Delivery

This last weekend was pretty exciting. We got down to –100F on Saturday afternoon. That is the earliest in the season that the temperature has ever hit that mark, and it looks like we’ll be getting back down there again towards the end of the week. It was actually pretty perfect timing on the part of the weather, since we had a station-wide safety stand-down, which meant we got the afternoon to take a break and think about how to maintain a safe environment. About 15 of us took that to mean we should join the 300 Club. The club has been a tradition since the station has existed with a sauna. The requirements for joining are to take a 200F sauna and then run out to the pole. So we got the sauna heated up (to about 230F actually), then cooked in there for about 20 minutes. Once we were nice and toasty, we stripped down and ran outside in nothing but our boots, and got pictures. The nice thing about taking the sauna is that the cold didn’t really get to you until you were already on your way back in. The second time out, most of just walked, instead of sprinting. 

In the sauna, and on the screen

Other than that, Easter morning came with little baskets of candy in front of each of our doors. Thank you Easter Bunny!

After that I had a helium delivery to make. BICEP2, the telescope, needs a delivery of about 250L of LHe every 6-7 days. We usually plan for every 6 days, so that if the weather is bad (stormy, or cold, like it was Saturday) we can push it off for a day. The BICEP guy, Steffen, heads out to the telescope to get the dewar prepped for pick up, then gives me a call, and I go get Mad Max and the sled. 

Mad Max, the science machine

 Then it is out to the telescope to pick up the dewar, and back to cryo. Once the dewar is inside, Steffen takes Max back to the heavy shop, since it is way too cold to leave it idling outside. Meanwhile, I get things prepped inside, and take some initial measurements, like the weights for Fatman and whichever of the Chipmunks we’re filling from this time.

Weighing Fatman

    Once Steffen gets back, we get the transfer lines hooked up to one of the big dewars and then run it over to Fatman. 

Transfer line to Fatman. If you look close, you can see a small plume of
helium coming out of the end of the stinger.

    After that, it is mainly a matter of waiting and watching, adjusting some of the valves to throttle the flow to the Bouncy Castle and to the compressor. 

The Bouncy Castle, full of helium. It takes about 5 hours
for the compressor to pump it out and into the half-racks in
the background.

    Once Fatman is full, Steffen gets Max again, while I take final measurements and get things ready for the trip back to BICEP.

Riding back to the telescope (straight ahead).

Bringing the dewar alongside BICEP

Bringing the dewar up to the third floor via crane

The past week also saw our first moonrise in the dark. The sun is mostly set at this point; so watching the moon come up was pretty spectacular. By the time it sets again, in about two weeks, it should be full dark. 

Moon rise near the telesopes. The outline of SPT/BICEP2 is
just visible to the left of the moon.