In late May a group of us went to the cryo shack to see Al and Charlie fill some liquid helium containers (dewars). The temperature of liquid helium is about 4K (-269°C, -452°F). Some of the astronomers use the liquid helium to cool their detectors, which eliminates noise in their data.



Betty, our doctor, by the plume of liquid air that is venting from the 250 liter dewar that is being filled.



Al, the cryo tech, by the same plume as above.



This and the next two pictures show close ups of the vent. The stuff that looks like ice and flaking white paint is frozen air and the clear drops are liquid air. Nitrogen and oxygen (which make up 98% of air) both become liquids around 75K (-198°C, -325°F), and freeze at some temperature above 4K.





Charlie is transferring the pipe that carries the liquid helium into the 100 liter dewar.


Here is a movie showing the liquid air dripping off the vent. If it doesn't play you may have to download and install Quicktime.


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Page created 3 June 2001, Last updated 3 June 2001 15:16 New Zealand Standard Time.