in‐vacuum type undulator for production of undulator x rays in the 5–25 keV region

A new 179‐pole undulator with magnetic period of 4 cm for production of brilliant and quasimonochromatic hard x rays has been completed and installed in the TRISTAN Accumulation Ring (AR) in KEK, National Laboratory for High Energy Physics. The aperture of the undulator for the circulating electron can be flexibly changed to satisfy the operational requirements of AR, since the undulator magnets are encased in the vacuum chamber of the undulator. When it is operated at the magnet gap of 20 mm with 6.5‐GeV operation of AR, intense 14.4‐keV radiation for Mossbauer experiments is successfully obtained as the third harmonic of the undulator radiation.

Design and construction of beamline‐NE1 for circularly polarized synchrotron radiation from the 6‐GeV TRISTAN Accumulation Ring

The beamline for the circularly polarized synchrotron radiation at the 6‐GeV Accumulation Ring for the TRISTAN project is now under construction. The insertion device of this beamline was designed to produce circularly polarized x rays at the photon energy range of 200 eV∼100 keV. The beamline is divided into the following three branches: (1) High resolution Compton scattering and magnetic Compton scattering experiments; (2) multipurpose experiments such as magnetic x‐ray scattering and magnetic x‐ray absorption; and (3) completely circularly polarized soft x rays.

In‐vacuum undulator installed in a 6.5 GeV storage ring for producing brilliant 14.4 keV Mössbauer photons

Using a newly developed in‐vacuum type undulator installed in the 6.5 GeV TRISTAN Accumulation Ring at the National Laboratory for High Energy Physics, a beam comprising of more than 2.4×104 Mossbauer photons/s at 14.4 keV has been achieved from an enriched α‐57Fe2O3 single crystal. The spectrum in terms of brilliance in the region from 5 to 25 keV agrees well with the calculation.

Construction of a multiundulator, Revolver No. 19, at the Photon Factory

A multiundulator, Revolver No. 19, was constructed and installed at the straight section (B 18‐B19) of the 2.5‐GeV Photon Factory storage ring. The mechanical structure of Revolver No. 19 consists of a main frame and two rotatable beams with four base plates, on which undulator magnets with four different lengths of period are mounted. A pair of undulator magnets with a desired period length can be selected by revolving the rotatable beams. The energy range of the radiation covered by fundamental peaks from the undulator magnets is from 7.8 to 1150 eV.

Reconstruction for the brilliance-upgrading project of the Photon Factory storage ring

Reconstruction of the Photon Factory storage ring (PF ring; 2.5 GeV) is now in progress to provide very brilliant synchrotron radiation to users, i.e. the emittance is being reduced by a factor of five. Components, such as the quadrupole and sextupole magnets, vacuum chambers, beamlines and beam-position monitors, are being replaced by new ones in 16 normal-cell sections of the PF ring. The accelerating cavities, injection systems and control systems are also being replaced. Operation will commence when the improvements are completed on 1 October 1997.

Construction of a multipole wiggler, MPW♯13, at the Photon Factory

An insertion device, MPW♯13, which can be operated in both wiggler and undulator modes, is presently under construction at the Photon Factory (PF). When installed in the PF storage ring, this device will produce wiggler radiation in the hard x‐ray region, and also undulator radiation in the vacuum‐ultraviolet (VUV) and soft x‐ray regions. The wiggler structure employs 27 magnetic poles with a period length of 18 cm. The maximum peak field of the device of 1.5 T is attained via the hybrid configuration of its magnetic poles. Calculations of the spectral brilliance of the device exhibits the following features: in the wiggler mode, the brilliance at 10 keV will exceed that of the PF bending magnet radiation by a factor of 30; and in the undulator mode it will be between 10 and 100 times higher, from 10 eV to 1 keV, utilizing up to the fifth harmonic.

The construction of the superconducting vertical wiggler and its operation in the photon factory

Abstract The superconducting vertical wiggler of the Photon Factory, KEK, was installed in the storage ring in October 1982. Its first operation with 2.5 GeV electron beam was successfully done in February 1983, the wiggler radiation was observed in the beamline through a Be window using a fluorescent screen as well as with a solid state detector, by changing the magnetic field strength of the wiggler. Since February 1984 it has been operated in the normal users time. The maximum magnetic field achieved after installation in the storage ring is 5.8 T. However, we have operated the wiggler magnet at 5.0 T in usual operation as to obtain long enough beam lifetimes for the users run. At this moment, we have achieved an average beam lifetime of 1500 min at a stored curret of 100 mA.

Operation of a fast polarization-switching source at the Photon Factory

We have been developing a fast polarization-switching source for the vacuum ultraviolet and soft X-ray region at the B15-16 straight section of the 2.5-GeV Photon Factory (PF) storage ring. The source consists of two tandem APPLE-II-type elliptically polarizing undulators (EPUs), namely, U#16-1 and U#16-2, and a fast kicker system. The target frequency of polarization switching is 10 Hz. As the first step, we installed U#16-1 and five identical bump kickers in the PF ring in March 2008. Then, we constructed U#16-2 and installed it in August 2010. The orbit switching operation at 10 Hz, for user experiments, started in January 2012. We describe the details of the operation status of two EPUs and the fast local bump system in this report.