Technical Description:
FMB has experience in building blade type X-ray beam position monitors (XBPMs). XBPMs made by FMB are widely used at many synchrotrons to measure the photon beam position at the micron level.
Staggered blade pairs beam position monitors (SPMs) are a type of XBPMs used if only vertical beam positions have to be determined, e.g. at dipole radiation sources. The FMB SPM design is based on a development by HZB (formerly BESSY, see e.g. Peatman, Holldack; J. Synchrotron Rad., Vol. 5 (1998), 639-641).
A typical FMB SPM system consists of the SPM insert, a vacuum chamber, a X-Y-Z manual alignment assembly and a support.
The SPM beam position monitors use four blades, whose narrow fronts are oriented towards the radiation source. They are arranged in two staggered pairs, one pair mounted above the other. With this blade setup the operator is able to scan the off-axis radiation of the source and determine on-line the position of the radiation source centre from the emitted signals.
Size and geometry of the blades will be adapted to the beam characteristics at the place of the position monitor in order to achieve a maximum photocurrent yield at a maximum sensibility.
The blades consist of OFHC copper or Tungsten and will be actively cooled via heat conducting ceramics to resist the thermal load of the radiation source.
Technical Data:
| SPM insert | ||
| Type | Staggered blade pairs beam position monitor | |
| Number of blades | 4 | |
| Blade material | Copper / Tungsten | |
| Aperture / blade opening, | Suggested by FMB, | |
| blade thickness / pair offset | dependent on beam specifications at installation position | |
| Cooling | Water cooling | |
| Temperature measurement | Thermocouple K-type close to aperture | |
| Electrical strength | 500 V | |
| Feedthroughs | Triax, miniature TC flat pin (others on customer request) | |
| Base flange | DN 150 CF fixed | |
| Fiducials | 2 / 3 / 4 Hubbs or laser tracker supports at base flange | |
| Pinhole array (optional) | Design according to customer requirements, 0.02 mm min. pinhole diameter dependent on foil thickness |
|
| SPM chamber | ||
| Chamber / flange material | 1.4301 / 1.4429 (similar 304 / 316LN) | |
| Beam entrance /exit flange | DN 40 CF or different on customer request | |
| SPM insert flange | DN 150 CF fixed, oriented with respect to SPM insert | |
| Additional flanges | Optional on customer request | |
| Support | ||
| Column material | Steel (Invar on request) | |
| Fill | Dry sand | |
| Manual chamber alignment | Lateral ± 20 mm, vertical ± 12.5 mm, resolution. (l, v) < 0.1 mm | |
| Alignment via X-Z-stage | Lateral (X) ± 5 mm, vertical (Z) ± 5 mm, | |
| (optional) | repeatability ± 10 µm (± 1 µm with optional encoder) |
