LN loss from Germanium Detectors -Reply

[FRAMEP@ORAU.GOV]

Gary Kramer wrote:

>I want to measure the rate of loss of LN from the Dewars attached to
>our Germanium detectors by looking at the gas flow from the vent
>tube of the dewar.
>Does anyone know of a source for sensitive gas flow meters? 

Gary:

Have you tried to make one? Maybe a soap bubble inside a volumetric
pipette connected to the tube, or a liquid displacement method. Of
course, the drop in weight of the dewar per unit time could be used
to measure the loss.

For what its worth, we never worry about how much nitrogen is in our
dewars. We fill them up every Monday/Tuesday. We prefer to follow
methods that don't require thinking.

Does anyone out there vent their nitrogen into the shield? I have
heard it reduces the background a little bit by displacing air, and
hence, radon. Never bothered to find out though.

Paul Frame
Professional Training Programs
Oak Ridge Associated Universities
framep@orau.gov