Stable top-up operation at SPring-8

Abstract

Top-up operation allows SPring-8 to provide highly stable X-ray beams with arbitrary filling patterns. The implementation of top-up operation is described, with a focus on the simultaneous achievement of stability of stored current, beam orbit, purity of an isolated single bunch, and beam injection efficiency. Stored-current fluctuations have been routinely reduced to a level of 10 À3 . Stored-beam oscillation on frequent beam injection, which was originally regarded as the most serious problem, has been successfully suppressed to a sufficiently low level that it never perturbs imaging experiments. Current impurities in nominally empty buckets have been reduced to a level of 10 À9 over more than one week of operation, making possible the measurement of timeresolved spectra using high-current bunches. Finally, excellent injection efficiency, higher than 80%, is routinely obtained, even for small undulator gaps, which is critical for preventing radiation damage to insertion-device magnets and to reduce leakage radiation. The process of achieving highly stabilized top-up operation at SPring-8 and its utility for user experiments are described.

Analysis of mutual coherence of x-ray beam from rocking curves by perfect crystal

“…The intensity of the incident beam into the silicon plate was not monitored, because the intensity was sufficiently stable due to the top-up operation of the SPring-8. 18 The rotations of the silicon plate for the rocking-curve measurements were carried out with a fine stepper goniometer. 19 For the easy change of the reflection indices, a 360 • -rotation stage was inserted between the silicon plate and the goniometer.…”

Observation of cleavage in DNA and nucleotides following oxygenK-shell ionization by measuring X-ray absorption near edge structure

“…Th e resolving power of the monochromator (E/ Δ E, where E is photon energy and Δ E is the energy diff erence) was ∼ 10 4 in the energy region used. Th e photon fl uxes were almost constant, because of the top-up electron injection to the storage ring of the SPring-8 (Tanaka et al 2006) during the irradiation. Th e 560 eV beam size at the sample position during the irradiation was 1.5 ϫ 0.5 mm.…”

Common operation metrics for storage ring light sources

“…SPring-8 [12] runs in nine operation modes, one of which is multibunch with twelve 160 bunch trains, also several-bunch modes and hybrid modes. The severalbunch modes consist of equally spaced bunches (or bunch trains), i.e.…”