ALBERT

Beschreibung: The development of arrays of infrared bolometers that are suitable for use in the Far Infrared and Submillimeter Telescope (FIRST) mission is reported. The array architecture is based on the silicon nitride micromesh bolometer currently baselined for use in the case of the Planck mission. This architecture allows each pixel to be efficiently coupled to one or both polarizations and to one or more spatial models of radiation. Micromesh structures are currently being developed, coupled with transistor-edge sensors and read out by a SQUID amplifier. If these devices are successful, then the relatively large cooling power available at 300 mK may enable a SQUID-based multiplexer to be integrated on the same wafer as the array, creating a monolithic, fully multiplexed, 2D array with relatively few connections to the sub-Kelvin stage.

Beschreibung: An instrument developed to measure the emissivity of reflective surfaces by comparing the thermal emission of a test sample to that of a reference surface is reported. The instrument can accurately measure the emissivity of mirrors made from lightweight thermally insulating materials such as glass and metallized carbon fiber reinforced plastics. Far infrared measurements at a wavelength of 165 micrometers are reported. The instrument has an absolute accuracy of Delta epsilon = 9 x 10(exp -4) and can reproducibly measure an emissivity of as small as 2 x 10(exp -4) between flat reflective surfaces. The instrument was used to measure mirror samples for balloon-borne and spaceborne experiments. An emissivity of (6.05 +/- 1.24) x 10(exp -3) was measured for gold evaporated on glass, and (6.75 +/- 1.17) x 10(exp -3) for aluminum evaporated on glass.

Beschreibung: We interpret the faint optical counterpart to the mid-infrared southern extension as being due to partial obscuration by the intervening disk of the host galaxy.

Beschreibung: The Millimeter-wave Bolometric Interferometer (MBI) is a proposed ground-based instrument designed for a wide range of cosmological and astrophysical observations including studies of the polarization of the cosmic microwave background (CMB). MBI combines the advantages of two well-developed technologies - interferometers and bolometric detectors. Interferometers have many advantages over .filled-aperture telescopes and are particularly suitable for high resolution imaging. Cooled bolometers are the highest sensitivity detectors at millimeter and sub-millimeter wavelengths. The combination of these two technologies results in an instrument with both high sensitivity and high angular resolution.

Beschreibung: The combination of sensitive direct detectors and a cooled aperture promises orders of magnitude improvement in the sensitivity and survey time for far-infrared and submillimeter spectroscopy compared to existing or planned capabilities. Continuing advances in direct detector technology enable spectroscopy that approaches the background limit available only from space at these wavelengths. Because the spectral confusion limit is significantly lower than the more familiar spatial confusion limit encountered in imaging applications, spectroscopy can be carried out to comparable depth with a significantly smaller aperture. We are developing a novel waveguide-coupled grating spectrometer that disperses radiation into a wide instantaneous bandwidth with moderate resolution (R ~ 1000) in a compact 2-dimensional format. A line survey instrument coupled to a modest cooled single aperture provides an attractive scientific application for spectroscopy with direct detectors. Using a suite of waveguide spectrometers, we can obtain complete coverage over the entire far-infrared and sub-millimeter. This concept requires no moving parts to modulate the optical signal. Such an instrument would be able to conduct a far-infrared line survey 10 6 times faster than planned capabilities, assuming existing detector technology. However, if historical improvements in bolometer sensitivity continue, so that photon-limited sensitivity is obtained, the integration time can be further reduced by 2 to 4 orders of magnitude, depending on wavelength. The line flux sensitivity would be comparable to ALMA, but at shorter wavelengths and with the continuous coverage needed to extract line fluxes for sources at unknown redshifts. For example, this capability would break the current spectroscopic bottleneck in the study of far-infrared galaxies, the recently discovered, rapidly evolving objects abundant at cosmological distances.

Beschreibung: The discovery of galaxies beyond z approximately equal to 1 which emit the bulk of their luminosity at long wavelengths has demonstrated the need for high sensitivity, broadband spectroscopy in the far-IR/submm/mm bands. Because many of these sources are not detectable in the optical, long wavelength spectroscopy is key to measuring their redshifts and ISM conditions. The continuum source list will increase in the next decade with new ground-based instruments (SCUBA2, Bolocam, MAMBO) and the surveys of HSO and SIRTF. Yet the planned spectroscopic capabilities lag behind, primarily due to the difficulty in scaling existing IR spectrograph designs to longer wavelengths. To overcome these limitations, we are developing WaFIRS, a novel concept for long-wavelength spectroscopy which utilizes a parallel-plate waveguide and a curved diffraction grating. WaFIRS provides the large (approximately 60%) instantaneous bandwidth and high throughput of a conventional grating system, but offers a dramatic reduction in volume and mass. WaFIRS requires no space overheads for extra optical elements beyond the diffraction grating itself, and is two-dimensional because the propagation is confined between two parallel plates. Thus several modules could be stacked to multiplex either spatially or in different frequency bands. The size and mass savings provide opportunities for spectroscopy from space-borne observatories which would be impractical with conventional spectrographs. With background-limited detectors and a cooled 3.5 telescope, the line sensitivity would be better than that of ALMA, with instantaneous broad-band coverage. We have built and tested a WaFIRS prototype for 1-1.6 mm, and are currently constructing Z-Spec, a 100 mK model to be used as a ground-based lambda/DELTAlambda approximately equal to 350 submillimeter galaxy redshift machine.

Beschreibung: We present a design for multipixel, multiband submillimeter instrument: SAMBA (Superconducting Antenna coupled, Multi-frequency, Bolometric Array).

Beschreibung: In this study, we fabricated and developed extremely sensitive Si(sub 3)N(sub 4) micromesh spider web bolometers for sub-millimeter astrophysics using microelectromechanical system (MEMS) techniques.

Beschreibung: We discuss the low noise, high thermal stability 0.1K test facility for the Planck HFI bolometers.

Beschreibung: This paper presents a measurement of the angular power spectrum of the Cosmic Microwave Background from l = 75 to l = 1025 (~10' to 5 degrees) from a combined analysis of four 150 GHz channels in the BOOMERANG experiment. The spectrum contains multiple peaks and minima, as predicted by standard adiabatic-inflationary models in which the primordial plasma undergoes acoustic oscillations.