The Submillimeter Array

Receiver Lab Talks

Questions: Edward Tong
Time: Tuesdays 1:00 PM EDT (5:00 PM UTC)
Where: Zoom

Date Speaker Title Summary
June 2Prof. Joseph Bardin
UMass Amherst
An update in SiGe cryogenic LNA research at UMassDuring the past 15 years, SiGe LNAs have emerged as a new option for use in applications in the sub-10 GHz frequency range; however, the performance of commercially available SiGe LNAs still lags that of InP HEMT amplifiers. In this talk, we will review recent progress in reducing the noise and power consumption of cryogenic LNAs. We will describe experimental results, including an amplifier with noise optimized SiGe HBTs. The talk will conclude with a discussion of ongoing research, such as amplifiers with digitally programmable response.
May 19Jonathan Weintroub
Wideband Digital Technology for SMA & wSMA and the EHT and ngEHTAs radio astronomy receiver bandwidth increases, it is necessary to increase the speed of analog-to-digital conversion (ADC) as well as the digital signal processing (DSP) in the telescope's back end. This introductory talk gives an overview of various projects active at SAO in ADC, DSP, fast digital communications, and software based big data processing. These projects service the Submillimeter Array, which is a component of the Event Horizon Telescope (EHT), and also the instrument needs of the EHT more broadly.
May 12Nimesh Patel
The Greenland Telescope: Current Status, Operations and Future PlansThe Greenland Telescope is a 12 m diameter ALMA (North America) Prototype Antenna that is refurbished and deployed at the Thule Air Force Base in northern Greenland. I will present a report on the status of the project and current operations for VLBI observations at 86, 230 and 345 GHz, and briefly describe plans for future developments.
May 5Edward Tong
SIS Mixer -- some basic concepts and historyThis is an introductory talk which touches on some basic concepts of the Superconductor-Insulator-Superconductor (SIS) mixer that is at the heart of the SMA. We will also look at some history of superconductivity and of the SIS mixer. The talk is suitable for those who has used the mixer and wants to know more about some of its basics.
April 28Martina Wiedner
Observatoire de Paris, France
The Origins Space Telescope and its Heterodyne Receiver StudyThe Origins Space Telescope is one of four large satellite studies that has been submitted to the Astro2020 Decadal Review. In this talk I will briefly lay out the science that defined the design of Origins. The satellite and its 5 instruments will be introduced. The HEterodyne Receiver for Origins (HERO) is one of the 5 instruments designed for Origins. I will give an overview of the HERO design and its defining features. HERO is the first heterodyne array receiver designed for a satellite and some of its components still require development. We therefore defined a receiver roadmap, which I will touch upon at the end of the talk.
April 21Jake Connors
NIST, Boulder CO
Towards Photon Counting Kinetic Inductance Detectors for Far-IR SpectroscopyMicrowave kinetic inductance detectors (MKIDs) are a developing bolometric detector technology, whose natural frequency multiplexing allows for simple readout of large highly sensitive arrays. A candidate for use in future far-infrared space based spectrometers, MKIDs are currently about a factor of ~10 behind superconducting transition edge sensors (TES) in terms of raw noise performance. I will describe our work towards developing more sensitive MKIDs, eventually aimed at achieving single-photon counting sensitivities, which could greatly benefit instruments on-board future missions such as the Origins Space Telescope (OST). In addition to novel fabrication processes and device design, I will describe our ultra-low background measurement facility and it's integrated cryogenic blackbody calibrator, which we plan to use in the characterization of our highly sensitive devices.
April 14Scott Paine
Atmospheric radiation in the submillimeter and far-infraredWater vapor plays a dominant role in atmospheric radiative transfer -- a fact keenly felt by ground-based submillimeter and infrared astronomers who struggle to see through it. This talk will review two field campaigns that aimed to improve spectroscopic data for water vapor in the thermal infrared. Along the way we'll touch on the basics of the submillimeter spectrum of the atmosphere, the greenhouse effect, and the use of modern meteorological reanalyses as a tool for interpreting and characterizing the radiative properties of the atmosphere.
April 7Alexander Raymond
EHT Team
EHT SitesThe Event Horizon Telescope is a VLBI array comprised of independent radio observatories like the Submillimeter Array.  There is an active effort to design a next-generation EHT that augments the existing stations with dedicated antennas at new sites around the globe (Blackburn et al., 2019). We will briefly describe our approach to evaluating candidate sites using the atmospheric modeling and radiative transfer code developed by Scott Paine and other tools.

Previous presentations available here: CfA managed Google Drive