Thursday, December 20, 2012

The Dark Sector

Keck Array at night, credit Keith Vanderlinde
The Dark Sector is a Radio Quiet (or "dark") area of the station kept quiet for radio and submillimeter telescopes.  This is where I have spent most of my working time thus far.  It's about a 3/4 mile walk from the dormitory, but it can be a moderate work-out between the snow, cold, and high altitude.  The path also crosses the runway, which means you can get stuck waiting on a plane at the wrong time of day.  To get a feel for this commute, here's a video that my friend and coworker Martin shot a few years back while in grad school:
The dark sector includes the IceCube facility, the Dark Sector Laboratory (DSL), and the Martin A Pomeritz Observatory (MAPO).  The most imposing structure in the entire base is probably the South Pole Telescope house in a structure attached to DSL:
South Pole Telescope (left) and BICEP-2 (right)
 I've never worked on this, although several friends have and there a plans in the works to upgrade their camera with the detectors that I developed in Grad School.  That large dish is 10m in diameter, which gives them sub-arcminute resolution on the sky.  They've used this telescope to search for distant galaxy clusters and are currently looking for a signature that will constrain the total mass of all the neutrinos.
BICEP-2 camera in the lab with spectrometer on top
By comparison, our telescopes are smaller.  Above is BICEP-2, which is housed in DSL, right next to SPT.  In contrast to SPT, it has no mirrors; It looks like a spy-glass with a couple of lenses and some filters.  Because the lenses are naturally smaller than a 10m mirror, it's resolution is limited to around a half degrees (30 arcmin).  However, these are much cheaper than SPT, which means you can build several and attain much higher sensitivity (lower collective noise). 

And that's exactly what we did- we built five more.  This is the Keck Array (aka SPUD) housed in MAPO and is the project I spend most of my time on.
Keck Array, with two cameras off the mount in the lab
Shoveling snow from the ground shield
 We are currently decommissioning BICEP-2 and pulling the best parts from it for use in an upgrade to one of the Keck cameras.  Perhaps I'll return next year to deploy BICEP-3 in that mount if it gets deployment funds.
BICEP-mount, empty after three years

 Those wooden structures around the telescopes are ground-shields, designed to prevent the telescope from seeing thermal emission from the ground.  SPT has one too, although it is attached to the telescope mount and moves with the instrument.  Here's on old one adjacent to MAPO used for the VIPER telescope in the 90s and by ACBAR in the 2000s.  It has been abandoned for a better part of a decade.
Abandoned Ground Shield

Have a look youself- Google Street Maps has even made it down here: DSL on Google Maps.

And finally, the world's coldest outhouse:

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