21 research outputs found
A waveguide-coupled thermally-isolated radiometric source
The design and validation of a dual polarization source for waveguide-coupled
millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal
source is a waveguide mounted absorbing conical dielectric taper. The absorber
is thermally isolated with a kinematic suspension that allows the guide to be
heat sunk to the lowest bath temperature of the cryogenic system. This approach
enables the thermal emission from the metallic waveguide walls to be
subdominant to that from the source. The use of low thermal conductivity Kevlar
threads for the kinematic mount effectively decouples the absorber from the
sensor cold stage. Hence, the absorber can be heated to significantly higher
temperatures than the sensor with negligible conductive loading. The kinematic
suspension provides high mechanical repeatability and reliability with thermal
cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over
the full waveguide band where the dominant deviation from unity arrises from
the waveguide ohmic loss. The observed thermal time constant of the source is
40 s when the absorber temperature is 15 K. The specific heat of the lossy
dielectric MF-117 is well approximated by C_v(T)=0.12\,T\,^{2.06} mJ g
K between 3.5 K and 15 K
A Truncated Waveguide Phase Shifter
The design, fabrication and performance of a simple phase shifter based upon truncated circular and square waveguides is presented. An emphasis is placed upon validation of simple analytical formulae that describe the propagation properties of the structure. A test device is prototyped at approximately 40GHz; however, the concepts explored can be directly extended to millimeter and submillimeter applications
Design requirements for the Wide-field Infrared Transient Explorer (WINTER)
The Wide-field Infrared Transient Explorer (WINTER) is a 1x1 degree infrared survey telescope under devel- opment at MIT and Caltech, and slated for commissioning at Palomar Observatory in 2021. WINTER is a seeing-limited infrared time-domain survey and has two main science goals: (1) the discovery of IR kilonovae and r-process materials from binary neutron star mergers and (2) the study of general IR transients, including supernovae, tidal disruption events, and transiting exoplanets around low mass stars. We plan to meet these science goals with technologies that are relatively new to astrophysical research: hybridized InGaAs sensors as an alternative to traditional, but expensive, HgCdTe arrays and an IR-optimized 1-meter COTS telescope. To mitigate risk, optimize development efforts, and ensure that WINTER meets its science objectives, we use model-based systems engineering (MBSE) techniques commonly featured in aerospace engineering projects. Even as ground-based instrumentation projects grow in complexity, they do not often have the budget for a full-time systems engineer. We present one example of systems engineering for the ground-based WINTER project, featuring software tools that allow students or staff to learn the fundamentals of MBSE and capture the results in a formalized software interface. We focus on the top-level science requirements with a detailed example of how the goal of detecting kilonovae flows down to WINTER’s optical design. In particular, we discuss new methods for tolerance simulations, eliminating stray light, and maximizing image quality of a fly’s-eye design that slices the telescope’s focus onto 6 non-buttable, IR detectors. We also include a discussion of safety constraints for a robotic telescope
An open source, FPGA-based LeKID readout for BLAST-TNG: Pre-flight results
We present a highly frequency multiplexed readout for large-format superconducting detector arrays intended for use in the next generation of balloon-borne and space-based sub-millimeter and far-infrared missions. We will demonstrate this technology on the upcoming NASA Next Generation Balloon-borne Large Aperture Sub-millimeter Telescope (BLAST-TNG) to measure the polarized emission of Galactic dust at wavelengths of 250, 350 and 500 microns. The BLAST-TNG receiver incorporates the first arrays of Lumped Element Kinetic Inductance Detectors (LeKID) along with the first microwave multiplexing readout electronics to fly in a space-like environment and will significantly advance the TRL for these technologies. After the flight of BLAST-TNG, we will continue to improve the performance of the detectors and readout electronics for the next generation of balloon-borne instruments and for use in a future FIR Surveyor.
Read More: http://www.worldscientific.com/doi/abs/10.1142/S225117171641003
The Balloon-Borne Large Aperture Submillimeter Telescope Observatory
The BLAST Observatory is a proposed superpressure balloon-borne polarimeter
designed for a future ultra-long duration balloon campaign from Wanaka, New
Zealand. To maximize scientific output while staying within the stringent
superpressure weight envelope, BLAST will feature new 1.8m off-axis optical
system contained within a lightweight monocoque structure gondola. The payload
will incorporate a 300L He cryogenic receiver which will cool 8,274
microwave kinetic inductance detectors (MKIDs) to 100mK through the use of an
adiabatic demagnetization refrigerator (ADR) in combination with a He
sorption refrigerator all backed by a liquid helium pumped pot operating at 2K.
The detector readout utilizes a new Xilinx RFSOC-based system which will run
the next-generation of the BLAST-TNG KIDPy software. With this instrument we
aim to answer outstanding questions about dust dynamics as well as provide
community access to the polarized submillimeter sky made possible by
high-altitude observing unrestricted by atmospheric transmission. The BLAST
Observatory is designed for a minimum 31-day flight of which 70 will be
dedicated to observations for BLAST scientific goals and the remaining 30
will be open to proposals from the wider astronomical community through a
shared-risk proposals program.Comment: Presented at SPIE Ground-based and Airborne Telescopes VIII, December
13-18, 202
Building the Next-Generation BLAST Experiment
Maps of the polarized thermal emission from dust in our galaxy hold the keys to unlock multiple astrophysical and cosmological questions. For measurements of the polarized cosmic microwave background (CMB), this dust emission is the dominant foreground. Subtracting this dust signal from the data is a critical step in the search for the weak primordial signatures of cosmic inflation. Mapping the magnetic field morphology of galactic dust can also shed light on the evolution of the giant molecular clouds which are the hotbeds of star formation in the galaxy. The Next Generation Balloon-Borne Large Aperture Submillimeter Telescope (BLAST-TNG) is a submillimeter mapping experiment which features three microwave kinetic inductance detector (MKID) arrays operating over 30% bandwidths centered at 250, 350, and 500 µm. These highly- multiplexed, high-sensitivity arrays, featuring 918, 469, and 272 dual-polarization pixels, are coupled to a 2.5 m diameter primary mirror and a cryogenic optical system providing diffraction-limited resolution of 30 , 41 , and 50 respectively. The arrays are cooled to ~275 mK in a liquid-helium-cooled cryogenic receiver which will enable observations over the course of a 28-day stratospheric balloon flight from McMurdo Station in Antarctica as part of NASA’s long-duration-balloon program, planned for the 2018/2019 winter campaign
An Infrared Search for Kilonovae with the WINTER Telescope. I. Binary Neutron Star Mergers
19 pages, 11 figures, submitted to ApJInternational audienceThe Wide-Field Infrared Transient Explorer (WINTER) is a new 1 seeing-limited time-domain survey instrument designed for dedicated near-infrared follow-up of kilonovae from binary neutron star (BNS) and neutron star-black hole mergers. WINTER will observe in the near-infrared Y, J, and short-H bands (0.9-1.7 microns, to magnitudes) on a dedicated 1-meter telescope at Palomar Observatory. To date, most prompt kilonova follow-up has been in optical wavelengths; however, near-infrared emission fades slower and depends less on geometry and viewing angle than optical emission. We present an end-to-end simulation of a follow-up campaign during the fourth observing run (O4) of the LIGO, Virgo, and KAGRA interferometers, including simulating 625 BNS mergers, their detection in gravitational waves, low-latency and full parameter estimation skymaps, and a suite of kilonova lightcurves from two different model grids. We predict up to five new kilonovae independently discovered by WINTER during O4, given a realistic BNS merger rate. Using a larger grid of kilonova parameters, we find that kilonova emission is 2 times longer lived and red kilonovae are detected 1.5 times further in the infrared than the optical. For 90% localization areas smaller than 150 (450) , WINTER will be sensitive to more than 10% of the kilonova model grid out to 350 (200) Mpc. We develop a generalized toolkit to create an optimal BNS follow-up strategy with any electromagnetic telescope and present WINTER's observing strategy with this framework. This toolkit, all simulated gravitational-wave events, and skymaps are made available for use by the community
Design requirements for the Wide-field Infrared Transient Explorer (WINTER)
The Wide-field Infrared Transient Explorer (WINTER) is a 1x1 degree infrared
survey telescope under development at MIT and Caltech, and slated for
commissioning at Palomar Observatory in 2021. WINTER is a seeing-limited
infrared time-domain survey and has two main science goals: (1) the discovery
of IR kilonovae and r-process materials from binary neutron star mergers and
(2) the study of general IR transients, including supernovae, tidal disruption
events, and transiting exoplanets around low mass stars.
We plan to meet these science goals with technologies that are relatively new
to astrophysical research: hybridized InGaAs sensors as an alternative to
traditional, but expensive, HgCdTe arrays and an IR-optimized 1-meter COTS
telescope. To mitigate risk, optimize development efforts, and ensure that
WINTER meets its science objectives, we use model-based systems engineering
(MBSE) techniques commonly featured in aerospace engineering projects. Even as
ground-based instrumentation projects grow in complexity, they do not often
have the budget for a full-time systems engineer. We present one example of
systems engineering for the ground-based WINTER project, featuring software
tools that allow students or staff to learn the fundamentals of MBSE and
capture the results in a formalized software interface. We focus on the
top-level science requirements with a detailed example of how the goal of
detecting kilonovae flows down to WINTER's optical design. In particular, we
discuss new methods for tolerance simulations, eliminating stray light, and
maximizing image quality of a fly's-eye design that slices the telescope's
focus onto 6 non-buttable, IR detectors. We also include a discussion of safety
constraints for a robotic telescope