BL-2A Undulator Soft X-Ray Double-Crystal Monochromator Station
Spokesperson :Yoshinori KITAJIMA
5641(PHS:4279)
yoshinori.kitajima@kek.jp
1. Outline
BL-2A provides soft X rays in the energy range between 1.8 keV and 5.0 keV with a double-crystal monochromator from an undulator U#02 source (l = 6 cm, 60 periods, K = 2.24 - 0.18). As a benefit of the prominent characteristics of high brilliance of the undulator source, high flux beams in a small spot with a high resolving power are easily obtainable. Users can tune the undulator gap at any time during their experiments where the photon energy of the first harmonics varies between 290 eV and 973 eV during 2.5-GeV operation. The 3rd or higher harmonics can be used at BL-2A. There is another station BL-11B for a similar energy region but at a bending-magnet source, which is suitable EXAFS measurements on Si, P, S, and Cl.
Fig. 1: Optics of BL-2A.
2. Performance
| Optics | Double-Crystal Monochromator [Si(111) or InSb(111)]/Focusing Mirrors |
|---|
| Energy Range | 2082 eV - 5000 eV [Si(111)] or 1745 eV - 3700 eV [InSb(111)] |
|---|
| Resolving Power | E/dE = 5000 - 8000 [Si(111)] or ca. 2000 [InSb(111)] |
|---|
| Spot Size | ca. 1 mm (H) x 1 mm (V) |
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| Photon Flux | maximum ca.2 x 1011 photons/s |
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Fig. 2: Example spectral distribution form the Si(111) monochromator.
![Spectrum of [S<sub>2</sub>O<sub>3</sub>]<sup>2-</sup>](bl2a-3.gif)
Fig. 3: Sulfur K-edge total electron yield apectra of [S2O3]2-. Energy resolution is much higher than BL-11B.
3. Equipments
- Personal computer for monochromator control [NEC PC-9801VM2 (MS-DOS) with 3.5"FDD(2HD)]
- Software for monochromator control and XAFS measurements (MS-FORTRAN; similar to other XAFS stations at PF)
- Photon intensity monitor system (mesh and pico-Ammeter)
- Stage for vacuum chambers (2.2 m x 1.4 m)
4. Remarks
- BL-2A does not have own vacuum chambers so that users should bring one. Many of experimental apparatuses of PF can be connected. Please contact the spokesperson for each apparatus.
- Sample chamber should be evacuated to < 10-4 Torr.
- Beam is ca. 1.31 m above the floor level but ca. 1.2 m from the above-mentioned stage at sample position. It comes upwards by 1.2 degree from the horizon.
- Beam time is shared with another branch BL-2C which covers lower energy range of 280 eV - 1400 eV.
- Available photon flux is increased with the reduced emittance operation of the PF ring since 1998 (See Fig. 4).
Fig. 4: Change in undulator spectrum by the emittance reduction of the PF ring in 1998. The peak intensity of the 5th harmonics becomes ca. 2.4 times as before with a small aperture. It is ca. 1.5 times higher when a larger aperture is used.
5. References
- H. Maezawa et al., Rev. Sci. Instrum., 60, 1889 (1989).
- Y. Kitajima et al., Rev. Sci. Instrum., 63, 886 (1992).
- Y. Kitajima, J. Elec. Spectrosc. Relat. Phenom., 80, 405 (1996).
- Y. Kitajima, J. Synchrotron Rad., 6, 167 (1999).
6. Publications
List of publications those registered to PF publication database is available.
Last modified: March 28, 2005.