Engineering topics

Shafer, Rick

Publications and source records attributed to Shafer, Rick.

4 records

NASA NTRS2002

SAFIRE: Far-Infrared Imaging Spectroscopy with SOFIA

The SOFIA airborne observatory will provide a high spatial resolution, low background telescope for far-infrared astrophysical investigations. Selected as a PI instrument for SOFIA, SAFIRE is an imaging Fabry-Perot spectrograph covering 145 microns-655microns, with spectral resolving power of approx. 1500 (200 kilometers per second). This resolution is well matched to extragalactic emission lines and yields the greatest sensitivity for line detection. SAFIRE will make important scientific contributions to the study of the powering of ULIRGs and AGN, the role of CII cooling in extragalactic star formation, the evolution of matter in the early Universe, and the energetics of the Galactic center. SAFIRE will employ a two-dimensional pop-up bolometer array to provide background limited imaging spectrometry. Superconducting transition edge bolometers and SQUID amplifiers have been developed for these detectors.

Benford, Dominic↗

NASA NTRS2002

Design and Fabrication of a Two-Dimensional Superconducting Bolometer Array

Large format, two dimensional arrays of close-packed bolometers will enable submillimeter cameras and spectrometers to obtain images and spectra orders of magnitude faster than present instruments. The South Pole Imaging Fabry-Perot Interferometer (SPIFI) for the AST/RO observatory and the Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory will employ a large-format, two-dimensional, closepacked bolometer arrays. Both these instruments are imaging Fabry-Perot spectrometers operating at wavelengths between 100 micron and 700 micron. The array format is 16x32 pixels, using a 32-element multiplexer developed in part for this purpose. The low backgrounds achieved in spectroscopy require very sensitive detectors with NEPs of order 5x10(exp 18) W/square root of Hz. Superconducting detectors can be close-packed using the Pop-Up Detector (PUD) format, and SQUID multiplexers operating at the detector bas temperature can be intimately coupled to them. We have fabricated an engineering model array with this technology which features a very compact, modular approach for large format arrays.

Benford, Dominic↗

NASA NTRS2002

Superconducting Bolometer Array Architectures

The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

Benford, Dominic↗

NASA NTRS2002

Design and Fabrication of Two-Dimensional Superconducting Bolometer Array for SAFIRE

The Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory will employ a large-format, two-dimensional, close-packed bolometer array. SAFIRE is an imaging Fabry-Perot spectrometer operating at wavelengths between 100 micron and 700 micron. The array format is 16x32 pixels, using a 32-element multiplexer developed in part for this instrument. The low backgrounds achieved in spectroscopy require very sensitive detectors with NEPs (Noise Equivalent Powers) of order 5x10(exp 18)W/square root of Hz. An architecture which permits 512 pixels to be placed adjacent to each other in an area the size of a postage stamp, integrate them with multiplexers, and provide all the necessary wiring interconnections is a complex proposition, but can be achieved. Superconducting detectors can be close-packed using the Pop-Up Detector (PUD) format, and SQUID multiplexers operating at the detector bas temperature can be intimately coupled to them. The result is a compact array, easily scalable to kilopixel arrays. Engineering results from the first such detector arrays will be presented.

Benford, Dominic↗