Grant Bunker, Director

Beamline Update 4/13/99

Over the last month we have continued to improve the beamline, particularly for XAFS experiments. The last run was abruptly ended (fortunately close to the end anyway) because miscommunication with a user resulted in a liquid nitrogen fill valve not being opened, the MG LN2 cooler ran dry, resulting in overpressure of the high pressure loop, rupture of the LN2 crystal seals, and venting of LN2 into the beamline!

Sounds terrible, doesn''t it? Well, it wasn't. The crystals resealed nicely, we baked out the beamline, and now the vacuum is better than ever. And yes, we built alarms that actually make loud noises when things go awry.

Another bit of news for displex users - we found and fixed a problem with the innards of the displex that impaired its performance. The cooling was slow and the vibrations at the sample were high (we bought the low-vibration model for good reasons!). The problem was a loose heat exchanger. Now the displex cools down to 13K from room temperature in about an hour, and vibration at the sample isn't noticeable. That's progress!

Testing continues on the multilayer analyzer, beam stability (which is now +-25 microns vertical over a scan), and detection systems for XAFS. Improving quality of XAFS data is our prime focus now, in terms of technology development.

We are also working hard to prepare our renewal application for the next five years of operation, and construction of a bend magnet line for diffraction enhanced imaging research, scattering, and XAFS.


Stay tuned! gb