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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Bolometeric detector arrays for CMB polarimetry

We describe the development of antenna coupled bolometers for CMB polarization experiments. The necessary components of a bolometric CMB polarimeter - a beam forming element, a band defining filter, and detectors - are all fabricated on a silicon chip with photolithography.

TES bolometers↗
NASA NTRS2014

The Primordial Inflation Polarization Explorer (PIPER)

The Primordial Inflation Polarization ExploreR (Piper) is a balloon-borne cosmic microwave background (CMB) polarimeter designed to search for evidence of inflation by measuring the large-angular scale CMB polarization signal. Bicep2 recently reported a detection of B-mode power corresponding to the tensor-to-scalar ratio r = 0.2 on approximately 2 degree scales. If the Bicep2 signal is caused by inflationary gravitational waves (IGWs), then there should be a corresponding increase in B-mode power on angular scales larger than 18 degrees. Piper is currently the only suborbital instrument capable of fully testing and extending the Bicep2 results by measuring the B-mode power spectrum on angular scales theta θ = approximately 0.6 deg to 90 deg, covering both the reionization bump and recombination peak, with sensitivity to measure the tensor-to-scalar ratio down to r = 0.007, and four frequency bands to distinguish foregrounds. Piper will accomplish this by mapping 85% of the sky in four frequency bands (200, 270, 350, 600 GHz) over a series of 8 conventional balloon flights from the northern and southern hemispheres. The instrument has background-limited sensitivity provided by fully cryogenic (1.5 K) optics focusing the sky signal onto four 32×40-pixel arrays of time-domain multiplexed Transition-Edge Sensor (TES) bolometers held at 140 milli-Kelvin. Polarization sensitivity and systematic control are provided by front-end Variabledelay Polarization Modulators (VPMs), which rapidly modulate only the polarized sky signal at 3 Hz and allow Piper to instantaneously measure the full Stokes vector (I,Q,U,0V) for each pointing. We describe the Piper instrument and progress towards its first flight.

polarimeter↗
NASA NTRS2013

The Atacama Cosmology Telescope: Beam Measurements and the Microwave Brightness Temperatures of Uranus and Saturn

We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures T(149/U) = 106.7 +/- 2.2 K and T(219/U) = 100.1 +/- 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of T(149/S) = 137.3 +/- 3.2 K and T(219/S) = 137.3 +/- 4.7 K.

Atacama Cosmology Telescope (ACT)↗
NASA NTRS2016

Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers

Advanced ACTPol (AdvACT) is a third-generation cosmic microwave background receiver to be deployed in 2016 on the Atacama Cosmology Telescope (ACT). Spanning five frequency bands from 25 to 280 GHz and having just over 5600 transition-edge sensor (TES) bolometers, this receiver will exhibit increased sensitivity and mapping speed compared to previously fielded ACT instruments. This paper presents the fabrication processes developed by NIST to scale to large arrays of feedhorn-coupled multichroic AlMn-based TES polarimeters on 150-mm diameter wafers. In addition to describing the streamlined fabrication process which enables high yields of densely packed detectors across larger wafers, we report the details of process improvements for sensor (AlMn) and insulator (SiN(sub x)) materials and microwave structures, and the resulting performance improvements.

Atacama Cosmology Telescope(ACT)↗
NASA NTRS2020

Assembly and Integration Process of the High-Density Detector Array Readout Modules for the Simons Observatory

The Simons Observatory will measure the cosmic microwave background tempera-ture and polarization using a suite of new telescopes in the Atacama Desert in Chile. The Simons Observatory will use dichroic transition edge sensor (TES) bolometer arrays spanning six frequency bands from 27 to 280 GHz. The Simons Observa-tory will pioneer the use of a densely packed multiplexing architecture based on the microwave SQUID multiplexer ( 𝜇mux), housing ∼2000 microwave resonators, each coupled to a TES. The Simons Observatory aims to multiplex each array of ∼2000 detectors with a single pair of coaxial cables and requires a multiplexing factor of ∼1000 . The Simons Observatory cryogenic readout system is called the universal microwave multiplexing module (UMM). The UMM couples to both horn and lenslet-coupled detector arrays and is integrated into the universal focal-plane module (UFM) after being independently characterized. We present processes we have developed for highly repeatable and automated integration methods of UMMs, which will be needed for the production of the 49 UFMs required for the first stage of the Simons Observatory.

CMB↗
NASA NTRS1971

Solar radio emission at 1.2 mm wavelength.

A 36-ft radio telescope was used in the investigations. The 1.2 mm wavelength receiver connected to the telescope is a helium-cooled germanium bolometer. The 1.2 mm solar maps were obtained by scanning the sun in right ascension at the rate of 1 deg per minute. A temperature of 6000 K was assumed for the 1.2 mm quiet sun temperature for all solar maps. Eight maps at 1.2 mm were obtained on six different days. The 1.2 mm regions are rather large and without much structure; they are closely associated with Ca-plage regions.

Kundu, M. R.↗
NASA NTRS1972

Measurements of the energy exchange between earth and space from satellites during the 1960's

The net radiation budget of the earth-atmosphere system can be obtained from satellite measurements of the infrared radiant emittance and reflected and scattered solar radiation along with a knowledge of the solar constant. During the 1960's experimental and operational meteorological satellites carrying thermistor bolometer sensors were in orbit for about 60 months. Results from these measurements are given including: a global planetary albedo of 30%, long-term global radiation balance within measurement accuracy (2-3%), the net equator-to-pole radiation gradients that drive our atmospheric and oceanic circulations, as well as selected measurements of radiation budget terms over particular geographical areas.

Vonderhaar, T. H.↗
NASA NTRS1972

Far-infrared brightness temperatures of the planets.

An airborne telescope operating in an altitude range from 45,000 to 50,000 feet together with a low-temperature germanium bolometer and six cooled filters were used in an investigation of the temperatures of the planets. The measurements conducted provide a basis for absolute calibration in the far infrared, confirm the high effective temperature and internal power of Jupiter, and give information on the far-infrared opacities and emissivities of the four bright planets.

Armstrong, K. R.↗
NASA NTRS1974

Research on infrared astrophysics and X ray and XUV astronomy

The infrared research was divided into two related subjects, observations at wavelengths less than 34 microns and millimeter wavelength observations. A new complex of infrared sources in the Orion Nebula observed along with a broad range of galactic and extragalactic objects. The Comet Kohoutek was measured in the 1-20 micron wavelength region and its thermal properties agreed closely with those of Comet Ikeya-Seki. Combined infrared and photoelectric studies of the Makarian galaxies showed them to have a composite spectrum with a large emission feature in the far infrared. The development of one millimeter photometry and composited bolometers is described. A technique of reconstructing two dimensional surface brightness distributions with appropriate errors from individual strip scans was developed. Model parameters were determined by fitting data in non-linear systems. Results show spectral parameter uncertainties are underestimated or incorrectly evaluated in most studies.

Source record↗
NASA NTRS1973

Observation of the J = 2 to J = 1 transition of interstellar CO at 1.3 millimeters

The NRAO 36-foot antenna at Kitt Peak with a novel type of millimeter-wave superheterodyne receiver was used in observations of 1.3-mm line interstellar radiation due to J ? 2-1 transitions of C(12)0(16) and C(13)0(16). The liquid-helium-cooled hot-electron bolometer mixer of the superheterodyne receiver was used as the detecting element. The Orion Nebula CO system was found to be thermalized, showing a peak excitation temperature of about 76 K.

Phillips, T. G.↗
NASA NTRS1974

Sky survey at far infrared wavelengths using a balloon-borne telescope

Localized sources of far infrared radiation (approximately 50 microns) have been detected during a high altitude balloon flight with a 40 cm telescope and silicon detectors. The flight system is described and preliminary results are presented. A large area of the sky has been scanned for localized sources of far infrared radiation, using a balloon-borne system that was sensitive to wavelengths beyond about 55 microns. Two Molectron silicon bolometers were used, with a Newtonian telescope having a 40 cm primary. The telescope was driven in azimuth at a fixed elevation; this mode of scanning was carried out for the duration of each of two balloon flights. The flight system is described.

Friedlander, M. W.↗
NASA NTRS1975

Astronomy at sub-millimeter wavelengths

The first flight test of a gondola containing a Newtonian telescope with a 16 in. primary mirror is described. Bolometer tests were conducted along with gondola design studies, and changes were made in the mechanical system as a result. Parts of the system were rebuilt and tested, and it was found that the flight system had redundant data recording capabilities. In the total flight record, about 160 large signals were noted; about half of these appeared to have the correct shape for genuine signals, and the other were clearly noise spikes (they were large but the signal shape could not have been produced by the observation of a celestial object).

Friedlander, M. W.↗