Wiggler beam lines

The final point raised in Section 5 is also repeated. In QEXAFS spectroscopy it is not usual that the scans need to be collected faster, but that the data quality needs to be higher, so that detailed structural information can be derived. This goal will likely be achieved in the future by the improved design of beam line optics, more experiments being performed on undulator or wiggler beam lines, and improvements in detector technology. 

Experience with the television detector system (Enraf-Nonius FAST) on the focussed wiggler beam line at Daresbury using a A of 0.9 A suggests that the intensity of the diffraction patterns is often somewhat too strong for the detector. Use of even shorter wavelengths than 0.9 A will reduce the strength of the pattern whilst giving further reduction in absorption errors and enhanced sample lifetime in the beam, etc, outlined above. 

Fig. 10. Brilliance of the X-rays as a function of photon energy from a bending magnet and from a Wiggler beam line at the Stanford Synchrotron Radiation Laboratory. Notice the difference in the flux between the bending and the Wiggle magnets. [Adapted from A. Bienenstock, Nucl. Instrum. Methods 172, 13 (1980).]...

The high intensity provided by synchrotron radiation emitted from a multi-pole wiggler insertion device was used to advantage to produce a sub-millimeter probe to record diffraction patterns as a function of position in the weld during welding to follow the phases and map their location in the HAZ or the FZ. The measurements were first performed on the 31-pole wiggler beam line, BL 10-2 °... 

Figure 1.8 Example of the spectral flux Ny of the undulator/wiggler radiation measured at the X-Al beam line at NSLS (National Synchrotron Light Source, Brookhaven National Laboratory, LISA) with the undulator parameters K = 1.50, X = 8 cm, N = 35, for a 500 mA beam current, with a 0.1% bandpass and a solid angle of 1 mrad2. The values are corrected for the beamline/monochromator efficiency and the photodiode detector response the dip at 4.4 nm is an artifact due to carbon contamination of the optical elements. From [BRA89], (Reproduced with permission from Review of Scientific Instruments.)...

Fig. 3. Schematic view of a beam line in a synchrotron radiation facility for x-ray absorption experiments using a wiggler as x-ray source and a fluorescence detection system. The incident radiationJlux is measured usually by a ionization chamber. The absorption is measured by the ratio of the x-ray fluorescence I detected by the photomultipliers and...

Wiggler Long beam line (75 m) Topography (possibly second Laue station) Multipole wiggler... 

Figure 5.16 An example of a long, single segment mirror and its bender prior to installation in the beam line on the SRS wiggler (station 9.6). From Helliwell et al (1986b) and reproduced with the permission of Daresbury Laboratory.

An oscillation camera film data collection facility has been established at Stanford. This station (beam line VI1-1) uses 1 mrad of beam from an eight-pole multipole wiggler (Winick and Spencer 1980). The optics consists of a bent Ge(lll) triangular monochromator followed by a bent metal coated mirror. The small number of available mrad of beam is easily compensated by the number of poles in the wiggler. The station has been used extensively. Examples of structures reported using data collected on this station are given in chapter 10. 

The addition of more magnet poles to a wiggler results in a multiplication of the flux generated. One of the first multipole wigglers to be developed was on SPEAR (Winick and Spencer 1980, table 4.1) and had five full poles this was later replaced by a seven full pole device which is detailed in table 4.2. The flux multiplication factor is this number of poles. However, because of the extra magnet length, the source size as viewed off centre line is increased and the intensity enhancement of a focussed beam is somewhat less than the number of poles. 

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