SCIENCE! Part III

MAPO

http://www.astro.caltech.edu/~lgg/keck/keck_front

MAPO, or the Martin A. Pomerantz Observatory, is the first building one encounters upon crossing the skiway. The blue box-like building housing the telescopes Viper (now complete and waiting demolition) and SPUD, used to sit high above the snow surface to avoid drifting issues, but the stilts are now long buried.

SPUD is looking at a similar radiation spectrum as the South Pole 10m telescope (about 2mm wavelength) but at a much larger scale with far less resolution. The project is described in the Science Planning Summary USAP-2011-2012 as:
Small Polimeter Upgrade for DASI (SPUD) is the next generation instrument in the ongoing Background Imaging of Cosmic Extragalactic Polarization (BICEPT/BICEP2) program of experiments. It will place multiple receivers similar to BICEP2 on the telescope mount originally built for the Degree Angular Scale Interferometer (DASI) experiment. SPUD will increase sensitivity over BICEP2 by increasing the number of detectors and in future seasons by also expanding to other frequencies to mitigate possible foreground contamination. The scientific objective is the same as BICEP2 – to attempt to measure B-mode polarization caused by gravity waves spawned in the first tiny fraction of a second after the big bang by the process of “inflation.” Inflation is the favored cosmo-genic model and finding direct “smoking-gun” evidence for it is one of the highest priorities in cosmology today. SPUD will increase sensitivity over BICEP2 by increasing the number of detectors, and, in future seasons, by also expanding to other frequencies to mitigate possible foreground contamination.

The South Pole Telescope as seen through the SPUD telescope

As with the South Pole Telescope this is not an optical telescope. The image to the right is of the South Pole Telescope as seen through SPUD.

The telescope is extremely simple as far as telescopes go; inside each receiver two lenses focus the radiation on the primary sensor. Opaque Teflon and nylon disks, looking a bit like the plastic from a milk jug, help filter out unwanted wavelengths. The sensor is comprised of four silicon chips with extremely thin metal resistors imprinted upon the surface. Very slight changes in temperature from the incoming radiation induce resistance variations, producing a temperature map of the sky, of the Cosmic Microwave Background. Five receivers will be mounted inside the ground shield and can rotate 360 degrees as well as scan vertically. From the station the Ground Shield looks like a giant plywood flower or bowl, but inside it’s lined with mirror-like metal. The purpose is to limit radiation bouncing off the buildings and snow surrounding MAPO.

The SPUD telescope attached to the side of MAPO as seen from ground level

The commemoration plaque by the entrance to MAPO

The view from inside the receiver housing, looking down the ladder to MAPO

The walls inside the receiver housing

One of the new receivers before being mounted inside the housing

The silicone film inside the receiver itself

The door into the shield - the part of the telescope visible to the rest of the station

The receiver housing as seen from the outside - note the station seen just above the edge of the ground shield

The mirror lined ground shield reflecting the mottled cloudy sky

The Station as seen from MAPO

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