[time-nuts] OT, looking for a good science forum

[Frank Stellmach]

Hello Chris,

I don*t know a good scientific forum, either. But I would also be 
interested, at least to have some ideas, what to do try out with those 
high precision gadgets, I have collected already ;-)

For the question about low temperature measurements, I recommend sensors 
following a standard curve, which gives about 0.5K accuracy, or 
calibrated ones, which might give 0.1..0.2K for relatively low budget.

Fuddling around with a temperature bath is not necessary, normally.

At university, I have checked  my set of sensors with liquid nitrogen, 
pure liquid oxygen and He(4).
Today, liquid nitrogen might be accessible, where electronic 
manufacturing is done. (The gas is used for reflow process)

I have used PT100 sensors down to pumped liquid nitrogen at 63k, and 
much less.
A good 4 wire Ohm DMM with Offset Compensation is required, or a 
precise, switchable 1mA DC source.

The most versatile sensor was a standard table Si diode, e.g. the DT-470 
from Lake Shore; it works between 1.4K and room temperature, but 
requires a precise 10µA external current source, (easy and inexpensive 
to build on your own) but no offest compensation.

http://www.lakeshore.com/products/Cryogenic-Temperature-Sensors/Silicon-Diodes/Pages/Model-Landing.aspx

1% grade NTCs are fine for temperatures down to -55°C.

Frank