Abstracts Brochure - CERN

THPLS — Poster Session 29-Jun-06 16:00 - 18:00
Next Generation Light Source Storage Ring at SPring-8
A linac-based XFEL and an ERL are widely
accepted as next-generation light sources. K. Tsumaki, N. Kumagai (JASRI/SPring-8)
But they still have many technologically difficult
problems to overcome. In contrast, electron beams in a storage ring are very stable. Thus, we examined the
possibility of the storage ring as a next-generation light source. We designed a storage ring with an energy of 6 GeV
and a circumference of 1436 m. The ring consists of 24 ten-bend achromat cells and has a natural emittance of 83
pm·rad. The circumference is equal to that of SPring-8 storage ring and the cell length is two times, which enables us
to replace the existing storage ring with this new one in the SPring-8 tunnel and use the photon beam-lines without
constructing new ones. Particle tracking simulation showed that the horizontal dynamic aperture at the center of
a straight section is -3.7 mm and +3.4 mm and that it can be increased to -6.6 mm and +10.0 mm by changing the
sextupole strength for chromaticity correction while keeping zero chromaticity. In this paper, we describe the design
and the dynamic aperture of the extremely low emittance storage ring at SPring-8.
Status of the Photon Factory Storage Ring after the Straight-sections Upgrade
At the 2.5-GeV ring of the Photon Factory
(PF), a large reconstruction of the lattice
around the straight sections* has been
accomplished in 2005. As a result, four
short straight sections of 1.5 m have been
newly created, and the lengths of the existing
straight sections have been much improved.
For example, the length of the
T. Honda, S. Asaoka, W.X. Cheng, K. Haga, K. Harada, Y. Hori,
M. Izawa, T. Kasuga, Y. Kobayashi, H. Maezawa, A. Mishina, T.
Mitsuhashi, T. Miyajima, H. Miyauchi, S. Nagahashi, T. Nogami,
T. Obina, C.O. Pak, S. Sakanaka, Y. Sato, T. Shioya, M. Tadano,
T. Takahashi, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K.
Umemori, S. Yamamoto (KEK)
longest straight section has been extended to 9 m from 5 m. The optics has been optimized for installing shortperiod
narrow-gap (in-vacuum) undulators at the new straight sections. The reconstruction work on the ring was
held from March to September 2005. In the range over two-thirds of the storage ring, all the quadrupole magnets and
all the beam ducts have been renewed and rearranged. Commissioning of the storage ring was started from the end
of September 2005 and continued for one month. The operation for the user experiment was resumed from the end
of October on schedule. Though we made no in-situ baking after the installation for the beam ducts, the vacuum
scrubbing by the synchrotron radiation is running very well. The product of the beam lifetime and the beam current
exceeded 700 A min for the operation current 450 mA at the end of December 2005.
*S. Asaoka et al. "New Upgrade Project for the Photon Factory Storage Ring", AIP Conf. Proc. 705, p161 (2004).
Beam Position and Angular Monitor for Undulator by Using SR Monitor Technique
We presented a beam position monitor by
using SR monitor technique in the last PAC05. T. Mitsuhashi, M. Tadano (KEK)
In this monitor, a visible SR in far tail of the
undulator spectrum is extracted by a water-cooled beryllium mirror. We applied a focusing system to observe a beam
position in the undulator through an optical image of beam. We continue further study of this monitor, and this time,
we add the afocal system like a Kepler type telescope to measure the angular deviation of the beam. This system
converts the angular deviation of optical axis of input ray into position deviation, and we can measure an angular
deviation of the beam through its position deviation on the CCD. The results show us this method is applicable to
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