Saturday, April 9, 2011

Day 11, 04/09/11 -- The Birth of Cool

We spent a half day in the high bay today getting the cryostat ready to cool with liquid nitrogen. Jeff and I worked on getting electronics boards mounted to the bottom of the cryostat as well as connecting their cables inside the metallic 'can' that sits at the bottom of the cryostat. Kyle meanwhile worked on getting the cryostat housekeeping (temperature sensors, heaters, and current monitors) up and running.

After installing cables and the RF can, we flipped the cryostat upright to begin the cooldown. The liquid nitrogen tank obviously holds liquid nitrogen, but we pre-cool the liquid helium tank with liquid nitrogen as well. Liquid nitrogen has a much higher heat capacity and is much less expensive than liquid helium, so we use LN2 to get us from 300K to 77K first, and then fill with LHe. That process went quite smoothly despite (or perhaps because?) the cryogen vendor gave us high pressure (250 psi!) LN2 tanks instead of the 22psi ones we requested. At any rate, it worked, and Kyle got the housekeeping system up and running after some minor wiring tweaks to account for some changes inside the cryostat.

After leaving the high bay, Kyle headed back to our lodgings while Jeff and I decided to take a bike ride. It turns out that not only is the Palestine area quite pretty as we've noticed since being here, with lots of trees and green fields, but the Texas drivers were surprisingly accommodating of two guys riding skinny-tired bikes on the farm roads and state highways. On the smaller roads, drivers without fail gave us a wide berth, and we were not once honked at from someone behind us (one guy in town coming the opposite way honked at us for some unknown reason...or perhaps he was honking at someone else). Also, Palestine's hills are surprisingly painful for someone (me) who hasn't done any real riding since last October in Minneapolis (which is largely flat). Still, the 14 miles we did today was a good start -- hopefully we'll have a chance to do some longer rides in the future.

The few pictures today were taken with my cell phone, as my DSLR's memory card was left in the apartment. Sorry.

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