-
Adam L. Woodcraft,
Peter A. R. Ade,
Dan Bintley,
Julian S. House,
Cynthia L. Hunt,
Rashmi V. Sudiwala,
William B. Doriese, William D. Duncan,
Gene C. Hilton,
Kent D. Irwin, [......],
Michael D. Audley,
Maureen A. Ellis,
Wayne S. Holland,
Mike MacIntosh,
Camelia C. Dunare,
William Parkes,
Anthony J. Walton,
Jan B. Kycia,
Mark Halpern,
Eric Schulte
[show abstract]
[hide abstract]
ABSTRACT: SCUBA-2 is a submillimeter camera being built for the James Clerk Maxwell Telescope in Hawaii. Bringing CCD style imaging to the submillimeter for the first time, with over 10 000 pixels, it will provide a revolutionary improvement in sensitivity and mapping speed. We present results of the first tests on a prototype 1280 pixel SCUBA-2 subarray; the full instrument will be made up of eight such subarrays. The array is made up of transition edge sensor (TES) detectors, with Mo/Cu bilayers as the sensing element. To keep the number of wires reasonable, a multiplexed readout is used. Unlike previous TES arrays, an in-focal plane multiplexer configuration is used, in which the multiplexing elements are located beneath each pixel. To achieve the required performance, the detectors are operated at a temperature of approximately 120 mK. We describe the results of a basic electrical and optical characterization of the array, demonstrating that it is fully operational. Noise measurements were made on several pixels and gave a noise equivalent power below 2.5×10−17 W HZ−0.5, within the requirements for SCUBA-2. The construction of the testbed used to carry out these measurements is also described.
Review of Scientific Instruments 02/2007; 78(2):024502-024502-7. · 1.37 Impact Factor
-
Michael D. Audley,
Robert W. Barker,
Michael Crane,
Roger Dace,
Dorota Glowacka,
David J. Goldie,
Anthony N. Lasenby,
Howard M. Stevenson,
Vassilka Tsaneva,
Stafford Withington,
Paul Grimes,
Bradley Johnson,
Ghassan Yassin,
Lucio Piccirillo,
Giampaolo Pisano, William D. Duncan,
Gene C. Hilton,
Kent D. Irwin,
Carl D. Reintsema,
Mark Halpern
[show abstract]
[hide abstract]
ABSTRACT: CLOVER is an experiment which aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of three telescopes operating at 97, 150, and 220 GHz. The 97-GHz telescope has 160 feedhorns in its focal plane while the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a hexagonal array and feed a polarimeter which uses finline-coupled TES bolometers as detectors. To detect the two polarizations the 97-GHz telescope has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each. To achieve the target NEPs (1.5, 2.5, and 4.5x10^-17 W/rtHz) the detectors are cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz polarimeter. Each detector is fabricated as a single chip to ensure a 100% operational focal plane. The detectors are contained in linear modules made of copper which form split-block waveguides. The detector modules contain 16 or 20 detectors each for compatibility with the hexagonal arrays of horns in the telescopes' focal planes. Each detector module contains a time-division SQUID multiplexer to read out the detectors. Further amplification of the multiplexed signals is provided by SQUID series arrays. The first prototype detectors for CLOVER operate with a bath temperature of 230 mK and are used to validate the detector design as well as the polarimeter technology. We describe the design of the CLOVER detectors, detector blocks, and readout, and present preliminary measurements of the prototype detectors performance.
09/2006;
-
Michael D. Audley,
Robert W. Barker,
Michael Crane,
Roger Dace,
Dorota Glowacka,
David J. Goldie,
Anthony N. Lasenby,
Howard M. Stevenson,
Vassilka Tsaneva,
Stafford Withington,
Paul Grimes,
Bradley Johnson,
Ghassan Yassin,
Lucio Piccirillo,
Giampaolo Pisano, William D. Duncan,
Gene C. Hilton,
Kent D. Irwin,
Carl D. Reintsema,
Mark Halpern
[show abstract]
[hide abstract]
ABSTRACT: CLOVER is an experiment which aims to detect the signature of gravitational waves from inflation by measuring the B-mode polarization of the cosmic microwave background. CLOVER consists of three telescopes operating at 97, 150, and 220 GHz. The 97-GHz telescope has 160 horns in its focal plane while the 150 and 220-GHz telescopes have 256 horns each. The horns are arranged in a hexagonal array and feed a polarimeter which uses finline-coupled TES bolometers as detectors. To detect the two polarizations the 97-GHz telescope has 320 detectors while the 150 and 220-GHz telescopes have 512 detectors each. To achieve the required NEPs the detectors are cooled to 100 mK for the 97 and 150-GHz polarimeters and 230 mK for the 220-GHz polarimeter. Each detector is fabricated as a single chip to guarantee fully functioning focal planes. The detectors are contained in linear modules made of copper which form split-block waveguides. The detector modules contain 16 or 20 detectors each for compatibility with the hexagonal arrays of horns in the telescopes' focal planes. Each detector module contains a time-division SQUID multiplexer to read out the detectors. Further amplification of the multiplexed signals is provided by SQUID series arrays. The first prototype detectors for CLOVER operate with a bath temperature of 230 mK and are used to validate the detector design as well as the polarimeter technology. We describe the design of the CLOVER detectors, detector blocks, and readout, and give an update on the detector development. Comment: 9 pages, 7 figures, SPIE Orlando 24-31 May 2006, Conference 6275
07/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: SCUBA-2 is a new wide-field submillimeter camera under construction for the James Clerk Maxwell Telescope on Mauna Kea in Hawaii. SCUBA-2 images simultaneously at 450 and 850 μm using large-scale arrays of superconducting bolometers, with over five thousand pixels at each wavelength. Time division multiplexed readouts and cryogenic amplifiers, both based on superconducting quantum interference devices (SQUIDs), are also used in the design. The SCUBA-2 detector arrays must be well shielded against magnetic fields, since the performance of the bolometers can be seriously affected by the presence of a strong field, and the SQUIDs are themselves sensitive magnetometers. This shielding is to be provided by a combination of high-permeability and superconducting layers on both the ambient temperature and cryogenic stages of the instrument. To optimise and demonstrate the effectiveness of the shielding design, a finite-element modelling method was employed, using the Ansoft(R) Maxwell 3DTM package. Although a number of approximations had to be made in the modelling, the finite-element results allow a good estimation of the effectiveness of the shielding at attenuating external magnetic fields to be made. This paper describes the modelling process, outlines the key results and summarises the final shielding design.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
06/2006;
-
Adam L Woodcraft,
Matthew I Hollister,
Dan Bintley,
Maureen A Ellis,
Xiaofeng Gao,
Wayne S Holland,
Michael J Macintosh,
Peter A R Ade,
Julian S House,
Cynthia L Hunt, [......],
Gene C Hilton,
Kent D Irwin,
Carl D Reintsema,
Camelia C Dunare,
William Parkes,
Anthony J Walton,
Jan B Kycia,
Mandana Amiri,
Bryce Burger,
Mark Halpern
[show abstract]
[hide abstract]
ABSTRACT: We present the results of characterization measurements on a 1280 pixel superconducting bolometer array designed for operation at wavelengths around 450 µm. The array is a prototype for the sub-arrays which will form the focal plane for the SCUBA-2 sub-mm camera, being built for the James Clerk Maxwell Telescope (JCMT) in Hawaii. With over 10 000 pixels in total, it will provide a huge improvement in both sensitivity and mapping speed over existing instruments. The array consists of molybdenum-copper bi-layer TES (transition edge sensor) pixels, bonded to a multiplexer. The detectors operate at a temperature of approximately 175 mK, and require a heat sink at a temperature of approximately 60 mK. In contrast to previous TES arrays, the multiplexing elements are located beneath each pixel (an "in-focal plane" configuration). We present the results of electrical and optical measurements, and show that the optical NEP (noise equivalent power) is less than 1.4 × 10 −16 W Hz −0.5 , and thus within the requirement of 2.9 × 10 −16 W Hz −0.5 .
Proc SPIE 01/2006; 6275.
-
Wayne S. Holland,
E. I. Robson,
Walter K. Gear,
Colin R. Cunningham,
John F. Lightfoot,
Tim Jenness,
Rob J. Ivison,
Jason A. Stevens,
Peter A. R. Ade,
M. J. Griffin, William D. Duncan,
J. A. Murphy,
David A. Naylor
[show abstract]
[hide abstract]
ABSTRACT: SCUBA, the Submillimetre Common-User Bolometer Array, built by the Royal Observatory Edinburgh for the James Clerk Maxwell Telescope, is the most versatile and powerful of a new generation of submillimetre cameras. It combines a sensitive dual-waveband imaging array with a three-band photometer, and is sky-background limited by the emission from the Mauna Kea atmosphere at all observing wavelengths from 350 microns to 2 mm. The increased sensitivity and array size mean that SCUBA maps close to 10,000 times faster than its single-pixel predecessor (UKT14). SCUBA is a facility instrument, open to the world community of users, and is provided with a high level of user support. We give an overview of the instrument, describe the observing modes and user interface, performance figures on the telescope, and present a sample of the exciting new results that have revolutionised submillimetre astronomy. Comment: 15 pages, 15 figures, accepted for Monthly Notices of RAS
Monthly Notices of the Royal Astronomical Society 09/1998; · 4.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Pitch-bonded graphites are among the best-known thermal insulators at sub-Kelvin temperatures. At higher temperatures, however, they are good conductors. Graphite supports can therefore be used to allow a relatively rapid cool down of structures which must be thermally isolated when cold. The low temperature conductivity of graphites varies by many orders of magnitude depending on the manufacturing process. AGOT graphite is known to be a very good insulator, but is no longer commercially available. We suggest a replacement, and present thermal conductivity measurements demonstrating its suitability.
Physica B: Condensed Matter.
