Philippe Berger, Laura Newburgh, Mandana Amiri, Kevin Bandura, Jean-François Cliche, Liam Connor, Meiling Deng, Nolan Denman, Matt Dobbs, Mateus Fandino, Adam Gilbert, Deborah Good, Mark Halpern, David Hanna, Adam Hincks, Gary Hinshaw, Carolin Höfer, Andre Johnson, Tom Landecker, Kiyoshi Masui, Juan Mena Parra, Niels Oppermann, Ue-Li Pen, Jeffrey Peterson, Andre Recnik, Timothy Robishaw, J. Richard Shaw, Seth Siegel, Kris Sigurdson, Kendrick Smith, Emilie Storer, Ian Tretyakov, Kwinten Van Gassen, Keith Vanderlinde, Donald Wiebe
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder radio telescope is currently surveying the northern hemisphere between 400 and 800 MHz. By mapping the large scale structure of neutral hydrogen through its redshifted 21 cm line emission between z∼0.8-2.5 CHIME will contribute to our understanding of Dark Energy. Bright astrophysical foregrounds must be separated from the neutral hydrogen signal, a task which requires precise characterization of the polarized telescope beams. Using the DRAO John A. Galt 26 m telescope, we have developed a holography instrument and technique for mapping the CHIME Pathfinder beams. We report the status of the instrument and initial results of this effort.
EBEX is a balloon-borne telescope designed to measure the polarization of the cosmic microwave background radiation. During its eleven day science flight in the Austral Summer of 2012, it operated 955 spider-web transition edge sensor (TES) bolometers separated into bands at 150, 250 and 410 GHz. This is the first time that an array of TES bolometers has been used on a balloon platform to conduct science observations. Polarization sensitivity was provided by a wire grid and continuously rotating half-wave plate. The balloon implementation of the bolometer array and readout electronics presented unique development requirements. Here we present an outline of the readout system, the remote tuning of the bolometers and Superconducting QUantum Interference Device (SQUID) amplifiers, and preliminary current noise of the bolometer array and readout system.
Laura Newburgh, Graeme Addison, Mandana Amiri, Kevin Bandura, J. Richard Bond, Liam Connor, Jean-François Cliche, Greg Davis, Meiling Deng, Nolan Denman, Matt Dobbs, Mateus Fandino, Heather Fong, Kenneth Gibbs, Adam Gilbert, Elizabeth Griffin, Mark Halpern, David Hanna, Adam Hincks, Gary Hinshaw, Carolin Höfer, Peter Klages, Tom Landecker, Kiyoshi Masui, Juan Mena Parra, Ue-Li Pen, Jeff Peterson, Andre Recnik, J. Richard Shaw, Kris Sigurdson, Micheal Sitwell, Graeme Smecher, Rick Smegal, Keith Vanderlinde, Don Wiebe
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral hydrogen in the frequency range 400 { 800MHz over half of the sky, producing a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 { 2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that will yield constraints on the BAO power spectrum and provide a test-bed for our calibration scheme. I will discuss the CHIME calibration requirements and describe instrumentation we are developing to meet these requirements.
Kevin Bandura, Graeme Addison, Mandana Amiri, J. Richard Bond, Duncan Campbell-Wilson, Liam Connor, Jean-François Cliche, Greg Davis, Meiling Deng, Nolan Denman, Matt Dobbs, Mateus Fandino, Kenneth Gibbs, Adam Gilbert, Mark Halpern, David Hanna, Adam Hincks, Gary Hinshaw, Carolin Höfer, Peter Klages, Tom Landecker, Kiyoshi Masui, Juan Mena Parra, Laura Newburgh, Ue-li Pen, Jeffrey Peterson, Andre Recnik, J. Richard Shaw, Kris Sigurdson, Mike Sitwell, Graeme Smecher, Rick Smegal, Keith Vanderlinde, Don Wiebe
A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently being commissioned at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical interferometer designed to measure the large scale neutral hydrogen power spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used to measure the baryon acoustic oscillation (BAO) scale across this poorly probed redshift range where dark energy becomes a significant contributor to the evolution of the Universe. The instrument revives the cylinder design in radio astronomy with a wide field survey as a primary goal. Modern low-noise amplifiers and digital processing remove the necessity for the analog beam forming that characterized previous designs. The Pathfinder consists of two cylinders 37m long by 20m wide oriented north-south for a total collecting area of 1,500 square meters. The cylinders are stationary with no moving parts, and form a transit instrument with an instantaneous field of view of ~100 degrees by 1-2 degrees. Each CHIME Pathfinder cylinder has a feedline with 64 dual polarization feeds placed every ~30 cm which Nyquist sample the north-south sky over much of the frequency band. The signals from each dual-polarization feed are independently amplified, filtered to 400-800 MHz, and directly sampled at 800 MSps using 8 bits. The correlator is an FX design, where the Fourier transform channelization is performed in FPGAs, which are interfaced to a set of GPUs that compute the correlation matrix. The CHIME Pathfinder is a 1/10th scale prototype version of CHIME and is designed to detect the BAO feature and constrain the distance-redshift relation. The lessons learned from its implementation will be used to inform and improve the final CHIME design.
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