E. F. Lauria

Development of the ALMA Band-3 and Band-6 Sideband-Separating SIS Mixers

As the Atacama Large Millimeter/submillimeter Array (ALMA) nears completion, 73 dual-polarization receivers have been delivered for each of Bands 3 (84-116 GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting Nb/Al-AlOx/Nb tunnel-junction (SIS) mixers, developed for ALMA to suppress atmospheric noise in the image band. The mixers were designed taking into account dynamic range, input return loss, and signal-to-image conversion (which can be significant in SIS mixers). Typical SSB receiver noise temperatures in Bands 3 and 6 are 30 and 60 K, respectively, and the image rejection is typically 15 dB.

Development of the ALMA-North America sideband-separating SIS mixers

As ALMA nears completion, 73 dual-polarization receivers have been delivered for each of Bands 3 (84-116 GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting tunnel-junction (SIS) mixers, developed for ALMA to suppress atmospheric noise in the image band. The mixers were designed taking into account input return loss, dynamic range and signal-to-image conversion (which can degrade the image rejection). Results are given for typical production receivers.

A VLBI receiving system for the South Pole Telescope

The Event Horizon Telescope (EHT) is a very-long-baseline interferometry (VLBI) experiment that aims to observe supermassive black holes with an angular resolution that is comparable to the event horizon scale. The South Pole occupies an important position in the array, greatly increasing its north-south extent and therefore its resolution. The South Pole Telescope (SPT) is a 10-meter diameter, millimeter-wavelength telescope equipped for bolometric observations of the cosmic microwave background. To enable VLBI observations with the SPT we have constructed a coherent signal chain suitable for the South Pole environment. The dual-frequency receiver incorporates state-of-the-art SIS mixers and is installed in the SPT receiver cabin. The VLBI signal chain also includes a recording system and reference frequency generator tied to a hydrogen maser. Here we describe the SPT VLBI system design in detail and present both the lab measurements and on-sky results.

The Arizona radio observatory: A new 12-M telescope and other developments

The Arizona Radio Observatory (ARO) operates two radio telescopes in the millimeter and sub-millimeter wavelength region. Recently, one of these instruemnts, the aging, former NRAO 12 meter telescope on Kitt Peak, was replaced with one of the 12 m ALMA prototype antennas. The high performance design of this new instrument, including its 20 microns surface and sub-arcsecond pointing, will expand observational capabilites at the ARO. New receivers and backends are also in development at ARO. A dual polarization sideband separating SIS mixer covering the 0.7 mm atmospheric windw, ranging from 385 GHz to 500 GHz, has been installed as a facility instrument on the Sub-Millimeter Telescope (SMT) on Mount Graham. A prototype Band 2 receiever, based on HEMT amplifier technology, has been built and tested on the sky. These new additions and other developments will be presented.

New technical and scientific developments at the Arizona Radio Observatory

Astronomical observations in the millimeter and sub-millimeter regions are performed at the two facilities of the Arizona Radio Observatory (ARO). The Sub-Millimeter Telescope (SMT) located on Mount Graham utilizes 3 heterodyne SIS receivers to cover 3 of the 4 atmospheric windows from 210 to 720 GHz and soon a new receiver will cover the remaining window. The 12-Meter telescope located on Kitt Peak use 3 heterodyne SIS receivers to the cover the 2 windows from 68 to 180 GHz. All receivers now employ orthogonal polarization optics and soon 4 will utilize wideband dual channel sideband separating mixer technology. Presented here are new instrumentation developments and recent scientific results from the ARO.