From 2008, we have developed a scheme of short X-ray pulse generation by head-tail oscillation with a vertical kicker in SPring-8 storage ring in order to fulfill the demand of shorter pulse ...undulator radiation for the time resolved experiment. The developed system generates a vertical kick of 0.143 mrad and pulse width as short as 2.4 μs with 200 Hz repetition. With this system we successfully observed a bunch profile which tilted 362 mrad by visible light streak camera measurement for bending magnet light source. The expected tilt angle on the undulator position is 163 mrad, whose tilt angle has a capability of generating the 630 fs (RMS) without the beam spread effect after 50 μm slitting. As a preliminary test, we observed the reduction of the X-ray pulse duration as a function of the tilt angle by X-ray streak camera for the undulator radiation. From this result, we observed the saturation of the minimum short pulse duration at 4.5±2.1 ps (RMS) by 50 μm slitting, which almost corresponds to the detection limit of the X-ray streak camera, in the tilt angle region larger than 40 mrad.
We demonstrated a method with practical value for the measurement and global compensation of a complex coupling driving term C of linear difference resonance, using a turn-by-turn beam position ...monitor (BPM) at the SPring-8 storage ring. The method is based on the perturbation theory with the single-resonance approximation. The accurate complex C was obtained from coefficients of the eigenmode expansion of the coupled betatron oscillation observed near a target linear difference resonance. The global compensation for the measured C was successfully carried out by determining optimal strengths of the two independent correcting skew quadrupoles for generating a counterterm −C without using empirical methods. Meanwhile, we then confirmed that the determined optimal strengths gave a minimum vertical beam size by scanning the strength of the correcting skew quadrupole field. To demonstrate the validity of our method, C was also measured while varying the strengths of the correcting magnets around the optimal values to generate deliberate skew quadrupole error fields. We confirmed that the measured values of C agreed with those coming from the deliberate error fields.
The 10-T superconducting wiggler at SPring-8 is an ideal photon source for nuclear astrophysics experiments because it produces high-energy synchrotron radiations with equivalent blackbody ...temperatures being billions of Kelvin. We discuss the characteristics of the high-energy radiation from the superconducting wiggler and its applications to (
γ
,n) measurements.
The universe is filled with cosmic microwave background radiation at 2.73 K (Figure 1). It is a relic of the "fire-ball" that the universe once underwent shortly after its birth. This is the ...lowest-temperature black-body radiation that mankind has ever witnessed. Where can we expect highest-temperature black-body radiations? An answer may be found in the explosion of massive stars. Stars more massive than 10 solar masses that are destined to die as type II supernovae (Figure 2) evolve to form an onion-like pre-supernova structure consisting of multi-layers of hydrogen, helium, carbon, silicon, and the iron core as dominant elements. The gravitational collapse of the iron core triggers the explosion. Typically energy of about 1% (˜10
51
erg) of the gravitational energy is sufficient to explode massive stars, blowing off the outer layers and leaving neutron-stars (black-holes) as remnants. During the supernova explosion, the shock wave propagates the outer layers and heats material behind it, making, for example, the O-Ne-rich layers ideal heat baths filled with black-body radiation at multi-billions of Kelvin cc.
In general, a closed orbit distortion is observed as the sum of beam orbit and various noises such as beam position monitor (BPM) setting errors, BPM's electric response errors, etc. In order to ...obtain a beam with high performance in a low emittance ring with strong sextupole magnets, it is important to pick up information only of the beam orbit and perform orbit corrections by using this information. For this purpose we developed a new method of estimating BPM offsets to suppress the noise in the orbit data, based on the concept of “two-stage magnet alignment with common girders”. This alignment scheme, adopted in an 8 GeV electron storage ring at SPring-8, reduces high harmonic Fourier components of the orbit which results from magnet misalignment. Then, the main part of high harmonic components of a measured closed orbit is the artificial noise, and these harmful high harmonic components can be extracted as “effective” BPM offsets by filtering a measured closed orbit. This method was applied to the SPring-8 storage ring and found to be effective for reducing residual orbit distortions and a leakage of the dispersion function. To check the reliability of the resulting effective offsets, a beam-based measurement was also carried out at some BPMs and the beam position was measured with respect to the center of a nearby quadrupole magnet. The results were compared with the effective offsets and a reasonable agreement was found.
In 1999, in the frame of the project ISTC #767 “Budker INP/RIKEN Slow Positron Source”, the Budker Institute of Nuclear Physics had made a 10
T Three-pole Superconducting Wiggler. The wiggler will be ...the keystone of this project by its installation on the SPring-8 storage ring for powerful gamma ray generation (
λ
c
=450
keV
), that will be used for slow positron production (
N
γ
(
ε>1
MeV)∼10
15,
γ/s
I
e
=0.1
A
). A. Ando et al., Proposal of the high magnetic field super conducting WLS for slow positron source at SPring-8, presented at SR1 ’97 Conference. In January, 2000, the wiggler was transported to SPring-8, where the last test and measurements were carried out in collaboration with Japan. In this article, the results of measurements of the magnetic field, finding the magnetic field amplitude by an NMR probe, the definition of feed current relations by stretch current wire method, the calibration of a Hall probe in the high magnetic field, and the measurement of the magnetic field profile by a Hall probe are presented.
In a low‐emittance synchrotron radiation source it is difficult to provide magnet‐free long straight sections (MLSSs) a few tens of metres long because introducing MLSSs to the radiation source ...causes symmetry breaking and markedly reduces dynamic stability. To overcome this difficulty and realize MLSSs in such a ring, a method of building MLSSs is proposed starting from the stable lattice with high symmetry and proceeding via a transient lattice.
We propose a scheme to suppress leakage of an injection bump orbit caused by sextupole magnets within the bump orbit. Since the bump leakage excites a stored beam oscillation synchronized with beam ...injection, its suppression is one of the most crucial issues for achieving top-up operation at third generation synchrotron radiation (SR) sources. In the common case where sextupole magnets are located within the bump orbit, the condition for closing the bump depends on the amplitude of the bump orbit due to the nonlinear kicks by the sextupole magnets. Accordingly the bump orbit never closes for all amplitudes even under ideal condition. To solve this problem, we use a minimal condition for emittance increase due to the bump leakage caused by sextupole magnets in the lowest order of the nonlinear perturbation. The condition is obtained by optimizing linear optics and satisfying specific relation among integrated strengths of the sextupole magnets within the bump orbit. Furthermore, the condition does not depend on the bump amplitude. Calculations using the perfectly similar field patterns reveal that the proposed scheme can reduce the rms of the stored beam oscillation down to a few tens of microns for all bump amplitudes. The residual oscillation is negligibly small compared to the horizontal beam sizes presently achieved in the SR sources. The suppression effect of the scheme was also confirmed experimentally by the results obtained at the SPring-8 storage ring.
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