The Gang's All Here!


(Photo credit: John Kovac with Adrian's camera. Click here for a higher-res version.)

For a brief couple of weeks, we have assembled the entire SPT 2006-2007 South Pole Science team --- i.e., every scientist on the SPT project that's coming down this year. As you can see, we're quite a crew:

Lying down: Steve Padin

Kneeling (left to right): Tom Crawford, Kathryn Miknaitis, Tom Plagge, Matt Dobbs, Ryan Keisler

Standing, 1st row (left to right): Ken Aird, Zak Staniszewski, John Carlstrom, Joaquin Vieira, Martin Lueker, Erik Leitch, Jeff McMahon, Adrian Lee

Standing, back row (left to right): Clem Pryke, Steve Meyer, Brad Benson, Bill Holzapfel

Looming, background: The SPT

The Receiver Has Arrived.

The final (and possibly most complex) piece of the great puzzle that is the South Pole Telescope has arrived: The receiver. This is the end of the line for the light gathered by the telescope. Those ancient photons will end their existence being absorbed as heat onto the web of one of the ~1000 ultra-cold (1/2 degree above absolute zero) detectors, sensed as tiny temperature fluctuations by the tiny superconducting thermometer attached to the detector's web, and read out by the SQUID (superconducting quantum interference device) current meter / amplifier coupled to the detector. Computer records of these tiny temperature fluctuations will allow us to reconstruct the small-scale brightness pattern of the Cosmic Microwave Background (CMB) with unprecedented sensitivity, eventually enabling us (we hope) to measure the abundance of distant galaxy clusters through the distortion they imprint on the CMB and use this measurement to constrain properties of Dark Energy.

So we're pretty excited to have the receiver here. And already together and about to undergo some pre-installments tests. Amazing as it may sound (at least, it sounds amazing to me), the crew of newly arrived SPT scientists working on the receiver managed to unpack the receiver, open it down to its guts, install the detectors, close the receiver back up, and get it on the vacuum pump and cooling down within about 48 hours of its (and their) arrival.

(Speaking of which, we should note that we are now about a three times larger group of scientists than we were a few short days ago. Just arrived are: the receiver team of Bill Holzapfel, Adrian Lee, Brad Benson, Martin Lueker, and Tom Plagge (all from UC Berkeley) and Zak Staniszewski (from Case Western); Steve Meyer from Chicago (providing yet more receiver-type expertise and general wisdom); and software mavens Ken Aird and Kathryn Miknaitis from Chicago and Erik Leitch from JPL.)

Assuming that the receiver tests go well, we will be in position to couple it to the cryostat that contains the secondary mirror (which has also arrived at Pole but has not been unpacked and installed yet). And if that goes well, then it's onto the telescope with both of them, and we're off.

That's getting a bit ahead of things, but it's easy to get carried away when things are this exciting. For now, here are some pictures of the receiver and its contents.
(Thanks to Ryan for the pix.)

Adrian Lee working on the receiver focal plane (six wedges of 160 detectors each).


The fully assembled receiver on the pump and cooling down.

The Reflector Is Up.

As promised, the reflector has been placed on the telescope. This is one of the major milestones on the path to first light. It was a complicated two-crane lift (three if you count the one carrying people up to bolt the reflector down), and it was managed beautifully by Raytheon's Eric Nichols and Bill Johnson. As you can see from the mini-gallery below, it went off without a hitch, and we now have a darned impressive looking telescope --- just some testing and a camera away from mapping the sky.

The lift begins.


Docking the flying saucer.


Steve P., Joaquin, and Tim Hughes prepare to enter the belly of the beast (to attach the reflector center hub to the telescope).


As Bill Johnson and Aaron Thompson look on, the last of Steve disappears into the maw.


Ryan, Jeff, and I look on as the crane gently lowers the reflector into just the right place. (Photo credit: Jerry Marty)


The reflector in place, Eric Nichols and Brian Hardin fasten up the bolts that Bill and Aaron can't reach.


The telescope, facing the horizon (grid south), seen from the roof of DSL.


The telescope, facing the horizon (grid east), seen from the roof of DSL.

Tomorrow, we look like a telescope.

Sorry about the long delay between posts. The Christmas and New Year's holidays have taken up most of our free time, but there has been lots of work going on as well. The most exciting news is that after our first round of photogrammetry, analysis by Jeff, and tweaking of the mirror panel positions, the surface of the mirror looks to be within a tenth of a millimeter of bang on, and the path looks clear to getting it significantly better than that. Since then, the mirror has been lifted off the large invar cone that will attach it to the telescope, and the invar cone itself has been lifted and attached to the telescope. And tonight, when the mirror and back-up structure get lifted and attached, we'll have a telescope that looks darn near complete.

Then comes the minor detail of something at the telescope focus to detect the incoming light. Two cryostats and 10 scientists show up later in the week to start that process. Stay tuned.