humudity sensors - visit at MBW Elektronik AG in nearby Wettingen/AG

[Claude Petitjean <claude.petitjean@psi.ch>]

Dear Peter,

following your suggestion, I visited today the firm MBW Elektronik AG in
Wettingen who offers calibrated chilled mirror devices for humidity
measurements, see e.g. http://www.mbw.ch/products/373/index.html .
I spoke with the manager (Daniel Mutter) and one of his specialists
(Mr. Padiath) and explained him our problems and interests.

Mr. Mutter realized of course very quickly, that what we want (a calibrated
15 ppb H2O measurement before and during our next run) is on the very
limit of technical possibilities. He proposes, that we do next year 
first a test
with his device 373, which is absolutely calibrated at -90 C, and see if
we can get things operational on this level. He could prepare such a device
within a month notice. (-90 C is of course not the limit of operation, 
but the
absolute calibration point.)

Conc. the absolute calibrations, MBW is closely collaborating with PTB
Braunschweig (PTB = Physikalisch Technische Bundesanstalt in Braunschweig,
Germany) who seems to have a leading group in this field. If our test is
successful, and if Mr. Mutter succeeds to raise the scientific interest 
of the
PTB people, we can then discuss about getting even better systems to be
brought to our site for the final measurements.

The ultimate system as I understood, would be to use laser beams crossing
many times the gas and measuring the absorption of H2O spectral lines.

In conclusion, we would need to plan a test with such a 373 device much
ahead of our final run, e.g. in spring 2007. Perhaps this test could be
combined with other needs, e.g. analyzing our gas for residual deuterium.
Definitively, MBW is quite interested in our plans, since it goes to the
technical limits.

Now I'm looking foreward to your reactions to all this!

With best regards

Claude