Vector magnetic field observations with the Haleakala polarimeter

NASA Technical Reports Server (NTRS)

Mickey, D. L.

1985-01-01

Several enhancements were recently made to the Haleakala polarimeter. Linear array detectors provide simultaneous resolution over a 3-A wavelength range, with spectral resolution of 40 mA. Optical fibers are now used to carry the intensity-modulated light from the rotating quarter-wave plate polarimeter to the echelle spectrometer, permitting its removal from the spar to a more stable environment. These changes, together with improved quarter-wave plates, reduced systematic errors to a few parts in 10,000 for routine observations. Examples of Stokes profiles and derived magnetic field maps are presented.

Terrace retro-reflector array for poloidal polarimeter on ITER.

PubMed

Imazawa, R; Kawano, Y; Ono, T; Kusama, Y

2011-02-01

A new concept of a terrace retro-reflector array (TERRA) as part of the poloidal polarimeter for ITER is proposed in this paper. TERRA reflects a laser light even from a high incident angle in the direction of the incident-light path, while a conventional retro-reflector array cannot. Besides, TERRA can be installed in a smaller space than a corner-cube retro-reflector. In an optical sense, TERRA is equivalent to a Littrow grating, the blaze angle of which varies, depending on the incident angle. The reflected light generates a bright and dark fringe, and the bright fringe is required to travel along the incident-light path to achieve the objects of laser-aided diagnostics. In order to investigate the propagation properties of laser light reflected by TERRA, we have developed a new diffraction formula. Conditions for the propagation of the bright fringe in the direction of the incident light have been obtained using the Littrow grating model and have been confirmed in a simulation applying the new diffraction formula. Finally, we have designed laser transmission optics using TERRA for the ITER poloidal polarimeter and have calculated the light propagation of the system. The optical design obtains a high transmission efficiency, with 88.6% of the incident power returned. These results demonstrate the feasibility of applying TERRA to the ITER poloidal polarimeter.

Total elimination of sampling errors in polarization imagery obtained with integrated microgrid polarimeters.

PubMed

Tyo, J Scott; LaCasse, Charles F; Ratliff, Bradley M

2009-10-15

Microgrid polarimeters operate by integrating a focal plane array with an array of micropolarizers. The Stokes parameters are estimated by comparing polarization measurements from pixels in a neighborhood around the point of interest. The main drawback is that the measurements used to estimate the Stokes vector are made at different locations, leading to a false polarization signature owing to instantaneous field-of-view (IFOV) errors. We demonstrate for the first time, to our knowledge, that spatially band limited polarization images can be ideally reconstructed with no IFOV error by using a linear system framework.

Development of real-time rotating waveplate Stokes polarimeter using multi-order retardation for ITER poloidal polarimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imazawa, R., E-mail: imazawa.ryota@jaea.go.jp; Kawano, Y.; Ono, T.

The rotating waveplate Stokes polarimeter was developed for ITER (International Thermonuclear Experimental Reactor) poloidal polarimeter. The generalized model of the rotating waveplate Stokes polarimeter and the algorithm suitable for real-time field-programmable gate array (FPGA) processing were proposed. Since the generalized model takes into account each component associated with the rotation of the waveplate, the Stokes parameters can be accurately measured even in unideal condition such as non-uniformity of the waveplate retardation. Experiments using a He-Ne laser showed that the maximum error and the precision of the Stokes parameter were 3.5% and 1.2%, respectively. The rotation speed of waveplate was 20 000more » rpm and time resolution of measuring the Stokes parameter was 3.3 ms. Software emulation showed that the real-time measurement of the Stokes parameter with time resolution of less than 10 ms is possible by using several FPGA boards. Evaluation of measurement capability using a far-infrared laser which ITER poloidal polarimeter will use concluded that measurement error will be reduced by a factor of nine.« less

Development of real-time rotating waveplate Stokes polarimeter using multi-order retardation for ITER poloidal polarimeter.

PubMed

Imazawa, R; Kawano, Y; Ono, T; Itami, K

2016-01-01

The rotating waveplate Stokes polarimeter was developed for ITER (International Thermonuclear Experimental Reactor) poloidal polarimeter. The generalized model of the rotating waveplate Stokes polarimeter and the algorithm suitable for real-time field-programmable gate array (FPGA) processing were proposed. Since the generalized model takes into account each component associated with the rotation of the waveplate, the Stokes parameters can be accurately measured even in unideal condition such as non-uniformity of the waveplate retardation. Experiments using a He-Ne laser showed that the maximum error and the precision of the Stokes parameter were 3.5% and 1.2%, respectively. The rotation speed of waveplate was 20 000 rpm and time resolution of measuring the Stokes parameter was 3.3 ms. Software emulation showed that the real-time measurement of the Stokes parameter with time resolution of less than 10 ms is possible by using several FPGA boards. Evaluation of measurement capability using a far-infrared laser which ITER poloidal polarimeter will use concluded that measurement error will be reduced by a factor of nine.

Faint Submillimeter Galaxies Behind Lensing Clusters

NASA Astrophysics Data System (ADS)

Hsu, Li-Yen; Lauchlan Cowie, Lennox; Barger, Amy J.; Desai, Vandana; Murphy, Eric J.

2017-01-01

Faint submillimeter galaxies are the major contributors to the submillimeter extragalactic background light and hence the dominant star-forming population in the dusty universe. Determining how much these galaxies overlap the optically selected samples is critical to fully account for the cosmic star formation history. Observations of massive cluster fields are the best way to explore this faint submillimeter population, thanks to gravitational lensing effects. We have been undertaking a lensing cluster survey with the SCUBA-2 camera on the James Clerk Maxwell Telescope to map nine galaxy clusters, including the northern five clusters in the HST Frontier Fields program. We have also been using the Submillimeter Array and the Very Large Array to determine the accurate positions of our detected sources. Our observations have discovered high-redshift dusty galaxies with far-infrared luminosities similar to that of the Milky Way or luminous infrared galaxies. Some of these galaxies are still undetected in deep optical and near-infrared images. These results suggest that a substantial amount of star formation in even the faint submillimeter population may be hidden from rest-frame optical surveys.

Parallel, Real-Time and Pipeline Data Reduction for the ROVER Sub-mm Heterodyne Polarimeter on the JCMT with ACSIS and ORAC-DR

NASA Astrophysics Data System (ADS)

Leech, J.; Dewitt, S.; Jenness, T.; Greaves, J.; Lightfoot, J. F.

2005-12-01

ROVER is a rotating waveplate polarimeter for use with (sub)mm heterodyne instruments, particularly the 16 element focal plane Heterodyne Array Receiver HARP tep{Smit2003} due for commissioning on the JCMT in 2004. The ROVER/HARP back-end will be a digital auto-correlation spectrometer, known as ACSIS, designed specifically for the demanding data volumes from the HARP array receiver. ACSIS is being developed by DRAO, Penticton and UKATC. This paper will describe the data reduction of ROVER polarimetry data both in real-time by ACSIS-DR, and through the ORAC-DR data reduction pipeline.

The Inauguration of the Atacama Large Millimeter/submillimeter Array

NASA Astrophysics Data System (ADS)

Testi, L.; Walsh, J.

2013-06-01

On 13 March 2013 the official inauguration of the Atacama Large Millimeter/submillimeter Array (ALMA) took place at the Operations Support Facility in northern Chile. A report of the event and the preceding press conference is presented and the texts of the speeches by the President of Chile, Sebastián Piñera, and the Director General of ESO, Tim de Zeeuw, are included.

The First Multichroic Polarimeter Array on the Atacama Cosmology Telescope: Characterization and Performance

NASA Technical Reports Server (NTRS)

Ho, S. P.; Pappas, C. G.; Austermann, J.; Beall, J. A.; Becker, D.; Choi, S. K.; Datta, R.; Duff, S. M.; Gallardo, P. A.; Grace, E.;

The First Multichroic Polarimeter Array on the Atacama Cosmology Telescope: Characterization and Performance

NASA Astrophysics Data System (ADS)

Ho, S. P.; Pappas, C. G.; Austermann, J.; Beall, J. A.; Becker, D.; Choi, S. K.; Datta, R.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Hasselfield, M.; Henderson, S. W.; Hilton, G. C.; Hubmayr, J.; Koopman, B. J.; Lanen, J. V.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Niraula, P.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Ward, J. T.; Wollack, E. J.; Vavagiakis, E. M.

2016-08-01

The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive receiver for the 6-m Atacama Cosmology Telescope (ACT) and measures the small angular scale polarization anisotropies in the cosmic microwave background (CMB). The full focal plane is composed of three detector arrays, containing over 3000 transition edge sensors (TES detectors) in total. The first two detector arrays, observing at 146 GHz, were deployed in 2013 and 2014, respectively. The third and final array is composed of multichroic pixels sensitive to both 90 and 146 GHz and saw first light in February 2015. Fabricated at NIST, this dichroic array consists of 255 pixels, with a total of 1020 polarization sensitive bolometers and is coupled to the telescope with a monolithic array of broad-band silicon feedhorns. The detectors are read out using time-division SQUID multiplexing and cooled by a dilution refrigerator at 110 mK. We present an overview of the assembly and characterization of this multichroic array in the lab, and the initial detector performance in Chile. The detector array has a TES detector electrical yield of 85 %, a total array sensitivity of less than 10 \\upmu K√{ {s}}, and detector time constants and saturation powers suitable for ACT CMB observations.

MESAS: Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter Wavelengths

NASA Astrophysics Data System (ADS)

White, Jacob Aaron; Aufdenberg, Jason; Boley, A. C.; Hauschildt, Peter; Hughes, Meredith; Matthews, Brenda; Wilner, David

2018-06-01

In the early stages of planet formation, small dust grains grow to become millimeter-sized particles in debris disks around stars. These disks can in principle be characterized by their emission at submillimeter and millimeter wavelengths. Determining both the occurrence and abundance of debris in unresolved circumstellar disks of A-type main-sequence stars requires that the stellar photospheric emission be accurately modeled. To better constrain the photospheric emission for such systems, we present observations of Sirius A, an A-type star with no known debris, from the James Clerk Maxwell Telescope, Submillimeter Array, and Jansky Very Large Array at 0.45, 0.85, 0.88, 1.3, 6.7, and 9.0 mm. We use these observations to inform a PHOENIX model of Sirius A’s atmosphere. We find the model provides a good match to these data and can be used as a template for the submillimeter/millimeter emission of other early A-type stars where unresolved debris may be present. The observations are part of an ongoing observational campaign entitled Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths.

Prospects for Studying Interstellar Magnetic Fields with a Far-Infrared Polarimeter for SAFIR

NASA Technical Reports Server (NTRS)

Dowell, C. Darren; Chuss, D. T.; Dotson, J. L.

2008-01-01

Polarimetry at mid-infrared through millimeter wavelengths using airborne and ground-based telescopes has revealed magnetic structures in dense molecular clouds in the interstellar medium, primarily in regions of star formation. Furthermore, spectropolarimetry has offered clues about the composition of the dust grains and the mechanism by which they are aligned with respect to the local magnetic field. The sensitivity of the observations to date has been limited by the emission from the atmosphere and warm telescopes. A factor of 1000 in sensitivity can be gained by using instead a cold space telescope. With 5 arcminute resolution, Planck will make the first submillimeter polarization survey of the full Galaxy early in the next decade. We discuss the science case for and basic design of a far-infrared polarimeter on the SAFIR space telescope, which offers resolution in the few arcsecond range and wavelength selection of cold and warm dust components. Key science themes include the formation and evolution of molecular clouds in nearby spiral galaxies, the magnetic structure of the Galactic center, and interstellar turbulence.

Status of a Novel 4-Band Submm/mm Camera for the Caltech Submillimeter Observatory

NASA Astrophysics Data System (ADS)

Noroozian, Omid; Day, P.; Glenn, J.; Golwala, S.; Kumar, S.; LeDuc, H. G.; Mazin, B.; Nguyen, H. T.; Schlaerth, J.; Vaillancourt, J. E.; Vayonakis, A.; Zmuidzinas, J.

2007-12-01

Submillimeter observations are important to the understanding of galaxy formation and evolution. Determination of the spectral energy distribution in the millimeter and submillimeter regimes allows important and powerful diagnostics. To this end, we are undertaking the construction of a 4-band (750, 850, 1100, 1300 microns) 8-arcminute field of view camera for the Caltech Submillimeter Observatory. The focal plane will make use of three novel technologies: photolithographic phased array antennae, on-chip band-pass filters, and microwave kinetic inductance detectors (MKID). The phased array antenna design obviates beam-defining feed horns. On-chip band-pass filters eliminate band-defining metal-mesh filters. Together, the antennae and filters enable each spatial pixel to observe in all four bands simultaneously. MKIDs are highly multiplexable background-limited photon detectors. Readout of the MKID array will be done with software-defined radio (See poster by Max-Moerbeck et al.). This camera will provide an order-of-magnitude larger mapping speed than existing instruments and will be comparable to SCUBA 2 in terms of the detection rate for dusty sources, but complementary to SCUBA 2 in terms of wavelength coverage. We present results from an engineering run with a demonstration array, the baseline design for the science array, and the status of instrument design, construction, and testing. We anticipate the camera will be available at the CSO in 2010. This work has been supported by NASA ROSES APRA grants NNG06GG16G and NNG06GC71G, the NASA JPL Research and Technology Development Program, and the Gordon and Betty Moore Foundation.

Synthetic Aperture Imaging Polarimeter: Postprint

DTIC Science & Technology

2010-02-01

mechanical design of the SAlP prototype revol .... es around the concept of a modular array. The modular aspect allows for the array to be built in...imagery of source . The top row images are of the actual fringe pattern incident on the SAlP prototype array. These pictures were taken through the...processed images associated with each of the inputs. The results demonstrated that the SAlP prototype array works in conjunction with the algorithm

POET: a SMEX mission for gamma ray burst polarimetry

NASA Astrophysics Data System (ADS)

McConnell, Mark L.; Baring, Matthew; Bloser, Peter; Dwyer, Joseph F.; Emslie, A. Gordon; Ertley, Camden D.; Greiner, Jochen; Harding, Alice K.; Hartmann, Dieter H.; Hill, Joanne E.; Kaaret, Philip; Kippen, R. M.; Mattingly, David; McBreen, Sheila; Pearce, Mark; Produit, Nicolas; Ryan, James M.; Ryde, Felix; Sakamoto, Takanori; Toma, Kenji; Vestrand, W. Thomas; Zhang, Bing

2014-07-01

Polarimeters for Energetic Transients (POET) is a mission concept designed to t within the envelope of a NASA Small Explorer (SMEX) mission. POET will use X-ray and gamma-ray polarimetry to uncover the energy release mechanism associated with the formation of stellar-mass black holes and investigate the physics of extreme magnetic ields in the vicinity of compact objects. Two wide-FoV, non-imaging polarimeters will provide polarization measurements over the broad energy range from about 2 keV up to about 500 keV. A Compton scatter polarimeter, using an array of independent scintillation detector elements, will be used to collect data from 50 keV up to 500 keV. At low energies (2{15 keV), data will be provided by a photoelectric polarimeter based on the use of a Time Projection Chamber for photoelectron tracking. During a two-year baseline mission, POET will be able to collect data that will allow us to distinguish between three basic models for the inner jet of gamma-ray bursts.

Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers

NASA Astrophysics Data System (ADS)

Duff, S. M.; Austermann, J.; Beall, J. A.; Becker, D.; Datta, R.; Gallardo, P. A.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Hubmayr, J.; Koopman, B. J.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Pappas, C. G.; Salatino, M.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Van Lanen, J.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

2016-08-01

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_x) materials and microwave structures, and the resulting performance improvements.

Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers

NASA Technical Reports Server (NTRS)

Duff, S. M.; Austermann, J.; Beall, J. A.; Becker, D.; Datta, R.; Gallardo, P. A.; Henderson, S. W.; Hilton, G. C.; Ho, S. P.; Hubmayr, J.;

A Kinematic, Flexure-based Mechanism for Precise, Parallel Motion for the Hertz Variable-delay Polarization Modulator (VPM)

NASA Technical Reports Server (NTRS)

Voellmer, G. M.; Chuss, D. T.; Jackson, M.; Krejny, M.; Moseley, S. H.; Novak, G.; Wollack, E. J.

2008-01-01

We describe the design of the linear motion stage for a Variable-delay Polarization Modulator (VPM) and of a grid flattener that has been built and integrated into the Hertz ground-based, submillimeter polarimeter. VPMs allow the modulation of a polarized source by controlling the phase difference between two linear, orthogonal polarizations. The size of the gap between a mirror and a very flat polarizing grid determines the amount of the phase difference. This gap must be parallel to better than 1% of the wavelength. A novel, kinematic, flexure-based mechanism is described that passively maintains the parallelism of the mirror and the grid to 1.5 pm over a 150 mm diameter, with a 400 pm throw. A single piezoceramic actuator is used to modulate the gap, and a capacitive sensor provides position feedback for closed-loop control. A simple device that ensures the planarity of the polarizing grid is also described. Engineering results from the deployment of this device in the Hertz instrument April 2006 at the Submillimeter Telescope Observatory (SMTO) in Arizona are presented.

Performance of Backshort-Under-Grid Kilopixel TES Arrays for HAWC+

NASA Technical Reports Server (NTRS)

Staguhn, J. G.; Benford, D. J.; Dowell, C. D.; Fixsen, D. J.; Hilton, G. C.; Irwin, K. D.; Jhabvala, C. A.; Maher, S. F.; Miller, T. M.; Moseley, S. H.;

Submillimeter-wave antennas on thin membranes

NASA Technical Reports Server (NTRS)

Rebeiz, Gabriel M.; Regehr, Wade G.; Rutledge, David B.; Savage, Richard L.; Luhmann, Neville C., Jr.

1987-01-01

Submillimeter-wave antennas have been fabricated on 1-micron thick silicon-oxynitride membranes. This approach results in better patterns than previous lens-coupled antennas, and eliminates the dielectric loss associated with the substrate lens. Measurements on a wideband log-periodic antenna at 700 GHz, 370 GHz and 167 GHz show no sidelobes and 3-dB beamwidths between 40 and 60 deg. A linear imaging array has similar patterns at 700 GHz. Possible applications for membrane antennas include wideband superconducting tunnel-junction receivers for radio astronomy and imaging arrays for radiometry and plasma diagnostics.

Surveying Low-Mass Star Formation with the Submillimeter Array

NASA Astrophysics Data System (ADS)

Dunham, Michael

2018-01-01

Large astronomical surveys yield important statistical information that can’t be derived from single-object and small-number surveys. In this talk I will review two recent surveys in low-mass star formation undertaken by the Submillimeter Array (SMA): a millimeter continuum survey of disks surrounding variably accreting young stars, and a complete continuum and molecular line survey of all protostars in the nearby Perseus Molecular Cloud. I will highlight several new insights into the processes by which low-mass stars gain their mass that have resulted from the statistical power of these surveys.

ALMA, APEX and beyond

NASA Astrophysics Data System (ADS)

Zwaan, M.; Testi, L.

The Atacama Large Millimeter/submillimeter Array (ALMA) is currently being constructed at the 5000m Chajnantor plateau in the Chilean Andes. ALMA has been designed and is being built to deliver transformational science in the millimeter and submillimeter regime for many years to come. We briefly describe the project status and timeline. The Atacama Pathfinder Experiment (APEX), built at the same site, is already operational and proves to be an effective survey instrument. We discuss which niches in millimeter/submillimeter astronomy will remain open for a possible facility in Antarctica.

The ALMA Phasing System: A Beamforming Capability for Ultra-high-resolution Science at (Sub)Millimeter Wavelengths

NASA Astrophysics Data System (ADS)

Matthews, L. D.; Crew, G. B.; Doeleman, S. S.; Lacasse, R.; Saez, A. F.; Alef, W.; Akiyama, K.; Amestica, R.; Anderson, J. M.; Barkats, D. A.; Baudry, A.; Broguière, D.; Escoffier, R.; Fish, V. L.; Greenberg, J.; Hecht, M. H.; Hiriart, R.; Hirota, A.; Honma, M.; Ho, P. T. P.; Impellizzeri, C. M. V.; Inoue, M.; Kohno, Y.; Lopez, B.; Martí-Vidal, I.; Messias, H.; Meyer-Zhao, Z.; Mora-Klein, M.; Nagar, N. M.; Nishioka, H.; Oyama, T.; Pankratius, V.; Perez, J.; Phillips, N.; Pradel, N.; Rottmann, H.; Roy, A. L.; Ruszczyk, C. A.; Shillue, B.; Suzuki, S.; Treacy, R.

2018-01-01

The Atacama Millimeter/submillimeter Array (ALMA) Phasing Project (APP) has developed and deployed the hardware and software necessary to coherently sum the signals of individual ALMA antennas and record the aggregate sum in Very Long Baseline Interferometry (VLBI) Data Exchange Format. These beamforming capabilities allow the ALMA array to collectively function as the equivalent of a single large aperture and participate in global VLBI arrays. The inclusion of phased ALMA in current VLBI networks operating at (sub)millimeter wavelengths provides an order of magnitude improvement in sensitivity, as well as enhancements in u–v coverage and north–south angular resolution. The availability of a phased ALMA enables a wide range of new ultra-high angular resolution science applications, including the resolution of supermassive black holes on event horizon scales and studies of the launch and collimation of astrophysical jets. It also provides a high-sensitivity aperture that may be used for investigations such as pulsar searches at high frequencies. This paper provides an overview of the ALMA Phasing System design, implementation, and performance characteristics.

Improved Grid-Array Millimeter-Wave Amplifier

NASA Technical Reports Server (NTRS)

Rosenberg, James J.; Rutledge, David B.; Smith, R. Peter; Weikle, Robert

1993-01-01

Improved grid-array amplifiers operating at millimeter and submillimeter wavelengths developed for use in communications and radar. Feedback suppressed by making input polarizations orthogonal to output polarizations. Amplifier made to oscillate by introducing some feedback. Several grid-array amplifiers concatenated to form high-gain beam-amplifying unit.

Development of a hard x-ray focal plane compton polarimeter: a compact polarimetric configuration with scintillators and Si photomultipliers

NASA Astrophysics Data System (ADS)

Chattopadhyay, T.; Vadawale, S. V.; Goyal, S. K.; Mithun, N. P. S.; Patel, A. R.; Shukla, R.; Ladiya, T.; Shanmugam, M.; Patel, V. R.; Ubale, G. P.

2016-02-01

X-ray polarization measurement of cosmic sources provides two unique parameters namely degree and angle of polarization which can probe the emission mechanism and geometry at close vicinity of the compact objects. Specifically, the hard X-ray polarimetry is more rewarding because the sources are expected to be intrinsically highly polarized at higher energies. With the successful implementation of Hard X-ray optics in NuSTAR, it is now feasible to conceive Compton polarimeters as focal plane detectors. Such a configuration is likely to provide sensitive polarization measurements in hard X-rays with a broad energy band. We are developing a focal plane hard X-ray Compton polarimeter consisting of a plastic scintillator as active scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. The scatterer is 5 mm diameter and 100 mm long plastic scintillator (BC404) viewed by normal PMT. The photons scattered by the plastic scatterer are collected by a cylindrical array of 16 CsI(Tl) scintillators (5 mm × 5 mm × 150 mm) which are read by Si Photomultiplier (SiPM). Use of the new generation SiPMs ensures the compactness of the instrument which is essential for the design of focal plane detectors. The expected sensitivity of such polarimetric configuration and complete characterization of the plastic scatterer, specially at lower energies have been discussed in [11, 13]. In this paper, we characterize the CsI(Tl) absorbers coupled to SiPM. We also present the experimental results from the fully assembled configuration of the Compton polarimeter.

CMZoom: The Submillimeter Array Survey of our Galaxy’s Central Molecular Zone

NASA Astrophysics Data System (ADS)

Battersby, Cara; CMZoom Team

2018-01-01

The inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey, completed this year, and has mapped out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4” (0.2 pc) and good image fidelity up to large spatial scales.

Report of the submillimeter splinter group

NASA Astrophysics Data System (ADS)

Harris, A. I.; Lequeux, J.

1992-12-01

The aim of the submillimeter splinter group of the LIST (Lunar Interferometry Study Team) was to examine the scientific and technical aspects of a submillimeter interferometer with an emphasis on heterodyne detection. The main elements of the scientific logic that lead to the conclusions that a heterodyne submillimeter array should have a collecting area of at order 1000 sq m are summarized. This conclusion is based on sensitivity constraints and the following points: anything that can be done from the ground, will be; an instrument as complex and expensive as a large submillimeter interferometer must be capable of significant extragalactic observations; and no matter what the future scientific trends are, looking at the main coolants will always be important. It is clear that an instrument of this size is several steps past the next generation of spaceborne observatories.

Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER

NASA Astrophysics Data System (ADS)

Hubmayr, Johannes; Austermann, Jason E.; Beall, James A.; Becker, Daniel T.; Benton, Steven J.; Bergman, A. Stevie; Bond, J. Richard; Bryan, Sean; Duff, Shannon M.; Duivenvoorden, Adri J.; Eriksen, H. K.; Filippini, Jeffrey P.; Fraisse, A.; Galloway, Mathew; Gambrel, Anne E.; Ganga, K.; Grigorian, Arpi L.; Gualtieri, Riccardo; Gudmundsson, Jon E.; Hartley, John W.; Halpern, M.; Hilton, Gene C.; Jones, William C.; McMahon, Jeffrey J.; Moncelsi, Lorenzo; Nagy, Johanna M.; Netterfield, C. B.; Osherson, Benjamin; Padilla, Ivan; Rahlin, Alexandra S.; Racine, B.; Ruhl, John; Rudd, T. M.; Shariff, J. A.; Soler, J. D.; Song, Xue; Ullom, Joel N.; Van Lanen, Jeff; Vissers, Michael R.; Wehus, I. K.; Wen, Shyang; Wiebe, D. V.; Young, Edward

2016-07-01

We describe 280 GHz bolometric detector arrays that instrument the balloon-borne polarimeter spider. A primary science goal of spider is to measure the large-scale B-mode polarization of the cosmic microwave background (cmb) in search of the cosmic-inflation, gravitational-wave signature. 280 GHz channels aid this science goal by constraining the level of B-mode contamination from galactic dust emission. We present the focal plane unit design, which consists of a 16x16 array of conical, corrugated feedhorns coupled to a monolithic detector array fabricated on a 150 mm diameter silicon wafer. Detector arrays are capable of polarimetric sensing via waveguide probe-coupling to a multiplexed array of transition-edge-sensor (TES) bolometers. The spider receiver has three focal plane units at 280 GHz, which in total contains 765 spatial pixels and 1,530 polarization sensitive bolometers. By fabrication and measurement of single feedhorns, we demonstrate 14.7° FHWM Gaussian-shaped beams with <1% ellipticity in a 30% fractional bandwidth centered at 280 GHz. We present electromagnetic simulations of the detection circuit, which show 94% band-averaged, single-polarization coupling efficiency, 3% reflection and 3% radiative loss. Lastly, we demonstrate a low thermal conductance bolometer, which is well-described by a simple TES model and exhibits an electrical noise equivalent power (NEP) = 2.6 x 10-17 W/√Hz, consistent with the phonon noise prediction.

Bolometeric detector arrays for CMB polarimetry

NASA Technical Reports Server (NTRS)

Kuo, C. L.; Bock, J. J.; Day, P.; Goldin, A.; Golwala, S.; Holmes, W.; Irwin, K.; Kenyon, M.; Lange, A. E.; LeDuc, H. G.;

Fabrication of an Absorber-Coupled MKID Detector and Readout for Sub-Millimeter and Far-Infrared Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari-David; Hsieh, Wen-Ting; Moseley, S. Harvey; Stevenson, Thomas R.; U-yen, Kongpop; Wollack, Edward J.

2010-01-01

We have fabricated absorber-coupled microwave kinetic inductance detector (MKID) arrays for sub-millimeter and far-infrared astronomy. Each detector array is comprised of lambda/2 stepped impedance resonators, a 1.5 micrometer thick silicon membrane, and 380 micrometer thick silicon walls. The resonators consist of parallel plate aluminum transmission lines coupled to low impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The Al transmission lines simultaneously act to absorb optical power and are designed to have a surface impedance and filling fraction so as to match the impedance of free space. Our novel fabrication techniques demonstrate high fabrication yield of MKID arrays on large single crystal membranes and sub-micron front-to-back alignment of the microstrip circuit.

Fabrication of an Absorber-Coupled MKID Detector and Readout for Sub-Millimeter and Far-Infrared Astronomy

NASA Technical Reports Server (NTRS)

Brown, Ari-David; Hsieh, Wen-Ting; Moseley, S. Harvey; Stevenson, Thomas R.; U-yen, Kongpop; Wollack, Edward J.

2010-01-01

We have fabricated absorber-coupled microwave kinetic inductance detector (MKID) arrays for sub-millimeter and farinfrared astronomy. Each detector array is comprised of lambda/2 stepped impedance resonators, a 1.5µm thick silicon membrane, and 380µm thick silicon walls. The resonators consist of parallel plate aluminum transmission lines coupled to low impedance Nb microstrip traces of variable length, which set the resonant frequency of each resonator. This allows for multiplexed microwave readout and, consequently, good spatial discrimination between pixels in the array. The Al transmission lines simultaneously act to absorb optical power and are designed to have a surface impedance and filling fraction so as to match the impedance of free space. Our novel fabrication techniques demonstrate high fabrication yield of MKID arrays on large single crystal membranes and sub-micron front-to-back alignment of the microstrip circuit.

Coherent Detector Arrays for Continuum and Spectral Line Applications

NASA Technical Reports Server (NTRS)

Gaier, Todd C.

2006-01-01

This viewgraph presentation reviews the requirements for improved coherent detector arrays for use in continuum and spectral line applications. With detectors approaching fundamental limits, large arrays offer the only path to sensitivity improvement. Monolithic Microwave Integrated Circuit (MMIC) technology offers a straightforward path to massive focal plane millimeter wave arrays: The technology will readily support continuum imagers, polarimeters and spectral line receivers from 30-110 GHz. Science programs, particularly large field blind surveys will benefit from simultaneous observations of hundreds or thousands of pixels 1000 element array is competitive with a cost less than $2M.

Non-uniformity calibration for MWIR polarization imagery obtained with integrated microgrid polarimeters

NASA Astrophysics Data System (ADS)

Liu, Hai-Zheng; Shi, Ze-Lin; Feng, Bin; Hui, Bin; Zhao, Yao-Hong

2016-03-01

Integrating microgrid polarimeters on focal plane array (FPA) of an infrared detector causes non-uniformity of polarization response. In order to reduce the effect of polarization non-uniformity, this paper constructs an experimental setup for capturing raw flat-field images and proposes a procedure for acquiring non-uniform calibration (NUC) matrix and calibrating raw polarization images. The proposed procedure takes the incident radiation as a polarization vector and offers a calibration matrix for each pixel. Both our matrix calibration and two-point calibration are applied to our mid-wavelength infrared (MWIR) polarization imaging system with integrated microgrid polarimeters. Compared with two point calibration, our matrix calibration reduces non-uniformity by 30 40% under condition of flat-field data test with polarization. The ourdoor scene observation experiment indicates that our calibration can effectively reduce polarization non-uniformity and improve the image quality of our MWIR polarization imaging system.

The SOFIA/SAFIRE Far-Infrared Spectrometer: Highlighting Submillimeter Astrophysics and Technology

NASA Technical Reports Server (NTRS)

Benford, Dominic J.

2009-01-01

The Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory is an imaging spectrometer for wavelengths between 28 microns and 440 microns. Our design is a dual-band long-slit grating spectrometer, which provides broadband (approx. 4000 km/s) observations in two lines simultaneously over a field of view roughly 10" wide by 320" long. The low backgrounds in spectroscopy require very sensitive detectors with noise equivalent powers of order 10(exp -18) W/square root of Hz. We are developing a kilopixel, filled detector array for SAFIRE in a 32 x 40 format. The detector consists of a transition edge sensor (TES) bolometer array, a per-pixel broadband absorbing backshort array, and a NIST SQUID multiplexer readout array. This general type of array has been used successfully in the GISMO instrument, so we extrapolate to the sensitivity needed for airborne spectroscopy. Much of the cryogenic, electronics, and software infrastructure for SAFIRE have been developed. I provide here an overview of the progress on SAFIRE.

Dust Properties of Local Dust-obscured Galaxies with the Submillimeter Array

NASA Astrophysics Data System (ADS)

Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J.

2013-11-01

We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S ν(880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S ν(880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 1011(L ⊙) and 4-14 × 107(M ⊙), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution.

Isotopic Ratios in Nitriles from Submillimeter Spectroscopy Using SMA and ALMA

NASA Astrophysics Data System (ADS)

Gurwell, Mark A.; Moreno, Raphael; Vinatier, Sandrine; Lellouch, Emmanuel; Butler, Bryan J.; Moullet, Arielle; Lara, Luisa; Hidayat, Taufiq

2016-10-01

We present submillimeter spectroscopic observations of Titan obtained using the Submillimeter Array (SMA) in 2011, and the Atacama Large Millimeter/Submillimeter Array (ALMA) in 2012, some of which have previously been presented but not fully analyzed (1, 2, 3). The SMA observations were obtained at low spatial resolution, providing disk average spectra, but the ALMA observations provide low resolution mapping of Titan (~0.4"-0.6" when Titan was 0.77" surface diameter). We will present detailed radiative transfer analysis of detected spectral lines to derive isotopic ratios in two nitriles: HCN (D/H, 13C/12C, 15N/14N) and HC3N (15N/14N). The analysis makes use of nearly concurrent CIRS temperature profiles as important constraints for the vertical profiles of these species, allowing high precision measurements of the ratios. Finally, we will highlight current and future ALMA observations that will allow monitoring of non-symmetric molecular species in Titan's upper atmosphere from Earth, beyond the end of the Cassini mission.(1) Gurwell et al (2011) EPSC-DPS Joint Meeting 2011, p270. (2) Moreno et al (2014) EPSC 2014 Abstracts, Vol. 9, id. EPSC2014-438. (3) Moreno etal (2014), DPS meeting #46, id.211.19

Development of a Crosstalk Suppression Algorithm for KID Readout

NASA Astrophysics Data System (ADS)

Lee, Kyungmin; Ishitsuka, H.; Oguri, S.; Suzuki, J.; Tajima, O.; Tomita, N.; Won, Eunil; Yoshida, M.

2018-06-01

The GroundBIRD telescope aims to detect B-mode polarization of the cosmic microwave background radiation using the kinetic inductance detector array as a polarimeter. For the readout of the signal from detector array, we have developed a frequency division multiplexing readout system based on a digital down converter method. These techniques in general have the leakage problems caused by the crosstalks. The window function was applied in the field programmable gate arrays to mitigate the effect of these problems and tested it in algorithm level.

A Submillimeter Survey of Dust Continuum Emission in Local Dust-Obscured Galaxies

NASA Astrophysics Data System (ADS)

Lee, Jong Chul; Hwang, Ho Seong; Lee, Gwang-Ho

2015-08-01

Dusty star-forming galaxies are responsible for the bulk of cosmic star formation at 1

Superconducting Bolometer Array Architectures

NASA Technical Reports Server (NTRS)

Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Shafer, Rick; Staguhn, Johannes; Wollack, Ed; Oegerle, William (Technical Monitor)

2002-01-01

The next generation of far-infrared and submillimeter instruments require large arrays of detectors containing thousands of elements. These arrays will necessarily be multiplexed, and superconducting bolometer arrays are the most promising present prospect for these detectors. We discuss our current research into superconducting bolometer array technologies, which has recently resulted in the first multiplexed detections of submillimeter light and the first multiplexed astronomical observations. Prototype arrays containing 512 pixels are in production using the Pop-Up Detector (PUD) architecture, which can be extended easily to 1000 pixel arrays. Planar arrays of close-packed bolometers are being developed for the GBT (Green Bank Telescope) and for future space missions. For certain applications, such as a slewed far-infrared sky survey, feedhorncoupling of a large sparsely-filled array of bolometers is desirable, and is being developed using photolithographic feedhorn arrays. Individual detectors have achieved a Noise Equivalent Power (NEP) of -10(exp 17) W/square root of Hz at 300mK, but several orders of magnitude improvement are required and can be reached with existing technology. The testing of such ultralow-background detectors will prove difficult, as this requires optical loading of below IfW. Antenna-coupled bolometer designs have advantages for large format array designs at low powers due to their mode selectivity.

Is There a Maximum Star Formation Rate in High-redshift Galaxies?

NASA Astrophysics Data System (ADS)

Barger, A. J.; Cowie, L. L.; Chen, C.-C.; Owen, F. N.; Wang, W.-H.; Casey, C. M.; Lee, N.; Sanders, D. B.; Williams, J. P.

2014-03-01

We use the James Clerk Maxwell Telescope's SCUBA-2 camera to image a 400 arcmin2 area surrounding the GOODS-N field. The 850 μm rms noise ranges from a value of 0.49 mJy in the central region to 3.5 mJy at the outside edge. From these data, we construct an 850 μm source catalog to 2 mJy containing 49 sources detected above the 4σ level. We use an ultradeep (11.5 μJy at 5σ) 1.4 GHz image obtained with the Karl G. Jansky Very Large Array together with observations made with the Submillimeter Array to identify counterparts to the submillimeter galaxies. For most cases of multiple radio counterparts, we can identify the correct counterpart from new and existing Submillimeter Array data. We have spectroscopic redshifts for 62% of the radio sources in the 9' radius highest sensitivity region (556/894) and 67% of the radio sources in the GOODS-N region (367/543). We supplement these with a modest number of additional photometric redshifts in the GOODS-N region (30). We measure millimetric redshifts from the radio to submillimeter flux ratios for the unidentified submillimeter sample, assuming an Arp 220 spectral energy distribution. We find a radio-flux-dependent K - z relation for the radio sources, which we use to estimate redshifts for the remaining radio sources. We determine the star formation rates (SFRs) of the submillimeter sources based on their radio powers and their submillimeter fluxes and find that they agree well. The radio data are deep enough to detect star-forming galaxies with SFRs >2000 M ⊙ yr-1 to z ~ 6. We find galaxies with SFRs up to ~6000 M ⊙ yr-1 over the redshift range z = 1.5-6, but we see evidence for a turn-down in the SFR distribution function above 2000 M ⊙ yr-1. The James Clerk Maxwell Telescope is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the National Research Council of Canada, and (until 2013 March 31) the Netherlands Organisation for Scientific Research. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

Design and Calibration of the QUIET CMB Polarimeter

NASA Astrophysics Data System (ADS)

Buder, Immanuel

2011-04-01

QUIET is a large--angular-scale Cosmic Microwave Background (CMB) polarimeter designed to measure the B-mode signal from inflation. The design incorporates a new time-stream "double-demodulation" technique, a 1.4-m Mizuguchi--Dragone telescope, natural sky rotation, and frequent boresight rotation to minimize systematic contamination. The levels of contamination in the inflationary signal are below r=0.1, the best yet achieved by any B-mode polarimeter. Moreover, QUIET is unique among B-mode polarimeters in using a large focal-plane array of miniaturized High--Electron-Mobility Transistor (HEMT) based coherent detectors. These detectors take advantage of a breakthrough in microwave-circuit packaging to achieve a field sensitivity of 69,K√s. QUIET has collected > 10,000,ours of data and recently released results from the first observing season at Q band (43 GHz). Analysis of W-band (95-GHz) data is ongoing. I will describe the Q-band calibration plan which uses a combination of astronomical and artificial sources to convert the raw data into polarization measurements with small and well-understood calibration errors. I will also give a status report on calibration for the upcoming W-band results.

Image processing methods to compensate for IFOV errors in microgrid imaging polarimeters

NASA Astrophysics Data System (ADS)

Ratliff, Bradley M.; Boger, James K.; Fetrow, Matthew P.; Tyo, J. Scott; Black, Wiley T.

2006-05-01

Long-wave infrared imaging Stokes vector polarimeters are used in many remote sensing applications. Imaging polarimeters require that several measurements be made under optically different conditions in order to estimate the polarization signature at a given scene point. This multiple-measurement requirement introduces error in the signature estimates, and the errors differ depending upon the type of measurement scheme used. Here, we investigate a LWIR linear microgrid polarimeter. This type of instrument consists of a mosaic of micropolarizers at different orientations that are masked directly onto a focal plane array sensor. In this scheme, each polarization measurement is acquired spatially and hence each is made at a different point in the scene. This is a significant source of error, as it violates the requirement that each polarization measurement have the same instantaneous field-of-view (IFOV). In this paper, we first study the amount of error introduced by the IFOV handicap in microgrid instruments. We then proceed to investigate means for mitigating the effects of these errors to improve the quality of polarimetric imagery. In particular, we examine different interpolation schemes and gauge their performance. These studies are completed through the use of both real instrumental and modeled data.

Centralized operations and maintenance planning at the Atacama Large Millimeter/submillimeter Array (ALMA)

NASA Astrophysics Data System (ADS)

Lopez, Bernhard; Whyborn, Nicholas D.; Guniat, Serge; Hernandez, Octavio; Gairing, Stefan

2016-07-01

The Atacama Large Millimeter/submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA consists of 54 twelve-meter antennas and 12 seven-meter antennas operating as an aperture synthesis array in the (sub)millimeter wavelength range. Since the inauguration of the observatory back in March 2013 there has been a continuous effort to establish solid operations processes for effective and efficient management of technical and administrative tasks on site. Here a key aspect had been the centralized maintenance and operations planning: input is collected from science stakeholders, the computerized maintenance management system (CMMS) and from the technical teams spread around the world, then this information is analyzed and consolidated based on the established maintenance strategy, the observatory long-term plan and the short-term priorities definitions. This paper presents the high-level process that has been developed for the planning and scheduling of planned- and unplanned maintenance tasks, and for site operations like the telescope array reconfiguration campaigns. We focus on the centralized planning approach by presenting its genesis, its current implementation for the observatory operations including related planning products, and we explore the necessary next steps in order to fully achieve a comprehensive centralized planning approach for ALMA in steady-state operations.

Design and Fabrication of Two-Dimensional Semiconducting Bolometer Arrays for the High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC-II)

NASA Technical Reports Server (NTRS)

Voellmer, George M.; Allen, Christine A.; Amato, Michael J.; Babu, Sachidananda R.; Bartels, Arlin E.; Benford, Dominic J.; Derro, Rebecca J.; Dowell, C. Darren; Harper, D. Al; Jhabvala, Murzy D.;

Design and Fabrication of Two-Dimensional Semiconducting Bolometer Arrays for the High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC-II)

NASA Technical Reports Server (NTRS)

Voellmer, George M.; Allen, Christine A.; Amato, Michael J.; Babu, Sachidananda R.; Bartels, Arlin E.; Benford, Dominic J.; Derro, Rebecca J.; Dowell, C. Darren; Harper, D. Al; Jhabvala, Murzy D.

2002-01-01

The High resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC II) will use almost identical versions of an ion-implanted silicon bolometer array developed at the National Aeronautics and Space Administration's Goddard Space Flight Center (GSFC). The GSFC 'Pop-up' Detectors (PUD's) use a unique folding technique to enable a 12 x 32-element close-packed array of bolometers with a filling factor greater than 95 percent. A kinematic Kevlar(trademark) suspension system isolates the 200 mK bolometers from the helium bath temperature, and GSFC - developed silicon bridge chips make electrical connection to the bolometers, while maintaining thermal isolation. The JFET preamps operate at 120 K. Providing good thermal heat sinking for these, and keeping their conduction and radiation from reaching the nearby bolometers, is one of the principal design challenges encountered. Another interesting challenge is the preparation of the silicon bolometers. They are manufactured in 32-element, planar rows using Micro Electro Mechanical Systems (MEMS) semiconductor etching techniques, and then cut and folded onto a ceramic bar. Optical alignment using specialized jigs ensures their uniformity and correct placement. The rows are then stacked to create the 12 x 32-element array. Engineering results from the first light run of SHARC II at the Caltech Submillimeter Observatory (CSO) are presented.

An Exploration of Dusty Galaxies

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-04-01

Submillimeter galaxies i.e., galaxies that we detect in the submillimeter wavelength range are mysterious creatures. Its only within the last couple decades that weve had telescope technology capable of observing them, and were only now getting to the point where angular resolution limits allow us to examine them closely. A new study has taken advantage of new capabilities to explore the properties of a sample of 52 of thesegalaxies.Dusty Star FormationSubmillimeter galaxies are generally observed in the early universe. Though theyre faint in other wavebands, theyre extremely luminous in infrared and submillimeter their infrared luminosities are typically trillions of times the Suns luminosity. This is thought to be because these galaxies are very actively forming stars at rates of hundreds of times that of the Milky Way!Example 10 10 true-color images of ten submillimeter galaxies in the authors ALMA-identified sample. [Simpson et al. 2017]Submillimeter galaxies are also extremely dusty, so we dont see their star formation directly in optical wavelengths. Instead, we see the stellar light after its been absorbed and reemitted by interstellar dust lanes were indirectly observing heavily obscured star formation.Why look for submillimeter galaxies? Studying them can help us to learn about galaxy and star formation early in our universes history, and help us to understand how the universe has evolved into what we see locally today.Submillimeter StrugglesDue to angular resolution limitations in the past, we often couldnt pin down the exact locations of submillimeter galaxies, preventing us from examining them properly. But now a team of scientists has used the Atacama Large Millimeter/submillimeter array (ALMA) to precisely locate 52 submillimeter galaxies identified by the Submillimeter Common-User Bolometer Array (SCUBA-2) in the UKIDSS Ultra Deep Survey field.The precise locations made possible by ALMA allowed the team led by James Simpson (University of Edinburgh and Durham University) to identify the multi-wavelength properties of these galaxies in a pilot study that they hope to extend to many more similar galaxies in the future.Lessons from Distant GalaxiesWhat did Simpson and collaborators learn in this study?Photometric redshift distribution of the ALMA-identified submillimeter galaxies in the authors sample (grey). [Simpson et al. 2017]For the set of galaxies for which the team could measure photometric redshifts, the median redshift was z 2.65 (though redshifts ranged up to z 5).Submillimeter galaxies are cooler and larger than local far-infrared galaxies (known as ULIRGs). The authors therefore argue that its unlikely that ULIRGs are evolved versions of submillimeter galaxies.Estimates of dust mass in these galaxies suggest that effectively all of the optical-to-near-infrared light from colocated stars is obscured by dust.Estimates of the future stellar mass of these galaxies suggest that they cannot evolve into lenticular or spiral galaxies. Instead, the authors conclude, submillimeter galaxies must be the progenitors of local elliptical galaxies.CitationJ. M. Simpson et al 2017 ApJ 839 58. doi:10.3847/1538-4357/aa65d0

Photon caliper to achieve submillimeter positioning accuracy

NASA Astrophysics Data System (ADS)

Gallagher, Kyle J.; Wong, Jennifer; Zhang, Junan

2017-09-01

The purpose of this study was to demonstrate the feasibility of using a commercial two-dimensional (2D) detector array with an inherent detector spacing of 5 mm to achieve submillimeter accuracy in localizing the radiation isocenter. This was accomplished by delivering the Vernier ‘dose’ caliper to a 2D detector array where the nominal scale was the 2D detector array and the non-nominal Vernier scale was the radiation dose strips produced by the high-definition (HD) multileaf collimators (MLCs) of the linear accelerator. Because the HD MLC sequence was similar to the picket fence test, we called this procedure the Vernier picket fence (VPF) test. We confirmed the accuracy of the VPF test by offsetting the HD MLC bank by known increments and comparing the known offset with the VPF test result. The VPF test was able to determine the known offset within 0.02 mm. We also cross-validated the accuracy of the VPF test in an evaluation of couch hysteresis. This was done by using both the VPF test and the ExacTrac optical tracking system to evaluate the couch position. We showed that the VPF test was in agreement with the ExacTrac optical tracking system within a root-mean-square value of 0.07 mm for both the lateral and longitudinal directions. In conclusion, we demonstrated the VPF test can determine the offset between a 2D detector array and the radiation isocenter with submillimeter accuracy. Until now, no method to locate the radiation isocenter using a 2D detector array has been able to achieve such accuracy.

The Atacama Large Millimeter/submillimeter Array - from Early Science to Full Operations.

NASA Astrophysics Data System (ADS)

Remijan, Anthony

2017-06-01

The Atacama Large Millimeter/Submillimeter Array (ALMA) is now entering its 6th cycle of scientific observations. Starting with Cycle 3, science observations were no longer considered "Early Science" or "best efforts". Cycle 5 is now the third cycle of "steady state" observations and Cycle 7 is advertised to begin ALMA "full science" operations. ALMA Full Science Operations will include all the capabilities that were agreed upon by the international consortium after the ALMA re-baselining effort. In this talk, I will detail the upcoming ALMA Cycle 5 observing capabilities, describe the process of selecting new observing modes for upcoming cycles and provide an update on the status of the ALMA Full Science capabilities.

DUST PROPERTIES OF LOCAL DUST-OBSCURED GALAXIES WITH THE SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Ho Seong; Andrews, Sean M.; Geller, Margaret J., E-mail: hhwang@cfa.harvard.edu, E-mail: sandrews@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu

We report Submillimeter Array observations of the 880 μm dust continuum emission for four dust-obscured galaxies (DOGs) in the local universe. Two DOGs are clearly detected with S{sub ν}(880 μm) =10-13 mJy and S/N > 5, but the other two are not detected with 3σ upper limits of S{sub ν}(880 μm) =5-9 mJy. Including an additional two local DOGs with submillimeter data from the literature, we determine the dust masses and temperatures for six local DOGs. The infrared luminosities and dust masses for these DOGs are in the ranges of 1.2-4.9 × 10{sup 11}(L{sub ☉}) and 4-14 × 10{sup 7}(M{submore » ☉}), respectively. The dust temperatures derived from a two-component modified blackbody function are 23-26 K and 60-124 K for the cold and warm dust components, respectively. Comparison of local DOGs with other infrared luminous galaxies with submillimeter detections shows that the dust temperatures and masses do not differ significantly among these objects. Thus, as argued previously, local DOGs are not a distinctive population among dusty galaxies, but simply represent the high-end tail of the dust obscuration distribution.« less

Millimeter and submillimeter observations from the Atacama plateau and high altitude balloons

NASA Astrophysics Data System (ADS)

Devlin, Mark

2002-05-01

A new generation of ground-based and sub-orbital platforms will be operational in the next few years. These telescopes will operate from high sites in Chile and Antarctica, and airborne platforms where the atmosphere is transparent enough to allow sensitive measurements in the millimeter and submillimeter bands. The telescopes will employ state-of-the-art instrumentation including large format bolometer arrays and spectrometers. I will discuss the results of our observations in the Atacama region of Chile (MAT/TOCO), our future observations on the Balloon-borne Large Aperture Submillimeter Telescope (BLAST) now under construction, and our proposed Atacama Cosmology Telescope (ACT). .

Cosmic evolution of star formation properties of galaxies

NASA Astrophysics Data System (ADS)

Kim, Sungeun

2014-01-01

Development of bolometer array and camera at submillimeter wavelength has played an important role in detecting submillimeter bright galaxies, so called submillimeter galaxies. These galaxies seem to be progenitors of present-day massive galaxies and account for their considerable contributions to the light from the early universe and their expected high star formation rates if there is a close link between the submillimeter galaxies and the star formation activities, and the interstellar dust in galaxies is mainly heated by the star light. We review assembly of submillimeter galaxies chosen from the AzTEC and the Herschel SPIRE/PACS data archives, and investigate their spectral energy distribution fits including the data at other wavelengths to deduce details about stellar parameters including star formation rates and parameters yielding the metallicity, composition and abundance in dust, and disc structure of these galaxies. This work has been supported in part by Mid-career Researcher Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology 2011-0028001.

Astronomical Polarimetry with the RIT Polarization Imaging Camera

NASA Astrophysics Data System (ADS)

Vorobiev, Dmitry V.; Ninkov, Zoran; Brock, Neal

2018-06-01

In the last decade, imaging polarimeters based on micropolarizer arrays have been developed for use in terrestrial remote sensing and metrology applications. Micropolarizer-based sensors are dramatically smaller and more mechanically robust than other polarimeters with similar spectral response and snapshot capability. To determine the suitability of these new polarimeters for astronomical applications, we developed the RIT Polarization Imaging Camera to investigate the performance of these devices, with a special attention to the low signal-to-noise regime. We characterized the device performance in the lab, by determining the relative throughput, efficiency, and orientation of every pixel, as a function of wavelength. Using the resulting pixel response model, we developed demodulation procedures for aperture photometry and imaging polarimetry observing modes. We found that, using the current calibration, RITPIC is capable of detecting polarization signals as small as ∼0.3%. The relative ease of data collection, calibration, and analysis provided by these sensors suggest than they may become an important tool for a number of astronomical targets.

SWARM: A 32 GHz Correlator and VLBI Beamformer for the Submillimeter Array

NASA Astrophysics Data System (ADS)

Primiani, Rurik A.; Young, Kenneth H.; Young, André; Patel, Nimesh; Wilson, Robert W.; Vertatschitsch, Laura; Chitwood, Billie B.; Srinivasan, Ranjani; MacMahon, David; Weintroub, Jonathan

2016-03-01

A 32GHz bandwidth VLBI capable correlator and phased array has been designed and deployeda at the Smithsonian Astrophysical Observatory’s Submillimeter Array (SMA). The SMA Wideband Astronomical ROACH2 Machine (SWARM) integrates two instruments: a correlator with 140kHz spectral resolution across its full 32GHz band, used for connected interferometric observations, and a phased array summer used when the SMA participates as a station in the Event Horizon Telescope (EHT) very long baseline interferometry (VLBI) array. For each SWARM quadrant, Reconfigurable Open Architecture Computing Hardware (ROACH2) units shared under open-source from the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) are equipped with a pair of ultra-fast analog-to-digital converters (ADCs), a field programmable gate array (FPGA) processor, and eight 10 Gigabit Ethernet (GbE) ports. A VLBI data recorder interface designated the SWARM digital back end, or SDBE, is implemented with a ninth ROACH2 per quadrant, feeding four Mark6 VLBI recorders with an aggregate recording rate of 64 Gbps. This paper describes the design and implementation of SWARM, as well as its deployment at SMA with reference to verification and science data.

Chemistry and Star Formation: A Love-Hate Relationship

NASA Astrophysics Data System (ADS)

Jiménez-Serra, Izaskun; Zhang, Qizhou; Patel, Nimesh; Lu, Xing; Wang, Ke; Testi, Leonardo; Caselli, Paola; Martin-Pintado, Jesus

2014-06-01

The development of the broad bandwidth receivers at the Submillimeter Array (SMA) a decade ago opened up the possibility to observe tens of molecular lines at high angular resolution simultaneously. The unprecedented wealth of molecular line data provided by the SMA allowed for the first time detailed studies of the chemistry in star-forming regions. These studies have revealed that chemistry is a useful tool to pin down the internal physical structure and the physical processes involved in the process of low-mass and high-mass star formation. In this talk, I will review the most important advances in our understanding of the star-formation process through chemistry thanks to the SMA, and I will present the challenges that will be faced in the next decade in this field of research thanks to the advent of new instrumentation such as the Atacama Large Millimeter/Submillimeter Array and the Square Kilometer Array.

Filters for Submillimeter Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Berdahl, C. M.

1986-01-01

New manufacturing process produces filters strong, yet have small, precise dimensions and smooth surface finish essential for dichroic filtering at submillimeter wavelengths. Many filters, each one essentially wafer containing fine metal grid made at same time. Stacked square wires plated, fused, and etched to form arrays of holes. Grid of nickel and tin held in brass ring. Wall thickness, thickness of filter (hole depth) and lateral hole dimensions all depend upon operating frequency and filter characteristics.

Far-infrared tangential interferometer/polarimeter design and installation for NSTX-U

DOE PAGES

Scott, E. R.; Barchfeld, R.; Riemenschneider, P.; ...

2016-08-09

Here, the Far-infrared Tangential Interferometer/Polarimeter (FIReTIP) system has been refurbished and is being reinstalled on the National Spherical Torus Experiment—Upgrade (NSTX-U) to supply real-time line-integrated core electron density measurements for use in the NSTX-U plasma control system (PCS) to facilitate real-time density feedback control of the NSTX-U plasma. Inclusion of a visible light heterodyne interferometer in the FIReTIP system allows for real-time vibration compensation due to movement of an internally mounted retroreflector and the FIReTIP front-end optics. Real-time signal correction is achieved through use of a National Instruments CompactRIO field-programmable gate array.

Interferometric Observations of the SiO High J Transition Maser associated with VY Canis Majoris with the Submillimeter Array

NASA Astrophysics Data System (ADS)

Shinnaga, H.; Moran, J. M.; Young, K. H.; Ho, P. T. P.

2005-12-01

We imaged the SiO maser emission of J=5-4 in the v=1 state associated with the peculiar red supergiant VY Canis Majoris using the partially completed Submillimeter Array. We identified seven maser components and measured the relative positions at sub-arcsecond scale in the high J transition for the first time. We have also measured the polarization of these maser components. The strongest maser feature has a linear polarization of ˜ 60%, and its direction of polarization is approximately aligned with the bipolar axis. Such a high degree of polarization suggests that radiative pumping is probably responsible for the maser inversion. Five of the other maser features have significant linear polarization.

A Submillimeter Resolution PET Prototype Evaluated With an 18F Inkjet Printed Phantom

NASA Astrophysics Data System (ADS)

Schneider, Florian R.; Hohberg, Melanie; Mann, Alexander B.; Paul, Stephan; Ziegler, Sibylle I.

2015-10-01

This work presents a submillimeter resolution PET (Positron Emission Tomography) scanner prototype based on SiPM/MPPC arrays (Silicon Photomultiplier/Multi Pixel Photon Counter). Onto each active area a 1 ×1 ×20 mm3 LYSO (Lutetium-Yttrium-Oxyorthosilicate) scintillator crystal is coupled one-to-one. Two detector modules facing each other in a distance of 10.0 cm have been set up with in total 64 channels that are digitized by SADCs (Sampling Analog to Digital Converters) with 80 MHz, 10 bit resolution and FPGA (Field Programmable Gate Array) based extraction of energy and time information. Since standard phantoms are not sufficient for testing submillimeter resolution at which positron range is an issue, a 18F inkjet printed phantom has been used to explore the limit in spatial resolution. The phantom could be successfully reconstructed with an iterative MLEM (Maximum Likelihood Expectation Maximization) and an analytically calculated system matrix based on the DRF (Detector Response Function) model. The system yields a coincidence time resolution of 4.8 ns FWHM, an energy resolution of 20%-30% FWHM and a spatial resolution of 0.8 mm.

Taiwanese antennas for the Sub-Millimeter Array: a progress report

NASA Astrophysics Data System (ADS)

Raffin, Phillippe A.; Liu, Ching-Tang; Cervera, Mathieu; Chang, Chi-Ling; Chen, Ming-Tang; Lee, Cheng-Ching; Lee, Typhoon; Lo, Kwok-Yung; Ma, Rwei-Ping; Martin, Robert N.; Martin-Cocher, Pierre; Ong, Ching-Long; Park, Yong-Sun; Tsai, Rong-Den; Wu, Enboa; Yang, Shun-Cheng; Yang, Tien-Szu

2000-07-01

The Academia Sinica, Institute for Astronomy and Astrophysics (ASIAA) is building two antennas to be added to the six antennas of the Sub-Millimeter Array (SMA) of the Smithsonian Astrophysical Observatory (SAO). The antennas have been designed at SAO and are currently under construction at Mauna Kea. ASIAA's two antennas are made in Taiwan from parts manufactured locally and imported from Europe and from the USA. This report will focus on the manufacturing and testing of 2 major components: the alidade and the reflector. We will emphasize the work done on the composite parts used in the 6- meter reflectors, namely the carbon fiber tubes for the backup structure, the carbon fiber legs of the quadrupod and the composite central hub. We will discuss the modal testing and pointing tests of the antennas. Finally this report will show how the Taiwanese industry was able to respond to the high manufacturing standards required to build sub-millimeter antennas. The design and manufacturing capabilities of the Aeronautical Research Laboratories and China Shipbuilding Corporation have made possible the construction of the telescopes in Taiwan.

Submillimeter Array reveals molecular complexity of dying stars

NASA Astrophysics Data System (ADS)

Tomasz

2018-01-01

The unique capabilities of the Submillimeter Array (SMA) have allowed unprecedented studies of cool evolved stars at submillimeter wavelengths. In particular, the SMA now offers the possibility to image multiple molecular transitions at once, owing to the 32-GHz wide instantaneous bandwidth of SWARM, the SMA’s new correlator. Molecular gas located far and very close to the photosphere of an asymptotic-giant branch (AGB) star, a red supergiant, or a pre-planetary nebula can now be examined in transitions observed simultaneously from a wide range of energy levels. This allows a very detailed quantitative investigation of physical and chemical conditions around these variable objects. Several imaging line surveys have been obtained with the SMA to reveal the beautiful complexity of these evolved systems. The surveys resulted in first submillimeter-wave identifications of molecules of prime astrophysical interest, e.g. of TiO, TiO2, and of rotational transitions at excited vibrational states of CO. An overview of recent SMA observations of cool evolved stars will be given with an emphasize on the interferometric line surveys. We will demonstrate their importance in unraveling the mass-loss phenomena, propagation of shocks in the circumstellar medium, and production of dust at elevated temperatures. The SMA studies of these molecular factories have a direct impact on our understanding of the chemical evolution of the Galaxy and stellar evolution at low and high masses.

Facilities for US Radioastronomy.

ERIC Educational Resources Information Center

Thaddeus, Patrick

1982-01-01

Discusses major developments in radioastronomy since 1945. Topics include proposed facilities, very-long-baseline interferometric array, millimeter-wave telescope, submillimeter-wave telescope, and funding for radioastronomy facilities and projects. (JN)

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, Amrendra

2015-05-01

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scatteredmore » photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (?1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.« less

Determination of electron beam polarization using electron detector in Compton polarimeter with less than 1% statistical and systematic uncertainty

NASA Astrophysics Data System (ADS)

Narayan, Amrendra

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (~1GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a high radiation environment and it has enabled us to achieve the desired precision in the measurement of the electron beam polarization which in turn has allowed the most precise determination of the weak charge of the proton.

Evaluation and display of polarimetric image data using long-wave cooled microgrid focal plane arrays

NASA Astrophysics Data System (ADS)

Bowers, David L.; Boger, James K.; Wellems, L. David; Black, Wiley T.; Ortega, Steve E.; Ratliff, Bradley M.; Fetrow, Matthew P.; Hubbs, John E.; Tyo, J. Scott

2006-05-01

Recent developments for Long Wave InfraRed (LWIR) imaging polarimeters include incorporating a microgrid polarizer array onto the focal plane array (FPA). Inherent advantages over typical polarimeters include packaging and instantaneous acquisition of thermal and polarimetric information. This allows for real time video of thermal and polarimetric products. The microgrid approach has inherent polarization measurement error due to the spatial sampling of a non-uniform scene, residual pixel to pixel variations in the gain corrected responsivity and in the noise equivalent input (NEI), and variations in the pixel to pixel micro-polarizer performance. The Degree of Linear Polarization (DoLP) is highly sensitive to these parameters and is consequently used as a metric to explore instrument sensitivities. Image processing and fusion techniques are used to take advantage of the inherent thermal and polarimetric sensing capability of this FPA, providing additional scene information in real time. Optimal operating conditions are employed to improve FPA uniformity and sensitivity. Data from two DRS Infrared Technologies, L.P. (DRS) microgrid polarizer HgCdTe FPAs are presented. One FPA resides in a liquid nitrogen (LN2) pour filled dewar with a 80°K nominal operating temperature. The other FPA resides in a cryogenic (cryo) dewar with a 60° K nominal operating temperature.

Polarization-polarization correlation measurement --- Experimental test of the PPCO methods

NASA Astrophysics Data System (ADS)

Droste, Ch.; Starosta, K.; Wierzchucka, A.; Morek, T.; Rohoziński, S. G.; Srebrny, J.; Wesolowski, E.; Bergstrem, M.; Herskind, B.

1998-04-01

A significant fraction of modern multidetector arrays used for "in-beam" gamma-ray spectroscopy consist of a detectors which are sensitive to linear polarization of gamma quanta. This yields the opportunity to carry out correlation measurements between the gamma rays registered in polarimeters to get information concerning spins and parities of excited nuclear states. The aim of the present work was to study the ability of the polarization- polarization correlation method (the PPCO method). The correlation between the linear polarization of one gamma quantum and the polarization of the second quantum emitted in a cascade from an oriented nucleus (due to a heavy ion reaction) was studied in detail. The appropriate formulae and methods of analysis are presented. The experimental test of the method was performed using the EUROGAM II array. The CLOVER detectors are the parts of the array used as polarimeters. The ^164Yb nucleus was produced via the ^138Ba(^30Si, 4n) reaction. It was found that the PPCO method together with the standard DCO analysis and the polarization- direction correlation method (PDCO) can be helpful for spin, parity and multipolarity assignments. The results suggest that the PPCO method can be applied to modern spectrometers in which a large number of detectors (e.g. CLOVER) are sensitive to polarization of gamma rays.

Imaging of Stellar Surfacess Using Radio Facilities Including ALMA

NASA Astrophysics Data System (ADS)

O'Gorman, Eamon

2018-04-01

Until very recently, studies focusing on imaging stars at continuum radio wavelengths (here defined as submillimeter, millimeter, and centimeter wavelengths) has been scarce. These studies have mainly been carried out with the Very Large Array on a handful of evolved stars (i.e., Asymptotic Giant Branch and Red Supergiant stars) whereby their stellar disks have just about been spatially resolved. Some of these results however, have challenged our historical views on the nature of evolved star atmospheres. Now, the very long baselines of the Atacama Large Millimeter/submillimeter Array and the newly upgraded Karl G. Jansky Very Large Array provide a new opportunity to image these atmospheres at unprecedented spatial resolution and sensitivity across a much wider portion of the radio spectrum. In this talk I will first provide a history of stellar radio imaging and then discuss some recent exciting ALMA results. Finally I will present some brand new multi-wavelength ALMA and VLA results for the famous red supergiant Antares.

Instrumentation for Kinetic-Inductance-Detector-Based Submillimeter Radio Astronomy

NASA Astrophysics Data System (ADS)

Duan, Ran

A substantial amount of important scientific information is contained within astronomical data at the submillimeter and far-infrared (FIR) wavelengths, including information regarding dusty galaxies, galaxy clusters, and star-forming regions; however, these wavelengths are among the least-explored fields in astronomy because of the technological difficulties involved in such research. Over the past 20 years, considerable efforts have been devoted to developing submillimeter- and millimeter-wavelength astronomical instruments and telescopes. The number of detectors is an important property of such instruments and is the subject of the current study. Future telescopes will require as many as hundreds of thousands of detectors to meet the necessary requirements in terms of the field of view, scan speed, and resolution. A large pixel count is one benefit of the development of multiplexable detectors that use kinetic inductance detector (KID) technology. This dissertation presents the development of a KID-based instrument including a portion of the millimeter-wave bandpass filters and all aspects of the readout electronics, which together enabled one of the largest detector counts achieved to date in submillimeter-/millimeter-wavelength imaging arrays: a total of 2304 detectors. The work presented in this dissertation has been implemented in the MUltiwavelength Submillimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).

Ghostly Boomerang

NASA Image and Video Library

2013-10-25

The Boomerang nebula, called the coldest place in the universe, reveals its true shape to the Atacama Large Millimeter/submillimeter Array ALMA telescope. The background blue structure, is seen in visible light by NASA Hubble Space Telescope.

Millimeter and submillimeter wave spectroscopy of propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Jørgensen, Jes K.; Schlemmer, Stephan

2017-12-01

The rotational spectra of the two stable conformers syn- and gauche-propanal (CH3CH2CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first excited states associated with the aldehyde torsion and with the methyl torsion, respectively, of the syn-conformer were analyzed. The newly obtained spectroscopic parameters yield better predictions, thus fulfill sensitivity and resolution requirements in new astronomical observations in order to unambiguously assign pure rotational transitions of propanal. This is demonstrated on a radio astronomical spectrum from the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (ALMA-PILS). In particular, an accurate description of observed splittings, caused by internal rotation of the methyl group in the syn-conformer and by tunneling rotation interaction from two stable degenerate gauche-conformers, is reported. The rotational spectrum of propanal is of additional interest because of its two large amplitude motions pertaining to the methyl and the aldehyde group, respectively.

A kinematic flexure-based mechanism for precise parallel motion for the Hertz Variable-delay Polarization Modulator (VPM)

NASA Astrophysics Data System (ADS)

Voellmer, G. M.; Chuss, D. T.; Jackson, M.; Krejny, M.; Moseley, S. H.; Novak, G.; Wollack, E. J.

2006-06-01

We describe the design and construction of a Variable-delay Polarization Modulator (VPM) that has been built and integrated into the Hertz ground-based, submillimeter polarimeter at the SMTO on Mt. Graham in Arizona. VPMs allow polarization modulation by controlling the phase difference between two linear, orthogonal polarizations. This is accomplished by utilizing a grid-mirror pair with a controlled separation. The size of the gap between the mirror and the polarizing grid determines the amount of the phase difference. This gap must be parallel to better than 1% of the wavelength. The necessity of controlling the phase of the radiation across this device drives the two novel features of the VPM. First, a novel, kinematic, flexure is employed that passively maintains the parallelism of the mirror and the grid to 1.5 μm over a 150 mm diameter, with a 400 μm throw. A single piezoceramic actuator is used to modulate the gap, and a capacitive sensor provides position feedback for closed-loop control. Second, the VPM uses a grid flattener that highly constrains the planarity of the polarizing grid. In doing so, the phase error across the device is minimized. Engineering results from the deployment of this device in the Hertz instrument April 2006 at the Submillimeter Telescope Observatory (SMTO) in Arizona are presented.

Evidence for a Population of High-Redshift Submillimeter Galaxies from Interferometric Imaging

NASA Astrophysics Data System (ADS)

Younger, Joshua D.; Fazio, Giovanni G.; Huang, Jia-Sheng; Yun, Min S.; Wilson, Grant W.; Ashby, Matthew L. N.; Gurwell, Mark A.; Lai, Kamson; Peck, Alison B.; Petitpas, Glen R.; Wilner, David J.; Iono, Daisuke; Kohno, Kotaro; Kawabe, Ryohei; Hughes, David H.; Aretxaga, Itziar; Webb, Tracy; Martínez-Sansigre, Alejo; Kim, Sungeun; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Lowenthal, James D.; Schinnerer, Eva; Smolčić, Vernesa

2007-12-01

We have used the Submillimeter Array to image a flux-limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890 μm with ~2" resolution. All of the sources-two radio-bright and five radio-dim-are detected as single point sources at high significance (>6 σ), with positions accurate to ~0.2" that enable counterpart identification at other wavelengths observed with similarly high angular resolution. All seven have IRAC counterparts, but only two have secure counterparts in deep HST ACS imaging. As compared to the two radio-bright sources in the sample, and those in previous studies, the five radio-dim sources in the sample (1) have systematically higher submillimeter-to-radio flux ratios, (2) have lower IRAC 3.6-8.0 μm fluxes, and (3) are not detected at 24 μm. These properties, combined with size constraints at 890 μm (θ<~1.2''), suggest that the radio-dim submillimeter galaxies represent a population of very dusty starbursts, with physical scales similar to local ultraluminous infrared galaxies, with an average redshift higher than radio-bright sources.

The AzTEC/SMA Interferometric Imaging Survey of Submillimeter-selected High-redshift Galaxies

NASA Astrophysics Data System (ADS)

Younger, Joshua D.; Fazio, Giovanni G.; Huang, Jia-Sheng; Yun, Min S.; Wilson, Grant W.; Ashby, Matthew L. N.; Gurwell, Mark A.; Peck, Alison B.; Petitpas, Glen R.; Wilner, David J.; Hughes, David H.; Aretxaga, Itziar; Kim, Sungeun; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Lowenthal, James D.

2009-10-01

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size ~2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology—including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared—of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation—which struggle to account for such objects even under liberal assumptions—and dust production models given the limited time since the big bang.

Compact Submillimeter-Wave Receivers Made with Semiconductor Nano-Fabrication Technologies

NASA Technical Reports Server (NTRS)

Jung, C.; Thomas, B.; Lee, C.; Peralta, A.; Chattopadhyay, G.; Gill, J.; Cooper, K.; Mehdi, I.

2011-01-01

Advanced semiconductor nanofabrication techniques are utilized to design, fabricate and demonstrate a super-compact, low-mass (<10 grams) submillimeter-wave heterodyne front-end. RF elements such as waveguides and channels are fabricated in a silicon wafer substrate using deep-reactive ion etching (DRIE). Etched patterns with sidewalls angles controlled with 1 deg precision are reported, while maintaining a surface roughness of better than 20 nm rms for the etched structures. This approach is being developed to build compact 2-D imaging arrays in the THz frequency range.

Detector characterization, optimization, and operation for ACTPol

NASA Astrophysics Data System (ADS)

Grace, Emily Ann

2016-01-01

Measurements of the temperature anisotropies of the Cosmic Microwave Background (CMB) have provided the foundation for much of our current knowledge of cosmology. Observations of the polarization of the CMB have already begun to build on this foundation and promise to illuminate open cosmological questions regarding the first moments of the universe and the properties of dark energy. The primary CMB polarization signal contains the signature of early universe physics including the possible imprint of inflationary gravitational waves, while a secondary signal arises due to late-time interactions of CMB photons which encode information about the formation and evolution of structure in the universe. The Atacama Cosmology Telescope Polarimeter (ACTPol), located at an elevation of 5200 meters in Chile and currently in its third season of observing, is designed to probe these signals with measurements of the CMB in both temperature and polarization from arcminute to degree scales. To measure the faint CMB polarization signal, ACTPol employs large, kilo-pixel detector arrays of transition edge sensor (TES) bolometers, which are cooled to a 100 mK operating temperature with a dilution refrigerator. Three such arrays are currently deployed, two with sensitivity to 150 GHz radiation and one dichroic array with 90 GHz and 150 GHz sensitivity. The operation of these large, monolithic detector arrays presents a number of challenges for both assembly and characterization. This thesis describes the design and assembly of the ACTPol polarimeter arrays and outlines techniques for their rapid characterization. These methods are employed to optimize the design and operating conditions of the detectors, select wafers for deployment, and evaluate the baseline array performance. The results of the application of these techniques to wafers from all three ACTPol arrays is described, including discussion of the measured thermal properties and time constants. Finally, aspects of the characterization and calibration of the deployed detectors during field operations are discussed.

Mitigation of image artifacts in LWIR microgrid polarimeter images

NASA Astrophysics Data System (ADS)

Ratliff, Bradley M.; Tyo, J. Scott; Boger, James K.; Black, Wiley T.; Bowers, David M.; Kumar, Rakesh

2007-09-01

Microgrid polarimeters, also known as division of focal plane (DoFP) polarimeters, are composed of an integrated array of micropolarizing elements that immediately precedes the FPA. The result of the DoFP device is that neighboring pixels sense different polarization states. The measurements made at each pixel can be combined to estimate the Stokes vector at every reconstruction point in a scene. DoFP devices have the advantage that they are mechanically rugged and inherently optically aligned. However, they suffer from the severe disadvantage that the neighboring pixels that make up the Stokes vector estimates have different instantaneous fields of view (IFOV). This IFOV error leads to spatial differencing that causes false polarization signatures, especially in regions of the image where the scene changes rapidly in space. Furthermore, when the polarimeter is operating in the LWIR, the FPA has inherent response problems such as nonuniformity and dead pixels that make the false polarization problem that much worse. In this paper, we present methods that use spatial information from the scene to mitigate two of the biggest problems that confront DoFP devices. The first is a polarimetric dead pixel replacement (DPR) scheme, and the second is a reconstruction method that chooses the most appropriate polarimetric interpolation scheme for each particular pixel in the image based on the scene properties. We have found that these two methods can greatly improve both the visual appearance of polarization products as well as the accuracy of the polarization estimates, and can be implemented with minimal computational cost.

Dead pixel replacement in LWIR microgrid polarimeters.

PubMed

Ratliff, Bradley M; Tyo, J Scott; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P

2007-06-11

LWIR imaging arrays are often affected by nonresponsive pixels, or "dead pixels." These dead pixels can severely degrade the quality of imagery and often have to be replaced before subsequent image processing and display of the imagery data. For LWIR arrays that are integrated with arrays of micropolarizers, the problem of dead pixels is amplified. Conventional dead pixel replacement (DPR) strategies cannot be employed since neighboring pixels are of different polarizations. In this paper we present two DPR schemes. The first is a modified nearest-neighbor replacement method. The second is a method based on redundancy in the polarization measurements.We find that the redundancy-based DPR scheme provides an order-of-magnitude better performance for typical LWIR polarimetric data.

Progress in passive submillimeter-wave video imaging

NASA Astrophysics Data System (ADS)

Heinz, Erik; May, Torsten; Born, Detlef; Zieger, Gabriel; Peiselt, Katja; Zakosarenko, Vyacheslav; Krause, Torsten; Krüger, André; Schulz, Marco; Bauer, Frank; Meyer, Hans-Georg

2014-06-01

Since 2007 we are developing passive submillimeter-wave video cameras for personal security screening. In contradiction to established portal-based millimeter-wave scanning techniques, these are suitable for stand-off or stealth operation. The cameras operate in the 350GHz band and use arrays of superconducting transition-edge sensors (TES), reflector optics, and opto-mechanical scanners. Whereas the basic principle of these devices remains unchanged, there has been a continuous development of the technical details, as the detector array, the scanning scheme, and the readout, as well as system integration and performance. The latest prototype of this camera development features a linear array of 128 detectors and a linear scanner capable of 25Hz frame rate. Using different types of reflector optics, a field of view of 1×2m2 and a spatial resolution of 1-2 cm is provided at object distances of about 5-25m. We present the concept of this camera and give details on system design and performance. Demonstration videos show its capability for hidden threat detection and illustrate possible application scenarios.

Functional Description of Read-out Electronics for Time-Domain Multiplexed Bolometers for Millimeter and Sub-millimeter Astronomy

NASA Astrophysics Data System (ADS)

Battistelli, E. S.; Amiri, M.; Burger, B.; Halpern, M.; Knotek, S.; Ellis, M.; Gao, X.; Kelly, D.; Macintosh, M.; Irwin, K.; Reintsema, C.

2008-05-01

We have developed multi-channel electronics (MCE) which work in concert with time-domain multiplexors developed at NIST, to control and read signals from large format bolometer arrays of superconducting transition edge sensors (TESs). These electronics were developed as part of the Submillimeter Common-User Bolometer Array-2 (SCUBA2 ) camera, but are now used in several other instruments. The main advantages of these electronics compared to earlier versions is that they are multi-channel, fully programmable, suited for remote operations and provide a clean geometry, with no electrical cabling outside of the Faraday cage formed by the cryostat and the electronics chassis. The MCE is used to determine the optimal operating points for the TES and the superconducting quantum interference device (SQUID) amplifiers autonomously. During observation, the MCE execute a running PID-servo and apply to each first stage SQUID a feedback signal necessary to keep the system in a linear regime at optimal gain. The feedback and error signals from a ˜1000-pixel array can be written to hard drive at up to 2 kHz.

Study of retro reflector array for the polarimeter-interferometer system on EAST Tokamak

NASA Astrophysics Data System (ADS)

Lan, T.; Wang, S. X.; Liu, H. Q.; Liu, J.; Jie, Y. X.; Zou, Z. Y.; Li, W. M.; Gao, X.; Qin, H.

2015-12-01

In this paper, we experimentally verify the feasibility of replacing individual retro reflectors (RRs) with retro reflector array (RRA) in EAST POlarimeter/INTerferometer (POINT) system, by considering mode transformation and power wastage. Being exposed to plasma environment directly, RRs have risks of deformation, erosion and deposition. RRA is preferable because it can be installed within a smaller space and provide a gap of several centimeters for the shutter design. This protective structure can reduce the cost of device maintenance and bring down system errors. According to Helmholtz-Kirchhoff integral theorem, the optimized incident diameter for the RRA, constituted by seven hexagonal RR cells, is 40 mm in POINT system. The corresponding bench tests are carried out by measuring the propagation properties of reflected beams by plane RRA for perpendicular incidence and reflected beams by terrace RRA for oblique incidence. The experimental results illustrate that RRA can be satisfactorily applied in POINT system at the optimized incident diameter. In view of the energy wastage caused by plasma film coating, it is found that RRA has more advantages for diagnostics using shorter wavelengths, such as the case in ITER.

High-resolution two-dimensional and three-dimensional modeling of wire grid polarizers and micropolarizer arrays

NASA Astrophysics Data System (ADS)

Vorobiev, Dmitry; Ninkov, Zoran

2017-11-01

Recent advances in photolithography allowed the fabrication of high-quality wire grid polarizers for the visible and near-infrared regimes. In turn, micropolarizer arrays (MPAs) based on wire grid polarizers have been developed and used to construct compact, versatile imaging polarimeters. However, the contrast and throughput of these polarimeters are significantly worse than one might expect based on the performance of large area wire grid polarizers or MPAs, alone. We investigate the parameters that affect the performance of wire grid polarizers and MPAs, using high-resolution two-dimensional and three-dimensional (3-D) finite-difference time-domain simulations. We pay special attention to numerical errors and other challenges that arise in models of these and other subwavelength optical devices. Our tests show that simulations of these structures in the visible and near-IR begin to converge numerically when the mesh size is smaller than ˜4 nm. The performance of wire grid polarizers is very sensitive to the shape, spacing, and conductivity of the metal wires. Using 3-D simulations of micropolarizer "superpixels," we directly study the cross talk due to diffraction at the edges of each micropolarizer, which decreases the contrast of MPAs to ˜200∶1.

Motion-based nonuniformity correction in DoFP polarimeters

NASA Astrophysics Data System (ADS)

Kumar, Rakesh; Tyo, J. Scott; Ratliff, Bradley M.

2007-09-01

Division of Focal Plane polarimeters (DoFP) operate by integrating an array of micropolarizer elements with a focal plane array. These devices have been investigated for over a decade, and example systems have been built in all regions of the optical spectrum. DoFP devices have the distinct advantage that they are mechanically rugged, inherently temporally synchronized, and optically aligned. They have the concomitant disadvantage that each pixel in the FPA has a different instantaneous field of view (IFOV), meaning that the polarization component measurements that go into estimating the Stokes vector across the image come from four different points in the field. In addition to IFOV errors, microgrid camera systems operating in the LWIR have the additional problem that FPA nonuniformity (NU) noise can be quite severe. The spatial differencing nature of a DoFP system exacerbates the residual NU noise that is remaining after calibration, and is often the largest source of false polarization signatures away from regions where IFOV error dominates. We have recently presented a scene based algorithm that uses frame-to-frame motion to compensate for NU noise in unpolarized IR imagers. In this paper, we have extended that algorithm so that it can be used to compensate for NU noise on a DoFP polarimeter. Furthermore, the additional information provided by the scene motion can be used to significantly reduce the IFOV error. We have found a reduction of IFOV error by a factor of 10 if the scene motion is known exactly. Performance is reduced when the motion must be estimated from the scene, but still shows a marked improvement over static DoFP images.

A Submillimeter Perspective on the Goods Fields. II. The High Radio Power Population in the Goods-N

NASA Astrophysics Data System (ADS)

Barger, A. J.; Cowie, L. L.; Owen, F. N.; Hsu, L.-Y.; Wang, W.-H.

2017-01-01

We use ultradeep 20 cm data from the Karl G. Jansky Very Large Array and 850 μm data from SCUBA-2 and the Submillimeter Array of an 124 arcmin2 region of the Chandra Deep Field-north to analyze the high radio power ({P}20{cm}> {10}31 erg s-1 Hz-1) population. We find that 20 (42 ± 9%) of the spectroscopically identified z> 0.8 sources have consistent star formation rates (SFRs) inferred from both submillimeter and radio observations, while the remaining sources have lower (mostly undetected) submillimeter fluxes, suggesting that active galactic nucleus (AGN) activity dominates the radio power in these sources. We develop a classification scheme based on the ratio of submillimeter flux to radio power versus radio power and find that it agrees with AGN and star-forming galaxy classifications from Very Long Baseline Interferometry. Our results provide support for an extremely rapid drop in the number of high SFR galaxies above about a thousand solar masses per year (Kroupa initial mass function) and for the locally determined relation between X-ray luminosity and radio power for star-forming galaxies applying at high redshifts and high radio powers. We measure far-infrared (FIR) luminosities and find that some AGNs lie on the FIR-radio correlation, while others scatter below. The AGNs that lie on the correlation appear to do so based on their emission from the AGN torus. We measure a median radio size of 1.″0 ± 0.3 for the star-forming galaxies. The radio sizes of the star-forming galaxies are generally larger than those of the AGNs. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

Superconducting Microwave Resonator Arrays for Submillimeter/Far-Infrared Imaging

NASA Astrophysics Data System (ADS)

Noroozian, Omid

Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next-generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104--10 6 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing ˜ 10 3 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity. An MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be detected using a cryogenic amplifier and subsequent homodyne mixing at room temperature. In an array of MKIDs, all the resonators are coupled to a shared feedline and are tuned to slightly different frequencies. They can be read out simultaneously using a comb of frequencies generated and measured using digital techniques. This thesis documents an effort to demonstrate the basic operation of ˜ 256 pixel arrays of lumped-element MKIDs made from superconducting TiN x on silicon. The resonators are designed and simulated for optimum operation. Various properties of the resonators and arrays are measured and compared to theoretical expectations. A particularly exciting observation is the extremely high quality factors (˜ 3 x 107) of our TiNx resonators which is essential for ultra-high sensitivity. The arrays are tightly packed both in space and in frequency which is desirable for larger full-size arrays. However, this can cause a serious problem in terms of microwave crosstalk between neighboring pixels. We show that by properly designing the resonator geometry, crosstalk can be eliminated; this is supported by our measurement results. We also tackle the problem of excess frequency noise in MKIDs. Intrinsic noise in the form of an excess resonance frequency jitter exists in planar superconducting resonators that are made on dielectric substrates. We conclusively show that this noise is due to fluctuations of the resonator capacitance. In turn, the capacitance fluctuations are thought to be driven by two-level system (TLS) fluctuators in a thin layer on the surface of the device. With a modified resonator design we demonstrate with measurements that this noise can be substantially reduced. An optimized version of this resonator was designed for the multiwavelength submillimeter kinetic inductance camera (MUSIC) instrument for the Caltech Submillimeter Observatory.

Interpolation strategies for reducing IFOV artifacts in microgrid polarimeter imagery.

PubMed

Ratliff, Bradley M; LaCasse, Charles F; Tyo, J Scott

2009-05-25

Microgrid polarimeters are composed of an array of micro-polarizing elements overlaid upon an FPA sensor. In the past decade systems have been designed and built in all regions of the optical spectrum. These systems have rugged, compact designs and the ability to obtain a complete set of polarimetric measurements during a single image capture. However, these systems acquire the polarization measurements through spatial modulation and each measurement has a varying instantaneous field-of-view (IFOV). When these measurements are combined to estimate the polarization images, strong edge artifacts are present that severely degrade the estimated polarization imagery. These artifacts can be reduced when interpolation strategies are first applied to the intensity data prior to Stokes vector estimation. Here we formally study IFOV error and the performance of several bilinear interpolation strategies used for reducing it.

THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Younger, Joshua D.; Fazio, Giovanni G.; Huang Jiasheng

We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-includingmore » the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.« less

Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.

2011-01-01

Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter-wave and terahertz bands: a) Antenna fabrication compatible with lithographic techniques. b) Much simpler fabrication of the lens. c) A simple quarter-wavelength matching layer of the lens will be more efficient if a smaller portion of the lens is used. d) The directivity is given by the lens diameter instead of the leaky pole (the bandwidth will not depend anymore on the directivity but just on the initial cavity). The feed is a standard waveguide, which is compatible with proven Schottky diode mixer/detector technologies. The development of such technology will benefit applications where submillimeter- wave heterodyne array designs are required. The main fields are national security, planetary exploration, and biomedicine. For national security, wideband submillimeter radars could be an effective tool for the standoff detection of hidden weapons or bombs concealed by clothing or packaging. In the field of planetary exploration, wideband submillimeter radars can be used as a spectrometer to detect trace concentrations of chemicals in atmospheres that are too cold to rely on thermal imaging techniques. In biomedicine, an imaging heterodyne system could be helpful in detecting skin diseases.

Design and fabrication of two-dimensional semiconducting bolometer arrays for HAWC and SHARC-II

NASA Astrophysics Data System (ADS)

Voellmer, George M.; Allen, Christine A.; Amato, Michael J.; Babu, Sachidananda R.; Bartels, Arlin E.; Benford, Dominic J.; Derro, Rebecca J.; Dowell, C. D.; Harper, D. A.; Jhabvala, Murzy D.; Moseley, S. H.; Rennick, Timothy; Shirron, Peter J.; Smith, W. W.; Staguhn, Johannes G.

2003-02-01

The High resolution Airborne Wideband Camera (HAWC) and the Submillimeter High Angular Resolution Camera II (SHARC II) will use almost identical versions of an ion-implanted silicon bolometer array developed at the National Aeronautics and Space Administration's Goddard Space Flight Center (GSFC). The GSFC "Pop-Up" Detectors (PUD's) use a unique folding technique to enable a 12 × 32-element close-packed array of bolometers with a filling factor greater than 95 percent. A kinematic Kevlar suspension system isolates the 200 mK bolometers from the helium bath temperature, and GSFC - developed silicon bridge chips make electrical connection to the bolometers, while maintaining thermal isolation. The JFET preamps operate at 120 K. Providing good thermal heat sinking for these, and keeping their conduction and radiation from reaching the nearby bolometers, is one of the principal design challenges encountered. Another interesting challenge is the preparation of the silicon bolometers. They are manufactured in 32-element, planar rows using Micro Electro Mechanical Systems (MEMS) semiconductor etching techniques, and then cut and folded onto a ceramic bar. Optical alignment using specialized jigs ensures their uniformity and correct placement. The rows are then stacked to create the 12 × 32-element array. Engineering results from the first light run of SHARC II at the Caltech Submillimeter Observatory (CSO) are presented.

Spatially Resolved Sub-millimeter Continuum Imaging of Neptune with ALMA

NASA Astrophysics Data System (ADS)

Iino, Takahiro; Yamada, Takayoshi

2018-02-01

This paper reports the result of spatially resolved 646 GHz sub-millimeter imaging observation of Neptune obtained by the Atacama Large Millimeter and sub-millimeter Array. The observation was performed in 2012 August as the flux calibration and synthesized beam size were small enough to resolve Neptune’s disk at this time. This analysis aims to constrain the vertical structure of deep and upper-tropospheric South polar hot spot detected previously with mid-IR, millimeter, and centimeter wavelength. The probed atmospheric pressure region estimated by the radiative-transfer method was between 1.0 and 0.6 bar for the nadir and South pole views, respectively. The South polar hot spot was not detected clearly with an uncertainty of 2.1 K. The apparent discontinuity of tropospheric and stratospheric hot spot may be caused by the vertical wind shear of South polar zonal jet.

Optically-switched submillimeter-wave oscillator and radiator having a switch-to-switch propagation delay

NASA Technical Reports Server (NTRS)

Spencer, Michael G. (Inventor); Maserjian, Joseph (Inventor)

1995-01-01

A submillimeter wave-generating integrated circuit includes an array of N photoconductive switches biased across a common voltage source and an optical path difference from a common optical pulse of repetition rate f sub 0 providing a different optical delay to each of the switches. In one embodiment, each incoming pulse is applied to successive ones of the N switches with successive delays. The N switches are spaced apart with a suitable switch-to-switch spacing so as to generate at the output load or antenna radiation of a submillimeter wave frequency f on the order of N f sub 0. Preferably, the optical pulse has a repetition rate of at least 10 GHz and N is of the order of 100, so that the circuit generates radiation of frequency of the order of or greater than 1 Terahertz.

A Proposed Robotic Astronomy Mission to the Lunar South Polar Regions

NASA Technical Reports Server (NTRS)

Lowman, Paul D., Jr.

2003-01-01

This paper outlines a possible mission to emplace a robotic infrared / submillimeter wave interferometer array near the lunar south pole. This region has now been investigated by the Clementine and Lunar Prospector missions, and by Earth-based radar, and its topography and thermal environment are fairly well-known. The area would be exceptionally suitable for infrared / submillimeter astronomy because of the continually low temperatures, approaching that of liquid nitrogen (77K) in some places. A submillimeter spaceborne interferometer mission, Submillimeter Probe of the Evolution of the Cosmic Structure (SPECS) has been proposed by John Mather and others, covering the 40 - 500 micron region with 3 formation flying telescopes. The present paper proposes a lunar adaptation of the SPECS concept, LSPECS. This adaptation would involve landing 4 telescopes on the area north of Shackleton crater at zero degrees longitude. This is in nearly year round darkness but is continually radar visible from Earth. The landed payload of LSPECS would include a telerobotic rover, 4 three meter submm telescopes, a solar power array to be emplaced on the continually sunlit north rim of Shackleton crater, and an S-band antenna for data relay to Earth. Passive cooling without the use of expendable cryogenics. might be possible, trading long exposure time for instrument temperatures above that of liquid helium. The LSPECS would permit long-term study of an extremely wide range of cosmic and solar system phenomena in the southern celestial hemisphere. For complete sky coverage, a similar installation near the north pole would be required. The LSPECS site would also be suitable other types of observation, such as optical interferometry or centimeter wavelength radio astronomy. The lunar south pole is also of great interest because of its extensive ice deposits, which may represent cometary infall with pre-biotic compounds.

The Detector System for the Stratospheric Kinetic Inductance Polarimeter ( Skip)

NASA Astrophysics Data System (ADS)

Johnson, B. R.; Ade, P. A. R.; Araujo, D.; Bradford, K. J.; Chapman, D.; Day, P. K.; Didier, J.; Doyle, S.; Eriksen, H. K.; Flanigan, D.; Groppi, C.; Hillbrand, S.; Jones, G.; Limon, M.; Mauskopf, P.; McCarrick, H.; Miller, A.; Mroczkowski, T.; Reichborn-Kjennerud, B.; Smiley, B.; Sobrin, J.; Wehus, I. K.; Zmuidzinas, J.

2014-09-01

The stratospheric kinetic inductance polarimeter is a proposed balloon-borne experiment designed to study the cosmic microwave background, the cosmic infrared background and Galactic dust emission by observing 1,133 deg of sky in the Northern Hemisphere with launches from Kiruna, Sweden. The instrument contains 2,317 single-polarization, horn-coupled, aluminum lumped-element kinetic inductance detectors ( Lekids). The Lekids will be maintained at 100 mK with an adiabatic demagnetization refrigerator. The polarimeter operates in two configurations, one sensitive to a spectral band centered on 150 GHz and the other sensitive to 260 and 350 GHz bands. The detector readout system is based on the ROACH-1 board, and the detectors will be biased below 300 MHz. The detector array is fed by an F/2.4 crossed-Dragone telescope with a 500 mm aperture yielding a 15 arcmin FWHM beam at 150 GHz. To minimize detector loading and maximize sensitivity, the entire optical system will be cooled to 1 K. Linearly polarized sky signals will be modulated with a metal-mesh half-wave plate that is mounted at the telescope aperture and rotated by a superconducting magnetic bearing. The observation program consists of at least two, 5-day flights beginning with the 150 GHz observations.

The Stratospheric Kinetic Inductance Polarimeter (SKIP)

NASA Astrophysics Data System (ADS)

Flanigan, Daniel; Ade, P.; Araujo, D.; Bradford, K. J.; Chapman, D.; Che, G.; Day, P.; Didier, J.; Doyle, S.; Eriksen, H.; Groppi, C. E.; Hillbrand, S. N.; Johnson, B.; Jones, G.; Limon, M.; Mauskopf, P.; McCarrick, H.; Miller, A. D.; Mroczkowski, T.; Reichborn-Kjennerud, B.; Smiley, B.; Sobrin, J.; Wehus, I. K.; Zmuidzinas, J.

2014-01-01

We discuss the Stratospheric Kinetic Inductance Polarimeter (SKIP). SKIP is a proposed balloon-borne experiment designed to study the cosmic microwave background, the cosmic infrared background, and Galactic dust emission by observing 1100 square degrees of sky in the Northern Hemisphere with launches from Kiruna, Sweden. The instrument contains 2317 single-polarization, horn-coupled, aluminum lumped-element kinetic inductance detectors (LEKIDs), which will be maintained at 100 mK by an adiabatic demagnetization refrigerator. The polarimeter will operate in two configurations, one sensitive to a spectral band centered on 150 GHz and the other sensitive to 260 and 350 GHz bands. The detector readout system is based on the ROACH-1 board, and the detectors will be biased below 300 MHz. The detector array is fed by an F/2.4 crossed-Dragone telescope with a 500 mm aperture yielding a 15 arcminute full-width half-maximum beam at 150 GHz. To minimize detector loading and maximize sensitivity, the entire optical system will be cooled to 1 K. Linearly polarized sky signals will be modulated with a metal-mesh half-wave plate that is mounted at the telescope aperture and is rotated on a superconducting magnetic bearing. The observation program consists of two or more five-day flights, and 150 GHz observations are planned to begin in 2017.

Spectroscopic Capabilities and Possibilities of the Far Infrared and Submillimeter Telescope Mission

NASA Technical Reports Server (NTRS)

Pearson, J. C.

2000-01-01

The Far Infrared and Submillimeter Telescope (FIRST) mission is the fourth European Space Agency corner stone mission. FIRST will be an observatory with a passively cooled (80 Kelvin) 3.5 meter class telescope and three cryogenic instruments covering the 670 to 80 mm spectral region. The mission is slated for a 4.5 year operational lifetime in an L2 orbit. It will share an Arian 5 launch with PLANCK in early 2007. The three payload instruments include the Spectral and Photometric Imaging Receiver (SPIRE), which is a bolometer array with Martin-Puplett FTS for 200-670 microns, the Photoconductor Array Camera and Spectrometer (PACS), which is a photoconductor array with a grating spectrometer for 80-210 microns and the Heterodyne Instrument for FIRST (HIFI), which is a series of seven heterodyne receivers covering 480-1250 GHz and portions of 1410-1910 GHz and 2400-2700 GHz. FIRST will make many detailed spectral surveys of a wide variety of objects previously obscured by the atmosphere and in regions of the spectrum seldom used for astronomical observations, With all of the spectroscopic capability on FIRST a great deal of laboratory spectroscopic support will be needed for accurate interpretation of the spectral data.

ZEUS-2: a second generation submillimeter grating spectrometer for exploring distant galaxies

NASA Astrophysics Data System (ADS)

Ferkinhoff, Carl; Nikola, Thomas; Parshley, Stephen C.; Stacey, Gordon J.; Irwin, Kent D.; Cho, Hsiao-Mei; Halpern, Mark

2010-07-01

ZEUS-2, the second generation (z)Redshift and Early Universe Spectrometer, like its predecessor is a moderate resolution (R~1000) long-slit, echelle grating spectrometer optimized for the detection of faint, broad lines from distant galaxies. It is designed for studying star-formation across cosmic time. ZEUS-2 employs three TES bolometer arrays (555 pixels total) to deliver simultaneous, multi-beam spectra in up to 4 submillimeter windows. The NIST Boulder-built arrays operate at ~100mK and are readout via SQUID multiplexers and the Multi-Channel Electronics from the University of British Columbia. The instrument is cooled via a pulse-tube cooler and two-stage ADR. Various filter configurations give ZEUS-2 access to 7 different telluric windows from 200 to 850 micron enabling the simultaneous mapping of lines from extended sources or the simultaneous detection of the 158 micron [CII] line and the [NII] 122 or 205 micron lines from z = 1-2 galaxies. ZEUS-2 is designed for use on the CSO, APEX and possibly JCMT.

The rectangular array of magnetic probes on J-TEXT tokamak.

PubMed

Chen, Zhipeng; Li, Fuming; Zhuang, Ge; Jian, Xiang; Zhu, Lizhi

2016-11-01

The rectangular array of magnetic probes system was newly designed and installed in the torus on J-TEXT tokamak to measure the local magnetic fields outside the last closed flux surface at a single toroidal angle. In the implementation, the experimental results agree well with the theoretical results based on the Spool model and three-dimensional numerical finite element model when the vertical field was applied. Furthermore, the measurements were successfully used as the input of EFIT code to conduct the plasma equilibrium reconstruction. The calculated Faraday rotation angle using the EFIT output is in agreement with the measured one from the three-wave polarimeter-interferometer system.

The rectangular array of magnetic probes on J-TEXT tokamak

NASA Astrophysics Data System (ADS)

Chen, Zhipeng; Li, Fuming; Zhuang, Ge; Jian, Xiang; Zhu, Lizhi

2016-11-01

The rectangular array of magnetic probes system was newly designed and installed in the torus on J-TEXT tokamak to measure the local magnetic fields outside the last closed flux surface at a single toroidal angle. In the implementation, the experimental results agree well with the theoretical results based on the Spool model and three-dimensional numerical finite element model when the vertical field was applied. Furthermore, the measurements were successfully used as the input of EFIT code to conduct the plasma equilibrium reconstruction. The calculated Faraday rotation angle using the EFIT output is in agreement with the measured one from the three-wave polarimeter-interferometer system.

ORAC-DR: A generic data reduction pipeline infrastructure

NASA Astrophysics Data System (ADS)

Jenness, Tim; Economou, Frossie

2015-03-01

ORAC-DR is a general purpose data reduction pipeline system designed to be instrument and observatory agnostic. The pipeline works with instruments as varied as infrared integral field units, imaging arrays and spectrographs, and sub-millimeter heterodyne arrays and continuum cameras. This paper describes the architecture of the pipeline system and the implementation of the core infrastructure. We finish by discussing the lessons learned since the initial deployment of the pipeline system in the late 1990s.

GASP-Galway astronomical Stokes polarimeter

NASA Astrophysics Data System (ADS)

Kyne, G.; Sheehan, B.; Collins, P.; Redfern, M.; Shearer, A.

2010-06-01

The Galway Astronomical Stokes Polarimeter (GASP) is an ultra-high-speed, full Stokes, astronomical imaging polarimeter based upon a Division of Amplitude Polarimeter. It has been developed to resolve extremely rapid stochastic (~ms) variations in objects such as optical pulsars, magnetars and magnetic cataclysmic variables. The polarimeter has no moving parts or modulated components so the complete Stokes vector can be measured from just one exposure - making it unique to astronomy. The time required for the determination of the full Stokes vector is limited only by detector efficiency and photon fluxes. The polarimeter utilizes a modified Fresnel rhomb that acts as a highly achromatic quarter wave plate and a beamsplitter (referred to as an RBS). We present a description of how the DOAP works, some of the optical design for the polarimeter. Calibration is an important and difficult issue with all polarimeters, but particularly in astronomical polarimeters. We give a description of calibration techniques appropriate to this type of polarimeter.

Development of adaptive liquid microlenses and microlens arrays

NASA Astrophysics Data System (ADS)

Berry, Shaun R.; Stewart, Jason B.; Thorsen, Todd A.; Guha, Ingrid

2013-03-01

We report on the development of sub-millimeter size adaptive liquid microlenses and microlens arrays using two immiscible liquids to form individual lenses. Microlenses and microlens arrays having aperture diameters as small as 50 microns were fabricated on a planar quartz substrate using patterned hydrophobic/hydrophilic regions. Liquid lenses were formed by a self-assembled oil dosing process that created well-defined lenses having a high fill factor. Variable focus was achieved by controlling the lens curvature through electrowetting. Greater than 70° of contact angle change was achieved with less than 20 volts, which results in a large optical power dynamic range.

Extreme Millimeter/Sub-millimeter and Radio Flares from V404 Cyg (GS 2023+338)

NASA Astrophysics Data System (ADS)

Tetarenko, A.; Sivakoff, G. R.; Young, Ken; Wouterloot, J. G. A.; Miller-Jones, J. C.

2015-06-01

We report follow up radio and mm/sub-mm observations (ATel #7671) of the current outburst of the black hole X-ray binary, V404 Cyg, with the VLA, Submillimeter Array (SMA), and James Clerk Maxwell Telescope SCUBA-2 (JCMT).

Status of the PAPPA experiment

NASA Technical Reports Server (NTRS)

Kogut, Alan

2006-01-01

The Primordial Anisotropy Polarization Pathfinder Array (PAPPA) is a balloonborne instrument to measure the polarization of the cosmic microwave background and search for the signature of primordial gravity waves. PAPPA uses a novel marriage of RF phase modulation and millimeter-wave bolometric detectors to produce a "polarimeter-on-a-chip" capable of simultaneously measuring the Stokes I, Q, and U parameters on the sky. I will discuss the current status and future plans for PAPPA.

Broadband Direct Detection Submillimeter Spectrometer with Multiplexed Superconducting Transition Edge Thermometer Bolometers

NASA Technical Reports Server (NTRS)

Benford, D. J.; Ames, T. A.; Chervenak, J. A.; Moseley, S. H.; Shafer, R. A.; Staguhn, J. G.; Voellmer, G. M.; Pajot, F.; Rioux, C.; Phillips, T. G.;

Broad-bandwidth Metamaterial Antireflection Coatings for Sub-Millimeter Astronomy and CMB Foreground Removal

NASA Astrophysics Data System (ADS)

McMahon, Jeff

Sub-millimeter observations are crucial for answering questions about star and galaxy formation; understanding galactic dust foregrounds; and for removing these foregrounds to detect the faint signature of inflationary gravitational waves in the polarization of the Cosmic Microwave Background (CMB). Achieving these goals requires improved, broad-band antireflection coated lenses and half-wave plates (HWPs). These optical elements will significantly boost the sensitivity and capability of future sub-millimeter and CMB missions. We propose to develop wide-bandwidth metamaterial antireflection coatings for silicon lenses and sapphire HWPs with 3:1 ratio bandwidth that are scalable across the sub-millimeter band from 300 GHz to 3 THz. This is an extension of our successful work on saw cut metamaterial AR coatings for silicon optics at millimeter wave lengths. These, and the proposed coatings consist of arrays of sub-wavelength scale features cut into optical surfaces that behave like simple dielectrics. We have demonstrated saw cut 3:1 bandwidth coatings on silicon lenses, but these coatings are limited to the millimeter wave band by the limitations of dicing saw machining. The crucial advance needed to extend these broad band coatings throughout the sub-millimeter band is the development of laser cut graded index metamaterial coatings. The proposed work includes developing the capability to fabricate these coatings, optimizing the design of these metamaterials, fabricating and testing prototype lenses and HWPs, and working with the PIPER collaboration to achieve a sub-orbital demonstration of this technology. The proposed work will develop potentially revolutionary new high performance coatings for the sub-millimeter bands, and cary this technology to TRL 7 paving the way for its use in space. We anticipate that there will be a wide range of applications for these coatings on future NASA balloons and satellites.

Nobeyama Radio Observatory

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

Nobeyama Radio Observatory has telescopes at millimeter and submillimeter wavelengths. It was established in 1982 as an observatory of Tokyo Astronomical Observatory (NATIONAL ASTRONOMICAL OBSERVATORY, JAPAN since 1987), and operates the 45 m telescope, Nobeyama Millimeter Array, and Radioheliograph. High-resolution images of star forming regions and molecular clouds have revealed many aspects of...

VizieR Online Data Catalog: Molecular clouds in the dwarf galaxy NGC6822 (Schruba+, 2017)

NASA Astrophysics Data System (ADS)

Schruba, A.; Leroy, A. K.; Kruijssen, J. M. D.; Bigiel, F.; Bolatto, A. D.; de Blok, W. J. G.; Tacconi, L.; van Dishoeck, E. F.; Walter, F.

2017-09-01

We observed five fields in NGC 6822 with the Atacama Large Millimeter/submillimeter Array (ALMA) in Cycle 1 using the 1.3mm Band 6 receivers (project code: 2013.1.00351.S; PI. A. Schruba) in 2014 Mar 23-25. (1 data file).

New 50-m-class single-dish telescope: Large Submillimeter Telescope (LST)

NASA Astrophysics Data System (ADS)

Kawabe, Ryohei; Kohno, Kotaro; Tamura, Yoichi; Takekoshi, Tatsuya; Oshima, Tai; Ishii, Shun

2016-08-01

We report on a plan to construct a 50-m-class single-dish telescope, the Large Submillimeter Telescope (LST). The conceptual design and key science behind the LST are presented, together with its tentative specifications. This telescope is optimized for wide-area imaging and spectroscopic surveys in the 70-420 GHz frequency range, which spans the main atmospheric windows at millimeter and submillimeter wavelengths for good observation sites such as the Atacama Large Millimeter/submillimeter Array (ALMA) site in Chile. We also target observations at higher frequencies of up to 1 THz, using an inner high-precision surface. Active surface control is required in order to correct gravitational and thermal deformations of the surface, and will be useful for correction of the wind-load deformation. The LST will facilitate new discovery spaces such as wide-field imaging with both continuum and spectral lines, along with new developments for time-domain science. Through exploitation of its synergy with ALMA and other telescopes, the LST will contribute to research on a wide range of topics in the fields of astronomy and astrophysics, e.g., astrochemistry, star formation in our Galaxy and galaxies, the evolution of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect, the search for transients such as γ-ray burst reverse shocks produced during the epoch of re-ionization, electromagnetic follow up of detected gravitational wave sources, and examination of general relativity in the vicinity of super massive black holes via submillimeter very-long-baseline interferometry (VLBI).

An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna

NASA Technical Reports Server (NTRS)

Buttgenbach, Thomas H.

1993-01-01

The hybrid antenna discussed here is defined as a dielectric lens-antenna as a special case of an extended hemi-spherical dielectric lens that is operated in the diffraction limited regime. It is a modified version of the planar antenna on a lens scheme developed by Rutledge. The dielectric lens-antenna is fed by a planar-structure antenna, which is mounted on the flat side of the dielectric lens-antenna using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of extension of the hemi- spherical lens and different lens sizes. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. At 115 GHz the aperture efficiency was measured to be (76 4 +/- 6) % for a diffraction limited beam with sidelobes below -17 dB. Results of a single hybrid antenna with an integrated Superconductor-Insulator-Superconductor (SIS) detector and a broad-band matching structure at submillimeter wavelengths are presented. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays.

Science with the wideband Submillimeter Array: A Strategy for the Decade 2017-2027

NASA Astrophysics Data System (ADS)

Wilner, D.; Keto, E.; Bower, G.; Ching, T. C.; Gurwell, M.; Hirano, N.; Keating, G.; Lai, S. P.; Patel, N.; Petitpas, G.; Qi, C.; Sridharan, T. K.; Urata, Y.; Young, K.; Zhang, Q.; Zhao, J.-H.

2017-01-01

The Submillimeter Array (SMA) comprises eight movable 6-meter diameter antennas sited on Maunakea, Hawaii, designed for high spatial and spectral resolution observations at submillimeter wavelengths. Pioneering observations with the SMA have provided new insights into a wide variety of astrophysical phenomena, including the formation and evolution of galaxies, stars and planets, and the nature of the supermassive black hole at the center of the Milky Way. Following careful deliberation, the SMA project is embarking on an ambitious, staged, strategic upgrade that will increase its instantaneous bandwidth and dramatically improve its observational sensitivity and speed. The unique capabilities of this ultra-wideband SMA - the "wSMA" promise to spark a new era of forefront discoveries. In brief, the wSMA upgrade will provide a core receiver set providing dual-polarization observing bands covering the 345 GHz and 230 GHz atmospheric windows, each with 32 GHz of spectral coverage. Together with upgrades of the signal transport system and digital correlator, this brings a factor of 16 increase in instantaneous bandwidth from the original SMA capability. For continuum observations, speed increases linearly with bandwidth to a given level of sensitivity, enabling more observations to the same depth in the same amount of time. Or, for a given amount of time, the sensitivity increases as the square root of bandwidth, enabling deeper observations. For line observations, spectral coverage increases linearly with bandwidth, enabling observations of many lines simultaneously, all at high spectral resolution. In effect, every wSMA observation of an astronomical source is an imaging spectral line survey, and an enormous amount of information can be extracted from such data in conjunction with physical, chemical and dynamical models. This whitepaper elaborates on illustrative examples in key scientific areas, including the evolutionary state of protostellar sources, the chemistry of evolved star envelopes, the constituents of planetary atmospheres, starburst galaxies in the local Universe and at high redshifts, and even low-mass galaxies at high redshifts through the technique of intensity mapping. The wSMA speeds up observations to allow systematic, comparative studies of large numbers of spectral surveys for the first time. The wSMA also will be ideally suited for the study of sources in the time domain. Illustrative examples include the variability of the accretion flow onto the SgrA* black hole, capturing emission from gamma ray bursts from massive star deaths in the early universe and the mergers of compact objects that produce gravitational waves, and resolved spectroscopy of the pristine material that escapes from comets as they traverse the inner Solar System. The wSMA will be complementary to the larger international Atacama Large Millimeter/ submillimeter Array (ALMA) in Chile, which followed the SMA into submillimeter interferometry in 2011. The immense time pressure on ALMA from its many constituencies only creates an increasing need for the wSMA, notably for the large class of observations that do not require ALMA's full sensitivity or angular resolution, as well as for unique submillimeter access to the northern sky. The wSMA will play a leading role in select science areas in the ALMA era, including those requiring long-term programs to build large samples, or rapid response based on flexible scheduling, as well as for high risk seed studies specifically designed for subsequent ALMA follow-up. In addition, the wSMA will be a critical station for submillimeter VLBI observations of supermassive black holes in the global Event Horizon Telescope, which will be bolstered by the inclusion of ALMA in 2017. Finally, the wSMA design explicitly incorporates open space for additional instrumentation to pursue new and compelling science goals and technical innovations, continuing its role as a pathfinder for submillimeter astronomy.

Performance assessment study of the balloon-borne astronomical soft gamma-ray polarimeter PoGOLite

NASA Astrophysics Data System (ADS)

Arimoto, M.; Kanai, Y.; Ueno, M.; Kataoka, J.; Kawai, N.; Tanaka, T.; Yamamoto, K.; Takahashi, H.; Mizuno, T.; Fukazawa, Y.; Axelsson, M.; Kiss, M.; Marini Bettolo, C.; Carlson, P.; Klamra, W.; Pearce, M.; Chen, P.; Craig, B.; Kamae, T.; Madejski, G.; Ng, J. S. T.; Rogers, R.; Tajima, H.; Thurston, T. S.; Saito, Y.; Takahashi, T.; Gunji, S.; Bjornsson, C.-I.; Larsson, S.; Ryde, F.; Bogaert, G.; Varner, G.

2007-12-01

Measurements of polarization play a crucial role in the understanding of the dominant emission mechanism of astronomical sources. Polarized Gamma-ray Observer-Light version (PoGOLite) is a balloon-borne astronomical soft gamma-ray polarimeter at the 25 80 keV band. The PoGOLite detector consists of a hexagonal close-packed array of 217 Phoswich detector cells (PDCs) and side anti-coincidence shields (SASs) made of BGO crystals surrounding PDCs. Each PDC consists of a slow hollow scintillator, a fast scintillator and a BGO crystal that connects to a photomultiplier tube at the end. To examine the PoGOLite's capability and estimate the performance, we conducted experiments with the PDC using radioisotope 241Am. In addition, we compared this result with performance expected by Monte Carlo simulation with Geant4. As a result, we found that the actual PDC has the capability to detect a 100 m Crab source until 80 keV.

Polarimetry with the JCMT

NASA Astrophysics Data System (ADS)

Moriarty-Schieven, Gerald H.; Greaves, Jane S.

1999-10-01

Polarization of dust or synchrotron emission in the sub-millimetre-wave regime directly traces magnetic field directions. The magnetic field energy is similar to that of gravity and turbulence in interstellar gas, and so plays a major role in the dynamics and evolution of the interstellar medium. We present some early results from the aperture polarimeter on the SCUBA sub-mm bolometer array on the JCMT from a wide variety of sources, and briefly discuss the importance of a polarimetric capability for ALMA.

LSPECS: A Proposed Robotic Astronomy Mission to the Lunar South Polar Regions

NASA Technical Reports Server (NTRS)

Lowman, Paul D., Jr.

2003-01-01

This paper outlines a possible mission to emplace a robotic infrared/submillimeter wave interferometer array near the lunar south pole. This region has now been investigated by the Clementine and Lunar Prospector missions, and by Earth-based radar, and its topography and thermal environment are fairly well-known. The area would be exceptionally suitable for infrared/submillimeter astronomy because of the continually low temperatures, approaching that of liquid nitrogen (77K) in some places. The presence of ice has been inferred independently from Clementine and Lunar Prospector, providing another incentive for a south polar mission. A submillimeter spaceborne interferometer mission, Submillimeter Probe of the Evolution of the Cosmic Structure (SPECS) has been proposed by John Mather and others, covering the 40 - 500 micron region with 3 formation flying telescopes. The present paper proposes a lunar adaptation of the SPECS concept, LSPECS. This adaptation would involve landing 4 telescopes on the area north of Shackleton crater at zero degrees longitude. This is in nearly year round darkness but is continually radar visible from Earth. The landed payload of LSPECS would include a telerobotic rover, 4 three meter submm telescopes, a solar power array to be emplaced on the continually sunlit north rim of Shackleton crater, and an S-band antenna for data relay to Earth. Operation without the use of expendable cryogenics for cooling might be possible, trading long exposure time for instrument temperatures above that of liquid helium. The LSPECS would permit long-term study of an extremely wide range of cosmic and solar system phenomena in the southern celestial hemisphere. For complete sky coverage, a similar installation near the north pole would be required. The LSPECS site would also be suitable other types of observation, such as optical interferometry or centimeter wavelength radio astronomy. The lunar south pole is also of great interest because of its extensive ice deposits, which may represent cometary infall with pre-biotic compounds.

Deciphering Debris Disk Structure with the Submillimeter Array

NASA Astrophysics Data System (ADS)

MacGregor, Meredith Ann

2018-01-01

More than 20% of nearby main sequence stars are surrounded by dusty disks continually replenished via the collisional erosion of planetesimals, larger bodies similar to asteroids and comets in our own Solar System. The material in these ‘debris disks’ is directly linked to the larger bodies such as planets in the system. As a result, the locations, morphologies, and physical properties of dust in these disks provide important probes of the processes of planet formation and subsequent dynamical evolution. Observations at millimeter wavelengths are especially critical to our understanding of these systems, since they are dominated by larger grains that do not travel far from their origin and therefore reliably trace the underlying planetesimal distribution. The Submillimeter Array (SMA) plays a key role in advancing our understanding of debris disks by providing sensitivity at the short baselines required to determine the structure of wide-field disks, such as the HR 8799 debris disk. Many of these wide-field disks are among the closest systems to us, and will serve as cornerstone templates for the interpretation of more distant, less accessible systems.

Antenna-Coupled Bolometer Arrays for Astrophysics

NASA Astrophysics Data System (ADS)

Bock, James

Bolometers offer the best sensitivity in the far-infrared to millimeter-wave region of the electromagnetic spectrum. We are developing arrays of feedhorn-coupled bolometers for the ESA/NASA Planck Surveyor and Herschel Space Observatory. Advances in the format and sensitivity of bolometric focal plane array enables future astrophysics mission opportunities, such as CMB polarimetry and far-infrared/submillimeter spectral line surveys. Compared to bolometers with extended area radiation absorbers, antenna-coupled bolometers offer active volumes that are orders of magnitude smaller. Coupled to lithographed micro-strip filters and antennas, antenna-coupled bolometer arrays allow flexible focal plane architectures specialized for imaging, polarimetry, and spectroscopy. These architectures greatly reduce the mass of sub-Kelvin bolometer focal planes that drive the design of bolometric instrumentation.

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics and architectural comparison of polarimeter techniques

NASA Astrophysics Data System (ADS)

Yang, Ruonan; Sen, Pratik; O'Connor, B. T.; Kudenov, M. W.

2017-08-01

An intrinsic coincident full-Stokes polarimeter is demonstrated by using stain-aligned polymer-based organic photovoltaics (OPVs) which can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. Two wave plates were incorporated into the system to modulate the S3 stokes parameter so as to reduce the condition number of the measurement matrix. The model for the full-Stokes polarimeter was established and validated, demonstrating an average RMS error of 0.84%. The optimization, based on minimizing the condition number of the 4-cell OPV design, showed that a condition number of 2.4 is possible. Performance of this in-line polarimeter concept was compared to other polarimeter architectures, including Division of Time (DoT), Division of Amplitude (DoAm), Division of Focal Plane (DoFP), and Division of Aperture (DoA) from signal-to-noise ratio (SNR) perspective. This in-line polarimeter concept has the potential to enable both high temporal (as compared with a DoT polarimeter) and high spatial resolution (as compared with DoFP and DoA polarimeters). We conclude that the intrinsic design has the same √2 SNR advantage as the DoAm polarimeter, but with greater compactness.

The Microwave SQUID Multiplexer

NASA Astrophysics Data System (ADS)

Mates, John Arthur Benson

2011-12-01

This thesis describes a multiplexer of Superconducting Quantum Interference Devices (SQUIDs) with low-noise, ultra-low power dissipation, and great scalability. The multiplexer circuit measures the magnetic flux in a large number of unshunted rf SQUIDs by coupling each SQUID to a superconducting microwave resonator tuned to a unique resonance frequency and driving the resonators from a common feedline. A superposition of microwave tones measures each SQUID simultaneously using only two coaxial cables between the cryogenic device and room temperature. This multiplexer will enable the instrumentation of arrays with hundreds of thousands of low-temperature detectors for new applications in cosmology, materials analysis, and nuclear non-proliferation. The driving application of the Microwave SQUID Multiplexer is the readout of large arrays of superconducting transition-edge sensors, by some figures of merit the most sensitive detectors of electromagnetic signals over a span of more than nine orders of magnitude in energy, from 40 GHz microwaves to 200 keV gamma rays. Modern transition-edge sensors have noise-equivalent power as low as 10-20 W / Hz1/2 and energy resolution as good as 2 eV at 6 keV. These per-pixel sensitivities approach theoretical limits set by the underlying signals, motivating a rapid increase in pixel count to access new science. Compelling applications, like the non-destructive assay of nuclear material for treaty verification or the search for primordial gravity waves from inflation use arrays of these detectors to increase collection area or tile a focal plane. We developed three generations of SQUID multiplexers, optimizing the first for flux noise 0.17 muPhi0 / Hz1/2, the second for input current noise 19 pA / Hz1/2, and the last for practical multiplexing of large arrays of cosmic microwave background polarimeters based on transition-edge sensors. Using the last design we demonstrated multiplexed readout of prototype polarimeters with the performance required for the future development of a large-scale astronomical instrument.

SMURF: SubMillimeter User Reduction Facility

NASA Astrophysics Data System (ADS)

Jenness, Tim; Chapin, Edward L.; Berry, David S.; Gibb, Andy G.; Tilanus, Remo P. J.; Balfour, Jennifer; Tilanus, Vincent; Currie, Malcolm J.

2013-10-01

SMURF reduces submillimeter single-dish continuum and heterodyne data. It is mainly targeted at data produced by the James Clerk Maxwell Telescope but data from other telescopes have been reduced using the package. SMURF is released as part of the bundle that comprises Starlink (ascl:1110.012) and most of the packages that use it. The two key commands are MAKEMAP for the creation of maps from sub millimeter continuum data and MAKECUBE for the creation of data cubes from heterodyne array instruments. The software can also convert data from legacy JCMT file formats to the modern form to allow it to be processed by MAKECUBE. SMURF is a core component of the ORAC-DR (ascl:1310.001) data reduction pipeline for JCMT.

ALMA OBSERVATIONS OF Ly α BLOB 1: HALO SUBSTRUCTURE ILLUMINATED FROM WITHIN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geach, J. E.; Narayanan, D.; Matsuda, Y.

2016-11-20

We present new Atacama Large Millimeter/Submillimeter Array (ALMA) 850 μ m continuum observations of the original Ly α Blob (LAB) in the SSA22 field at z = 3.1 (SSA22-LAB01). The ALMA map resolves the previously identified submillimeter source into three components with a total flux density of S {sub 850} = 1.68 ± 0.06 mJy, corresponding to a star-formation rate of ∼150 M {sub ⊙} yr{sup -1}. The submillimeter sources are associated with several faint ( m ≈ 27 mag) rest-frame ultraviolet sources identified in Hubble Space Telescope Imaging Spectrograph (STIS) clear filter imaging ( λ ≈ 5850 Å). Onemore » of these companions is spectroscopically confirmed with the Keck Multi-Object Spectrometer For Infra-Red Exploration to lie within 20 projected kpc and 250 km s{sup -1} of one of the ALMA components. We postulate that some of these STIS sources represent a population of low-mass star-forming satellites surrounding the central submillimeter sources, potentially contributing to their growth and activity through accretion. Using a high-resolution cosmological zoom simulation of a 10{sup 13} M {sub ⊙} halo at z = 3, including stellar, dust, and Ly α radiative transfer, we can model the ALMA+STIS observations and demonstrate that Ly α photons escaping from the central submillimeter sources are expected to resonantly scatter in neutral hydrogen, the majority of which is predicted to be associated with halo substructure. We show how this process gives rise to extended Ly α emission with similar surface brightness and morphology to observed giant LABs.« less

A sub-millimeter resolution detector module for small-animal PET applications

NASA Astrophysics Data System (ADS)

Sacco, I.; Dohle, R.; Fischer, P.; Gola, A.; Piemonte, C.; Ritzert, M.

2017-01-01

We present a gamma detection module optimized for very high resolution PET applications, able to resolve arrays of scintillating crystals with sub-millimeter pitch. The detector is composed of a single ceramic substrate (LTCC): it hosts four flip-chip mounted PETA5 ASICs on the bottom side and an array of SiPM sensors on the top surface, fabricated in HD-RGB technology by FBK. Each chip has 36 channels, for a maximum of 144 readout channels on a sensitive area of about 32 mm × 32 mm. The module is MR-compatible. The thermal decoupling of the readout electronics from the photon sensors is obtained with an efficient internal liquid channel, integrated within the ceramic substrate. Two modules have been designed, based on different SiPM topologies: • Light spreader-based: an array of 12 × 12 SiPMs, with an overall pitch of 2.5 mm, is coupled with a scintillators array using a 1 mm thick glass plate. The light from one crystal is spread over a group of SiPMs, which are read out in parallel using PETA5 internal neighbor logic. • Interpolating SiPM-based: ISiPMs are intrinsic position-sensitive sensors. The photon diodes in the array are connected to one of the four available outputs so that the center of gravity of any bunch of detected photons can be reconstructed using a proper weight function of the read out amplitudes. An array of ISiPMs, each 7.5 mm× 5 mm sized, is directly coupled with the scintillating crystals. Both modules can clearly resolve LYSO arrays with a pitch of only 0.833 mm. The detector can be adjusted for clinical PET, where it has already shown ToF resolution of about 230 ps CRT at FWHM. The module designs, their features and results are described.

The Primordial Inflation Polarization Explorer (PIPER)

NASA Technical Reports Server (NTRS)

Chuss, David

2010-01-01

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne polarimeter that will measure the polarization of the cosmic microwave background to search for evidence for inflation. PIPER will observe more than half of the sky in four frequency bands from 200 to 600 GHz with a beam size of 21 arcminutes at the lowest frequency. PIPER simultaneously measures all four Stokes parameters using four co-aligned 32 by 40 element planar bolometer arrays. We give an instrument overview and report on the current status of the instrument.

Submillimeter video imaging with a superconducting bolometer array

NASA Astrophysics Data System (ADS)

Becker, Daniel Thomas

Millimeter wavelength radiation holds promise for detection of security threats at a distance, including suicide bombers and maritime threats in poor weather. The high sensitivity of superconducting Transition Edge Sensor (TES) bolometers makes them ideal for passive imaging of thermal signals at millimeter and submillimeter wavelengths. I have built a 350 GHz video-rate imaging system using an array of feedhorn-coupled TES bolometers. The system operates at standoff distances of 16 m to 28 m with a measured spatial resolution of 1.4 cm (at 17 m). It currently contains one 251-detector sub-array, and can be expanded to contain four sub-arrays for a total of 1004 detectors. The system has been used to take video images that reveal the presence of weapons concealed beneath a shirt in an indoor setting. This dissertation describes the design, implementation and characterization of this system. It presents an overview of the challenges associated with standoff passive imaging and how these problems can be overcome through the use of large-format TES bolometer arrays. I describe the design of the system and cover the results of detector and optical characterization. I explain the procedure used to generate video images using the system, and present a noise analysis of those images. This analysis indicates that the Noise Equivalent Temperature Difference (NETD) of the video images is currently limited by artifacts of the scanning process. More sophisticated image processing algorithms can eliminate these artifacts and reduce the NETD to 100 mK, which is the target value for the most demanding passive imaging scenarios. I finish with an overview of future directions for this system.

The Hyper-Angular Rainbow Polarimeter (HARP) CubeSat Observatory and the Characterization of Cloud Properties

NASA Astrophysics Data System (ADS)

Neilsen, T. L.; Martins, J. V.; Fernandez Borda, R. A.; Weston, C.; Frazier, C.; Cieslak, D.; Townsend, K.

2015-12-01

The Hyper-Angular Rainbow Polarimeter HARP instrument is a wide field-of-view imager that splits three spatially identical images into three independent polarizers and detector arrays.This technique achieves simultaneous imagery of the same ground target in three polarization states and is the key innovation to achieve high polarimetric accuracy with no moving parts. The spacecraft consists of a 3U CubeSat with 3-axis stabilization designed to keep the image optics pointing nadir during data collection but maximizing solar panel sun pointing otherwise. The hyper-angular capability is achieved by acquiring overlapping images at very fast speeds.An imaging polarimeter with hyper-angular capability can make a strong contribution to characterizing cloud properties. Non-polarized multi-angle measurements have been shown to besensitive to thin cirrus and can be used to provide climatology ofthese clouds. Adding polarization and increasing the number ofobservation angles allows for the retrieval of the complete sizedistribution of cloud droplets, including accurate information onthe width of the droplet distribution in addition to the currentlyretrieved effective radius.The HARP mission is funded by the NASA Earth Science Technology Office as part of In-Space Validation of Earth Science Technologies (InVEST) program. The HARP instrument is designed and built by a team of students and professionals lead by Dr. Vanderlei Martines at University of Maryland, Baltimore County. The HARP spacecraft is designed and built by a team of students and professionals and The Space Dynamics Laboratory.

Antenna-coupled TES bolometer arrays for CMB polarimetry

NASA Astrophysics Data System (ADS)

Kuo, C. L.; Bock, J. J.; Bonetti, J. A.; Brevik, J.; Chattopadhyay, G.; Day, P. K.; Golwala, S.; Kenyon, M.; Lange, A. E.; LeDuc, H. G.; Nguyen, H.; Ogburn, R. W.; Orlando, A.; Transgrud, A.; Turner, A.; Wang, G.; Zmuidzinas, J.

2008-07-01

We describe the design and performance of polarization selective antenna-coupled TES arrays that will be used in several upcoming Cosmic Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully lithographic polarimeter arrays utilize planar phased-antennas for collimation (F/4 beam) and microstrip filters for band definition (25% bandwidth). These devices demonstrate high optical efficiency, excellent beam shapes, and well-defined spectral bands. The dual-polarization antennas provide well-matched beams and low cross polarization response, both important for high-fidelity polarization measurements. These devices have so far been developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave atmospheric windows for CMB observations. In the near future, the flexible microstrip-coupled architecture can provide photon noise-limited detection for the entire frequency range of the CMBPOL mission. This paper is a summary of the progress we have made since the 2006 SPIE meeting in Orlando, FL.

The Atacama Cosmology Telescope: Instrument

NASA Astrophysics Data System (ADS)

Thornton, Robert J.; Atacama Cosmology Telescope Team

2010-01-01

The 6-meter Atacama Cosmology Telescope (ACT) is making detailed maps of the Cosmic Microwave Background at Cerro Toco in northern Chile. In this talk, I focus on the design and operation of the telescope and its commissioning instrument, the Millimeter Bolometer Array Camera. The camera contains three independent sets of optics that operate at 148 GHz, 217 GHz, and 277 GHz with arcminute resolution, each of which couples to a 1024-element array of Transition Edge Sensor (TES) bolometers. I will report on the camera performance, including the beam patterns, optical efficiencies, and detector sensitivities. Under development for ACT is a new polarimeter based on feedhorn-coupled TES devices that have improved sensitivity and are planned to operate at 0.1 K.

A BRIGHT SUBMILLIMETER SOURCE IN THE BULLET CLUSTER (1E0657-56) FIELD DETECTED WITH BLAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rex, Marie; Devlin, Mark J.; Dicker, Simon R.

2009-09-20

We present the 250, 350, and 500 {mu}m detection of bright submillimeter emission in the direction of the Bullet Cluster measured by the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST). The 500 {mu}m centroid is coincident with an AzTEC 1.1 mm point-source detection at a position close to the peak lensing magnification produced by the cluster. However, the 250 {mu}m and 350 {mu}m centroids are elongated and shifted toward the south with a differential shift between bands that cannot be explained by pointing uncertainties. We therefore conclude that the BLAST detection is likely contaminated by emission from foreground galaxies associated with themore » Bullet Cluster. The submillimeter redshift estimate based on 250-1100 {mu}m photometry at the position of the AzTEC source is z{sub phot} = 2.9{sup +0.6}{sub -0.3}, consistent with the infrared color redshift estimation of the most likely Infrared Array Camera counterpart. These flux densities indicate an apparent far-infrared (FIR) luminosity of L{sub FIR} = 2 x 10{sup 13} L {sub sun}. When the amplification due to the gravitational lensing of the cluster is removed, the intrinsic FIR luminosity of the source is found to be L{sub FIR} <= 10{sup 12} L{sub sun}, consistent with typical luminous infrared galaxies.« less

First detection of equatorial dark dust lane in a protostellar disk at submillimeter wavelength

PubMed Central

Lee, Chin-Fei; Li, Zhi-Yun; Ho, Paul T. P.; Hirano, Naomi; Zhang, Qizhou; Shang, Hsien

2017-01-01

In the earliest (so-called “Class 0”) phase of Sun-like (low-mass) star formation, circumstellar disks are expected to form, feeding the protostars. However, these disks are difficult to resolve spatially because of their small sizes. Moreover, there are theoretical difficulties in producing these disks in the earliest phase because of the retarding effects of magnetic fields on the rotating, collapsing material (so-called “magnetic braking”). With the Atacama Large Millimeter/submillimeter Array (ALMA), it becomes possible to uncover these disks and study them in detail. HH 212 is a very young protostellar system. With ALMA, we not only detect but also spatially resolve its disk in dust emission at submillimeter wavelength. The disk is nearly edge-on and has a radius of ~60 astronomical unit. It shows a prominent equatorial dark lane sandwiched between two brighter features due to relatively low temperature and high optical depth near the disk midplane. For the first time, this dark lane is seen at submillimeter wavelength, producing a “hamburger”-shaped appearance that is reminiscent of the scattered-light image of an edge-on disk in optical and near infrared light. Our observations open up an exciting possibility of directly detecting and characterizing small disks around the youngest protostars through high-resolution imaging with ALMA, which provides strong constraints on theories of disk formation. PMID:28439561

VizieR Online Data Catalog: Selecting IRAC counterparts to SMGs (Alberts+, 2013)

NASA Astrophysics Data System (ADS)

Alberts, S.; Wilson, G. W.; Lu, Y.; Johnson, S.; Yun, M. S.; Scott, K. S.; Pope, A.; Aretxaga, I.; Ezawa, H.; Hughes, D. H.; Kawabe, R.; Kim, S.; Kohno, K.; Oshima, T.

2014-05-01

We present a new submm/mm galaxy counterpart identification technique which builds on the use of Spitzer Infrared Array Camera (IRAC) colours as discriminators between likely counterparts and the general IRAC galaxy population. Using 102 radio- and Submillimeter Array-confirmed counterparts to AzTEC sources across three fields [Great Observatories Origins Deep Survey-North, -South and Cosmic Evolution Survey (COSMOS)], we develop a non-parametric IRAC colour-colour characteristic density distribution, which, when combined with positional uncertainty information via likelihood ratios, allows us to rank all potential IRAC counterparts around submillimetre galaxies (SMGs) and calculate the significance of each ranking via the reliability factor. We report all robust and tentative radio counterparts to SMGs, the first such list available for AzTEC/COSMOS, as well as the highest ranked IRAC counterparts for all AzTEC SMGs in these fields as determined by our technique. We demonstrate that the technique is free of radio bias and thus applicable regardless of radio detections. For observations made with a moderate beam size (~18"), this technique identifies ~85% of SMG counterparts. For much larger beam sizes (>~30"), we report identification rates of 33-49%. Using simulations, we demonstrate that this technique is an improvement over using positional information alone for observations with facilities such as AzTEC on the Large Millimeter Telescope and Submillimeter Common User Bolometer Array 2 on the James Clerk Maxwell Telescope. (3 data files).

A Simple Polarimeter and Experiments Utilizing an Overhead Projector.

ERIC Educational Resources Information Center

Dorn, H. C.; And Others

1984-01-01

Although polarimeters that illustrate rotation of plane-polarized light by chiral solutions have been previously described, the polarimeter described in this paper has certain advantages when used in conjunction with an overhead projector. Instructions for constructing this polarimeter and its use in demonstrating the optical activity of sugars…

Europe, Japan and North America Prepare for Joint Construction of the Giant Radio Telescope "ALMA" in Chile

NASA Astrophysics Data System (ADS)

2001-04-01

Caption : PR Photo 14/01 shows how the ALMA facility may look like when it is ready at Chajnantor. Courtesy NAOJ . Representatives from Europe, Japan, and North America met in Tokyo today and signed a Resolution affirming their mutual intent to construct and operate a giant radio telescope in co-operation with the Republic of Chile, where the telescope will be located. The Atacama Large Millimeter/Submillimeter Array (ALMA) is conceived as a radio telescope comprised of sixty-four transportable 12-meter diameter antennas distributed over an area 14 km in extent. Japanese participation will allow enhanced imaging and spectroscopy, especially at submillimeter wavelengths. By pointing all the antennas in unison toward a single astronomical object, and combining the signals detected by all the antennas with a super-fast digital signal processor, this gigantic radio telescope achieves an imaging detail 10 times better than that of the Hubble Space Telescope. The combined area of all 64 antennas used to collect signals from celestial objects is more than 40 times larger than that available to astronomers using existing submillimeter telescopes. ALMA will be built on the Andean plateau at 5,000 meters altitude near the Atacama Desert of northern Chile. This site provides the exceptionally dry atmospheric conditions necessary for astronomical observations at millimeter and submillimeter wavelengths (wavelengths between the radio and far-infrared spectral regions). Observations with this telescope will have a profound impact on virtually all fields of astrophysical research. The most important targets include the most distant (i.e., the youngest) galaxies as they emerged in the early Universe. These are expected to have become rapidly enshrouded in the dust produced by the first stars; the dust absorbs much of the starlight making the galaxies difficult to see in the optical wavebands, but these same galaxies shine brightly at millimeter and submillimeter wavelengths. In our own Galaxy, ALMA will study the morphology, the motions and the chemistry of dust-enshrouded regions where stars and planets are being formed. ALMA will shed light on these optically `dark' celestial regions that carry key information on the origin of the richness of structure in the Universe and clues to the origin of life. ALMA is a merger of three large projects - The Millimeter Array (MMA) of the United States, the Large Southern Array (LSA) of Europe, and the Large Millimeter and Submillimeter Array (LMSA) of Japan - each of which has been endorsed as the top-priority project in their respective astronomical communities. The European and North American projects were merged into ALMA in 1999 and joint design and development of ALMA began at that time. The National Research Council of Canada is participating with the U.S. in the project. With Japan joining the project as a third partner equal with North America and Europe, and with Chile also taking part, ALMA has become one of the first truly global projects in the history of fundamental science. In the agreement signed today, the partners pledge to use their best efforts to obtain full approval and funding for their participation in ALMA. With the schedule planned, the telescope should be in full operation in 2010. Note [1]: This Press Release is issued jointly by ESO for its members plus UK and Spain, by the National Astronomical Observatory of Japan (NAOJ), by the US National Science Foundation (NSF) and by CONICYT in Chile. The embargo period coincides with a Press Conference by the partners in Tokyo (Japan). Links to earlier Press Releases etc. about ALMA are found on the dedicated webpage.

Submillimeter Bolometer Array for the CSO

NASA Astrophysics Data System (ADS)

Wang, Ning; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

We are building a bolometer array for use as a submillimeter continuum camera for the Caltech Submillimeter Observatory (CSO) located on Mauna Kea. This effort is a collaboration with Moseley et al. at Goddard Space Flight Center, who have developed the technique for fabricating monolithic bolometer arrays on Si wafers, as well as a sophisticated data taking system to use with these arrays (Moseley et al. 1984). Our primary goal is to construct a camera with 1x24 bolometer pixels operating at 350 and 450 microns using a 3He refrigerator. The monolithic bolometer arrays are fabricated using the techniques of photolithography and micromachining. Each pixel of the array is suspended by four thin Si legs 2 mm long and 12x14 square microns in cross section. These thin legs, obtained by wet Si etching, provide the weak thermal link between the bolometer pixel and the heat sink. A thermistor is formed on each bolometer pixel by P implantation compensated with 50% B. The bolometer array to be used for the camera will have a pixel size of 1x2 square millimeters, which is about half of the CSO beam size at a wavelength of 400 microns. We plan to use mirrors to focus the beam onto the pixels intead of Winston cones. In order to eliminate background radiation from warm surroundings reaching the bolometers, cold baffles will be inserted along the beam passages. To increase the bolometer absorption to radiation, a thin metal film will be deposited on the back of each bolometer pixel. It has been demonstrated that a proper impedance match of the bolometer element can increase the bolometer absorption efficiency to about 50% (Clarke et al., 1978). The use of baffle approach to illumination will make it easier for us to expand to more pixels in the future. The first stage amplification will be performed with cold FETs, connected to each bolometer pixel. Signals from each bolometer will be digitized using a 16 bit A/D with differential inputs. The digitizing frequency will be up to 40 kHz, though 1 kHz should be sufficient for our application. The output from the A/D will be fed to a digital signal processing (DSP) board via fiber optic cables, which will minimize the RF interference to the bolometers. To date, we have assembled a 1x24 bolometer array, and we are in the process of testing it. We are also designing and bulding cryogenic optics. The data acquisition hardware is nearly completed, as well as the electronics. Our goal is to get the instrument working after a new chopping secondary mirror in installed at the CSO in the summer of 1994. References: Moseley, S.H. et al. 1984, J. Appl. Phys.,56,1257; Clarke et al. 1977, J. Appl. Phys., 48, 4865.

Ground-based full-sky imaging polarimeter based on liquid crystal variable retarders.

PubMed

Zhang, Ying; Zhao, Huijie; Song, Ping; Shi, Shaoguang; Xu, Wujian; Liang, Xiao

2014-04-07

A ground-based full-sky imaging polarimeter based on liquid crystal variable retarders (LCVRs) is proposed in this paper. Our proposed method can be used to realize the rapid detection of the skylight polarization information with hemisphere field-of-view for the visual band. The characteristics of the incidence angle of light on the LCVR are investigated, based on the electrically controlled birefringence. Then, the imaging polarimeter with hemisphere field-of-view is designed. Furthermore, the polarization calibration method with the field-of-view multiplexing and piecewise linear fitting is proposed, based on the rotation symmetry of the polarimeter. The polarization calibration of the polarimeter is implemented with the hemisphere field-of-view. This imaging polarimeter is investigated by the experiment of detecting the skylight image. The consistency between the obtained experimental distribution of polarization angle with that due to Rayleigh scattering model is 90%, which confirms the effectivity of our proposed imaging polarimeter.

Time Projection Chamber Polarimeters for X-ray Astrophysics

NASA Astrophysics Data System (ADS)

Hill, Joanne; Black, Kevin; Jahoda, Keith

2015-04-01

Time Projection Chamber (TPC) based X-ray polarimeters achieve the sensitivity required for practical and scientifically significant astronomical observations, both galactic and extragalactic, with a combination of high analyzing power and good quantum efficiency. TPC polarimeters at the focus of an X-ray telescope have low background and large collecting areas providing the ability to measure the polarization properties of faint persistent sources. TPCs based on drifting negative ions rather than electrons permit large detector collecting areas with minimal readout electronics enabling wide field of view polarimeters for observing unpredictable, bright transient sources such as gamma-ray bursts. We described here the design and expected performance of two different TPC polarimeters proposed for small explorer missions: The PRAXyS (Polarimetry of Relativistic X-ray Sources) X-ray Polarimeter Instrument, optimized for observations of faint persistent sources and the POET (Polarimetry of Energetic Transients) Low Energy Polarimeter, designed to detect and measure bright transients. also NASA/GSFC.

Bolometric detector systems for IR and mm-wave space astronomy

NASA Technical Reports Server (NTRS)

Church, S. E.; Lange, A. E.; Mauskopf, P. D.; Hristov, V.; Bock, J. J.; DelCastillo, H. M.; Beeman, J.; Ade, P. A. R.; Griffin, M. J.

1996-01-01

Recent developments in bolometric detector systems for millimeter and submillimeter wave space astronomy are described. Current technologies meet all the requirements for the high frequency instrument onboard the cosmic background radiation anisotropy satellite/satellite for the measurement of background anisotropies (COBRAS/SAMBA) platform. It is considered that the technologies that are currently being developed will significantly reduce the effective time constant and/or the cooling requirements of bolometric detectors. These technologies lend themselves to the fabrication of the large format arrays required for the Far Infrared and Submillimeter Space Telescope (FIRST). The scientific goals and detector requirements of the COBRAS/SAMBA platform that will use infrared bolometers are reviewed and the baseline detector system is described, including the feed optics, the infrared filters, the cold amplifiers and the warm readout electronics.

Ultralow-Background Large-Format Bolometer Arrays

NASA Technical Reports Server (NTRS)

Benford, Dominic; Chervenak, Jay; Irwin, Kent; Moseley, S. Harvey; Oegerle, William (Technical Monitor)

2002-01-01

In the coming decade, work will commence in earnest on large cryogenic far-infrared telescopes and interferometers. All such observatories - for example, SAFIR, SPIRIT, and SPECS - require large format, two dimensional arrays of close-packed detectors capable of reaching the fundamental limits imposed by the very low photon backgrounds present in deep space. In the near term, bolometer array architectures which permit 1000 pixels - perhaps sufficient for the next generation of space-based instruments - can be arrayed efficiently. Demonstrating the necessary performance, with Noise Equivalent Powers (NEPs) of order 10-20 W/square root of Hz, will be a hurdle in the coming years. Superconducting bolometer arrays are a promising technology for providing both the performance and the array size necessary. We discuss the requirements for future detector arrays in the far-infrared and submillimeter, describe the parameters of superconducting bolometer arrays able to meet these requirements, and detail the present and near future technology of superconducting bolometer arrays. Of particular note is the coming development of large format planar arrays with absorber-coupled and antenna-coupled bolometers.

Three-Stage InP Submillimeter-Wave MMIC Amplifier

NASA Technical Reports Server (NTRS)

Pukala, David; Samoska, Lorene; Man, King; Gaier, Todd; Deal, William; Lai, Richard; Mei, Gerry; Makishi, Stella

2008-01-01

A submillimeter-wave monolithic integrated- circuit (S-MMIC) amplifier has been designed and fabricated using an indium phosphide (InP) 35-nm gate-length high electron mobility transistor (HEMT) device, developed at Northrop Grumman Corporation. The HEMT device employs two fingers each 15 micrometers wide. The HEMT wafers are grown by molecular beam epitaxy (MBE) and make use of a pseudomorphic In0.75Ga0.25As channel, a silicon delta-doping layer as the electron supply, an In0.52Al0.48As buffer layer, and an InP substrate. The three-stage design uses coplanar waveguide topology with a very narrow ground-to-ground spacing of 14 micrometers. Quarter-wave matching transmission lines, on-chip metal-insulator-metal shunt capacitors, series thin-film resistors, and matching stubs were used in the design. Series resistors in the shunt branch arm provide the basic circuit stabilization. The S-MMIC amplifier was measured for S-parameters and found to be centered at 320 GHz with 13-15-dB gain from 300-345 GHz. This chip was developed as part of the DARPA Submillimeter Wave Imaging Focal Plane Technology (SWIFT) program (see figure). Submillimeter-wave amplifiers could enable more sensitive receivers for earth science, planetary remote sensing, and astrophysics telescopes, particularly in radio astronomy, both from the ground and in space. A small atmospheric window at 340 GHz exists and could enable ground-based observations. However, the submillimeter-wave regime (above 300 GHz) is best used for space telescopes as Earth s atmosphere attenuates most of the signal through water and oxygen absorption. Future radio telescopes could make use of S-MMIC amplifiers for wideband, low noise, instantaneous frequency coverage, particularly in the case of heterodyne array receivers.

The Galway astronomical Stokes polarimeter: optical development

NASA Astrophysics Data System (ADS)

Collins, P.; Redfern, M.; Shearer, A.; Sheehan, B.

2010-06-01

The acquisition time of astronomical polarimeters has in the past been restricted to by the use of polarimeters utilizing modulated or rotating components [1]. If the polarisation state being measured is changing in the order of nanoseconds, how does one measure this? The Galway Astronomical Stokes Polarimeter (GASP) is an instantaneous full Stokes Division Of Amplitude Polarimeter (DOAP) that has been developed for astronomical imaging polarimetry. It also uses just one camera thus restricting the acquisition time to photon statistics. Following the work of Compain and Drévillon [2], the main component - the Retarding Beam-Splitter, was redesigned and enhanced for imaging use. We present how the polarization and imaging optics were developed to create a broadband imaging instantaneous polarimeter. unknown author type, collab

Super-resolution for imagery from integrated microgrid polarimeters.

PubMed

Hardie, Russell C; LeMaster, Daniel A; Ratliff, Bradley M

2011-07-04

Imagery from microgrid polarimeters is obtained by using a mosaic of pixel-wise micropolarizers on a focal plane array (FPA). Each distinct polarization image is obtained by subsampling the full FPA image. Thus, the effective pixel pitch for each polarization channel is increased and the sampling frequency is decreased. As a result, aliasing artifacts from such undersampling can corrupt the true polarization content of the scene. Here we present the first multi-channel multi-frame super-resolution (SR) algorithms designed specifically for the problem of image restoration in microgrid polarization imagers. These SR algorithms can be used to address aliasing and other degradations, without sacrificing field of view or compromising optical resolution with an anti-aliasing filter. The new SR methods are designed to exploit correlation between the polarimetric channels. One of the new SR algorithms uses a form of regularized least squares and has an iterative solution. The other is based on the faster adaptive Wiener filter SR method. We demonstrate that the new multi-channel SR algorithms are capable of providing significant enhancement of polarimetric imagery and that they outperform their independent channel counterparts.

The Third International Symposium on Space Terahertz Technology: Symposium proceedings

NASA Technical Reports Server (NTRS)

1992-01-01

Papers from the symposium are presented that are relevant to the generation, detection, and use of the terahertz spectral region for space astronomy and remote sensing of the Earth's upper atmosphere. The program included thirteen sessions covering a wide variety of topics including solid-state oscillators, power-combining techniques, mixers, harmonic multipliers, antennas and antenna arrays, submillimeter receivers, and measurement techniques.

Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/Submillimeter Array

NASA Technical Reports Server (NTRS)

Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Palmer, Maureen; Kisiel, Zbigniew

2015-01-01

Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iono, Daisuke; Hatsukade, Bunyo; Kawabe, Ryohei

The central structure in three of the brightest unlensed z = 3–4 submillimeter galaxies is investigated through 0.″015–0.″05 (120–360 pc) 860 μ m continuum images obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). The distribution in the central kiloparsec in AzTEC1 and AzTEC8 is extremely complex, and they are composed of multiple ∼200 pc clumps. AzTEC4 consists of two sources that are separated by ∼1.5 kpc, indicating a mid-stage merger. The peak star formation rate densities in the central clumps are ∼300–3000 M {sub ⊙} yr{sup −1} kpc{sup −2}, suggesting regions with extreme star formation near the Eddington limit. Bymore » comparing the flux obtained by ALMA and Submillimeter Array, we find that 68%–90% of the emission is extended (≳1 kpc) in AzTEC4 and 8. For AzTEC1, we identify at least 11 additional compact (∼200 pc) clumps in the extended 3–4 kpc region. Overall, the data presented here suggest that the luminosity surface densities observed at ≲150 pc scales are roughly similar to that observed in local ULIRGs, as in the eastern nucleus of Arp 220. Between 10% and 30% of the 860 μ m continuum is concentrated in clumpy structures in the central kiloparsec, while the remaining flux is distributed over ≳1 kpc regions, some of which could also be clumpy. These sources can be explained by a rapid inflow of gas such as a merger of gas-rich galaxies, surrounded by extended and clumpy starbursts. However, the cold mode accretion model is not ruled out.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunter, T. R.; Brogan, C. L.; Indebetouw, R.

Based on sub-arcsecond Atacama Large Millimeter/submillimeter Array (ALMA) and Submillimeter Array (SMA) 1.3 mm continuum images of the massive protocluster NGC 6334I obtained in 2015 and 2008, we find that the dust emission from MM1 has increased by a factor of 4.0 ± 0.3 during the intervening years, and undergone a significant change in morphology. The continuum emission from the other cluster members (MM2, MM4, and the UCH ii region MM3 = NGC 6334F) has remained constant. Long-term single-dish maser monitoring at HartRAO finds that multiple maser species toward NGC 6334I flared beginning in early 2015, a few months beforemore » our ALMA observation, and some persist in that state. New ALMA images obtained in 2016 July–August at 1.1 and 0.87 mm confirm the changes with respect to SMA 0.87 mm images from 2008, and indicate that the (sub)millimeter flaring has continued for at least a year. The excess continuum emission, centered on the hypercompact H ii region MM1B, is extended and elongated (1.″6 × 1.″0 ≈ 2100 × 1300 au) with multiple peaks, suggestive of general heating of the surrounding subcomponents of MM1, some of which may trace clumps in a fragmented disk rather than separate protostars. In either case, these remarkable increases in maser and dust emission provide direct observational evidence of a sudden accretion event in the growth of a massive protostar yielding a sustained luminosity surge by a factor of 70 ± 20, analogous to the largest events in simulations by Meyer et al. This target provides an excellent opportunity to assess the impact of such a rare event on a protocluster over many years.« less

The X-Ray Polarimeter Instrument on Board the Polarimeter for Relativistic Astrophysical X-Ray Sources (PRAXyS) Mission

NASA Technical Reports Server (NTRS)

Hill, J. E.; Black, J. K.; Jahoda, K.; Tamagawa, T.; Iwakiri, W.; Kitaguchi, T.; Kubota, M.; Kaaret, P.; Mccurdy, R.; Miles, D. M.;

An upgraded SCUBA-2 for JCMT

NASA Astrophysics Data System (ADS)

Bintley, Dan; Dempsey, Jessica T.; Friberg, Per; Holland, Wayne S.; MacIntosh, Michael J.

2016-07-01

SCUBA-2 is a state of the art wide field camera on the JCMT. SCUBA-2 has been fully operational since November 2011, producing a wide range of science results, including a unique series of survey programs. A new large survey programme commenced in 2015, which included for the first time, polarisation sensitive measurements using POL-2, the polarimeter ancillary instrument. We discuss proposals and the science case for upgrading SCUBA-2 with new detector arrays that will keep SCUBA-2 and the JCMT at the forefront of continuum submillimetre science.

The Hyper-Angular Rainbow Polarimeter (HARP) CubeSat Observatory and the Characterization of Cloud Properties

NASA Astrophysics Data System (ADS)

Neilsen, T. L.; Martins, J. V.; Fish, C. S.; Fernandez Borda, R. A.

2014-12-01

The Hyper-Angular Rainbow Polarimeter HARP instrument is a wide field-of-view imager that splits three spatially identical images into three independent polarizers and detector arrays. This technique achieves simultaneous imagery of the same ground target in three polarization states and is the key innovation to achieve high polarimetric accuracy with no moving parts. The spacecraft consists of a 3U CubeSat with 3-axis stabilization designed to keep the image optics pointing nadir during data collection but maximizing solar panel sun pointing otherwise. The hyper-angular capability is achieved by acquiring overlapping images at very fast speeds. An imaging polarimeter with hyper-angular capability can make a strong contribution to characterizing cloud properties. Non-polarized multi-angle measurements have been shown to be sensitive to thin cirrus and can be used to provide climatology of these clouds. Adding polarization and increasing the number of observation angles allows for the retrieval of the complete size distribution of cloud droplets, including accurate information on the width of the droplet distribution in addition to the currently retrieved e­ffective radius. The HARP mission is funded by the NASA Earth Science Technology Office as part of In-Space Validation of Earth Science Technologies (InVEST) program. The HARP instrument is designed and built by a team of students and professionals lead by Dr. Vanderlei Martines at University of Maryland, Baltimore County. The HARP spacecraft is designed and built by a team of students and professionals and The Space Dynamics Laboratory.

High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

NASA Astrophysics Data System (ADS)

Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

2013-05-01

We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to <= 400 kcps per channel. We selected Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) and a brand-new scintillator, Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) due to their high light yield and density. To improve the spatial resolution, these scintillators were fabricated into 15 × 15 matrices of 0.5 × 0.5 mm2 pixels. The Ce:LYSO and Ce:GAGG scintillator matrices were assembled into phosphor sandwich (phoswich) detectors, and then coupled to the MPPC array along with an acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

Submm/mm galaxy counterpart identification using a characteristic density distribution

NASA Astrophysics Data System (ADS)

Alberts, Stacey; Wilson, Grant W.; Lu, Yu; Johnson, Seth; Yun, Min S.; Scott, Kimberly S.; Pope, Alexandra; Aretxaga, Itziar; Ezawa, Hajime; Hughes, David H.; Kawabe, Ryohei; Kim, Sungeun; Kohno, Kotaro; Oshima, Tai

2013-05-01

We present a new submm/mm galaxy counterpart identification technique which builds on the use of Spitzer Infrared Array Camera (IRAC) colours as discriminators between likely counterparts and the general IRAC galaxy population. Using 102 radio- and Submillimeter Array-confirmed counterparts to AzTEC sources across three fields [Great Observatories Origins Deep Survey-North, -South and Cosmic Evolution Survey (COSMOS)], we develop a non-parametric IRAC colour-colour characteristic density distribution, which, when combined with positional uncertainty information via likelihood ratios, allows us to rank all potential IRAC counterparts around submillimetre galaxies (SMGs) and calculate the significance of each ranking via the reliability factor. We report all robust and tentative radio counterparts to SMGs, the first such list available for AzTEC/COSMOS, as well as the highest ranked IRAC counterparts for all AzTEC SMGs in these fields as determined by our technique. We demonstrate that the technique is free of radio bias and thus applicable regardless of radio detections. For observations made with a moderate beam size (˜18 arcsec), this technique identifies ˜85 per cent of SMG counterparts. For much larger beam sizes (≳30 arcsec), we report identification rates of 33-49 per cent. Using simulations, we demonstrate that this technique is an improvement over using positional information alone for observations with facilities such as AzTEC on the Large Millimeter Telescope and Submillimeter Common User Bolometer Array 2 on the James Clerk Maxwell Telescope.

Multi-angle polarimeter inter-comparison: the PODEX and ACEPOL field campaigns

NASA Astrophysics Data System (ADS)

Knobelspiesse, K. D.; Tan, Q.; Redemann, J.; Cairns, B.; Diner, D. J.; Ferrare, R. A.; van Harten, G.; Hasekamp, O. P.; Kalashnikova, O. V.; Martins, J. V.; Yorks, J. E.; Seidel, F. C.

2017-12-01

A multi-angle polarimeter has been proposed for the NASA Aerosol-Cloud-Ecosystem (ACE) mission, recommended by the National Research Council's Decadal Survey. Such instruments are uncommon in orbit, and there is a great diversity of prototype instrument characteristics. For that reason, NASA funded two field campaigns where airborne polarimeter prototypes were deployed on the high altitude ER-2 aircraft. The first field campaign, POlarimeter DEfinition EXperiment (PODEX), was carried out in southern California in early 2013. Three polarimeters participated: the Airborne Multi-angle SpectroPolarimeter Imager (AirMSPI), the Passive Aerosol and Cloud Suite (PACS) and the Research Scanning Polarimeter (RSP). PACS, on its first deployment, suffered detector problems, while AirMSPI and RSP performed within expectations. Initial comparisons of AirMSPI and RSP observations found Degree of Linear Polarization (DoLP) biases. Following corrections to both instrument's calibration and/or geolocation techniques, these issues have improved. We will present the details of this comparison. The recent ACEPOL mission returned to southern California in October-November with a larger compliment of multi-angle polarimeters. This included AirMSPI and RSP, like in PODEX. Additional polarimetric instruments included AirHARP (Airborne HyperAngular Rainbow Polarimeter, a successor to PACS) and SPEX Airborne (SPectropolarimeter for Planetary Exploration). Two Lidars were also deployed: The High Spectral Resolution Lidar -2 (HSRL-2) and the Cloud Physics Lidar (CPL). While data processing is still underway, we will describe the objectives of this campaign and give a preview of what to expect in subsequent analysis.

Advanced ACTPol Cryogenic Detector Arrays and Readout

NASA Astrophysics Data System (ADS)

Henderson, S. W.; Allison, R.; Austermann, J.; Baildon, T.; Battaglia, N.; Beall, J. A.; Becker, D.; De Bernardis, F.; Bond, J. R.; Calabrese, E.; Choi, S. K.; Coughlin, K. P.; Crowley, K. T.; Datta, R.; Devlin, M. J.; Duff, S. M.; Dunkley, J.; Dünner, R.; van Engelen, A.; Gallardo, P. A.; Grace, E.; Hasselfield, M.; Hills, F.; Hilton, G. C.; Hincks, A. D.; Hloẑek, R.; Ho, S. P.; Hubmayr, J.; Huffenberger, K.; Hughes, J. P.; Irwin, K. D.; Koopman, B. J.; Kosowsky, A. B.; Li, D.; McMahon, J.; Munson, C.; Nati, F.; Newburgh, L.; Niemack, M. D.; Niraula, P.; Page, L. A.; Pappas, C. G.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Sehgal, N.; Sherwin, B. D.; Sievers, J. L.; Simon, S. M.; Spergel, D. N.; Staggs, S. T.; Stevens, J. R.; Thornton, R.; Van Lanen, J.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

2016-08-01

Advanced ACTPol is a polarization-sensitive upgrade for the 6 m aperture Atacama Cosmology Telescope, adding new frequencies and increasing sensitivity over the previous ACTPol receiver. In 2016, Advanced ACTPol will begin to map approximately half the sky in five frequency bands (28-230 GHz). Its maps of primary and secondary cosmic microwave background anisotropies—imaged in intensity and polarization at few arcminute-scale resolution—will enable precision cosmological constraints and also a wide array of cross-correlation science that probes the expansion history of the universe and the growth of structure via gravitational collapse. To accomplish these scientific goals, the Advanced ACTPol receiver will be a significant upgrade to the ACTPol receiver, including four new multichroic arrays of cryogenic, feedhorn-coupled AlMn transition edge sensor polarimeters (fabricated on 150 mm diameter wafers); a system of continuously rotating meta-material silicon half-wave plates; and a new multiplexing readout architecture which uses superconducting quantum interference devices and time division to achieve a 64-row multiplexing factor. Here we present the status and scientific goals of the Advanced ACTPol instrument, emphasizing the design and implementation of the Advanced ACTPol cryogenic detector arrays.

Advanced ACTPol Cryogenic Detector Arrays and Readout

NASA Technical Reports Server (NTRS)

Henderson, S.W.; Allison, R.; Austermann, J.; Baildon, T.; Battaglia, N.; Beall, J. A.; Becker, D.; De Bernardis, F.; Bond, J. R.; Wollack, E. J.

2016-01-01

Advanced ACTPol is a polarization-sensitive upgrade for the 6 m aperture Atacama Cosmology Telescope, adding new frequencies and increasing sensitivity over the previous ACTPol receiver. In 2016, Advanced ACTPol will begin to map approximately half the sky in five frequency bands (28-230 GHz). Its maps of primary and secondary cosmic microwave background anisotropies-imaged in intensity and polarization at few arcminute-scale resolution-will enable precision cosmological constraints and also awide array of cross-correlation science that probes the expansion history of the universe and the growth of structure via gravitational collapse. To accomplish these scientific goals, the AdvancedACTPol receiver will be a significant upgrade to the ACTPol receiver, including four new multichroic arrays of cryogenic, feedhorn-coupled AlMn transition edge sensor polarimeters (fabricated on 150 mm diameter wafers); a system of continuously rotating meta-material silicon half-wave plates; and a new multiplexing readout architecture which uses superconducting quantum interference devices and time division to achieve a 64-row multiplexing factor. Here we present the status and scientific goals of the Advanced ACTPol instrument, emphasizing the design and implementation of the AdvancedACTPol cryogenic detector arrays.

LUMINOUS INFRARED GALAXIES WITH THE SUBMILLIMETER ARRAY. IV. {sup 12}CO J = 6-5 OBSERVATIONS OF VV 114

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sliwa, Kazimierz; Wilson, Christine D.; Krips, Melanie

We present high-resolution (∼2.''5) observations of {sup 12}CO J = 6-5 toward the luminous infrared galaxy VV 114 using the Submillimeter Array. We detect {sup 12}CO J = 6-5 emission from the eastern nucleus of VV 114 but do not detect the western nucleus or the central region. We combine the new {sup 12}CO J = 6-5 observations with previously published or archival low-J CO observations, which include {sup 13}CO J = 1-0 Atacama Large Millimeter/submillimeter Array cycle 0 observations, to analyze the beam-averaged physical conditions of the molecular gas in the eastern nucleus. We use the radiative transfer codemore » RADEX and a Bayesian likelihood code to constrain the temperature (T{sub kin}), density (n{sub H{sub 2}}), and column density (N{sub {sup 1}{sup 2}CO}) of the molecular gas. We find that the most probable scenario for the eastern nucleus is a cold (T{sub kin} = 38 K), moderately dense (n{sub H{sub 2}} = 10{sup 2.89} cm{sup –3}) molecular gas component. We find that the most probable {sup 12}CO to {sup 13}CO abundance ratio ([{sup 12}CO]/[{sup 13}CO]) is 229, which is roughly three times higher than the Milky Way value. This high abundance ratio may explain the observed high {sup 12}CO/ {sup 13}CO line ratio (>25). The unusual {sup 13}CO J = 2-1/J = 1-0 line ratio of 0.6 is produced by a combination of moderate {sup 13}CO optical depths (τ = 0.4-1.1) and extremely subthermal excitation temperatures. We measure the CO-to-H{sub 2} conversion factor, α{sub CO}, to be 0.5{sup +0.6}{sub -0.3} M{sub ☉} (K km s{sup –1} pc{sup 2}){sup –1}, which agrees with the widely used factor for ultra luminous infrared galaxies of Downes and Solomon (α{sub CO} = 0.8 M{sub ☉} (K km s{sup –1} pc{sup 2}){sup –1})« less

LWIR Snapshot Imaging Polarimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dr. Robert E Sampson

This report describes the results of a phase 1 STTR to design a longwave infrared imaging polarimeter. The system design, expected performance and components needed to construct the imaging polarimeter are described. Expected performance is modeled and sytem specifications are presented.

Calibration and Compensation of Instrumental Errors in Imaging Polarimeters

DTIC Science & Technology

2007-04-01

procedures for polarimeters 3. Examine impact of focal plane nonuniformity on polarimeters 4. Understand the role of bandwidth in broadband polarimetry. 5... nonuniformity (NU) noise. NU noise is a results from pixel-to-pixel variations in the photodetector response. NU noise is a persistent problem for all... nonuniformity noise in imaging polarimeters," Proc SPIE Vol. 5888: Polarization Science and Remote Sensing 11, pp. 58880J 1 - 10, J. A. Shaw and J. S

High-Sensitivity X-ray Polarimetry with Amorphous Silicon Active-Matrix Pixel Proportional Counters

NASA Technical Reports Server (NTRS)

Black, J. K.; Deines-Jones, P.; Jahoda, K.; Ready, S. E.; Street, R. A.

2003-01-01

Photoelectric X-ray polarimeters based on pixel micropattern gas detectors (MPGDs) offer order-of-magnitude improvement in sensitivity over more traditional techniques based on X-ray scattering. This new technique places some of the most interesting astronomical observations within reach of even a small, dedicated mission. The most sensitive instrument would be a photoelectric polarimeter at the focus of 2 a very large mirror, such as the planned XEUS. Our efforts are focused on a smaller pathfinder mission, which would achieve its greatest sensitivity with large-area, low-background, collimated polarimeters. We have recently demonstrated a MPGD polarimeter using amorphous silicon thin-film transistor (TFT) readout suitable for the focal plane of an X-ray telescope. All the technologies used in the demonstration polarimeter are scalable to the areas required for a high-sensitivity collimated polarimeter. Leywords: X-ray polarimetry, particle tracking, proportional counter, GEM, pixel readout

Study of ablation and implosion stages in wire arrays using coupled ultraviolet and X-ray probing diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, A. A.; Ivanov, V. V.; Astanovitskiy, A. L.

2015-11-15

Star and cylindrical wire arrays were studied using laser probing and X-ray radiography at the 1-MA Zebra pulse power generator at the University of Nevada, Reno. The Leopard laser provided backlighting, producing a laser plasma from a Si target which emitted an X-ray probing pulse at the wavelength of 6.65 Å. A spherically bent quartz crystal imaged the backlit wires onto X-ray film. Laser probing diagnostics at the wavelength of 266 nm included a 3-channel polarimeter for Faraday rotation diagnostic and two-frame laser interferometry with two shearing interferometers to study the evolution of the plasma electron density at the ablation and implosionmore » stages. Dynamics of the plasma density profile in Al wire arrays at the ablation stage were directly studied with interferometry, and expansion of wire cores was measured with X-ray radiography. The magnetic field in the imploding plasma was measured with the Faraday rotation diagnostic, and current was reconstructed.« less

MCM Polarimetric Radiometers for Planar Arrays

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Dawson, Douglas; Gaier, Todd

2007-01-01

A polarimetric radiometer that operates at a frequency of 40 GHz has been designed and built as a prototype of multiple identical units that could be arranged in a planar array for scientific measurements. Such an array is planned for use in studying the cosmic microwave background (CMB). All of the subsystems and components of this polarimetric radiometer are integrated into a single multi-chip module (MCM) of substantially planar geometry. In comparison with traditional designs of polarimetric radiometers, the MCM design is expected to greatly reduce the cost per unit in an array of many such units. The design of the unit is dictated partly by a requirement, in the planned CMB application, to measure the Stokes parameters I, Q, and U of the CMB radiation with high sensitivity. (A complete definition of the Stokes parameters would exceed the scope of this article. In necessarily oversimplified terms, I is a measure of total intensity of radiation, while Q and U are measures of the relationships between the horizontally and vertically polarized components of radiation.) Because the sensitivity of a single polarimeter cannot be increased significantly, the only way to satisfy the high-sensitivity requirement is to make a large array of polarimeters that operate in parallel. The MCM includes contact pins that can be plugged into receptacles on a standard printed-circuit board (PCB). All of the required microwave functionality is implemented within the MCM; any required supporting non-microwave ("back-end") electronic functionality, including the provision of DC bias and control signals, can be implemented by standard PCB techniques. On the way from a microwave antenna to the MCM, the incoming microwave signal passes through an orthomode transducer (OMT), which splits the radiation into an h + i(nu) beam and an h - i(nu) beam (where, using complex-number notation, h denotes the horizontal component, nu denotes the vertical component, and +/-i denotes a +/-90deg phase shift). Each of these beams enters the MCM through one of two WR-22 waveguide input terminals in the lid of the MCM. The h + i(nu0 and h - i(nu) signals are amplified, then fed to a phase-discriminator hybrid designed specifically to fit the predominantly planar character of the MCM geometry and to enable determination of Q and U. The phase-discriminator hybrid generates four outputs, which are detected and used to calculate I, Q, and U.

Experimental test of liquid droplet radiator performance

NASA Astrophysics Data System (ADS)

Mattick, A. T.; Simon, M. A.

The liquid droplet radiator (LDR) is a heat rejection system for space power systems wherein an array of heated liquid droplets radiates energy directly to space. The use of submillimeter droplets provides large radiating area-to-mass ratio, resulting in radiator systems which are several times lighter than conventional solid surface radiators. An experiment is described in which the power radiated by an array of 2300 streams of silicone oil droplets is measured to test a previously developed theory of the LDR radiation process. This system would be capable of rejecting several kW of heat in space. Furthermore, it would be suitable as a modular unit of an LDR designed for 100-kW power levels. The experiment provided confirmation of the theoretical dependence of droplet array emissivity on optical depth. It also demonstrated the ability to create an array of more than 1000 droplet streams having a divergence less than 1 degree.

Experimental test of liquid droplet radiator performance

NASA Technical Reports Server (NTRS)

Mattick, A. T.; Simon, M. A.

1987-01-01

The liquid droplet radiator (LDR) is a heat rejection system for space power systems wherein an array of heated liquid droplets radiates energy directly to space. The use of submillimeter droplets provides large radiating area-to-mass ratio, resulting in radiator systems which are several times lighter than conventional solid surface radiators. An experiment is described in which the power radiated by an array of 2300 streams of silicone oil droplets is measured to test a previously developed theory of the LDR radiation process. This system would be capable of rejecting several kW of heat in space. Furthermore, it would be suitable as a modular unit of an LDR designed for 100-kW power levels. The experiment provided confirmation of the theoretical dependence of droplet array emissivity on optical depth. It also demonstrated the ability to create an array of more than 1000 droplet streams having a divergence less than 1 degree.

The Space Infrared Interferometric Telescope (SPIRIT)

NASA Technical Reports Server (NTRS)

Rinehart, Stephen

2007-01-01

The Space Infrared Interferometric Telescope (SPIRIT) is a candidate NASA Origins Probe Mission. SPIRIT is a two-telescope Michelson interferometer covering wavelengths from 25-400 microns, providing simultaneously high spectral resolution and high angular resolution. With comparable sensitivity to Spitzer, but two orders of magnitude improvement in angular resolution, SPIRIT will enable us to address a wide array of compelling scientific questions, including how planetary systems form in disks and how new planets interact with the disk. Further, SPIRIT will lay the technological groundwork for an array of future interferometry missions with ambitious scientific goals, including the Terrestrial Planet Finder Interferometer / Darwin, and the Submillimeter Probe of the Evolution of Cosmic Structure.

The Space Infrared Interferometric Telescope (SPIRIT)

NASA Technical Reports Server (NTRS)

Rinehart, Stephen

2007-01-01

The Space Infrared Interferometric Telescope (SPIRIT) is a candidate NASA Origins Probe Mission. SPIRIT is a two-telescope Michelson interferometer covering wavelengths from 25-400 microns, providing simultaneously high spectral resolution and high angular resolution. With comparable sensitivity to Spitzer, but two orders of magnitude improvement in angular resolution, SPIRIT will enable us to address a wide array of compelling scientific questions, including how planetary systems form in disks and how new planets interact with the disk. Further, SPIRIT will lay the technological groundwork for an array of future interferometry missions with ambitious scientific goals, including the Terrestrial Planet Finder Interferometer/Darwin, and the Submillimeter Probe of the Evolution of Cosmic Structure.

Atacama B-mode Search: Scientific Motivations and Design Overview

NASA Astrophysics Data System (ADS)

Yoon, Ki Won

2009-05-01

The Atacama B-mode Search (ABS) is a new experiment designed to characterize the polarization of the cosmic microwave background (CMB) to unprecedented levels at degree angular scales, where the signature of primordial gravitational waves from an inflationary epoch in the early universe is expected to peak. ABS employs a novel optical design using a cryogenically-cooled crossed-Dragone reflective telescope coupled to an array of ˜200 direct-machined feedhorns, each of which in turn couples the incoming radiation onto a ``polarimeter-on-a-chip'' consisting of a planar ortho-mode transducer, microstrip band-defining filters, and a pair of transition-edge sensors (TES) that measure both polarizations simultaneously. The array will be initially designed for operation at 145 GHz. ABS is currently scheduled to begin observation in the Atacama Desert of Chile in late 2009.

Integrated Dual Imaging Detector

NASA Technical Reports Server (NTRS)

Rust, David M.

1999-01-01

A new type of image detector was designed to simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging detector (IDID) consists of a lenslet array and a polarizing beamsplitter bonded to a commercial charge coupled device (CCD). The IDID simplifies the design and operation of solar vector magnetographs and the imaging polarimeters and spectroscopic imagers used, for example, in atmosphere and solar research. When used in a solar telescope, the vector magnetic fields on the solar surface. Other applications include environmental monitoring, robot vision, and medical diagnoses (through the eye). Innovations in the IDID include (1) two interleaved imaging arrays (one for each polarization plane); (2) large dynamic range (well depth of 10(exp 5) electrons per pixel); (3) simultaneous readout and display of both images; and (4) laptop computer signal processing to produce polarization maps in field situations.

Wide-field Imaging Survey of Dust Continuum Emissions at lambda = 1.1 mm toward the Chamaeleon and Lupus Regions with AzTEC on ASTE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Momose, Munetake; Hiramatsu, Masaaki; Tsukagoshi, Takashi

2009-08-05

We carried out an imaging survey of dust continuum emissions toward the Chamaeleon and Lupus regions. Observations were made with the 144-element bolometer array camera AzTEC mounted on the 10-meter sub-millimeter telescope ASTE during 2007-2008. The preliminary results of disk search and the cloud structure of Lupus III are presented.

338-GHz Semiconductor Amplifier Module

NASA Technical Reports Server (NTRS)

Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Fung, King Man; Rasisic, Vesna; Deal, William; Leong, Kevin; Mei, Xiao Bing; Yoshida, Wayne; Liu, Po-Hsin;

New technologies for the detection of millimeter and submillimeter waves

NASA Technical Reports Server (NTRS)

Richards, P. L.; Clarke, J.; Gildemeister, J. M.; Lanting, T.; Lee, A. T.

2001-01-01

Voltage-biased superconducting bolometers have many operational advantages over conventional bolometer technology including sensitivity, linearity, speed, and immunity from environmental disturbance. A review is given of the Berkeley program for developing this new technology. Developments include fully lithographed individual bolometers in the spiderweb configuration, arrays of 1024 close-packed absorber-coupled bolometers, antenna-coupled bolometers, and a frequency-domain SQUID (superconducting quantum interference device) readout multiplexer.

Micromachined Millimeter- and Submillimeter-wave SIS Heterodyne Receivers for Remote Sensing

NASA Technical Reports Server (NTRS)

Hu, Qing

1997-01-01

This is a progress report for the second year of a NASA-sponsored project. The report discusses the design and fabrication of micromachined Superconductor Insulator Superconductor (SIS) heterodyne receivers with integrated tuning elements. These receivers tune out the functional capacitance at desired frequencies, resulting in less noise, lower temperatures and broader bandwidths. The report also discusses the design and fabrication of the first monolithic 3x3 focal-plane arrays for a frequency range of 170-210 GHz. Also addressed is the construction of a 9-channel bias and read-out system, as well as the redesign of the IF connections to reduce cross talk between SIS junctions, which become significant a frequency of 1.5 GHz IF. Uniformity of the junction arrays were measured and antenna beam patterns of several array elements under operating conditions also were measured. Finally, video and heterodyne responses of our focal-plane arrays were measured as well. Attached is a paper on: 'Development of a 170-210 GHz 3x3 micromachined SIS imaging array'.

Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation using Superconducting Tunnel Junctions with Radio-Frequency Single-Electron Transistors

NASA Technical Reports Server (NTRS)

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Wollack, E. J.; Schoelkopf, R. J.; Krebs, Carolyn (Technical Monitor)

2002-01-01

The science drivers for the SPIRIT/SPECS missions demand sensitive, fast, compact, low-power, large-format detector arrays for high resolution imaging and spectroscopy in the far infrared and submillimeter. Detector arrays with 10,000 pixels and sensitivity less than 10(exp 20)-20 W/Hz(exp 20)0.5 are needed. Antenna-coupled superconducting tunnel junction detectors with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique when forming arrays. The device consists of an antenna structure to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure currents through tunnel junction contacts to the absorber volume. We will describe optimization of device parameters, and recent results on fabrication techniques for producing devices with high yield for detector arrays. We will also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

Submillimeter Array {sup 12}CO (2-1) Imaging of the NGC 6946 Giant Molecular Clouds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ya-Lin; Sakamoto, Kazushi; Pan, Hsi-An, E-mail: yalinwu@email.arizona.edu

2017-04-10

We present a {sup 12}CO (2–1) mosaic map of the spiral galaxy NGC 6946 by combining data from the Submillimeter Array and the IRAM 30 m telescope. We identify 390 giant molecular clouds (GMCs) from the nucleus to 4.5 kpc in the disk. GMCs in the inner 1 kpc are generally more luminous and turbulent, some of which have luminosities >10{sup 6} K km s{sup −1} pc{sup 2} and velocity dispersions >10 km s{sup −1}. Large-scale bar-driven dynamics likely regulate GMC properties in the nuclear region. Similar to the Milky Way and other disk galaxies, GMC mass function of NGCmore » 6946 has a shallower slope (index > −2) in the inner region, and a steeper slope (index < −2) in the outer region. This difference in mass spectra may be indicative of different cloud formation pathways: gravitational instabilities might play a major role in the nuclear region, while cloud coalescence might be dominant in the outer disk. Finally, the NGC 6946 clouds are similar to those in M33 in terms of statistical properties, but they are generally less luminous and turbulent than the M51 clouds.« less

The next generation balloon-borne large aperture submillimeter telescope (BLAST-TNG)

NASA Astrophysics Data System (ADS)

Dober, Bradley Jerald

Large areas of astrophysics, such as precision cosmology, have benefited greatly from large maps and datasets, yielded by telescopes of ever-increasing number and ability. However, due to the unique challenges posed by submillimeter polarimetry, the study of molecular cloud dynamics and star formation remain stunted. Previously, polarimetry data was limited to a few vectors on only the brightest areas of molecular clouds. This made drawing statistically-driven conclusions a daunting task. However, the successful flight of the Balloon-born Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) generated maps with thousands of independent polarization measurements of molecular clouds, and ushered in a new era of empirical modeling of molecular cloud dynamics. Now that the potential benefits from large-scale maps of magnetic fields in molecular clouds had been identified, a successor that would truly unlock the secrets must be born. The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG), the successor to BLASTPol, has the ability to make larger and more detailed maps of magnetic fields in molecular clouds. It will push the field of star formation into a statistics-driven, empirical realm. With these large, detailed datasets, astronomers will be able to find new relationships between the dust dynamics and the magnetic fields. The field will surge to a new level of understanding. One of the key enabling technologies of BLAST-TNG is its three arrays of polarization-sensitive Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are superconducting RLC circuits with a resonant frequency that shifts proportionally to the amount of incident radiation. The key feature of MKIDs is that thousands of detectors, each with their own unique resonant frequency, can be coupled to the same readout line. This technology will be able to drive the production of large-scale monolithic arrays, containing tens or hundreds of thousands of detectors, resulting in an ever-increasing rate of scientific progress. The current limiting factor that determines how many MKIDs can be placed on the same readout line is the bandwidth and processing limitations of the readout hardware. BLAST-TNG has pushed this technology forward by implementing the first Reconfigurable Open-Architecture Computing Hardware (ROACH2) based readout system. This has significantly raised the processing abilities of the MKID readout electronics, enabling over 1000 MKIDs to be read out on a single line. It is also the first ever ROACH (1 or 2) based system to ever be flown on a long duration balloon (LDB) payload. This thesis documents the first-ever deployment of MKIDs on a balloon payload. This is a significant technological step towards an MKID-based satellite payload. This thesis overviews the balloon payload, details the underlying detector physics, catalogs the detector and full-scale array development, and ends with the room-temperature readout electronics.

[CII] At 1 < z < 2: Observing Star Formation in the Early Universe with Zeus (1 and 2)

NASA Technical Reports Server (NTRS)

Ferkinhoff, Carl; Hailey-Dunsheath, S.; Nikola, T.; Oberst, T.; Parshley, S.; Stacey, G.; Benford, D.; staguhn, J.

2010-01-01

We report the detection of the [CII] 158 micron fine structure line from six submillimeter galaxies with redshifts between 1.12 and 1.73. This more than doubles the total number of [CII] 158 micron detections reported from high redshift sources. These observations were made with the Redshift(z) and Early Universe Spectrometer(ZEUS) at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii between December 2006 and March 2009. ZEUS is a background limited submm echelle grating spectrometer (Hailey-Dunsheath 2009). Currently we are constructing ZEUS-2. This new instrument will utilize the same grating but will feature a two dimensional transition-edge sensed bolometer array with SQUID multiplexing readout system enabling simultaneous background limited observations in the 200, 340,450 and 650 micron telluric windows. ZEUS-2 will allow for long slit imaging spectroscopy in nearby galaxies and a [CII] survey from z 0.25 to 2.5.

A Brief Update on the CMZoom Survey

NASA Astrophysics Data System (ADS)

Battersby, C.; Keto, E.; Zhang, Q.; Longmore, S. N.; Kruijssen, J. M. D.; Pillai, T.; Kauffmann, J.; Walker, D.; Lu, X.; Ginsburg, A.; Bally, J.; Mills, E. A. C.; Henshaw, J.; Immer, K.; Patel, N.; Tolls, V.; Walsh, A.; Johnston, K.; Ho, L. C.

2017-01-01

The inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey in its final year and is mapping out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4'' (0.2 pc) and good image fidelity up to large spatial scales.

ALMA Telescope Reaches New Heights

NASA Astrophysics Data System (ADS)

2009-09-01

The ALMA (Atacama Large Millimeter/submillimeter Array) astronomical observatory took another step forward and upward, as one of its state-of-the-art antennas was carried for the first time to Chile's 16,500-foot-high plateau of Chajnantor on the back of a giant, custom-built transporter. The 40-foot-diameter antenna, weighing about 100 tons, was moved to ALMA's high-altitude Array Operations Site, where the extremely dry and rarefied air is ideal for observing the Universe. The conditions at the Array Operations Site on Chajnantor, while excellent for astronomy, are also very harsh. Only about half as much oxygen is available as at sea level, making it very difficult to work there. This is why ALMA's antennas are assembled and tested at the lower 9,500-foot altitude of the ALMA Operations Support Facility (OSF). It was from this relatively hospitable base camp that the ALMA antenna began its journey to the high Chajnantor site. "The successful transport of the first ALMA Antenna to the high site marks the start of the next phase of the project. Now that we are starting to move the ALMA antennas to the high site, the real work begins and the exciting part is just beginning," said Adrian Russell, North American ALMA Project Manager. The antenna's trip began when one of the two ALMA transporters lifted the antenna onto its back, carrying its heavy load along the 17-mile road from the Operations Support Facility up to the Array Operations Site. While the transporter is capable of speeds of up to 8 miles per hour when carrying an antenna, this first journey was made more slowly to ensure that everything worked as expected, taking about seven hours. The ALMA antennas use state-of-the-art technology, and are the most advanced submillimeter-wavelength antennas ever made. They are designed to operate fully exposed in the harsh conditions of the Array Operations Site, to survive strong winds and extreme temperatures, to point precisely enough that they could pick out a golf ball at a distance of nine miles, and to keep their smooth reflecting surfaces accurate to less than the thickness of a human hair. Once the transporter reached the high plateau it carried the antenna to a concrete pad -- a docking station with connections for power and fiber optics -- and positioned it with an accuracy of a small fraction of an inch. The transporter is guided by a laser steering system and, just like some cars, also has ultrasonic collision detectors. These sensors ensure the safety of the state-of-the-art antennas as the transporter drives them across what will soon be a rather crowded plateau. Ultimately, ALMA will have at least 66 antennas distributed over about 200 pads, spread over distances of up to 11.5 miles and operating as a single, giant telescope. Even when ALMA is fully operational, the transporters will be used to move the antennas between pads to reconfigure the telescope for different kinds of observations. This first ALMA antenna at the high site will soon be joined by others, and the ALMA team looks forward to making their first observations from the Chajnantor plateau. They plan to link three antennas by early 2010, and to make the first scientific observations with ALMA in the second half of 2011. ALMA will help astronomers answer important questions about our cosmic origins. The telescope will observe the Universe using light with millimeter and submillimeter wavelengths, between infrared light and radio waves in the electromagnetic spectrum. Light at these wavelengths comes from some of the coldest, and from some of the most distant objects in the cosmos. These include cold clouds of gas and dust where new stars are being born, or remote galaxies towards the edge of the observable universe. The Universe is relatively unexplored at submillimeter wavelengths, as the telescopes need extremely dry atmospheric conditions, such as those at Chajnantor, and advanced detector technology. The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. The National Radio Astronomy Observatory is the North American partner in ALMA. ALMA, the largest astronomical project in existence, is a revolutionary telescope, comprising an array of 66 giant 40-foot and 23-foot diameter antennas. Russell noted that the first antenna's move to the high site illustrates the international nature of the project. "A Japanese antenna with North American electronics was carried by a European transporter," he explained.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

NASA Astrophysics Data System (ADS)

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B.; Tai, Yuan-Chuan

2010-05-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array.

PubMed

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-05-07

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm(3) and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and +/-5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when +/-10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

PubMed Central

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-01-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications. PMID:20393236

Airborne Polarimeter Intercomparison for the NASA Aerosols-Clouds-Ecosystems (ACE) Mission

NASA Technical Reports Server (NTRS)

Knobelspiesse, Kirk; Redemann, Jens

2014-01-01

The Aerosols-Clouds-Ecosystems (ACE) mission, recommended by the National Research Council's Decadal Survey, calls for a multi-angle, multi-spectral polarimeter devoted to observations of atmospheric aerosols and clouds. In preparation for ACE, NASA funds the deployment of airborne polarimeters, including the Airborne Multi-angle SpectroPolarimeter Imager (AirMSPI), the Passive Aerosol and Cloud Suite (PACS) and the Research Scanning Polarimeter (RSP). These instruments have been operated together on NASA's ER-2 high altitude aircraft as part of field campaigns such as the POlarimeter DEfinition EXperiment (PODEX) (California, early 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, California and Texas, summer 2013). Our role in these efforts has been to serve as an assessment team performing level 1 (calibrated radiance, polarization) and level 2 (retrieved geophysical parameter) instrument intercomparisons, and to promote unified and generalized calibration, uncertainty assessment and retrieval techniques. We will present our progress in this endeavor thus far and describe upcoming research in 2015.

Progress in Airborne Polarimeter Inter Comparison for the NASA Aerosols-Clouds-Ecosystems (ACE) Mission

NASA Technical Reports Server (NTRS)

Knobelspiesse, Kirk; Redemann, Jens

2014-01-01

The Aerosols-Clouds-Ecosystems (ACE) mission, recommended by the National Research Council's Decadal Survey, calls for a multi-angle, multi-spectral polarimeter devoted to observations of atmospheric aerosols and clouds. In preparation for ACE, NASA funds the deployment of airborne polarimeters, including the Airborne Multiangle SpectroPolarimeter Imager (AirMSPI), the Passive Aerosol and Cloud Suite (PACS) and the Research Scanning Polarimeter (RSP). These instruments have been operated together on NASA's ER-2 high altitude aircraft as part of field campaigns such as the POlarimeter DEfinition EXperiment (PODEX) (California, early 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, California and Texas, summer 2013). Our role in these efforts has been to serve as an assessment team performing level 1 (calibrated radiance, polarization) and level 2 (retrieved geophysical parameter) instrument intercomparisons, and to promote unified and generalized calibration, uncertainty assessment and retrieval techniques. We will present our progress in this endeavor thus far and describe upcoming research in 2015.

Performance of the PRAXyS X-Ray Polarimeter

NASA Technical Reports Server (NTRS)

Iwakiri, W. B.; Black, J. K.; Cole, R.; Enoto, T.; Hayato, A.; Hill, J. E.; Jahoda, Keith M.; Kaaret, P.; Kitaguchi, T.; Kubota, M.

2016-01-01

The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

Intrinsic coincident full-Stokes polarimeter using stacked organic photovoltaics.

PubMed

Yang, Ruonan; Sen, Pratik; O'Connor, B T; Kudenov, M W

2017-02-20

An intrinsic coincident full-Stokes polarimeter is demonstrated by using strain-aligned polymer-based organic photovoltaics (OPVs) that can preferentially absorb certain polarized states of incident light. The photovoltaic-based polarimeter is capable of measuring four Stokes parameters by cascading four semitransparent OPVs in series along the same optical axis. This in-line polarimeter concept potentially ensures high temporal and spatial resolution with higher radiometric efficiency as compared to the existing polarimeter architecture. Two wave plates were incorporated into the system to modulate the S₃ Stokes parameter so as to reduce the condition number of the measurement matrix and maximize the measured signal-to-noise ratio. Radiometric calibration was carried out to determine the measurement matrix. The polarimeter presented in this paper demonstrated an average RMS error of 0.84% for reconstructed Stokes vectors after normalized to S₀. A theoretical analysis of the minimum condition number of the four-cell OPV design showed that for individually optimized OPV cells, a condition number of 2.4 is possible.

Performance of the PRAXyS X-ray polarimeter

NASA Astrophysics Data System (ADS)

Iwakiri, W. B.; Black, J. K.; Cole, R.; Enoto, T.; Hayato, A.; Hill, J. E.; Jahoda, K.; Kaaret, P.; Kitaguchi, T.; Kubota, M.; Marlowe, H.; McCurdy, R.; Takeuchi, Y.; Tamagawa, T.

2016-12-01

The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

Lifetime Estimation of a Time Projection Chamber X-ray Polarimeter

NASA Technical Reports Server (NTRS)

Hill, Joanne E.; Black, J. Kevin; Brieda, Lubos; Dickens, Patsy L.; deGarcia, Kristina Montt; Hawk, Douglas L.; Hayato, Asami; Jahoda, Keith; Mohammed, Jelila

2013-01-01

The Gravity and Extreme Magnetism Small Explorer (GEMS) X-ray polarimeter Instrument (XPI) was designed to measure the polarization of 23 sources over the course of its 9 month mission. The XPI design consists of two telescopes each with a polarimeter assembly at the focus of a grazing incidence mirror. To make sensitive polarization measurements the GEMS Polarimeter Assembly (PA) employed a gas detection system based on a Time Projection Chamber (TPC) technique. Gas detectors are inherently at risk of degraded performance arising from contamination from outgassing of internal detector components or due to loss of gas. This paper describes the design and the materials used to build a prototype of the flight polarimeter with the required GEMS lifetime. We report the results from outgassing measurements of the polarimeter subassemblies and assemblies, enclosure seal tests, life tests, and performance tests that demonstrate that the GEMS lifetime is achievable. Finally we report performance measurements and the lifetime enhancement from the use of a getter.

Passive millimeter-wave imaging polarimeter system

NASA Astrophysics Data System (ADS)

Persons, Christopher M.; Martin, Christopher A.; Jones, Michael W.; Kolinko, Vladimir; Lovberg, John A.

2009-05-01

The Army has identified a need to rapidly identify, map, and classify natural and manmade features to aid situational awareness as well as mission and tactical planning. To address these needs, Digital Fusion and Trex Enterprises have designed a full Stokes, passive MMW imaging polarimeter that is capable of being deployed on an unmanned aerial vehicle. Results of a detailed trade study are presented, where an architecture, waveband and target platform are selected. The selected architecture is a pushbroom phased-array system, which allows the system to collect a wide fieldof- view image with minimal components and weight. W band is chosen as a trade-off between spatial resolution, weather penetration, and component availability. The trade study considers several unmanned aerial system (UAS) platforms that are capable of low-level flight and that can support the MMW antenna. The utility of the passive Stokes imager is demonstrated through W band phenomenology data collections at horizontal and vertical polarization using a variety of natural and manmade materials. The concept design is detailed, along with hardware and procedures for both radiometric and polarimetric calibration. Finally, a scaled version of the concept design is presented, which is being fabricated for an upcoming demonstration on a small, manned aircraft.

FPGA-Based X-Ray Detection and Measurement for an X-Ray Polarimeter

NASA Technical Reports Server (NTRS)

Gregory, Kyle; Hill, Joanne; Black, Kevin; Baumgartner, Wayne

2013-01-01

This technology enables detection and measurement of x-rays in an x-ray polarimeter using a field-programmable gate array (FPGA). The technology was developed for the Gravitational and Extreme Magnetism Small Explorer (GEMS) mission. It performs precision energy and timing measurements, as well as rejection of non-x-ray events. It enables the GEMS polarimeter to detect precisely when an event has taken place so that additional measurements can be made. The technology also enables this function to be performed in an FPGA using limited resources so that mass and power can be minimized while reliability for a space application is maximized and precise real-time operation is achieved. This design requires a low-noise, charge-sensitive preamplifier; a highspeed analog to digital converter (ADC); and an x-ray detector with a cathode terminal. It functions by computing a sum of differences for time-samples whose difference exceeds a programmable threshold. A state machine advances through states as a programmable number of consecutive samples exceeds or fails to exceed this threshold. The pulse height is recorded as the accumulated sum. The track length is also measured based on the time from the start to the end of accumulation. For track lengths longer than a certain length, the algorithm estimates the barycenter of charge deposit by comparing the accumulator value at the midpoint to the final accumulator value. The design also employs a number of techniques for rejecting background events. This innovation enables the function to be performed in space where it can operate autonomously with a rapid response time. This implementation combines advantages of computing system-based approaches with those of pure analog approaches. The result is an implementation that is highly reliable, performs in real-time, rejects background events, and consumes minimal power.

STUDIES OF THE ORIGIN OF HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS OF MASS-ACCRETING BLACK HOLES IN X-RAY BINARIES WITH NEXT-GENERATION X-RAY TELESCOPES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beheshtipour, Banafsheh; Hoormann, Janie K.; Krawczynski, Henric, E-mail: b.beheshtipour@wustl.edu

Observations with RXTE ( Rossi X-ray Timing Explorer ) revealed the presence of high-frequency quasi-periodic oscillations (HFQPOs) of the X-ray flux from several accreting stellar-mass black holes. HFQPOs (and their counterparts at lower frequencies) may allow us to study general relativity in the regime of strong gravity. However, the observational evidence today does not yet allow us to distinguish between different HFQPO models. In this paper we use a general-relativistic ray-tracing code to investigate X-ray timing spectroscopy and polarization properties of HFQPOs in the orbiting Hotspot model. We study observational signatures for the particular case of the 166 Hz quasi-periodicmore » oscillation (QPO) in the galactic binary GRS 1915+105. We conclude with a discussion of the observability of spectral signatures with a timing-spectroscopy experiment such as the LOFT ( Large Observatory for X-ray Timing ) and polarization signatures with space-borne X-ray polarimeters such as IXPE ( Imaging X-ray Polarimetry Explorer ), PolSTAR ( Polarization Spectroscopic Telescope Array ), PRAXyS ( Polarimetry of Relativistic X-ray Sources ), or XIPE ( X-ray Imaging Polarimetry Explorer ). A mission with high count rate such as LOFT would make it possible to get a QPO phase for each photon, enabling the study of the QPO-phase-resolved spectral shape and the correlation between this and the flux level. Owing to the short periods of the HFQPOs, first-generation X-ray polarimeters would not be able to assign a QPO phase to each photon. The study of QPO-phase-resolved polarization energy spectra would thus require simultaneous observations with a first-generation X-ray polarimeter and a LOFT -type mission.« less

Optimization of the GRAPE Polarimeter Design

NASA Astrophysics Data System (ADS)

McConnell, Mark

The Gamma Ray Polarimeter Experiment (GRAPE) is designed to investigate one of the most exotic phenomena in the universe - gamma-ray bursts (GRB). There has been intense observational and theoretical research in recent years, but research in this area has been largely focused on studies of time histories, spectra, and spatial distributions. Theoretical models show that a more complete understanding of the inner structure of GRBs, including the geometry and physical processes close to the central engine, requires the exploitation of gamma-ray polarimetry. Over the past several years, we have developed the GRAPE instrument to measure the polarization of gamma-rays from GRBs over the energy range of 50 to 500 keV. The GRAPE design is a modular one in which several independent modules are required to achieve sufficient sensitivity. A single module fits on the front end of a 2-inch square flat-panel multi-anode photomultiplier tube (MAPMT). The first operational balloon flight took in place in September of 2011 from Ft. Sumner, NM. The purpose of the 2011 flight was to validate the science capability of GRAPE by measuring the Crab polarization with a collimated array of 16 modules. The limited success of that flight led to a second validation flight (also from Ft. Sumner) in the fall of 2014, with significantly improved shielding and a larger array of modules. That flight proved too short to make a full observation of the Crab. Although we did not succeed in measuring the polarization of the Crab with a high degree of confidence, we feel that we are nonetheless prepared to move forward with our program. Our next goal is to fly GRAPE on a long duration balloon (LDB) platform to collect data on a significant sample of GRBs. Our experience with the first two balloon flights, coupled with further design efforts focused on orbital payloads, has led to an improved polarimeter concept that represents a natural evolution of the current design. It is this new concept that we are now proposing to develop and test before embarking on a long-duration balloon program. This new design, with improved sensitivity, will ensure that the science objectives can be achieved within the context of a viable balloon program.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yokosawa, A.

The production of polarized antiproton beams at Fermilab is briefly reviewed. Two types of high-energy anti p polarimeters are described - the Coulomb-nuclear polarimeter and the Primakoff-effect polarimeter. The production of 8.9 GeV/c polarized antiprotons before entering the Fermilab accumulator ring is then discussed. 5 refs., 6 figs. (LEW)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steele, Amy; Hughes, A. Meredith; Carpenter, John

The presence of debris disks around young main-sequence stars hints at the existence and structure of planetary systems. Millimeter-wavelength observations probe large grains that trace the location of planetesimal belts. The Formation and Evolution of Planetary Systems Spitzer Legacy survey of nearby young solar analogues yielded a sample of five debris disk-hosting stars with millimeter flux suitable for interferometric follow-up. We present observations with the Submillimeter Array (SMA) and the Combined Array for Research in Millimeter-wave Astronomy at ∼2″ resolution that spatially resolve the debris disks around these nearby (d ∼ 50 pc) stars. Two of the five disks (HDmore » 377, HD 8907) are spatially resolved for the first time and one (HD 104860) is resolved at millimeter wavelengths for the first time. We combine our new observations with archival SMA and Atacama Large Millimeter/Submillimeter Array data to enable a uniform analysis of the full five-object sample. We simultaneously model the broadband photometric data and resolved millimeter visibilities to constrain the dust temperatures and disk morphologies, and perform a Markov Chain Monte Carlo analysis to fit for basic structural parameters. We find that the radii and widths of the cold outer belts exhibit properties consistent with scaled-up versions of the Solar System's Kuiper Belt. All the disks exhibit characteristic grain sizes comparable to the blowout size, and all the resolved observations of emission from large dust grains are consistent with an axisymmetric dust distribution to within the uncertainties. These results are consistent with comparable studies carried out at infrared wavelengths.« less

Molecular Gas Excitation and the Evolutionary Connection Between Submillimeter Galaxies and AGN at z~2-3

NASA Astrophysics Data System (ADS)

Sharon, Chelsea; Riechers, Dominik Alexander; Carilli, Christopher; Hodge, Jacqueline; Walter, Fabian

2015-08-01

Theoretical work has suggested that active galactic nuclei (AGN) may play an important role in quenching star formation in massive galaxies. Due to sensitivity demands, direct evidence for AGN affecting the molecular ISM (the gas phase that fuels star formation) has so far been limited to detections of molecular outflows in low-redshift systems. Indirect evidence for an interplay between AGN and their host galaxies' cold gas phase may be provided by measurements of the gas excitation (and dynamics). At z~2-3, the peak epoch of star formation and AGN activity, previous observations of the CO(1-0) line revealed that submillimeter galaxies have substantial reservoirs of cold molecular gas. However, the molecular gas in AGN-host galaxies appears highly excited, potentially supporting an evolutionary connection between these two populations. We will present a new larger Karl G. Jansky Very Large Array sample that nearly doubles the number of CO(1-0) detections in z~2-3 submillimeter galaxies and AGN-host galaxies with existing CO(3-2) detections (from 13 to 23, plus four new upper limits) that allows us to better compare the low-excitation molecular gas properties of these systems and further investigate potential evidence for gas excitation due to active black holes.

A Shoebox Polarimeter: An Inexpensive Analytical Tool for Teachers and Students

ERIC Educational Resources Information Center

Mehta, Akash; Greenbowe, Thomas J.

2011-01-01

A polarimeter can determine the optical activity of an organic or inorganic compound by providing information about the optical rotation of plane-polarized light when transmitted through that compound. This "Journal" has reported various construction methods for polarimeters. We report a unique construction using a shoebox, recycled office…

Birefringence Polarimeter Using Dual LiNbO3 Electrooptic Crystal Modulators

NASA Astrophysics Data System (ADS)

Saitou, Takeshi; Nurdin Bin, Muhammad; Kowa, Hiroyuki; Umeda, Norihiro; Takizawa, Kuniharu; Kondoh, Eiichi; Jin, Lianhua

2012-08-01

A birefringence polarimeter that uses dual LiNbO3 electrooptic crystal modulators operating at a frequency ratio of 4:1 is described. The significance of this polarimeter is that the birefringent parameters of a sample are obtained only from the modulated polarization status. The measurement, therefore, avoids depolarization effects resulting from the sample itself and the rest of the optical system. The high speed and accuracy of this polarimeter are shown by measurements using a quarter-wave plate, a Babinet-Soleil compensator, and a phase modulator.

A low-cost polarimeter for an undergraduate laboratory to study the polarization pattern of skylight

NASA Astrophysics Data System (ADS)

Abayaratne, Chula P.; Bandara, Vibodha

2017-03-01

A simple, low-cost, fully automated polarimeter, which demonstrates fundamental properties of skylight scattering and polarization for undergraduate physics students, is described. The polarimeter includes a microprocessor-based control unit, a Sun tracker, an elevation-azimuth mount with two degrees of freedom, and a polarization sensor unit equipped with a light-dependent resistor for measuring light intensity. Results obtained in the principal plane of the Sun using the polarimeter on a relatively clear day, together with the theoretically expected results for a molecular atmosphere, are presented. A root-mean-square error comparison indicates fairly good agreement between theory and experiment. Construction and experimentation with the polarimeter will provide students with insight into important physical concepts involved in skylight scattering and polarization as well as improve their instrumentation capabilities.

Development of the GEM-TPC X-ray Polarimeter with the Scalable Readout System

NASA Astrophysics Data System (ADS)

Kitaguchi, Takao; Hayato, Asami; Iwakiri, Wataru; Takeuchi, Yoko; Kubota, Megu; Nishida, Kazuki; Enoto, Teruaki; Tamagawa, Toru

2018-02-01

We have developed a gaseous Time Projection Chamber (TPC) containing a single-layered foil of a gas electron multiplier (GEM) to open up a new window on cosmic X-ray polarimetry in the 2-10 keV band. The micro-pattern TPC polarimeter in combination with the Scalable Readout System produced by the RD51 collaboration has been built as an engineering model to optimize detector parameters and improve polarimeter sensitivity. The polarimeter was characterized with unpolarized X-rays from an X-ray generator in a laboratory and polarized X-rays on the BL32B2 beamline at the SPring-8 synchrotron radiation facility. Preliminary results show that the polarimeter has a comparable modulation factor to a prototype of the flight one.

A Combined Retrieval of Aerosol Microphysical Properties using active HSRL and Passive Polarimeter Multi-sensor Data

NASA Astrophysics Data System (ADS)

Liu, X.; Stamnes, S.; Ferrare, R. A.; Hostetler, C. A.; Burton, A. S.; Chemyakin, E.; Sawamura, P.; Mueller, D.

2017-12-01

Vertically resolved measurements of aerosol optical, microphysical, and macrophysical parameters are required to better understand the influence of aerosols on climate and air quality. We will describe an Optimal Estimation (OE) retrieval framework which can perform aerosol property retrievals in three modes: 1) lidar-only, 2) polarimeter-only, and 3) combined lidar-polarimeter muti-sensor system. The lidar data can be profile measurements by any high spectral resolution lidar (HSRL) and/or Raman lidar with multiple wavelengths of aerosol backscattering (β) and extinction (α). The polarimeter data can be any multi-angle and multi-wavelength measurements with 2 or 3 polarization components. We will show aerosol microphysical retrieval results from the HSRL-2 data measured from various NASA airborne field campaigns including the recent ORACLES mission. We will also show the OE retrieval results from the polarimeter-only mode. Finally, we will demonstrate how the information content of the aerosol microphysical retrieval is increased by combining the active HSRL and passive polarimeter data in our simultaneous OE retrieval system.

Instrumentation for single-dish observations with The Greenland Telescope

NASA Astrophysics Data System (ADS)

Grimes, Paul K.; Asada, K.; Blundell, R.; Burgos, R.; Chang, H.-H.; Chen, M. T.; Goldie, D.; Groppi, C.; Han, C. C.; Ho, P. T. P.; Huang, Y. D.; Inoue, M.; Kubo, D.; Koch, P.; Leech, J.; de Lera Acedo, E.; Martin-Cocher, P.; Nishioka, H.; Nakamura, M.; Matsushita, S.; Paine, S. N.; Patel, N.; Raffin, P.; Snow, W.; Sridharan, T. K.; Srinivasan, R.; Thomas, C. N.; Tong, E.; Wang, M.-J.; Wheeler, C.; Withington, S.; Yassin, G.; Zeng, L.-Z.

2014-07-01

The Greenland Telescope project will deploy and operate a 12m sub-millimeter telescope at the highest point of the Greenland i e sheet. The Greenland Telescope project is a joint venture between the Smithsonian As- trophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). In this paper we discuss the concepts, specifications, and science goals of the instruments being developed for single-dish observations with the Greenland Telescope, and the coupling optics required to couple both them and the mm-VLBI receivers to antenna. The project will outfit the ALMA North America prototype antenna for Arctic operations and deploy it to Summit Station,1 a NSF operated Arctic station at 3,100m above MSL on the Greenland I e Sheet. This site is exceptionally dry, and promises to be an excellent site for sub-millimeter astronomical observations. The main science goal of the Greenland Telescope is to carry out millimeter VLBI observations alongside other telescopes in Europe and the Americas, with the aim of resolving the event horizon of the super-massive black hole at the enter of M87. The Greenland Telescope will also be outfitted for single-dish observations from the millimeter-wave to Tera-hertz bands. In this paper we will discuss the proposed instruments that are currently in development for the Greenland Telescope - 350 GHz and 650 GHz heterodyne array receivers; 1.4 THz HEB array receivers and a W-band bolometric spectrometer. SAO is leading the development of two heterodyne array instruments for the Greenland Telescope, a 48- pixel, 325-375 GHz SIS array receiver, and a 4 pixel, 1.4 THz HEB array receiver. A key science goal for these instruments is the mapping of ortho and para H2D+ in old protostellar ores, as well as general mapping of CO and other transitions in molecular louds. An 8-pixel prototype module for the 350 GHz array is currently being built for laboratory and operational testing on the Greenland Telescope. Arizona State University are developing a 650 GHz 256 pixel SIS array receiver based on the KAPPa SIS mixer array technology and ASIAA are developing 1.4 THz HEB single pixel and array receivers. The University of Cambridge and SAO are collaborating on the development of the CAMbridge Emission Line Surveyor (CAMELS), a W-band `on- hip' spectrometer instrument with a spectral resolution of R ~ 3000. CAMELS will consist of two pairs of horn antennas, feeding super conducting niobium nitride filter banks read by tantalum based Kinetic Inductance Detectors.

Cotton-Mouton polarimeter with HCN laser on CHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akiyama, T.; Kawahata, K.; Ito, Y.

Polarimeters based on the Cotton-Mouton effect hold promise for electron density measurements. We have designed and installed a Cotton-Mouton polarimeter on the Compact Helical System. The Cotton-Mouton effect is measured as the phase difference between probe and reference beams. In this system, an interferometric measurement can be performed simultaneously with the same probe chord. The light source is a HCN laser (wavelength of 337 {mu}m). Digital complex demodulation is adopted for small phase analysis. The line averaged density evaluated from the polarimeter along a plasma center chord is almost consistent with that from the interferometer.

The LABOCA/ACT Survey of Clusters at All Redshifts: Multiwavelength Analysis of Background Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Aguirre, Paula; Lindner, Robert R.; Baker, Andrew J.; Bond, J. Richard; Dünner, Rolando; Galaz, Gaspar; Gallardo, Patricio; Hilton, Matt; Hughes, John P.; Infante, Leopoldo; Lima, Marcos; Menten, Karl M.; Sievers, Jonathan; Weiss, Axel; Wollack, Edward J.

2018-03-01

We present a multiwavelength analysis of 48 submillimeter galaxies (SMGs) detected in the Large APEX Bolometer Camera/Atacama Cosmology Telescope (ACT) Survey of Clusters at All Redshifts, LASCAR, which acquired new 870 μm and Australia Telescope Compact Array 2.1 GHz observations of 10 galaxy clusters detected through their Sunyaev–Zel’dovich effect (SZE) signal by the ACT. Far-infrared observations were also conducted with the Photodetector Array Camera and Spectrometer (100/160 μm) and SPIRE (250/350/500 μm) instruments on Herschel for sample subsets of five and six clusters. LASCAR 870 μm maps were reduced using a multiscale iterative pipeline that removes the SZE increment signal, yielding point-source sensitivities of σ ∼ 2 mJy beam‑1. We detect in total 49 sources at the 4σ level and conduct a detailed multiwavelength analysis considering our new radio and far-IR observations plus existing near-IR and optical data. One source is identified as a foreground galaxy, 28 SMGs are matched to single radio sources, four have double radio counterparts, and 16 are undetected at 2.1 GHz but tentatively associated in some cases to near-IR/optical sources. We estimate photometric redshifts for 34 sources with secure (25) and tentative (9) matches at different wavelengths, obtaining a median z={2.8}-1.7+2.1. Compared to previous results for single-dish surveys, our redshift distribution has a comparatively larger fraction of sources at z > 3, and the high-redshift tail is more extended. This is consistent with millimeter spectroscopic confirmation of a growing number of high-z SMGs and relevant for testing of cosmological models. Analytical lens modeling is applied to estimate magnification factors for 42 SMGs at clustercentric radii >1.‧2 with the demagnified flux densities and source-plane areas, we obtain integral number counts that agree with previous submillimeter surveys.

A New Cost-Effective Diode Laser Polarimeter Apparatus Constructed by Undergraduate Students

ERIC Educational Resources Information Center

Lisboa, Pedro; Sotomayor, Joo; Ribeiro, Paulo

2010-01-01

The construction of a diode laser polarimeter apparatus by undergraduate students is described. The construction of the modular apparatus by undergraduate students gives them an insight into how it works and how the measurement of a physical or chemical property is conducted. The students use the polarimeter to obtain rotation angle values for the…

Infrared Luminosities and Dust Properties of z ≈ 2 Dust-obscured Galaxies

NASA Astrophysics Data System (ADS)

Bussmann, R. S.; Dey, Arjun; Borys, C.; Desai, V.; Jannuzi, B. T.; Le Floc'h, E.; Melbourne, J.; Sheth, K.; Soifer, B. T.

2009-11-01

We present SHARC-II 350 μm imaging of twelve 24 μm bright (F 24 μm > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Boötes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 μm imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 μm flux density. The 350 μm upper limits for the 8 non-detected DOGs are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ≈3 × 108 M sun. In comparison to other dusty z ~ 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 × 1013 L sun versus 6 × 1012 L sun for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus ~30 K) and lower inferred dust masses (3 × 108 M sun versus 3 × 109 M sun). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 μm bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z ~ 2 involves a submillimeter bright, cold-dust, and star-formation-dominated phase followed by a 24 μm bright, warm-dust and AGN-dominated phase.

SUBMILLIMETER-HCN DIAGRAM FOR ENERGY DIAGNOSTICS IN THE CENTERS OF GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izumi, Takuma; Kohno, Kotaro; Aalto, Susanne

2016-02-10

Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4–3)/HCO{sup +}(4–3) and/or HCN(4–3)/CS(7–6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of themore » high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO{sup +} and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even ≳10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral–neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.« less

The AzTEC millimeter-wave camera: Design, integration, performance, and the characterization of the (sub-)millimeter galaxy population

NASA Astrophysics Data System (ADS)

Austermann, Jason Edward

One of the primary drivers in the development of large format millimeter detector arrays is the study of sub-millimeter galaxies (SMGs) - a population of very luminous high-redshift dust-obscured starbursts that are widely believed to be the dominant contributor to the Far-Infrared Background (FIB). The characterization of such a population requires the ability to map large patches of the (sub-)millimeter sky to high sensitivity within a feasible amount of time. I present this dissertation on the design, integration, and characterization of the 144-pixel AzTEC millimeter-wave camera and its application to the study of the sub-millimeter galaxy population. In particular, I present an unprecedented characterization of the "blank-field" (fields with no known mass bias) SMG number counts by mapping over 0.5 deg^2 to 1.1mm depths of ~1mJy - a previously unattained depth on these scales. This survey provides the tightest SMG number counts available, particularly for the brightest and rarest SMGs that require large survey areas for a significant number of detections. These counts are compared to the predictions of various models of the evolving mm/sub-mm source population, providing important constraints for the ongoing refinement of semi-analytic and hydrodynamical models of galaxy formation. I also present the results of an AzTEC 0.15 deg^2 survey of the COSMOS field, which uncovers a significant over-density of bright SMGs that are spatially correlated to foreground mass structures, presumably as a result of gravitational lensing. Finally, I compare the results of the available SMG surveys completed to date and explore the effects of cosmic variance on the interpretation of individual surveys.

Submillimeter-HCN Diagram for Energy Diagnostics in the Centers of Galaxies

NASA Astrophysics Data System (ADS)

Izumi, Takuma; Kohno, Kotaro; Aalto, Susanne; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hatsukade, Bunyo; Hsieh, Pei-Ying; Imanishi, Masatoshi; Krips, Melanie; Martín, Sergio; Matsushita, Satoki; Meier, David S.; Nakai, Naomasa; Nakanishi, Kouichiro; Schinnerer, Eva; Sheth, Kartik; Terashima, Yuichi; Turner, Jean L.

2016-02-01

Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(4-3) and/or HCN(4-3)/CS(7-6) integrated intensity ratios in circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO+ and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even ≳10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral-neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pérez, Laura M.; Chandler, Claire J.; Isella, Andrea

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations in the dust continuum (690 GHz, 0.45 mm) and {sup 12}CO J = 6-5 spectral line emission of the transitional disks surrounding the stars SAO 206462 and SR 21. These ALMA observations resolve the dust-depleted disk cavities and extended gaseous disks, revealing large-scale asymmetries in the dust emission of both disks. We modeled these disk structures with a ring and an azimuthal Gaussian, where the azimuthal Gaussian is motivated by the steady-state vortex solution from Lyra and Lin. Compared to recent observations of HD 142527, Oph IRS 48, and LkHα 330, these are low-contrastmore » (≲ 2) asymmetries. Nevertheless, a ring alone is not a good fit, and the addition of a vortex prescription describes these data much better. The asymmetric component encompasses 15% and 28% of the total disk emission in SAO 206462 and SR 21, respectively, which corresponds to a lower limit of 2 M {sub Jup} of material within the asymmetry for both disks. Although the contrast in the dust asymmetry is low, we find that the turbulent velocity inside it must be large (∼20% of the sound speed) in order to drive these azimuthally wide and radially narrow vortex-like structures. We obtain residuals from the ring and vortex fitting that are still significant, tracing non-axisymmetric emission in both disks. We compared these submillimeter observations with recently published H-band scattered light observations. For SR 21 the scattered light emission is distributed quite differently from the submillimeter continuum emission, while for SAO 206462 the submillimeter residuals are suggestive of spiral-like structure similar to the near-IR emission.« less

Formation, Detection and the Distribution of Complex Organic Molecules with the Atacama Large Millimeter/submillimeter Array (ALMA)

NASA Astrophysics Data System (ADS)

Remijan, Anthony John

2015-08-01

The formation and distribution of complex organic material in astronomical environments continues to be a focused research area in astrochemistry. For several decades now, emphasis has been placed on the millimeter/submillimeter regime of the radio spectrum for trying to detect new molecular species and to constrain the chemical formation route of complex molecules by comparing and contrasting their relative distributions towards varying astronomical environments. This effort has been extremely laborious as millimeter/submillimeter facilities have been only able to detect and map the distribution of the strongest transition(s) of the simplest organic molecules. Even then, these single transition "chemical maps" have been very low spatial resolution because early millimeter/submillimeter facilities did not have access to broadband spectral coverage or the imaging capabilities to truly ascertain the morphology of the molecular emission. In the era of ALMA, these limitations have been greatly lifted. Broadband spectral line surveys now hold the key to uncovering the full molecular complexity in astronomical environments. In addition, searches for complex organic material is no longer limited to investigating the strongest lines of the simplest molecules toward the strongest sources of emission in the Galaxy. ALMA is issuing a new era of exploration as the search for complex molecules will now be available to an increased suite of sources in the Galaxy and our understanding of the formation of this complex material will be greatly increased as a result. This presentation will highlight the current and future ALMA capabilities in the search for complex molecules towards astronomical environments, highlight the recent searches that ALMA scientists have conducted from the start of ALMA Early Science and provide the motivation for the next suite of astronomical searches to investigate our pre-biotic origins in the universe.

A submillimeter background galaxy projected on the debris disk of HD95086 revealed by ALMA

NASA Astrophysics Data System (ADS)

Zapata, Luis A.; Ho, Paul T. P.; Rodríguez, Luis F.

2018-06-01

We present sensitive observations carried out with the Atacama Large Millimeter/Submillimeter Array (ALMA) of the dusty debris disc HD 95086. These observations were made in bands 6 (223 GHz) and 7 (338 GHz) with an angular resolution of about 1 arcsec, which allowed us to resolve well the debris disc with a deconvolved size of 7.0 × 6.0 arcsec2 and with an inner depression of about 2 arcsec. We do not detect emission from the star itself and the possible inner dusty belt. We also do not detect CO (J = 2-1) and (J = 3-2) emission, excluding the possibility of an evolved gaseous primordial disc as noted in previous studies of HD95086. We estimated a lower limit for the gas mass of ≤0.01 M⊕ for the debris disc of HD95086. From the mm. emission, we computed a dust mass for the debris disc HD95086 of 0.5 ± 0.2 M⊕, resulting in a dust-to-gas ratio of ≥50. Finally, we confirm the detection of a strong submillimeter source to the north-west of the disc (ALMA-SMM1) revealed by recent ALMA observations. This new source might be interpreted as a planet in formation on the periphery of the debris disc HD 95086 or as a strong impact between dwarf planets. However, given the absence of the proper motions of ALMA-SMM1 similar to those reported in the debris disc (estimated from these new ALMA observations) and for the optical star, this is more likely to be a submillimeter background galaxy.

Observational Aspects of Hard X-ray Polarimetry

NASA Astrophysics Data System (ADS)

Chattopadhyay, Tanmoy

2016-04-01

Sensitive polarization measurements in X-ray may address a wealth of astrophysical phenomena, which so far remain beyond our understanding through available X-ray spectroscopic, imaging, and timing studies. Though scientific potential of X-ray polarimetry was realized long ago, there has not been any significant advancement in this field for the last four decades since the birth of X-ray astronomy. The only successful polarization measurement in X-rays dates back to 1976, when a Bragg polarimeter onboard OSO-8 measured polarization of Crab nebula. Primary reason behind the lack in progress is its extreme photon hungry nature, which results in poor sensitivity of the polarimeters. Recently, in the last decade or so, with the advancement in detection technology, X-ray polarimetry may see a significant progress in near future, especially in soft X-rays with the invention of photoelectron tracking polarimeters. Though photoelectric polarimeters are expected to provide sensitive polarization measurements of celestial X-ray sources, they are sensitive only in soft X-rays, where the radiation from the sources is dominated by thermal radiation and therefore expected to be less polarized. On the other hand, in hard X-rays, sources are ex-pected to be highly polarized due to the dominance of nonthermal emission over its thermal counterpart. Moreover, polarization measurements in hard X-rays promises to address few interesting scientific issues regarding geometry of corona for black hole sources, emission mechanism responsible for the higher energy peak in the blazars, accretion geometry close to the magnetic poles in accreting neutron star systems and acceleration mechanism in solar flares. Compton polarimeters provide better sensitivity than photoelectric polarimeters in hard X-rays with a broad energy band of operation. Recently, with the development of hard X-ray focusing optics e.g. NuSTAR, Astro-H, it is now possible to conceive Compton polarimeters at the focal plane of such hard X-ray telescopes, which may provide sensitive polarization measurements due to flux concentration in hard X-rays with a very low background. On the other hand, such a configuration ensures implementation of an optimized geometry close to an ideal one for the Compton polarimeters. In this context, we initiated the development of a focal plane Compton polarimeter, consisting of a plastic scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. Geant-4 simulations of the planned configuration estimates 1% MDP for a 100 mCrab source in 1 million seconds of exposure. Sensitivity of the instrument is found to be critically dependent on the lower energy detection limit of the plastic scatterer; lower the threshold, better is the sensitivity. In the actual experiment, the plastic is readout by a photomultiplier tube procured from Saint-Gobain. We carried out extensive experiments to characterize the plastic especially for lower energy depositions. The CsI(Tl) scintillators are readout by Si photomultipliers (SiPM). SiPMs are small in size and robust and therefore provide the compactness necessary for the designing of focal plane detectors. Each of the CsI(Tl)-SiPM systems was characterized precisely to estimate their energy threshold and detection probability along the length of the scintillators away from SiPM. Finally, we integrated the Compton polarimeter and tested its response to polarized and unpolarized radiation and compared the experimental results with Geant-4 simulation. Despite the growing realization of the scientific values of X-ray polarimetry and the efforts in developing sensitive X-ray polarimeters, there has not been a single dedicated X-ray polarimetry mission planned in near future. In this scenario, it is equally important to attempt polarization measurements from the existing or planned instruments which are not meant for X-ray polarization measurements but could be sensitive to it. There have been several attempts in past in retrieving polarization information from few of such spectroscopic instruments like RHESSI, INTEGRAL-IBIS, INTEGRAL-SPI. Cadmium Zinc Telluride Imager (CZTI) onboard Astrosat, India's first astronomical mission, is one of such instruments which is expected to provide sensitive polarization measurements for bright X-ray sources. CZTI consists of 64 CZT detector modules, each of which is 5 mm thick and 4 cm × 4 cm in size. Each CZT module is subdivided into 256 pixels with pixel pitch of 2.5 mm. Due to its pixelation nature and significant Compton scattering efficiency at energies beyond 100 keV, CZTI can work as a sensitive Compton polarimeter in hard X-rays. Detailed Geant-4 simulations and polarization experiments with the flight configuration of CZTI show that CZTI will have significant polarization measurement capability for bright sources in hard X-rays. CZTI is primarily a spectroscopic instrument with coded mask imaging. To properly utilize the spectroscopic capabilities of CZT detectors, it is important to generate accurate response matrix for CZTI, which in turn requires precise modelling of the CZT lines shapes for monoenergetic X-ray interaction. CZT detectors show an extended lower energy tail of an otherwise Gaussian line shape due to low mobility and lifetime of the charge carriers. On the other hand, interpixel charge sharing may also contribute to the lower energy tail making the line shape more complicated. We have developed a model to predict the line shapes from CZTI modules taking into account the mobility and lifetime of the charge carriers and charge sharing fractions. The model predicts the line shape quite well and can be used to generate pixel-wise response matrix for CZTI.

Advanced ACTPol Low-Frequency Array: Readout and Characterization of Prototype 27 and 39 GHz Transition Edge Sensors

NASA Astrophysics Data System (ADS)

Koopman, B. J.; Cothard, N. F.; Choi, S. K.; Crowley, K. T.; Duff, S. M.; Henderson, S. W.; Ho, S. P.; Hubmayr, J.; Gallardo, P. A.; Nati, F.; Niemack, M. D.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Vavagiakis, E. M.; Wollack, E. J.

2018-05-01

Advanced ACTPol (AdvACT) is a third-generation polarization upgrade to the Atacama Cosmology Telescope, designed to observe the cosmic microwave background (CMB). AdvACT expands on the 90 and 150 GHz transition edge sensor (TES) bolometer arrays of the ACT Polarimeter (ACTPol), adding both high-frequency (HF, 150/230 GHz) and low-frequency (LF, 27/39 GHz) multichroic arrays. The addition of the high- and low-frequency detectors allows for the characterization of synchrotron and spinning dust emission at the low frequencies and foreground emission from galactic dust and dusty star-forming galaxies at the high frequencies. The increased spectral coverage of AdvACT will enable a wide range of CMB science, such as improving constraints on dark energy, the sum of the neutrino masses, and the existence of primordial gravitational waves. The LF array will be the final AdvACT array, replacing one of the MF arrays for a single season. Prior to the fabrication of the final LF detector array, we designed and characterized prototype TES bolometers. Detector geometries in these prototypes are varied in order to inform and optimize the bolometer designs for the LF array, which requires significantly lower noise levels and saturation powers (as low as {˜ } 1 pW) than the higher-frequency detectors. Here we present results from tests of the first LF prototype TES detectors for AdvACT, including measurements of the saturation power, critical temperature, thermal conductance, and time constants. We also describe the modifications to the time-division SQUID readout architecture compared to the MF and HF arrays.

Comparison between Pixelated Scintillators: CsI(Tl), LaCl 3(Ce) and LYSO(Ce) when coupled to a Silicon Photomultipliers Array

NASA Astrophysics Data System (ADS)

Jeong, Manhee; Van, Benjamin; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

2018-06-01

A large area SiPM array is individually coupled to five different types of scintillators in and each is evaluated for the development of a coded aperture imaging system. In order to readout signals from the 144 pixel array, a resistor network with symmetric charge division circuitry was developed, which successfully provides a significant reduction in the multiplicity of the analog outputs and reduces the size of the accumulated data. Energy resolutions at 662 keV for pixelated arrays of dimensions and material types as follows: 3 × 3 × 20 mm3 CsI(Tl), 4 × 4 × 20 mm3 CsI(Tl), 4 × 4 × 5 mm3 LYSO(Ce), 4 × 4 × 10 mm3 LYSO(Ce), and 2 × 2 × 5 mm3 LaCl3(Ce) have been determined. In addition, sub-millimeter FWHM pixel-identification resolutions were acquired from all of the scintillators tested.

Next-generation Event Horizon Telescope developments: new stations for enhanced imaging

NASA Astrophysics Data System (ADS)

Palumbo, Daniel; Johnson, Michael; Doeleman, Sheperd; Chael, Andrew; Bouman, Katherine

2018-01-01

The Event Horizon Telescope (EHT) is a multinational Very Long Baseline Interferometry (VLBI) network of dishes joined to resolve general relativistic behavior near a supermassive black hole. The imaging quality of the EHT is largely dependent upon the sensitivity and spatial frequency coverage of the many baselines between its constituent telescopes. The EHT already contains many highly sensitive dishes, including the crucial Atacama Large Millimeter/Submillimeter Array (ALMA), making it viable to add smaller, cheaper telescopes to the array, greatly improving future capabilities of the EHT. We develop tools for optimizing the positions of new dishes in planned arrays. We also explore the feasibility of adding small orbiting dishes to the EHT, and develop orbital optimization tools for space-based VLBI imaging. Unlike the Millimetron mission planned to be at L2, we specifically treat near-earth orbiters, and find rapid filling of spatial frequency coverage across a large range of baseline lengths. Finally, we demonstrate significant improvement in image quality when adding small dishes to planned arrays in simulated observations.

A Virtual Sky with Extragalactic H I and CO Lines for the Square Kilometre Array and the Atacama Large Millimeter/Submillimeter Array

NASA Astrophysics Data System (ADS)

Obreschkow, D.; Klöckner, H.-R.; Heywood, I.; Levrier, F.; Rawlings, S.

2009-10-01

We present a sky simulation of the atomic H I-emission line and the first 10 12C16O rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500 h -1 Mpc; hence, the actual field of view depends on the (user-defined) maximal redshift z max; e.g., for z max = 10, the field of view yields ~4 × 4 deg2. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the H I and CO-emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 108 M sun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Λ cold dark matter (ΛCDM) cosmology. The evolving CDM distribution was adopted from the Millennium Simulation, an N-body CDM simulation in a cubic box with a side length of 500 h -1 Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such as the Square Kilometre Array, Large Millimeter Telescope, and Atacama Large Millimeter/Submillimeter Array. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz analyses for peak flux density limited and total flux limited surveys of H I and CO. A key prediction is that H I will be harder to detect at redshifts z gsim 2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models. -SAX-Sky"

System engineering of the Atacama Large Millimeter/submillimeter Array

NASA Astrophysics Data System (ADS)

Bhatia, Ravinder; Marti, Javier; Sugimoto, Masahiro; Sramek, Richard; Miccolis, Maurizio; Morita, Koh-Ichiro; Arancibia, Demián.; Araya, Andrea; Asayama, Shin'ichiro; Barkats, Denis; Brito, Rodrigo; Brundage, William; Grammer, Wes; Haupt, Christoph; Kurlandczyk, Herve; Mizuno, Norikazu; Napier, Peter; Pizarro, Eduardo; Saini, Kamaljeet; Stahlman, Gretchen; Verzichelli, Gianluca; Whyborn, Nick; Yagoubov, Pavel

2012-09-01

The Atacama Large Millimeter/submillimeter Array (ALMA) will be composed of 66 high precision antennae located at 5000 meters altitude in northern Chile. This paper will present the methodology, tools and processes adopted to system engineer a project of high technical complexity, by system engineering teams that are remotely located and from different cultures, and in accordance with a demanding schedule and within tight financial constraints. The technical and organizational complexity of ALMA requires a disciplined approach to the definition, implementation and verification of the ALMA requirements. During the development phase, System Engineering chairs all technical reviews and facilitates the resolution of technical conflicts. We have developed analysis tools to analyze the system performance, incorporating key parameters that contribute to the ultimate performance, and are modeled using best estimates and/or measured values obtained during test campaigns. Strict tracking and control of the technical budgets ensures that the different parts of the system can operate together as a whole within ALMA boundary conditions. System Engineering is responsible for acceptances of the thousands of hardware items delivered to Chile, and also supports the software acceptance process. In addition, System Engineering leads the troubleshooting efforts during testing phases of the construction project. Finally, the team is conducting System level verification and diagnostics activities to assess the overall performance of the observatory. This paper will also share lessons learned from these system engineering and verification approaches.

Characterizing and Modeling the Noise and Complex Impedance of Feedhorn-Coupled TES Polarimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Appel, J. W.; Beall, J. A.; Essinger-Hileman, T.

2009-12-16

We present results from modeling the electrothermal performance of feedhorn-coupled transition edge sensor (TES) polarimeters under development for use in cosmic microwave background (CMB) polarization experiments. Each polarimeter couples radiation from a corrugated feedhorn through a planar orthomode transducer, which transmits power from orthogonal polarization modes to two TES bolometers. We model our TES with two- and three-block thermal architectures. We fit the complex impedance data at multiple points in the TES transition. From the fits, we predict the noise spectra. We present comparisons of these predictions to the data for two TESes on a prototype polarimeter.

The Second-generation z (Redshift) and Early Universe Spectrometer. I. First-light Observation of a Highly Lensed Local-ulirg Analog at High-z

NASA Astrophysics Data System (ADS)

Ferkinhoff, Carl; Brisbin, Drew; Parshley, Stephen; Nikola, Thomas; Stacey, Gordon J.; Schoenwald, Justin; Higdon, James L.; Higdon, Sarah J. U.; Verma, Aprajita; Riechers, Dominik; Hailey-Dunsheath, Steven; Menten, Karl M.; Güsten, Rolf; Weiß, Axel; Irwin, Kent; Cho, Hsiao M.; Niemack, Michael; Halpern, Mark; Amiri, Mandana; Hasselfield, Matthew; Wiebe, D. V.; Ade, Peter A. R.; Tucker, Carol E.

2014-01-01

We recently commissioned our new spectrometer, the second-generation z(Redshift) and Early Universe Spectrometer (ZEUS-2) on the Atacama Pathfinder Experiment telescope. ZEUS-2 is a submillimeter grating spectrometer optimized for detecting the faint and broad lines from distant galaxies that are redshifted into the telluric windows from 200 to 850 μm. It uses a focal plane array of transition-edge sensed bolometers, the first use of these arrays for astrophysical spectroscopy. ZEUS-2 promises to be an important tool for studying galaxies in the years to come because of its synergy with Atacama Large Millimeter Array and its capabilities in the short submillimeter windows that are unique in the post-Herschel era. Here, we report on our first detection of the [C II] 158 μm line with ZEUS-2. We detect the line at z ~ 1.8 from H-ATLAS J091043.1-000322 with a line flux of (6.44 ± 0.42) × 10-18 W m-2. Combined with its far-IR luminosity and a new Herschel-PACS detection of the [O I] 63 μm line, we model the line emission as coming from a photo-dissociation region with far-ultraviolet radiation field, G ~ 2 × 104 G 0, gas density, n ~ 1 × 103 cm-3 and size between ~0.4 and 1 kpc. On the basis of this model, we conclude that H-ATLAS J091043.1-000322 is a high-redshift analog of a local ultra-luminous IR galaxy; i.e., it is likely the site of a compact starburst caused by a major merger. Further identification of these merging systems is important for constraining galaxy formation and evolution models.

Characterization of surface tilt of foundations for high-precision radio-astronomic antennas

NASA Astrophysics Data System (ADS)

Hoff, Brian D.; Puga, Jose P.

2010-07-01

The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA will consist of at least 54 twelve-meter antennas operating in the millimeter and sub-millimeter wavelength range. It will be located at an altitude above 5000m in the Chajnantor Plateau in northern Chile. There are 192 antenna foundations under construction at ALMA's Array Operations Site (AOS). Interchangeability between foundations will permit a variety of array configurations. Foundations provide the physical interface to the bedrock, as well as to the underground signal and power cable conduits. To achieve ALMA's precision requirements, the antenna pointing angular error budget is strict with anticipated non-repeatable error on the order of a few arc seconds. This level of precision imposes rigorous requirements on antenna foundations. The objective of this study is to demonstrate the methodology of precision tilt measurements combined with finite element simulation predictions to portray the qualitative nature of the antenna foundation surface deformation. Characteristics of foundation surface tilt have been examined in detail. Although the actual foundation has demonstrated much less resistance to tilt than the finite element representation, the simulation has predicted some key characteristics of the tilt pattern. The large deviations from the ideal have incited speculations into the compliance of materials, ambiguities in the construction, thermal effects and several other aspects described herein. This research has served as groundwork to characterize ALMA's foundation surface behavior on a micro-degree level and to identify subsequent studies to pursue. This in turn has contributed to the diagnosis of antenna pointing anomalies.

ALMA Observations of Dust Polarization and Molecular Line Emission from the Class 0 Protostellar Source Serpens SMM1

NASA Astrophysics Data System (ADS)

Hull, Charles L. H.; Girart, Josep M.; Tychoniec, Łukasz; Rao, Ramprasad; Cortés, Paulo C.; Pokhrel, Riwaj; Zhang, Qizhou; Houde, Martin; Dunham, Michael M.; Kristensen, Lars E.; Lai, Shih-Ping; Li, Zhi-Yun; Plambeck, Richard L.

2017-10-01

We present high angular resolution dust polarization and molecular line observations carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the Class 0 protostar Serpens SMM1. By complementing these observations with new polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (˜0.1 pc) scales—where the magnetic field is oriented E-W, perpendicular to the major axis of the dusty filament where SMM1 is embedded—and the intermediate and small scales probed by CARMA (˜1000 au resolution), the SMA (˜350 au resolution), and ALMA (˜140 au resolution). The ALMA maps reveal that the redshifted lobe of the bipolar outflow is shaping the magnetic field in SMM1 on the southeast side of the source; however, on the northwestern side and elsewhere in the source, low-velocity shocks may be causing the observed chaotic magnetic field pattern. High-spatial-resolution continuum and spectral-line observations also reveal a tight (˜130 au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both {CO}(J=2\\to 1) and {SiO}(J=5\\to 4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like SMM1.

Investigating the Early Evolution of Planetary Systems with ALMA and the Next Generation Very Large Array

NASA Astrophysics Data System (ADS)

Ricci, Luca; Liu, Shang-Fei; Isella, Andrea; Li, Hui

2018-02-01

We investigate the potential of the Atacama Large Millimeter/submillimeter Array (ALMA) and the Next Generation Very Large Array (ngVLA) to observe substructures in nearby young disks which are due to the gravitational interaction between disk material and planets close to the central star. We simulate the gas and dust dynamics in the disk using the LA-COMPASS hydrodynamical code. We generate synthetic images for the dust continuum emission at submillimeter to centimeter wavelengths and simulate ALMA and ngVLA observations. We explore the parameter space of some of the main disk and planet properties that would produce substructures that can be visible with ALMA and the ngVLA. We find that ngVLA observations with an angular resolution of 5 milliarcsec at 3 mm can reveal and characterize gaps and azimuthal asymmetries in disks hosting planets with masses down to ≈ 5 {M}\\oplus ≈ 1{--}5 {au} from a solar-like star in the closest star-forming regions, whereas ALMA can detect gaps down to planetary masses of ≈ 20 {M}\\oplus at 5 au. Gaps opened by super-Earth planets with masses ≈ 5{--}10 {M}\\oplus are detectable by the ngVLA in the case of disks with low viscosity (α ∼ {10}-5) and low pressure scale height (h ≈ 0.025 au at 5 au). The ngVLA can measure the proper motion of azimuthal asymmetric structures associated with the disk–planet interaction as well as possible circumplanetary disks on timescales as short as one to a few weeks for planets at 1–5 au from the star.

Progress Towards High-Sensitivity Arrays of Detectors of Sub-mm Radiation Using Superconducting Tunnel Junctions with Integrated Radio Frequency Single-Electron Transistors

NASA Technical Reports Server (NTRS)

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Prober, D. E.; Rhee, K. W.; Schoelkopf, R. J.; Stahle, C. M.; Teufel, J.; Wollack, E. J.

2004-01-01

For high resolution imaging and spectroscopy in the FIR and submillimeter, space observatories will demand sensitive, fast, compact, low-power detector arrays with 104 pixels and sensitivity less than 10(exp -20) W/Hz(sup 0.5). Antenna-coupled superconducting tunnel junctions with integrated rf single-electron transistor readout amplifiers have the potential for achieving this high level of sensitivity, and can take advantage of an rf multiplexing technique. The device consists of an antenna to couple radiation into a small superconducting volume and cause quasiparticle excitations, and a single-electron transistor to measure current through junctions contacting the absorber. We describe optimization of device parameters, and results on fabrication techniques for producing devices with high yield for detector arrays. We also present modeling of expected saturation power levels, antenna coupling, and rf multiplexing schemes.

Optics for MUSIC: a new (sub)millimeter camera for the Caltech Submillimeter Observatory

NASA Astrophysics Data System (ADS)

Sayers, Jack; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran P.; Gao, Jiansong; Glenn, Jason; Golwala, Sunil R.; Hollister, Matt I.; LeDuc, Henry G.; Mazin, Benjamin A.; Maloney, Philip R.; Noroozian, Omid; Nguyen, Hien T.; Schlaerth, James A.; Siegel, Seth; Vaillancourt, John E.; Vayonakis, Anastasios; Wilson, Philip R.; Zmuidzinas, Jonas

2010-07-01

We will present the design and implementation, along with calculations and some measurements of the performance, of the room-temperature and cryogenic optics for MUSIC, a new (sub)millimeter camera we are developing for the Caltech Submm Observatory (CSO). The design consists of two focusing elements in addition to the CSO primary and secondary mirrors: a warm off-axis elliptical mirror and a cryogenic (4K) lens. These optics will provide a 14 arcmin field of view that is diffraction limited in all four of the MUSIC observing bands (2.00, 1.33, 1.02, and 0.86 mm). A cold (4K) Lyot stop will be used to define the primary mirror illumination, which will be maximized while keeping spillover at the sub 1% level. The MUSIC focal plane will be populated with broadband phased antenna arrays that efficiently couple to factor of (see manuscript) 3 in bandwidth,1, 2 and each pixel on the focal plane will be read out via a set of four lumped element filters that define the MUSIC observing bands (i.e., each pixel on the focal plane simultaneously observes in all four bands). Finally, a series of dielectric and metal-mesh low pass filters have been implemented to reduce the optical power load on the MUSIC cryogenic stages to a quasi-negligible level while maintaining good transmission in-band.

Radio Interferometry with the SMA: Uncovering Hidden Star Formation in Our Extreme Galactic Center

NASA Astrophysics Data System (ADS)

Gutierrez, Elizabeth; Battersby, Cara; MacGregor, Meredith Ann

2018-01-01

Radio interferometry provides the best tool to identify embedded star-forming cores in cold, dense, molecular clouds of gas and dust. Observations at long, submillimeter wavelengths can be used to investigate the physical properties in the youngest stages of star formation. Interferometers provide the resolution necessary to resolve small scale structures like dense cores where star formation is expected to occur. CMZoom is the first large area survey of the Central Molecular Zone (CMZ) at high resolution in the submillimeter, allowing us to identify early sites of star formation. The survey uses both the subcompact and compact configurations of the Submillimeter Array (SMA) interferometric radio telescope. The CMZ, or the inner 500 pc of the Milky Way Galaxy, is a high extinction region comprised of hot, dense, and turbulent molecular gas. This region is forming about an order of magnitude fewer stars than predicted based on simple star formation prescriptions. Here, we present new high resolution images of G0.068-0.075, a region from the CMZoom survey, obtained using CASA. We highlight the importance of interferometric observations of different baseline lengths by comparing the spatial information obtained through different configurations. We will use these new images, in conjunction with the rest of the CMZoom survey, to reveal the mechanisms driving star formation at the center of the galaxy.

An Efficient, FPGA-Based, Cluster Detection Algorithm Implementation for a Strip Detector Readout System in a Time Projection Chamber Polarimeter

NASA Technical Reports Server (NTRS)

Gregory, Kyle J.; Hill, Joanne E. (Editor); Black, J. Kevin; Baumgartner, Wayne H.; Jahoda, Keith

2016-01-01

A fundamental challenge in a spaceborne application of a gas-based Time Projection Chamber (TPC) for observation of X-ray polarization is handling the large amount of data collected. The TPC polarimeter described uses the APV-25 Application Specific Integrated Circuit (ASIC) to readout a strip detector. Two dimensional photoelectron track images are created with a time projection technique and used to determine the polarization of the incident X-rays. The detector produces a 128x30 pixel image per photon interaction with each pixel registering 12 bits of collected charge. This creates challenging requirements for data storage and downlink bandwidth with only a modest incidence of photons and can have a significant impact on the overall mission cost. An approach is described for locating and isolating the photoelectron track within the detector image, yielding a much smaller data product, typically between 8x8 pixels and 20x20 pixels. This approach is implemented using a Microsemi RT-ProASIC3-3000 Field-Programmable Gate Array (FPGA), clocked at 20 MHz and utilizing 10.7k logic gates (14% of FPGA), 20 Block RAMs (17% of FPGA), and no external RAM. Results will be presented, demonstrating successful photoelectron track cluster detection with minimal impact to detector dead-time.

Millimeter and Submillimeter Wave Spectroscopy of Higher Energy Conformers of 1,2-PROPANEDIOL

NASA Astrophysics Data System (ADS)

Zakharenko, Olena; Bossa, Jean-Baptiste; Lewen, Frank; Schlemmer, Stephan; Müller, Holger S. P.

2017-06-01

We have performed a study of the millimeter/submillimeter wave spectrum of four higher energy conformers of 1,2-propanediol (continuation of the previous study on the three lowest energy conformers. The present analysis of rotational transitions carried out in the frequency range 38 - 400 GHz represents a significant extension of previous microwave work. The new data were combined with previously-measured microwave transitions and fitted using a Watson's S-reduced Hamiltonian. The final fits were within experimental accuracy, and included spectroscopic parameters up to sixth order of angular momentum, for the ground states of the four higher energy conformers following previously studied ones: g'Ga, gG'g', aGg' and g'Gg. The present analysis provides reliable frequency predictions for astrophysical detection of 1,2-propanediol by radio telescope arrays at millimeter wavelengths. J.-B. Bossa, M.H. Ordu, H.S.P. Müller, F. Lewen, S. Schlemmer, A&A 570 (2014) A12)

Bolometric kinetic inductance detector technology for sub-millimeter radiometric imaging

NASA Astrophysics Data System (ADS)

Hassel, Juha; Timofeev, Andrey V.; Vesterinen, Visa; Sipola, Hannu; Helistö, Panu; Aikio, Mika; Mäyrä, Aki; Grönberg, Leif; Luukanen, Arttu

2015-10-01

Radiometric sub-millimeter imaging is a candidate technology especially in security screening applications utilizing the property of radiation in the band of 0.2 - 1.0 THz to penetrate through dielectric substances such as clothing. The challenge of the passive technology is the fact that the irradiance corresponding to the blackbody radiation is very weak in this spectral band: about two orders of magnitude below that of the infrared band. Therefore the role of the detector technology is of ultimate importance to achieve sufficient sensitivity. In this paper we present results related to our technology relying on superconducting kinetic inductance detectors operating in a thermal (bolometric) mode. The detector technology is motivated by the fact that it is naturally suitable for scalable multiplexed readout systems, and operates with relatively simple cryogenics. We will review the basic concepts of the detectors, and provide experimental figures of merit. Furthermore, we will discuss the issues related to the scale-up of our detector technology into large 2D focal plane arrays.

Fabrication of Tunnel Junctions For Direct Detector Arrays With Single-Electron Transistor Readout Using Electron-Beam Lithography

NASA Technical Reports Server (NTRS)

Stevenson, T. R.; Hsieh, W.-T.; Li, M. J.; Stahle, C. M.; Rhee, K. W.; Teufel, J.; Schoelkopf, R. J.

2002-01-01

This paper will describe the fabrication of small aluminum tunnel junctions for applications in astronomy. Antenna-coupled superconducting tunnel junctions with integrated single-electron transistor readout have the potential for photon-counting sensitivity at sub-millimeter wavelengths. The junctions for the detector and single-electron transistor can be made with electron-beam lithography and a standard self-aligned double-angle deposition process. However, high yield and uniformity of the junctions is required for large-format detector arrays. This paper will describe how measurement and modification of the sensitivity ratio in the resist bilayer was used to greatly improve the reliability of forming devices with uniform, sub-micron size, low-leakage junctions.

Characteristics of an Imaging Polarimeter for the Powell Observatory

NASA Astrophysics Data System (ADS)

Hall, Shannon W.; Henson, Gary D.

2010-07-01

A dual-beam imaging polarimeter has been built for use on the 14-inch Schmidt-Cassegrain telescope at the ETSU Harry D. Powell Observatory. The polarimeter includes a rotating half-wave plate and a Wollaston prism to separate light into two orthogonal linearly polarized rays. A thermoelectrically cooled CCD camera is used to detect the modulated polarized light. We present here measurements of the polarization of polarimetric standard stars. By measuring unpolarized and polarized standard stars we are able to establish the instrumental polarization and the efficiency of the instrument. The polarimeter will initially be used as a dedicated instrument in an ongoing project to monitor the eclipsing binary star, Epsilon Aurigae.

POET: POlarimeters for Energetic Transients

NASA Technical Reports Server (NTRS)

Hill, J. E.; McConnell, M. L.; Bloser, P.; Legere, J.; Macri, J.; Ryan, J.; Barthelmy, S.; Angelini, L.; Sakamoto, T.; Black, J. K.;

PoET: Polarimeters for Energetic Transients

NASA Technical Reports Server (NTRS)

McConnell, Mark; Barthelmy, Scott; Hill, Joanne

2008-01-01

This presentation focuses on PoET (Polarimeters for Energetic Transients): a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2-15 keV and a high energy polarimeter (Gamma-Ray Polarimeter Experiment - GRAPE) that will measure polarization in the 60-500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The PoET spacecraft provides a zenith-pointed platform for maximizing the exposure to deep space. Spacecraft rotation will provide a means of effectively dealing with systematics in the polarization response. PoET will provide sufficient sensitivity and sky coverage to measure statistically significant polarization for up to 100 GRBs in a two-year mission. Polarization data will also be obtained for solar flares, pulsars and other sources of astronomical interest.

A high-energy Compton polarimeter for the POET SMEX mission

NASA Astrophysics Data System (ADS)

Bloser, Peter F.; McConnell, Mark L.; Legere, Jason S.; Ertley, Camden D.; Hill, Joanne E.; Kippen, Marc; Ryan, James M.

2014-07-01

The primary science goal of the Polarimeters for Energetic Transients (POET) mission is to measure the polarization of gamma-ray bursts over a wide energy range, from X rays to soft gamma rays. The higher-energy portion of this band (50 - 500 keV) will be covered by the High Energy Polarimeter (HEP) instrument, a non-imaging, wide field of view Compton polarimeter. Incident high-energy photons will Compton scatter in low-Z, plastic scintillator detector elements and be subsequently absorbed in high-Z, CsI(Tl) scintillator elements; polarization is detected by measuring an asymmetry in the azimuthal scatter angle distribution. The HEP design is based on our considerable experience with the development and flight of the Gamma-Ray Polarimeter Experiment (GRAPE) balloon payload. We present the design of the POET HEP instrument, which incorporates lessons learned from the GRAPE balloon design and previous work on Explorer proposal efforts, and its expected performance on a two-year SMEX mission.

Radio astronomy

NASA Technical Reports Server (NTRS)

Kellermann, Kenneth I.; Heeschen, David; Backer, Donald C.; Cohen, Marshall H.; Davis, Michael; Depater, Imke; Deyoung, David; Dulk, George A.; Fisher, J. R.; Goss, W. Miller

1991-01-01

The following subject areas are covered: (1) scientific opportunities (millimeter and sub-millimeter wavelength astronomy; meter to hectometer astronomy; the Sun, stars, pulsars, interstellar masers, and extrasolar planets; the planets, asteroids, and comets; radio galaxies, quasars, and cosmology; and challenges for radio astronomy in the 1990's); (2) recommendations for new facilities (the millimeter arrays, medium scale instruments, and small-scale projects); (3) continuing activities and maintenance, upgrading of telescopes and instrumentation; (4) long range programs and technology development; and (5) social, political, and organizational considerations.

Interferometric Mapping of Perseus Outflows with MASSES

NASA Astrophysics Data System (ADS)

Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

2017-01-01

The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

Nova Oph 2017 (TCP J17394608-2457555) detected at millimeter wavelengths

NASA Astrophysics Data System (ADS)

Kaminski, T.; Gehrz, R.

2017-06-01

Millimeter-wave continuum emission was detected in Nova Oph 2017 (ATel #10366, #10367) with the Submillimeter Array in Hawaii. The object was observed on July 20, 2017 in four spectral ranges: 224.3-232.3, 240.6-248.6, 336-344, and 352-360 GHz. The combined continuum flux in the two lower ranges (i.e., at a wavelength of 1.3 mm) is of 4.8 mJy, well above the noise with an rms of 0.6 mJy per beam.

Two Long-Wave Infrared Spectral Polarimeters for Use in Understanding Polarization Phenomenology

DTIC Science & Technology

2002-05-01

3550 Aberdeen SE Kirtland Air Force Base, New Mexico 87117 Abstract. Spectrally varying long-wave infrared ( LWIR ) polarization measurements can be used...to identify materials and to discriminate samples from a cluttered background. Two LWIR instruments have been built and fielded by the Air Force...Research Laboratory: a multispectral LWIR imaging polarimeter (LIP) and a full-Stokes Fourier transform in- frared (FTIR) spectral polarimeter (FSP

Using a polarizing film in the manufacture of panoramic Stokes polarimeters at the Main Astronomical Observatory of NAS of Ukraine

NASA Astrophysics Data System (ADS)

Syniavskyi, I.; Ivanov, Yu.; Vidmachenko, A. P.; Sergeev, A.

2015-08-01

The construction of an imaging Stokes-polarimeter in the MAO NAS of Ukraine is proposed. It allows measuring the three components of the Stokes vector simultaneously in large FOV without restrictions on the relative aperture of the system. Moreover, the polarimeter can be converted to a low resolution spectropolarimeter by placement into optical axis of the transparence diffraction grating.

A Burst Chasing X-ray Polarimeter

NASA Technical Reports Server (NTRS)

Hill, Joanne; Hill, Joe; Barthelmy, S.; Black, K.; Deines-Jones, P.; Jahoda, K.; Sakamoto, T.; Kaaret, P.; McConnell, M.; Bloser, P.;

SPICA, Stellar Parameters and Images with a Cophased Array: a 6T visible combiner for the CHARA array.

PubMed

Mourard, Denis; Bério, Philippe; Perraut, Karine; Clausse, Jean-Michel; Creevey, Orlagh; Martinod, Marc-Antoine; Meilland, Anthony; Millour, Florentin; Nardetto, Nicolas

2017-05-01

High angular resolution studies of stars in the optical domain have highly progressed in recent years. After the results obtained with the visible instrument Visible spEctroGraph and polArimeter (VEGA) on the Center for High Angular Resolution Astronomy (CHARA) array and the recent developments on adaptive optics and fibered interferometry, we have started the design and study of a new six-telescope visible combiner with single-mode fibers. It is designed as a low spectral resolution instrument for the measurement of the angular diameter of stars to make a major step forward in terms of magnitude and precision with respect to the present situation. For a large sample of bright stars, a medium spectral resolution mode will allow unprecedented spectral imaging of stellar surfaces and environments for higher accuracy on stellar/planetary parameters. To reach the ultimate performance of the instrument in terms of limiting magnitude (Rmag≃8 for diameter measurements and Rmag≃4 to 5 for imaging), Stellar Parameters and Images with a Cophased Array (SPICA) includes the development of a dedicated fringe tracking system in the H band to reach "long" (200 ms to 30 s) exposures of the fringe signal in the visible.

BICEP2 / Keck Array V: Measurements of B-mode polarization at degree angular scales and 150 GHz by the Keck Array

DOE PAGES

Ade, P. A. R.; Ahmed, Z.; Aikin, R. W.; ...

2015-09-29

Here, the Keck Array is a system of cosmic microwave background polarimeters, each similar to the Bicep2 experiment. In this paper we report results from the 2012 to 2013 observing seasons, during which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as Bicep2. We again find an excess of B-mode power over the lensed-ΛCDM expectation of >5σ in the range 30 < ℓ < 150 and confirm that this is not due to systematics using jackknife tests and simulations based on detailed calibration measurements. In map difference and spectralmore » difference tests these new data are shown to be consistent with Bicep2. Finally, we combine the maps from the two experiments to produce final Q and U maps which have a depth of 57 nK deg (3.4 μK arcmin) over an effective area of 400 deg 2 for an equivalent survey weight of 250,000 μK –2. The final BB band powers have noise uncertainty a factor of 2.3 times better than the previous results, and a significance of detection of excess power of >6σ.« less

BICEP2/KECK ARRAY V: MEASUREMENTS OF B-MODE POLARIZATION AT DEGREE ANGULAR SCALES AND 150 GHz BY THE KECK ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Ahmed, Z.; Aikin, R. W.

2015-10-01

The Keck Array is a system of cosmic microwave background polarimeters, each similar to the Bicep2 experiment. In this paper we report results from the 2012 to 2013 observing seasons, during which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as Bicep2. We again find an excess of B-mode power over the lensed-ΛCDM expectation of >5σ in the range 30 < ℓ < 150 and confirm that this is not due to systematics using jackknife tests and simulations based on detailed calibration measurements. In map difference and spectral differencemore » tests these new data are shown to be consistent with Bicep2. Finally, we combine the maps from the two experiments to produce final Q and U maps which have a depth of 57 nK deg (3.4 μK arcmin) over an effective area of 400 deg{sup 2} for an equivalent survey weight of 250,000 μK{sup −2}. The final BB band powers have noise uncertainty a factor of 2.3 times better than the previous results, and a significance of detection of excess power of >6σ.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yokosawa, A.

Production of polarized antiproton beams at Fermilab from the parity violating decay of antilambdas is discussed. Use of polarimeters such as the Coulomb-Nuclear and the Primakoff-Effect polarimeters is also mentioned.

5 MeV Mott Polarimeter Development at Jefferson Lab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, J. S.; Sinclair, C. K.; Cardman, L. S.

1997-01-01

Low energy (E{sub k}=100 keV) Mott scattering polarimeters are ill- suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections. Recent improvements in the CEBAF injector polarimeter scattering chamber have improved signal to noise.

Design and construction of a high-energy photon polarimeter

NASA Astrophysics Data System (ADS)

Dugger, M.; Ritchie, B. G.; Sparks, N.; Moriya, K.; Tucker, R. J.; Lee, R. J.; Thorpe, B. N.; Hodges, T.; Barbosa, F. J.; Sandoval, N.; Jones, R. T.

2017-09-01

We report on the design and construction of a high-energy photon polarimeter for measuring the degree of polarization of a linearly-polarized photon beam. The photon polarimeter uses the process of pair production on an atomic electron (triplet production). The azimuthal distribution of scattered atomic electrons following triplet production yields information regarding the degree of linear polarization of the incident photon beam. The polarimeter, operated in conjunction with a pair spectrometer, uses a silicon strip detector to measure the recoil electron distribution resulting from triplet photoproduction in a beryllium target foil. The analyzing power ΣA for the device using a 75 μm beryllium converter foil is about 0.2, with a relative systematic uncertainty in ΣA of 1.5%.

The test of the layout of polarimeter "UFP" on the telescope AZT-2

NASA Astrophysics Data System (ADS)

Levchenko, T. A.; Nevodovskyi, P. V.; Vidmachenko, A. P.; Morozhenko, O. V.; Saryboha, H. V.; Zbrutsky, O. V.; Ivakhiv, O. V.

2016-05-01

Main Astronomical Observatory of NAS of Ukraine in cooperation with the National Technical University of Ukraine "KPI" and National University "Lviv Polytechnic" for a long time working on the design of an optical polarimeter to study of the stratospheric layer of the Earth using of orbital satellite. During this time, was accumulated a large experience of such work, and was established a layout of compact ultraviolet polarimeter (UFP) on board of satellite

LWIR Microgrid Polarimeter for Remote Sensing Studies

DTIC Science & Technology

2010-02-28

Polarimeter for Remote Sensing Studies 5b. GRANT NUMBER FA9550-08-1-0295 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 1. Scott Tyo 5e. TASK...and tested at the University of Arizona, and preliminary images are shown in this final report. 15. SUBJECT TERMS Remote Sensing , polarimetry 16...7.0 LWIR Microgrid Polarimeter for Remote Sensing Studies J. Scott Tyo College of Optical Sciences University of Arizona Tucson, AZ, 85721 tyo

SODART telescopes on the Spectrum X-Gamma (SRG) and their complement of instruments

NASA Astrophysics Data System (ADS)

Schnopper, Herbert W.

1994-11-01

Two SODART thin foil X-ray telescopes will fly on SRG. In the focal plane of one telescope there are: HEPC/LEPC (high- and low energy imaging proportional counters), SIXA (solid state spectrometer array), and FRD (focal plane X-ray detector). In the other, there are: another HEPC/LEPC pair, SXRP (stellar X-ray polarimeter), and another FRD. Mounted alongside and co-aligned with the SODART telescopes is TAUVEX (UV telescope). An objective Bragg spectrometer is mounted in front of one of the telescopes. These instruments and their scientific goals will be described briefly. More detailed discussions will be given by the relevant PIs in the poster session.

Three axis vector atomic magnetometer utilizing polarimetric technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pradhan, Swarupananda, E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com

2016-09-15

The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity fieldmore » gradient measurement as required for biomedical application.« less

Spectrographic Polarimeter and Method of Recording State of Polarity

NASA Technical Reports Server (NTRS)

Sparks, William B. (Inventor)

2015-01-01

A single-shot real-time spectropolarimeter for use in astronomy and other sciences that captures and encodes some or all of the Stokes polarization parameters simultaneously using only static, robust optical components with no moving parts is described. The polarization information is encoded onto the spectrograph at each wavelength along the spatial dimension of the 2D output data array. The varying embodiments of the concept include both a two-Stokes implementation (in which any two of the three Stokes polarization parameters are measured) and a full Stokes implementation (in which all three of the Stokes polarization parameters are measured), each of which is provided in either single beam or dual beam forms.

HAWCPol: a first-generation far-infrared polarimeter for SOFIA

NASA Astrophysics Data System (ADS)

Dowell, C. Darren; Cook, Brant T.; Harper, D. Al; Lin, Lung-Sheng; Looney, Leslie W.; Novak, Giles; Stephens, Ian; Berthoud, Marc; Chuss, David T.; Crutcher, Richard M.; Dotson, Jessie L.; Hildebrand, Roger H.; Houde, Martin; Jones, Terry J.; Krejny, Megan; Lazarian, Alexandre; Moseley, S. Harvey; Tassis, Kostas; Vaillancourt, John E.; Werner, Michael W.

2010-07-01

We describe our ongoing project to build a far-infrared polarimeter for the HAWC instrument on SOFIA. Far-IR polarimetry reveals unique information about magnetic fields in dusty molecular clouds and is an important tool for understanding star formation and cloud evolution. SOFIA provides flexible access to the infrared as well as good sensitivity to and angular resolution of continuum emission from molecular clouds. We are making progress toward outfitting HAWC, a first-generation SOFIA camera, with a four-band polarimeter covering 50 to 220 microns wavelength. We have chosen a conservative design which uses quartz half-wave plates continuously rotating at ~0.5 Hz, ball bearing suspensions, fixed wire-grid polarizers, and cryogenic motors. Design challenges are to fit the polarimeter into a volume that did not originally envision one, to minimize the heating of the cryogenic optics, and to produce negligible interference in the detector system. Here we describe the performance of the polarimeter measured at cryogenic temperature as well as the basic method we intend for data analysis. We are on track for delivering this instrument early in the operating lifetime of SOFIA.

Analysis of the new polarimeter for the Marshall Space Flight Center vector magnetograph

NASA Technical Reports Server (NTRS)

West, E. A.

1985-01-01

The magnetograph was upgraded in both electronic control of the magnetograph hardware and in the polarization optics. The problems associated with the orignal polarimeter were: (1) field of view errors associated with the natural birefringence of the KD*P crystals; (2.) KD*P electrode failure due to the halfwave dc voltage required in one of the operational sequences; and (3) breakdown of the retardation properties of some KD*Ps when exposed to a zero to halfwave modulation (DC) scheme. The new polarimeter gives up the flexibility provided by two variable waveplates to adjust the retardances of the optics for a particular polarization measurement, but solves the problems associated with the original polarimeter. With the addition of the quartz quarterwave plates, a new optical alignment was developed to allow the remaining KD*P to correct for errors in the waveplates. The new optical alignment of the polarimeter is prescribed. The various sources of error, and how those errors are minimized so that the magnetograph can look at the transverse field in real time are discussed.

Strategies on solar observation of Atacama Large Millimeter/submillimeter Array (ALMA) band-1 receiver

NASA Astrophysics Data System (ADS)

Chiong, Chau-Ching; Chiang, Po-Han; Hwang, Yuh-Jing; Huang, Yau-De

2016-07-01

ALMA covering 35-950 GHz is the largest existing telescope array in the world. Among the 10 receiver bands, Band-1, which covers 35-50 GHz, is the lowest. Due to its small dimension and its time-variant frequency-dependent gain characteristics, current solar filter located above the cryostat cannot be applied to Band-1 for solar observation. Here we thus adopt new strategies to fulfill the goals. Thanks to the flexible dc biasing scheme of the HEMT-based amplifier in Band-1 front-end, bias adjustment of the cryogenic low noise amplifier is investigated to accomplish solar observation without using solar filter. Large power handling range can be achieved by the de-tuning bias technique with little degradation in system performance.

Kinetic inductance detectors for millimeter and submillimeter astronomy

NASA Astrophysics Data System (ADS)

Boudou, Nicolas; Benoit, Alain; Bourrion, Olivier; Calvo, Martino; Désert, François-Xavier; Macias-Perez, Juan; Monfardini, Alessandro; Roesch, Markus

2012-01-01

We present recent developments in Kinetic Inductance Detectors (KID) for large arrays of detectors. The main application is ground-based millimeter wave astronomy. We focus in particular, as a case study, on our own experiment: NIKA (Néel IRAM KID Arrays). NIKA is today the best in-the-field experiment using KID-based instruments, and consists of a dual-band imaging system designed for the IRAM 30 meter telescope at Pico Veleta. We describe in this article, after a general context introduction, the KID working principle and the readout electronics, crucial to take advantage of the intrinsic KID multiplexability. We conclude with a small subset of the astronomical sources observed simultaneously at 2 mm and 1.4 mm by NIKA during the last run, held in October 2010.

A photoelastic-modulator-based motional Stark effect polarimeter for ITER that is insensitive to polarized broadband background reflections.

PubMed

Thorman, A; Michael, C; De Bock, M; Howard, J

2016-07-01

A motional Stark effect polarimeter insensitive to polarized broadband light is proposed. Partially polarized background light is anticipated to be a significant source of systematic error for the ITER polarimeter. The proposed polarimeter is based on the standard dual photoelastic modulator approach, but with the introduction of a birefringent delay plate, it generates a sinusoidal spectral filter instead of the usual narrowband filter. The period of the filter is chosen to match the spacing of the orthogonally polarized Stark effect components, thereby increasing the effective signal level, but resulting in the destructive interference of the broadband polarized light. The theoretical response of the system to an ITER like spectrum is calculated and the broadband polarization tolerance is verified experimentally.

Design and construction of a high-energy photon polarimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dugger, M.; Ritchie, B. G.; Sparks, N.

Here, we report on the design and construction of a high-energy photon polarimeter for measuring the degree of polarization of a linearly-polarized photon beam. The photon polarimeter uses the process of pair production on an atomic electron (triplet production). The azimuthal distribution of scattered atomic electrons following triplet production yields information regarding the degree of linear polarization of the incident photon beam. Furthermore, the polarimeter, operated in conjunction with a pair spectrometer, uses a silicon strip detector to measure the recoil electron distribution resulting from triplet photoproduction in a beryllium target foil. The analyzing power Σ A for the devicemore » using a 75 μm beryllium converter foil is about 0.2, with a relative systematic uncertainty in Σ A of 1.5%.« less

Design and construction of a high-energy photon polarimeter

DOE PAGES

Dugger, M.; Ritchie, B. G.; Sparks, N.; ...

2017-06-12

Here, we report on the design and construction of a high-energy photon polarimeter for measuring the degree of polarization of a linearly-polarized photon beam. The photon polarimeter uses the process of pair production on an atomic electron (triplet production). The azimuthal distribution of scattered atomic electrons following triplet production yields information regarding the degree of linear polarization of the incident photon beam. Furthermore, the polarimeter, operated in conjunction with a pair spectrometer, uses a silicon strip detector to measure the recoil electron distribution resulting from triplet photoproduction in a beryllium target foil. The analyzing power Σ A for the devicemore » using a 75 μm beryllium converter foil is about 0.2, with a relative systematic uncertainty in Σ A of 1.5%.« less

INFRARED LUMINOSITIES AND DUST PROPERTIES OF z approx 2 DUST-OBSCURED GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bussmann, R. S.; Dey, Arjun; Jannuzi, B. T.

We present SHARC-II 350 mum imaging of twelve 24 mum bright (F{sub 24m}u{sub m} > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1 mm imaging of a subset of two DOGs. These objects are selected from the Booetes field of the NOAO Deep Wide-Field Survey. Detections of four DOGs at 350 mum imply infrared (IR) luminosities which are consistent to within a factor of 2 of expectations based on a warm-dust spectral energy distribution (SED) scaled to the observed 24 mum flux density. The 350 mum upper limits for the 8 non-detected DOGsmore » are consistent with both Mrk 231 and M82 (warm-dust SEDs), but exclude cold dust (Arp 220) SEDs. The two DOGs targeted at 1 mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T{sub dust} > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of approx3 x 10{sup 8} M{sub sun}. In comparison to other dusty z approx 2 galaxy populations such as submillimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2 x 10{sup 13} L{sub sun} versus 6 x 10{sup 12} L{sub sun} for the other galaxy populations) that are driven by warmer dust temperatures (>35-60 K versus approx30 K) and lower inferred dust masses (3 x 10{sup 8} M{sub sun} versus 3 x 10{sup 9} M{sub sun}). Wide-field Herschel and Submillimeter Common-User Bolometer Array-2 surveys should be able to detect hundreds of these power-law-dominated DOGs. We use the existing Hubble Space Telescope and Spitzer/InfraRed Array Camera data to estimate stellar masses of these sources and find that the stellar to gas mass ratio may be higher in our 24 mum bright sample of DOGs than in SMGs and other Spitzer-selected sources. Although much larger sample sizes are needed to provide a definitive conclusion, the data are consistent with an evolutionary trend in which the formation of massive galaxies at z approx 2 involves a submillimeter bright, cold-dust, and star-formation-dominated phase followed by a 24 mum bright, warm-dust and AGN-dominated phase.« less

An Explanation of the Very Low Radio Flux of Young Planet-mass Companions

NASA Astrophysics Data System (ADS)

Wu, Ya-Lin; Close, Laird M.; Eisner, Josh A.; Sheehan, Patrick D.

2017-12-01

We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum upper limits for five planetary-mass companions DH Tau B, CT Cha B, GSC 6214-210 B, 1RXS 1609 B, and GQ Lup B. Our survey, together with other ALMA studies, have yielded null results for disks around young planet-mass companions and placed stringent dust mass upper limits, typically less than 0.1 M ⊕, when assuming dust continuum is optically thin. Such low-mass gas/dust content can lead to a disk lifetime estimate (from accretion rates) much shorter than the age of the system. To alleviate this timescale discrepancy, we suggest that disks around wide companions might be very compact and optically thick in order to sustain a few Myr of accretion, yet have very weak (sub)millimeter flux so as to still be elusive to ALMA. Our order-of-magnitude estimate shows that compact optically thick disks might be smaller than 1000 R Jup and only emit ∼μJy of flux in the (sub)millimeter, but their average temperature can be higher than that of circumstellar disks. The high disk temperature could impede satellite formation, but it also suggests that mid- to far-infrared might be more favorable than radio wavelengths to characterize disk properties. Finally, the compact disk size might imply that dynamical encounters between the companion and the star, or any other scatterers in the system, play a role in the formation of planetary-mass companions.

ALMA OBSERVATIONS OF SPT-DISCOVERED, STRONGLY LENSED, DUSTY, STAR-FORMING GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hezaveh, Y. D.; Marrone, D. P.; Spilker, J. S.

2013-04-20

We present Atacama Large Millimeter/submillimeter Array (ALMA) 860 {mu}m imaging of four high-redshift (z = 2.8-5.7) dusty sources that were detected using the South Pole Telescope (SPT) at 1.4 mm and are not seen in existing radio to far-infrared catalogs. At 1.''5 resolution, the ALMA data reveal multiple images of each submillimeter source, separated by 1''-3'', consistent with strong lensing by intervening galaxies visible in near-IR imaging of these sources. We describe a gravitational lens modeling procedure that operates on the measured visibilities and incorporates self-calibration-like antenna phase corrections as part of the model optimization, which we use to interpretmore » the source structure. Lens models indicate that SPT0346-52, located at z = 5.7, is one of the most luminous and intensely star-forming sources in the universe with a lensing corrected FIR luminosity of 3.7 Multiplication-Sign 10{sup 13} L{sub Sun} and star formation surface density of 4200 M{sub Sun} yr{sup -1} kpc{sup -2}. We find magnification factors of 5 to 22, with lens Einstein radii of 1.''1-2.''0 and Einstein enclosed masses of 1.6-7.2 Multiplication-Sign 10{sup 11} M{sub Sun }. These observations confirm the lensing origin of these objects, allow us to measure their intrinsic sizes and luminosities, and demonstrate the important role that ALMA will play in the interpretation of lensed submillimeter sources.« less

Influence of higher harmonics of the undulator in X-ray polarimetry and crystal monochromator design.

PubMed

Marx-Glowna, Berit; Schulze, Kai S; Uschmann, Ingo; Kämpfer, Tino; Weber, Günter; Hahn, Christoph; Wille, Hans Christian; Schlage, Kai; Röhlsberger, Ralf; Förster, Eckhart; Stöhlker, Thomas; Paulus, Gerhard G

2015-09-01

The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs.

The polarimeter and the multispectral radiometer as remote probes of aerosols

NASA Technical Reports Server (NTRS)

Kuriyan, J. G.

1975-01-01

Attempts made to establish the viability of the polarimeter as a ground based remote probe of atmospheric aerosols under varying meteorological conditions are reported. Extension radiometer data are also given and a comparison was made with polarimeter data to determine if one could complement/supplement the other. The analyses show that the two instruments are complementary devices and any information obtained from one will greatly facilitate the analysis of the other. Detailed results are given in graphical form.

Warm water deuterium fractionation in IRAS 16293-2422. The high-resolution ALMA and SMA view

NASA Astrophysics Data System (ADS)

Persson, M. V.; Jørgensen, J. K.; van Dishoeck, E. F.

2013-01-01

Context. Measuring the water deuterium fractionation in the inner warm regions of low-mass protostars has so far been hampered by poor angular resolution obtainable with single-dish ground- and space-based telescopes. Observations of water isotopologues using (sub)millimeter wavelength interferometers have the potential to shed light on this matter. Aims: To measure the water deuterium fractionation in the warm gas of the deeply-embedded protostellar binary IRAS 16293-2422. Methods: Observations toward IRAS 16293-2422 of the 53,2 - 44,1 transition of H218O at 692.07914 GHz from Atacama Large Millimeter/submillimeter Array (ALMA) as well as the 31,3 - 22,0 of H218O at 203.40752 GHz and the 31,2 - 22,1 transition of HDO at 225.89672 GHz from the Submillimeter Array (SMA) are presented. Results: The 692 GHz H218O line is seen toward both components of the binary protostar. Toward one of the components, "source B", the line is seen in absorption toward the continuum, slightly red-shifted from the systemic velocity, whereas emission is seen off-source at the systemic velocity. Toward the other component, "source A", the two HDO and H218O lines are detected as well with the SMA. From the H218O transitions the excitation temperature is estimated at 124 ± 12 K. The calculated HDO/H2O ratio is (9.2 ± 2.6) × 10-4 - significantly lower than previous estimates in the warm gas close to the source. It is also lower by a factor of ~5 than the ratio deduced in the outer envelope. Conclusions: Our observations reveal the physical and chemical structure of water vapor close to the protostars on solar-system scales. The red-shifted absorption detected toward source B is indicative of infall. The excitation temperature is consistent with the picture of water ice evaporation close to the protostar. The low HDO/H2O ratio deduced here suggests that the differences between the inner regions of the protostars and the Earth's oceans and comets are smaller than previously thought. Appendix A is available in electronic form at http://www.aanda.org

Distributed Antenna-Coupled TES for FIR Detectors Arrays

NASA Technical Reports Server (NTRS)

Day, Peter K.; Leduc, Henry G.; Dowell, C. Darren; Lee, Richard A.; Zmuidzinas, Jonas

2007-01-01

We describe a new architecture for a superconducting detector for the submillimeter and far-infrared. This detector uses a distributed hot-electron transition edge sensor (TES) to collect the power from a focal-plane-filling slot antenna array. The sensors lay directly across the slots of the antenna and match the antenna impedance of about 30 ohms. Each pixel contains many sensors that are wired in parallel as a single distributed TES, which results in a low impedance that readily matches to a multiplexed SQUID readout These detectors are inherently polarization sensitive, with very low cross-polarization response, but can also be configured to sum both polarizations. The dual-polarization design can have a bandwidth of 50The use of electron-phonon decoupling eliminates the need for micro-machining, making the focal plane much easier to fabricate than with absorber-coupled, mechanically isolated pixels. We discuss applications of these detectors and a hybridization scheme compatible with arrays of tens of thousands of pixels.

Power Amplifier Module with 734-mW Continuous Wave Output Power

NASA Technical Reports Server (NTRS)

Fung, King Man; Samoska, Lorene A.; Kangaslahti, Pekka P.; Lamgrigtsen, Bjorn H.; Goldsmith, Paul F.; Lin, Robert H.; Soria, Mary M.; Cooperrider, Joelle T.; Micovic, Moroslav; Kurdoghlian, Ara

2010-01-01

Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers-to generate higher frequency signals in nonlinear Schottky diode-based LO sources. By advancing PA technology, the LO system performance can be increased with possible cost reductions compared to current GaAs PAs. High-power, high-efficiency GaN PAs are cross-cutting and can enable more efficient local oscillator distribution systems for new astrophysics and planetary receivers and heterodyne array instruments. It can also allow for a new, electronically scannable solid-state array technology for future Earth science radar instruments and communications platforms.

Calibration Errors in Interferometric Radio Polarimetry

NASA Astrophysics Data System (ADS)

Hales, Christopher A.

2017-08-01

Residual calibration errors are difficult to predict in interferometric radio polarimetry because they depend on the observational calibration strategy employed, encompassing the Stokes vector of the calibrator and parallactic angle coverage. This work presents analytic derivations and simulations that enable examination of residual on-axis instrumental leakage and position-angle errors for a suite of calibration strategies. The focus is on arrays comprising alt-azimuth antennas with common feeds over which parallactic angle is approximately uniform. The results indicate that calibration schemes requiring parallactic angle coverage in the linear feed basis (e.g., the Atacama Large Millimeter/submillimeter Array) need only observe over 30°, beyond which no significant improvements in calibration accuracy are obtained. In the circular feed basis (e.g., the Very Large Array above 1 GHz), 30° is also appropriate when the Stokes vector of the leakage calibrator is known a priori, but this rises to 90° when the Stokes vector is unknown. These findings illustrate and quantify concepts that were previously obscure rules of thumb.

POLIX: A Thomson X-ray polarimeter for a small satellite mission

NASA Astrophysics Data System (ADS)

Paul, Biswajit; Gopala Krishna, M. R.; Puthiya Veetil, Rishin

2016-07-01

POLIX is a Thomson X-ray polarimeter for a small satellite mission of ISRO. The instrument consists of a collimator, a scatterer and a set proportional counters to detect the scattered X-rays. We will describe the design, specifications, sensitivity, and development status of this instrument and some of the important scientific goals. This instrument will provide unprecedented opportunity to measure X-ray polarisation in the medium energy range in a large number of sources of different classes with a minimum detectable linear polarisation degree of 2-3%. The prime objects for observation with this instrument are the X-ray bright accretion powered neutron stars, accreting black holes in different spectral states, rotation powered pulsars, magnetars, and active galactic nuclei. This instrument will be a bridge between the soft X-ray polarimeters and the Compton polarimeters.

Third International Kharkov Symposium "Physics and Engineering of Millimeter and Submillimeter Waves" MSMW󈨦 Symposium Proceedings, Volume 1,

DTIC Science & Technology

1998-09-01

potential of the surface wave electromagnetic field; ea is the unit of the polarization vectors : ex = ela. = e2x= (qx/\\q\\)\\/L\\q\\/(ei + e0), ely... polarization basis of the incident wave: EB°=eB^(/kr), (1) where e„ is the cyclic unit vector , n = ±1, k is the wave vector . The equation describing...rectangular grid. From the direction determined by wave vector k0, the plane electromagnetic wave of linear polarization incidents onto the array. It

Protoplanetary Disks in Multiple Star Systems

NASA Astrophysics Data System (ADS)

Harris, Robert J.

Most stars are born in multiple systems, so the presence of a stellar companion may commonly influence planet formation. Theory indicates that companions may inhibit planet formation in two ways. First, dynamical interactions can tidally truncate circumstellar disks. Truncation reduces disk lifetimes and masses, leaving less time and material for planet formation. Second, these interactions might reduce grain-coagulation efficiency, slowing planet formation in its earliest stages. I present three observational studies investigating these issues. First is a spatially resolved Submillimeter Array (SMA) census of disks in young multiple systems in the Taurus-Auriga star-forming region to study their bulk properties. With this survey, I confirmed that disk lifetimes are preferentially decreased in multiples: single stars have detectable millimeter-wave continuum emission twice as often as components of multiples. I also verified that millimeter luminosity (proportional to disk mass) declines with decreasing stellar separation. Furthermore, by measuring resolved-disk radii, I quantitatively tested tidal-truncation theories: results were mixed, with a few disks much larger than expected. I then switch focus to the grain-growth properties of disks in multiple star systems. By combining SMA, Combined Array for Research in Millimeter Astronomy (CARMA), and Jansky Very Large Array (VLA) observations of the circumbinary disk in the UZ Tau quadruple system, I detected radial variations in the grain-size distribution: large particles preferentially inhabit the inner disk. Detections of these theoretically predicted variations have been rare. I related this to models of grain coagulation in gas disks and find that our results are consistent with growth limited by radial drift. I then present a study of grain growth in the disks of the AS 205 and UX Tau multiple systems. By combining SMA, Atacama Large Millimeter/submillimeter Array (ALMA), and VLA observations, I detected radial variations of the grain-size distribution in the AS 205 A disk, but not in the UX Tau A disk. I find that some combination of radial drift and fragmentation limits growth in the AS 205 A disk. In the final chapter, I summarize my findings that, while multiplicity clearly influences bulk disk properties, it does not obviously inhibit grain growth. Other investigations are suggested.

First Astronomical Use of Multiplexed Transition Edge Sensor Bolometers

NASA Technical Reports Server (NTRS)

Staguhn, J. G.; Ames, T. A.; Benford, D. J.; Chervenak, J. A.; Grossman, E. N.; Irwin, K. D.; Khan, S. A.; Maffei, B.; Moseley, S. H.; Pajot, F.

2004-01-01

We present performance results based on the first astronomical use of multiplexed superconducting bolometers. The Fabry-Perot Interferometer Bolometer Research Experiment (FIBRE) is a broadband submillimeter spectrometer that achieved first light in June 2001 at the Caltech Submillimeter Observatory (CSO). FIBRE's detectors are superconducting transition edge sensor (TES) bolometers read out by a SQUID multiplexer. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing 5 orders simultaneously from one position on the sky. With tuning of the Fabry-Perot over one free spectral range, a spectrum covering Delta lambda/lambda = 1/7 at a resolution of delta lambda/lambda approx. 1/1200 can be acquired. This spectral resolution is sufficient to resolve Doppler-broadened line emission from external galaxies. FIBRE operates in the 350 m and 450 m bands. These bands cover line emission from the important star formation tracers neutral carbon (CI) and carbon monoxide (CO). We have verified that the multiplexed bolometers are photon noise limited even with the low power present in moderate resolution spectrometry.

SIS Mixer Design for a Broadband Millimeter Spectrometer Suitable for Rapid Line Surveys and Redshift Determinations

NASA Technical Reports Server (NTRS)

Rice, F.; Sumner, M.; Zmuidzinas, J.; Hu, R.; LeDuc, H.; Harris, A.; Miller, D.

2004-01-01

We present some detail of the waveguide probe and SIS mixer chip designs for a low-noise 180-300 GHz double- sideband receiver with an instantaneous RF bandwidth of 24 GHz. The receiver's single SIS junction is excited by a broadband, fixed-tuned waveguide probe on a silicon substrate. The IF output is coupled to a 6-18 GHz MMIC low- noise preamplifier. Following further amplification, the output is processed by an array of 4 GHz, 128-channel analog autocorrelation spectrometers (WASP 11). The single-sideband receiver noise temperature goal of 70 Kelvin will provide a prototype instrument capable of rapid line surveys and of relatively efficient carbon monoxide (CO) emission line searches of distant, dusty galaxies. The latter application's goal is to determine redshifts by measuring the frequencies of CO line emissions from the star-forming regions dominating the submillimeter brightness of these galaxies. Construction of the receiver has begun; lab testing should begin in the fall. Demonstration of the receiver on the Caltech Submillimeter Observatory (CSO) telescope should begin in spring 2003.

First Astronomical Use Of Multiplexed Transition Edge Bolometers

NASA Technical Reports Server (NTRS)

Benford, D. J.; Chervenak, J. A.; Grossman, E. N.; Irwin, K. D.; DeKotwara, S. A.; Maffei, B.; Moseley, S. H.; Pajot, F.; Phillips, T. G.; Reintsema, C. D.

2001-01-01

We present performance results based on the first astronomical use of multiplexed superconducting bolometers. The Fabry-Perot Interferometer Bolometer Research Experiment (FIBRE) is a broadband submillimeter spectrometer that achieved first light in June 2001 at the Caltech Submillimeter Observatory (CSO). FIBRE's detectors are superconducting transition edge sensor (TES) bolometers read out by a SQUID multiplexer. The Fabry-Perot uses a low resolution grating to order sort the incoming light. A linear bolometer array consisting of 16 elements detects this dispersed light, capturing five orders simultaneously from one position on the sky. With tuning of the Fabry-Perot over one free spectral range, a spectrum covering delta-lamda/lamda = 1/7 at a resolution of delta-lamda/lamda = 1/1200 can be acquired. This spectral resolution is sufficient to resolve doppler broadened line emission from external galaxies. FIBRE operates in the 350 micrometer and 450 micrometer bands. These bands cover line emission from the important PDR tracers neutral carbon [CI] and carbon monoxide (CO). We have verified that the multiplexed bolometers are photon noise limited even with the low power present in moderate resolution spectrometry.

Silicon Alignment Pins: An Easy Way to Realize a Wafer-to-Wafer Alignment

NASA Technical Reports Server (NTRS)

Jung-Kubiak, Cecile; Reck, Theodore J.; Lin, Robert H.; Peralta, Alejandro; Gill, John J.; Lee, Choonsup; Siles, Jose; Toda, Risaku; Chattopadhyay, Goutam; Cooper, Ken B.;

A star-and-sky chopping polarimeter - Design and performance

NASA Astrophysics Data System (ADS)

Jain, S. K.; Srinivasulu, G.

1991-09-01

A star-and-sky chopping polarimeter is developed for accurate measurements of linear polarization of starlight in the standard astronomical photometric U, B, V, R, and I bands. The instrumental polarization, as determined by observing the standard unpolarized stars, is 0.04 percent. It is possible to use the instrument for the measurements of circular polarization as well. A Unicorn microcomputer controls the various operations of the instrument, acquires the data, and does the on-line data reduction. This paper describes the design and performance of the polarimeter.

Concerning the use of multifunctional photometer - polarimeter for studying the invasion of cosmic bodies into the Earth's atmosphere

NASA Astrophysics Data System (ADS)

Geraimchuk, M. D.; Vidmachenko, A. P.; Nevodovskyi, P. V.; Steklov, O. F.

2018-05-01

Main astronomical observatory of the National Academy of Sciences of Ukraine together with the National Technical University of Ukraine "KPI" for many years working on the development of photometers-polarimeters for the study of cosmic bodies and Earth's atmosphere. We proposed an option of the development of a multipurpose panoramic photometer-polarimeter, which takes into account the shortcomings of the previous versions of the instrument and also allows for the registration of tracks of bolides, and study of their tails, and weak meteor phenomena.

Use of Mueller and non-Mueller matrices to describe polarization properties of telescope-based polarimeters

NASA Astrophysics Data System (ADS)

Seagraves, P. H.; Elmore, David F.

1994-09-01

Systems using optical elements such as linear polarizers, retarders, and mirrors can be represented by Mueller matrices. Some polarimeters include elements with time-varying polarization properties, multiple light beams, light detectors, and signal processing equipment. Standard Mueller matrix forms describing time-varying retarders, and beam splitters are presented, as well as non-Mueller matrices which describe detection and signal processing. These matrices provide a compact and intuitive mathematical description of polarimeter response which can aid in the refining of instrument designs.

New Satellite Project Aerosol-UA: Remote Sensing of Aerosols in the Terrestrial Atmosphere

NASA Technical Reports Server (NTRS)

Milinevsky, G.; Yatskiv, Ya.; Degtyaryov, O.; Syniavskyi, I.; Mishchenko, Michael I.; Rosenbush, V.; Ivanov, Yu.; Makarov, A.; Bovchaliuk, A.; Danylevsky, V.;

X-ray polarimeter with a transmission multilayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitamoto, Shunji; Murakami, Hiroshi; Shishido, Youich

2010-02-15

We fabricated a novel x-ray polarimeter with a transmission multilayer and measured its performance with synchrotron radiation. A self standing multilayer with seven Mo/Si bilayers was installed with an incident angle of 45 deg. in front of a back-illuminated CCD. The multilayer can be rotated around the normal direction of the CCD keeping an incident angle of 45 deg. This polarimeter can be easily installed along the optical axis of x-ray optics. By using the CCD as a photon counting detector with a moderate energy resolution, the polarization of photons in a designed energy band can be measured along withmore » the image. At high photon energies, where the multilayer is transparent, the polarimeter can be used for imaging and spectroscopic observations. We confirmed a modulation factor of 45% with 45% and 17% transmission for P- and S-polarization, respectively.« less

Characteristics of an Imaging Polarimeter for the Powell Observatory

NASA Astrophysics Data System (ADS)

Hall, Shannon; Henson, G.

2010-01-01

A dual-beam imaging polarimeter has been built for use on the 14 inch Schmidt-Cassegrain telescope at the ETSU Harry D. Powell Observatory. The polarimeter includes a rotating half-wave plate and a Wollaston prism to separate light into two orthogonal linearly polarized rays. A TEC cooled CCD camera is used to detect the modulated polarized light. We present here measurements of the polarization of polarimetric standard stars. By measuring unpolarized and polarized standard stars we are able to establish the instrumental polarization and the efficiency of the instrument. The polarimeter will initially be used as a dedicated instrument in an ongoing project to monitor the eclipsing binary star, Epsilon Aurigae. This project was funded by a partnership between the National Science Foundation (NSF AST-0552798), Research Experience for Undergraduates (REU), and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs.

Modeling Systematic Error Effects for a Sensitive Storage Ring EDM Polarimeter

NASA Astrophysics Data System (ADS)

Stephenson, Edward; Imig, Astrid

2009-10-01

The Storage Ring EDM Collaboration has obtained a set of measurements detailing the sensitivity of a storage ring polarimeter for deuterons to small geometrical and rate changes. Various schemes, such as the calculation of the cross ratio [1], can cancel effects due to detector acceptance differences and luminosity differences for states of opposite polarization. Such schemes fail at second-order in the errors, becoming sensitive to geometrical changes, polarization magnitude differences between opposite polarization states, and changes to the detector response with changing data rates. An expansion of the polarimeter response in a Taylor series based on small errors about the polarimeter operating point can parametrize such effects, primarily in terms of the logarithmic derivatives of the cross section and analyzing power. A comparison will be made to measurements obtained with the EDDA detector at COSY-J"ulich. [4pt] [1] G.G. Ohlsen and P.W. Keaton, Jr., NIM 109, 41 (1973).

Calibration system with cryogenically-cooled loads for cosmic microwave background polarization detectors.

PubMed

Hasegawa, M; Tajima, O; Chinone, Y; Hazumi, M; Ishidoshiro, K; Nagai, M

2011-05-01

We present a novel system to calibrate millimeter-wave polarimeters for cosmic microwave background (CMB) polarization measurements. This technique is an extension of the conventional metal mirror rotation approach, however, it employs cryogenically-cooled blackbody absorbers. The primary advantage of this system is that it can generate a slightly polarized signal (∼100 mK) in the laboratory; this is at a similar level to that measured by ground-based CMB polarization experiments observing a ∼10 K sky. It is important to reproduce the observing condition in the laboratory for reliable characterization of polarimeters before deployment. In this paper, we present the design and principle of the system and demonstrate its use with a coherent-type polarimeter used for an actual CMB polarization experiment. This technique can also be applied to incoherent-type polarimeters and it is very promising for the next-generation CMB polarization experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jingwen; Wright, Edward L.; Bussmann, R. Shane

The Wide-field Infrared Survey Explorer (WISE) has discovered an extraordinary population of hyper-luminous dusty galaxies that are faint in the two bluer passbands (3.4 μm and 4.6 μm) but are bright in the two redder passbands of WISE (12 μm and 22 μm). We report on initial follow-up observations of three of these hot, dust-obscured galaxies, or Hot DOGs, using the Combined Array for Research in Millimeter-wave Astronomy and the Submillimeter Array interferometer arrays at submillimeter/millimeter wavelengths. We report continuum detections at ∼1.3 mm of two sources (WISE J014946.17+235014.5 and WISE J223810.20+265319.7, hereafter W0149+2350 and W2238+2653, respectively), and upper limitsmore » to CO line emission at 3 mm in the observed frame for two sources (W0149+2350 and WISE J181417.29+341224.8, hereafter W1814+3412). The 1.3 mm continuum images have a resolution of 1''-2'' and are consistent with single point sources. We estimate the masses of cold dust are 2.0 × 10{sup 8} M {sub ☉} for W0149+2350 and 3.9 × 10{sup 8} M {sub ☉} for W2238+2653, comparable to cold dust masses of luminous quasars. We obtain 2σ upper limits to the molecular gas masses traced by CO, which are 3.3 × 10{sup 10} M {sub ☉} and 2.3 × 10{sup 10} M {sub ☉} for W0149+2350 and W1814+3412, respectively. We also present high-resolution, near-IR imaging with the WFC3 on the Hubble Space Telescope for W0149+2653 and with NIRC2 on Keck for W2238+2653. The near-IR images show morphological structure dominated by a single, centrally condensed source with effective radius less than 4 kpc. No signs of gravitational lensing are evident.« less

An Outflow-shaped Magnetic Field Toward the Class 0 Protostellar Source Serpens SMM1

NASA Astrophysics Data System (ADS)

Hull, Charles; Girart, Josep M.; Tychoniec, Lukasz; Rao, Ramprasad; Cortés, Paulo; Pokhrel, Riwaj; Zhang, Qizhou; Houde, Martin; Dunham, Michael; Kristensen, Lars; Lai, Shih-Ping; Li, Zhi-Yun; Plambeck, Richard

2018-01-01

The results from the polarization system at the Atacama Large Millimeter/submillimeter Array (ALMA) have begun both to expand and to confound our understanding of the role of the magnetic field in low-mass star formation. Here we show the highest resolution and highest sensitivity polarization images made to date toward the very young, intermediate-mass Class 0 protostellar source Serpens SMM1, the brightest source in the Serpens Main star-forming region. These ALMA observations achieve ~140 AU resolution, allowing us to probe dust polarization—and thus magnetic field orientation—in the innermost regions surrounding the protostar. By complementing these observations with polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (~0.1 pc) scales—where the magnetic field is oriented E–W, perpendicular to the major axis of the dusty filament where SMM1 is embedded—and the intermediate and small scales probed by CARMA (~1000 au resolution), the SMA (~350 au resolution), and ALMA. The ALMA maps reveal that the redshifted lobe of the bipolar outflow is clearly shaping the magnetic field in SMM1 on the southeast side of the source. High-spatial-resolution continuum and spectral-line observations also reveal a tight (~130 au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both CO(2-1) and SiO(5-4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like SMM1.

Structured decomposition design of partial Mueller matrix polarimeters.

PubMed

Alenin, Andrey S; Scott Tyo, J

2015-07-01

Partial Mueller matrix polarimeters (pMMPs) are active sensing instruments that probe a scattering process with a set of polarization states and analyze the scattered light with a second set of polarization states. Unlike conventional Mueller matrix polarimeters, pMMPs do not attempt to reconstruct the entire Mueller matrix. With proper choice of generator and analyzer states, a subset of the Mueller matrix space can be reconstructed with fewer measurements than that of the full Mueller matrix polarimeter. In this paper we consider the structure of the Mueller matrix and our ability to probe it using a reduced number of measurements. We develop analysis tools that allow us to relate the particular choice of generator and analyzer polarization states to the portion of Mueller matrix space that the instrument measures, as well as develop an optimization method that is based on balancing the signal-to-noise ratio of the resulting instrument with the ability of that instrument to accurately measure a particular set of desired polarization components with as few measurements as possible. In the process, we identify 10 classes of pMMP systems, for which the space coverage is immediately known. We demonstrate the theory with a numerical example that designs partial polarimeters for the task of monitoring the damage state of a material as presented earlier by Hoover and Tyo [Appl. Opt.46, 8364 (2007)10.1364/AO.46.008364APOPAI1559-128X]. We show that we can reduce the polarimeter to making eight measurements while still covering the Mueller matrix subspace spanned by the objects.

Atacama Cosmology Telescope: Polarization calibration analysis for CMB measurements with ACTPol and Advanced ACTPol

NASA Astrophysics Data System (ADS)

Koopman, Brian; ACTPol Collaboration

2015-04-01

The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive upgrade for the Atacama Cosmology Telescope, located at an elevation of 5190 m on Cerro Toco in Chile. Achieving first light in 2013, ACTPol is entering its third observation season. Advanced ACTPol is a next generation upgrade for ACTPol, with additional frequencies, polarization modulation, and new detector arrays, that will begin in 2016. I will first present an overview of the two projects and then focus on describing the methods used for polarization angle calibration of the ACTPol detectors. These methods utilize polarization ray tracing in the optical design software CODEV together with detector positions determined from planet observations and represent a critical input for mapping the polarization of the CMB.

POLARIMETRY OF DG TAU AT 350 mum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krejny, M.; Matthews, T. G.; Novak, G.

2009-11-01

We present the first 350 mum polarization measurement for the disk of the T Tauri star (TTS) DG Tau. The data were obtained using the SHARP polarimeter at the Caltech Submillimeter Observatory. We measured normalized Stokes parameters q= -0.0086 +- 0.0060 and u = -0.0012 +- 0.0061, which gives a 2sigma upper limit for the percent polarization of 1.7%. We obtain information about the polarization spectrum by comparing our 350 mum measurement with an 850 mum polarization detection previously published for this source. Comparing the two measurements in Stokes space (not in percent polarization) shows that the two data pointsmore » are not consistent, i.e., either the degree of polarization or the angle of polarization (or both) must change significantly as one moves from 850 mum to 350 mum. This conclusion concerning the polarization spectrum disagrees with the predictions of a recent model for TTS disk polarization. We show that this discrepancy can be explained by optical depth effects. Specifically, we demonstrate that if one were to add more mass to the model disk, one would expect to obtain a model polarization spectrum in which the polarization degree falls sharply with increasing frequency, consistent with the observations at the two wavelengths. We suggest that multiwavelength polarimetry of TTS disk emission may provide a promising method for probing the opacity of TTS disks.« less

The Discovery of a New Massive Molecular Gas Component Associated with the Submillimeter Galaxy SMM J02399-0136

NASA Astrophysics Data System (ADS)

Frayer, David T.; Maddalena, Ronald J.; Ivison, R. J.; Smail, Ian; Blain, Andrew W.; Vanden Bout, Paul

2018-06-01

We present CO(1–0), CO(3–2), and CO(7–6) observations using the Green Bank Telescope (GBT) and the Atacama Large Millimeter Array (ALMA) of the z = 2.8 submillimeter galaxy SMM J02399‑0136. This was the first submillimeter-selected galaxy discovered and remains an archetype of the class, comprising a merger of several massive and active components, including a quasar-luminosity AGN and a highly obscured, gas-rich starburst spread over a ∼25 kpc extent. The GBT CO(1–0) line profile is comprised of two distinct velocity components separated by about 600 km s‑1 and suggests the presence of a new component of molecular gas that had not been previously identified. The CO(3–2) observations with ALMA show that this new component, designated W1, is associated with a large extended structure stretching 13 kpc westward from the AGN. W1 is not detected in the ALMA CO(7–6) data, implying that this gas has much lower CO excitation than the central starburst regions, which are bright in CO(7–6). The molecular gas mass of W1 is about 30% of the total molecular gas mass in the system, depending on the CO-to-H2 conversion factor. W1 is arguably a merger remnant; alternatively, it could be a massive molecular outflow associated with the AGN, or perhaps inflowing metal-enriched molecular gas fueling the ongoing activity.

Status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera

NASA Astrophysics Data System (ADS)

Golwala, Sunil R.; Bockstiegel, Clint; Brugger, Spencer; Czakon, Nicole G.; Day, Peter K.; Downes, Thomas P.; Duan, Ran; Gao, Jiansong; Gill, Amandeep K.; Glenn, Jason; Hollister, Matthew I.; LeDuc, Henry G.; Maloney, Philip R.; Mazin, Benjamin A.; McHugh, Sean G.; Miller, David; Noroozian, Omid; Nguyen, Hien T.; Sayers, Jack; Schlaerth, James A.; Siegel, Seth; Vayonakis, Anastasios K.; Wilson, Philip R.; Zmuidzinas, Jonas

2012-09-01

We present the status of MUSIC, the MUltiwavelength Sub/millimeter Inductance Camera, a new instrument for the Caltech Submillimeter Observatory. MUSIC is designed to have a 14', diffraction-limited field-of-view instrumented with 2304 detectors in 576 spatial pixels and four spectral bands at 0.87, 1.04, 1.33, and 1.98 mm. MUSIC will be used to study dusty star-forming galaxies, galaxy clusters via the Sunyaev-Zeldovich effect, and star formation in our own and nearby galaxies. MUSIC uses broadband superconducting phased-array slot-dipole antennas to form beams, lumpedelement on-chip bandpass filters to define spectral bands, and microwave kinetic inductance detectors to sense incoming light. The focal plane is fabricated in 8 tiles consisting of 72 spatial pixels each. It is coupled to the telescope via an ambient-temperature ellipsoidal mirror and a cold reimaging lens. A cold Lyot stop sits at the image of the primary mirror formed by the ellipsoidal mirror. Dielectric and metal-mesh filters are used to block thermal infrared and out-ofband radiation. The instrument uses a pulse tube cooler and 3He/ 3He/4He closed-cycle cooler to cool the focal plane to below 250 mK. A multilayer shield attenuates Earth's magnetic field. Each focal plane tile is read out by a single pair of coaxes and a HEMT amplifier. The readout system consists of 16 copies of custom-designed ADC/DAC and IF boards coupled to the CASPER ROACH platform. We focus on recent updates on the instrument design and results from the commissioning of the full camera in 2012.

Protoplanetary Disk Properties in the Orion Nebula Cluster: Initial Results from Deep, High-resolution ALMA Observations

NASA Astrophysics Data System (ADS)

Eisner, J. A.; Arce, H. G.; Ballering, N. P.; Bally, J.; Andrews, S. M.; Boyden, R. D.; Di Francesco, J.; Fang, M.; Johnstone, D.; Kim, J. S.; Mann, R. K.; Matthews, B.; Pascucci, I.; Ricci, L.; Sheehan, P. D.; Williams, J. P.

2018-06-01

We present Atacama Large Millimeter Array 850 μm continuum observations of the Orion Nebula Cluster that provide the highest angular resolution (∼0.″1 ≈ 40 au) and deepest sensitivity (∼0.1 mJy) of the region to date. We mosaicked a field containing ∼225 optical or near-IR-identified young stars, ∼60 of which are also optically identified “proplyds.” We detect continuum emission at 850 μm toward ∼80% of the proplyd sample, and ∼50% of the larger sample of previously identified cluster members. Detected objects have fluxes of ∼0.5–80 mJy. We remove submillimeter flux due to free–free emission in some objects, leaving a sample of sources detected in dust emission. Under standard assumptions of isothermal, optically thin disks, submillimeter fluxes correspond to dust masses of ∼0.5–80 Earth masses. We measure the distribution of disk sizes, and find that disks in this region are particularly compact. Such compact disks are likely to be significantly optically thick. The distributions of submillimeter flux and inferred disk size indicate smaller, lower-flux disks than in lower-density star-forming regions of similar age. Measured disk flux is correlated weakly with stellar mass, contrary to studies in other star-forming regions that found steeper correlations. We find a correlation between disk flux and distance from the massive star θ 1 Ori C, suggesting that disk properties in this region are influenced strongly by the rich cluster environment.

The Next-Generation Very Large Array: Technical Overview

NASA Astrophysics Data System (ADS)

McKinnon, Mark; Selina, Rob

2018-01-01

As part of its mandate as a national observatory, the NRAO is looking toward the long range future of radio astronomy and fostering the long term growth of the US astronomical community. NRAO has sponsored a series of science and technical community meetings to consider the science mission and design of a next-generation Very Large Array (ngVLA), building on the legacies of the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA).The basic ngVLA design emerging from these discussions is an interferometric array with approximately ten times the sensitivity and ten times higher spatial resolution than the VLA and ALMA radio telescopes, optimized for operation in the wavelength range 0.3cm to 3cm. The ngVLA would open a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milli-arcsecond resolution, as well as unprecedented broadband continuum polarimetric imaging of non-thermal processes. The specifications and concepts for major ngVLA system elements are rapidly converging.We will provide an overview of the current system design of the ngVLA. The concepts for major system elements such as the antenna, receiving electronics, and central signal processing will be presented. We will also describe the major development activities that are presently underway to advance the design.

Rapid spectro-polarimetry to probe molecular symmetry in multiplex coherent anti-Stokes Raman scattering.

PubMed

Würthwein, Thomas; Brinkmann, Maximilian; Hellwig, Tim; Fallnich, Carsten

2017-11-21

We present the simultaneous detection of the spectrum and the complete polarization state of a multiplex coherent anti-Stokes Raman scattering signal with a fast division-of-amplitude spectro-polarimeter. The spectro-polarimeter is based on a commercial imaging spectrograph, a birefringent wedge prism, and a segmented polarizer. Compared to the standard rotating-retarder fixed-analyzer spectro-polarimeter, only a single measurement is required and an up to 21-fold reduced acquisition time is shown. The measured Stokes parameters allow us to differentiate between vibrational symmetries and to determine the depolarization ratio ρ by data post-processing.

Development and application of an emitter for research of an on-board ultraviolet polarimeter

NASA Astrophysics Data System (ADS)

Nevodovskyi, P. V.; Geraimchuk, M. D.; Vidmachenko, A. P.; Ivakhiv, O. V.

2018-05-01

In carrying out of the work a layout of on-board small-sized ultraviolet polarimeter (UVP) was created. UVP is the device, which provides an implementation of passive remote studies of stratospheric aerosol from the board of the microsatellite of the Earth by the method of polarimetry. For carrying out of tests and the research of polarimetric equipment, a special stand was created at MAO of NAS of Ukraine. In its composition is an ultraviolet emitter. Emitter is one of the main components of a special stand for the study of on-board ultraviolet polarimeters.

The Atacama B-mode Search: Status and Prospect

NASA Astrophysics Data System (ADS)

Kusaka, Akito

2013-04-01

The Atacama B-mode Search (ABS) experiment is a 145 GHz polarimeter designed to measure the B-mode polarization of the Cosmic Microwave Background (CMB) at degre angular scales. In January 2012, ABS has deployed 240 polarimeters employing transition-edge sensor (TES) bolometers. ABS has unique advantages for the measurement of B modes. This includes a continuously rotating half-wave plate that provides fast and clean modulation, as well as systematically clean optics that consist of a cryogenic side-fed Dragone telescope and feedhorn coupled TES polarimeters. In this talk, we will present the status and prospect of ABS.

A burst chasing x-ray polarimeter

NASA Astrophysics Data System (ADS)

Hill, Joanne E.; Barthelmy, Scott; Black, J. Kevin; Deines-Jones, Philip; Jahoda, Keith; Sakamoto, Takanori; Kaaret, Philip; McConnell, Mark L.; Bloser, Peter F.; Macri, John R.; Legere, Jason S.; Ryan, James M.; Smith, Billy R., Jr.; Zhang, Bing

2007-09-01

Gamma-ray bursts are one of the most powerful explosions in the universe and have been detected out to distances of almost 13 billion light years. The exact origin of these energetic explosions is still unknown but the resulting huge release of energy is thought to create a highly relativistic jet of material and a power-law distribution of electrons. There are several theories describing the origin of the prompt GRB emission that currently cannot be distinguished. Measurements of the linear polarization would provide unique and important constraints on the mechanisms thought to drive these powerful explosions. We present the design of a sensitive, and extremely versatile gamma-ray burst polarimeter. The instrument is a photoelectric polarimeter based on a time-projection chamber. The photoelectric time-projection technique combines high sensitivity with broad band-pass and is potentially the most powerful method between 2 and 100 keV where the photoelectric effect is the dominant interaction process. We present measurements of polarized and unpolarized X-rays obtained with a prototype detector and describe the two mission concepts; the Gamma-Ray Burst Polarimeter (GRBP) for the U.S. Naval Academy satellite MidSTAR-2, and the Low Energy Polarimeter (LEP) onboard POET, a broadband polarimetry concept for a small explorer mission.

A Burst Chasing X-ray Polarimeter

NASA Technical Reports Server (NTRS)

Hill, Joanne E.; Barthelmy, Scott; Black, J. kevin; Deines-Jones, Philip; Jahoda, Keith; Sakamoto, Takanori; Kaaret, Philip; McConnell, Mark L.; Bloser, Peter F.; Macri, John R.;

SOLPOL: A Solar Polarimeter for Hard X-Rays and Gamma-Rays

NASA Technical Reports Server (NTRS)

McConnell, Michael L.

1999-01-01

Th goal of this project was to continue the development of a hard X-ray polarimeter for studying solar flares. In earlier work (funded by a previous SR&T grant), we had already achieved several goals, including the following: 1) development of a means of producing a polarized radiation source in the lab that could be used for prototype development; 2) demonstrated the basic Compton scatter polarimeter concept using a simple laboratory setup; 3) used the laboratory results to verify our Monte Carlo simulations; and 4) investigated various detector technologies that could be incorporated into the polarimeter design. For the current one-year program, we wanted to fabricate and test a laboratory science model based on our SOLPOL (Solar Polarimeter) design. The long-term goal of this effort is to develop and test a prototype design that could be used to study flare emissions from either a balloon- or space-borne platform. The current program has achieved its goal of fabricating and testing a science model of the SOLPOL design, although additional testing of the design (and detailed comparison with Monte Carlo simulations) is still desired. This one-year program was extended by six months (no-cost extension) to cover the summer of 1999, when undergraduate student support was available to complete some of the laboratory testing.

The Cold Gas History of the Universe as seen by the ngVLA

NASA Astrophysics Data System (ADS)

Riechers, Dominik A.; Carilli, Chris Luke; Casey, Caitlin; da Cunha, Elisabete; Hodge, Jacqueline; Ivison, Rob; Murphy, Eric J.; Narayanan, Desika; Sargent, Mark T.; Scoville, Nicholas; Walter, Fabian

2017-01-01

The Next Generation Very Large Array (ngVLA) will fundamentally advance our understanding of the formation processes that lead to the assembly of galaxies throughout cosmic history. The combination of large bandwidth with unprecedented sensitivity to the critical low-level CO lines over virtually the entire redshift range will open up the opportunity to conduct large-scale, deep cold molecular gas surveys, mapping the fuel for star formation in galaxies over substantial cosmic volumes. Informed by the first efforts with the Karl G. Jansky Very Large Array (COLDz survey) and the Atacama Large (sub)Millimeter Array (ASPECS survey), we here present initial predictions and possible survey strategies for such "molecular deep field" observations with the ngVLA. These investigations will provide a detailed measurement of the volume density of molecular gas in galaxies as a function of redshift, the "cold gas history of the universe". This will crucially complement studies of the neutral gas, star formation and stellar mass histories with large low-frequency arrays, the Large UV/Optical/Infrared Surveyor, and the Origins Space Telescope, providing the means to obtain a comprehensive picture of galaxy evolution through cosmic times.

ALMA observations towards G023.01-00.41 .

NASA Astrophysics Data System (ADS)

Sanna, A.; Moscadelli, L.; Cesaroni, R.; Caratti o Garatti, A.; Menten, K. M.; Kölligan, A.; Kuiper, R.

We want to understand whether or not young stars, with masses of tens of Solar masses, can form in the disk accretion scenario. This challenge requires to resolve the spatial morphology of gas and dust within a few 1000 au of a massive young stellar object, and to measure the gas kinematics with respect to the star. Also, because the gas kinematics near the young star can be a mixture of rotating, expanding, and infalling motions all together, to separate each velocity component it is necessary to map the emission of various gas tracers, as well as to image the circumstellar gas at different distances from the star. With this in mind, we made use of the Atacama Large Millimeter Array (ALMA) at wavelengths near 1 mm, with the aim to image the dense molecular gas in the vicinity of a well-known O-type young star. We previously observed this source with the Submillimeter Array (SMA), at scales of about 0.1 pc, with the Karl G. Jansky Very Large Array (VLA), at scales of the order of 1000 au, and with the Very Long Baseline Array (VLBA) and European VLBI Network (EVN), at scales of a few au.

The evolution of the simulation environment in the ALMA Observatory

NASA Astrophysics Data System (ADS)

Shen, Tzu-Chiang; Soto, Ruben; Saez, Norman; Velez, Gaston; Staig, Tomas; Sepulveda, Jorge; Saez, Alejandro; Ovando, Nicolas; Ibsen, Jorge

2016-07-01

The Atacama Large Millimeter /submillimeter Array (ALMA) has entered into operation phase since 2013. This transition changed the priorities within the observatory, in which, most of the available time will be dedicated to science observations at the expense of technical time. Therefore, it was planned to design and implement a new simulation environment, which must be comparable - or at least- be representative of the production environment. Concepts of model in the loop and hardware in the loop were explored. In this paper we review experiences gained and lessons learnt during the design and implementation of the new simulation environment.

VizieR Online Data Catalog: H2CO production in HD 163296 (Carney+)

NASA Astrophysics Data System (ADS)

Carney, M. T.; Hogerheijde, M. R.; Loomis, R. A.; Salinas, V. N.; Oberg, K. I.; Qi, C.; Wilner, D. J.

2017-07-01

The FITS files contain data cubes for H2CO(30 H2CO(322-221), H2CO(321-220), C18O(2-1), and a 2D image of the 1.3mm continuum. The observations were taken with the Atacama Large Millimeter/submillimeter Array (ALMA). The formaldehyde and 1.3mm continuum data have a spatial resolution of 0.5". The C18O(2-1) data is part of the ALMA Science Verification data set released for HD 163296, with an angular resolution of 0.8". (2 data files).

Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array

NASA Astrophysics Data System (ADS)

Lin, Yuting; Bentefour, Hassan; Flanz, Jacob; Kooy, Hanne; Clasie, Benjamin

2018-05-01

Pencil beam scanning (PBS) periodic quality assurance (QA) programs ensure the beam delivered to patients is within technical specifications. Two critical specifications for PBS delivery are the beam width and position. The aim of this study is to investigate whether a 2D ionization chamber array, such as the MatriXX detector (IBA Dosimetry, Schwarzenbruck, Germany), can be used to characterize submillimeter-sized PBS beam properties. The motivation is to use standard equipment, which may have pixel spacing coarser than the pencil beam size, and simplify QA workflow. The MatriXX pixels are cylindrical in shape with 4.5 mm diameter and are spaced 7.62 mm from center to center. Two major effects limit the ability of using the MatriXX to measure the spot position and width accurately. The first effect is that too few pixels sample the Gaussian shaped pencil beam profile and the second effect is volume averaging of the Gaussian profile over the pixel sensitive volumes. We designed a method that overcomes both limitations and hence enables the use of the MatriXX to characterize sub-millimeter-sized PBS beam properties. This method uses a cross-like irradiation pattern that is designed to increase the number of sampling data points and a modified Gaussian fitting technique to correct for volume averaging effects. Detector signals were calculated in this study and random noise and setup errors were added to simulate measured data. With the techniques developed in this work, the MatriXX detector can be used to characterize the position and width of sub-millimeter, σ  =  0.7 mm, sized pencil beams with uncertainty better than 3% relative to σ. With the irradiation only covering 60% of the MatriXX, the position and width of σ  =  0.9 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like irradiation pattern, then the position and width of σ  =  3.6 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like pattern nor volume averaging corrections, then the position and width of σ  =  5.0 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. This work helps to simplify periodic QA in proton therapy because more routinely used ionization chamber arrays can be used to characterize narrow pencil beam properties.

Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array.

PubMed

Lin, Yuting; Bentefour, Hassan; Flanz, Jacob; Kooy, Hanne; Clasie, Benjamin

2018-05-15

Pencil beam scanning (PBS) periodic quality assurance (QA) programs ensure the beam delivered to patients is within technical specifications. Two critical specifications for PBS delivery are the beam width and position. The aim of this study is to investigate whether a 2D ionization chamber array, such as the MatriXX detector (IBA Dosimetry, Schwarzenbruck, Germany), can be used to characterize submillimeter-sized PBS beam properties. The motivation is to use standard equipment, which may have pixel spacing coarser than the pencil beam size, and simplify QA workflow. The MatriXX pixels are cylindrical in shape with 4.5 mm diameter and are spaced 7.62 mm from center to center. Two major effects limit the ability of using the MatriXX to measure the spot position and width accurately. The first effect is that too few pixels sample the Gaussian shaped pencil beam profile and the second effect is volume averaging of the Gaussian profile over the pixel sensitive volumes. We designed a method that overcomes both limitations and hence enables the use of the MatriXX to characterize sub-millimeter-sized PBS beam properties. This method uses a cross-like irradiation pattern that is designed to increase the number of sampling data points and a modified Gaussian fitting technique to correct for volume averaging effects. Detector signals were calculated in this study and random noise and setup errors were added to simulate measured data. With the techniques developed in this work, the MatriXX detector can be used to characterize the position and width of sub-millimeter, σ  =  0.7 mm, sized pencil beams with uncertainty better than 3% relative to σ. With the irradiation only covering 60% of the MatriXX, the position and width of σ  =  0.9 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like irradiation pattern, then the position and width of σ  =  3.6 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like pattern nor volume averaging corrections, then the position and width of σ  =  5.0 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. This work helps to simplify periodic QA in proton therapy because more routinely used ionization chamber arrays can be used to characterize narrow pencil beam properties.

A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment

NASA Astrophysics Data System (ADS)

Hill, C. A.; Kusaka, A.; Barton, P.; Bixler, B.; Droster, A. G.; Flament, M.; Ganjam, S.; Jadbabaie, A.; Jeong, O.; Lee, A. T.; Madurowicz, A.; Matsuda, F. T.; Matsumura, T.; Rutkowski, A.; Sakurai, Y.; Sponseller, D. R.; Suzuki, A.; Tat, R.

2018-05-01

We describe the design of a cryogenic rotation stage (CRS) for use with the cryogenic half-wave plate (CHWP) polarization modulator on the POLARBEAR-2b and POLARBEAR-2c (PB2b/c) cosmic microwave background (CMB) experiments, the second and third installments of the Simons Array. Rapid modulation of the CMB polarization signal using a CHWP suppresses 1/f contamination due to atmospheric turbulence and allows a single polarimeter to measure both polarization states, mitigating systematic effects that arise when differencing orthogonal detectors. To modulate the full detector array while avoiding excess photon loading due to thermal emission, the CHWP must have a clear-aperture diameter of > 450 mm and be cooled to < 100 K. We have designed a 454 mm clear-aperture, < 65 K CRS using a superconducting magnetic bearing driven by a synchronous magnetic motor. We present the specifications for the CRS, its interfacing to the PB2b/c receiver cryostat, its performance in a stand-alone test, and plans for future work.

Precision Electron Beam Polarimetry in Hall C at Jefferson Lab

NASA Astrophysics Data System (ADS)

Gaskell, David

2013-10-01

The electron beam polarization in experimental Hall C at Jefferson Lab is measured using two devices. The Hall-C/Basel Møller polarimeter measures the beam polarization via electron-electron scattering and utilizes a novel target system in which a pure iron foil is driven to magnetic saturation (out of plane) using a superconducting solenoid. A Compton polarimeter measures the polarization via electron-photon scattering, where the photons are provided by a high-power, CW laser coupled to a low gain Fabry-Perot cavity. In this case, both the Compton-scattered electrons and backscattered photons provide measurements of the beam polarization. Results from both polarimeters, acquired during the Q-Weak experiment in Hall C, will be presented. In particular, the results of a test in which the Møller and Compton polarimeters made interleaving measurements at identical beam currents will be shown. In addition, plans for operation of both devices after completion of the Jefferson Lab 12 GeV Upgrade will also be discussed.

Digital Correlation Microwave Polarimetry: Analysis and Demonstration

NASA Technical Reports Server (NTRS)

Piepmeier, J. R.; Gasiewski, A. J.; Krebs, Carolyn A. (Technical Monitor)

2000-01-01

The design, analysis, and demonstration of a digital-correlation microwave polarimeter for use in earth remote sensing is presented. We begin with an analysis of three-level digital correlation and develop the correlator transfer function and radiometric sensitivity. A fifth-order polynomial regression is derived for inverting the digital correlation coefficient into the analog statistic. In addition, the effects of quantizer threshold asymmetry and hysteresis are discussed. A two-look unpolarized calibration scheme is developed for identifying correlation offsets. The developed theory and calibration method are verified using a 10.7 GHz and a 37.0 GHz polarimeter. The polarimeters are based upon 1-GS/s three-level digital correlators and measure the first three Stokes parameters. Through experiment, the radiometric sensitivity is shown to approach the theoretical as derived earlier in the paper and the two-look unpolarized calibration method is successfully compared with results using a polarimetric scheme. Finally, sample data from an aircraft experiment demonstrates that the polarimeter is highly-useful for ocean wind-vector measurement.

A new system model for radar polarimeters

NASA Technical Reports Server (NTRS)

Freeman, Anthony

1991-01-01

The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed by Zebker et al. (1987), is questioned. The model is found to be invalid for many practical realizations of radar polarimeters, which can lead to significant errors in the calibration of polarimetric radar images. A more general model is put forward, which addresses the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARCs in polarimetric calibration and to measure the orientation angle of the horizontal (H) and vertical (V) coordinate system are also presented.

A new system model for radar polarimeters

NASA Astrophysics Data System (ADS)

Freeman, Anthony

1991-09-01

The validity of the 2 x 2 receive R and transmit T model for radar polarimeter systems, first proposed by Zebker et al. (1987), is questioned. The model is found to be invalid for many practical realizations of radar polarimeters, which can lead to significant errors in the calibration of polarimetric radar images. A more general model is put forward, which addresses the system defects which cause the 2 x 2 model to break down. By measuring one simple parameter from a polarimetric active radar calibration (PARC), it is possible to transform the scattering matrix measurements made by a radar polarimeter to a format compatible with a 2 x 2 R and T matrix model. Alternatively, the PARC can be used to verify the validity of the 2 x 2 model for any polarimetric radar system. Recommendations for the use of PARCs in polarimetric calibration and to measure the orientation angle of the horizontal (H) and vertical (V) coordinate system are also presented.

First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward-Thompson, Derek; Pattle, Kate; Kirk, Jason M.

We present the first results from the B-fields In STar-forming Region Observations (BISTRO) survey, using the Sub-millimetre Common-User Bolometer Array 2 camera, with its associated polarimeter (POL-2), on the James Clerk Maxwell Telescope in Hawaii. We discuss the survey’s aims and objectives. We describe the rationale behind the survey, and the questions that the survey will aim to answer. The most important of these is the role of magnetic fields in the star formation process on the scale of individual filaments and cores in dense regions. We describe the data acquisition and reduction processes for POL-2, demonstrating both repeatability andmore » consistency with previous data. We present a first-look analysis of the first results from the BISTRO survey in the OMC 1 region. We see that the magnetic field lies approximately perpendicular to the famous “integral filament” in the densest regions of that filament. Furthermore, we see an “hourglass” magnetic field morphology extending beyond the densest region of the integral filament into the less-dense surrounding material, and discuss possible causes for this. We also discuss the more complex morphology seen along the Orion Bar region. We examine the morphology of the field along the lower-density northeastern filament. We find consistency with previous theoretical models that predict magnetic fields lying parallel to low-density, non-self-gravitating filaments, and perpendicular to higher-density, self-gravitating filaments.« less

The Primordial Inflation Polarization Explorer: Science from Circular Polarization Measurements

NASA Astrophysics Data System (ADS)

Switzer, Eric; Ade, P.; Benford, D. J.; Bennett, C. L.; Chuss, D. T.; Dotson, J. L.; Eimer, J.; Fixsen, D. J.; Halpern, M.; Hinshaw, G. F.; Irwin, K.; Jhabvala, C.; Johnson, B.; Kogut, A. J.; Lazear, J.; Mirel, P.; Moseley, S. H.; Staguhn, J.; Tucker, C. E.; Weston, A.; Wollack, E.

2014-01-01

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne CMB polarimeter designed to constrain the B-mode signature of cosmological inflation. Sequential one-day flights from Northern- and Southern- Hemisphere sites will yield maps of Stokes I, Q, U and V at 200, 270, 350 and 600 GHz over 85% of the sky. The full optical path is cooled to 1.5 K by liquid helium in the ARCADE bucket dewar, and a variable-delay polarization modulator (VPM) at the front of the optics modulates the polarization response. Independent Q and U cameras each have two 32x40 Transition Edge Sensor array receivers. In addition to its primary inflationary science goal, PIPER will also measure the circular (Stokes V) polarization to a depth similar to that of the primary linear polarization. The circular polarization has received relatively little attention in large-area surveys, with constraints from the 1980’s and recent results by the Milan Polarimeter. Astrophysical circular polarization is generally tied to the presence of magnetic fields, either in relativistic plasmas or Zeeman splitting of resonances. These effects are thought to be undetectable at PIPER's frequencies and resolution, despite the depth. The expectation of a null result makes the deep Stokes V map a good cross-check for experimental systematics. More fundamentally, the fact that the sky is expected to be dark in Stokes V makes it a sector sensitive to processes such as Lorentz-violating terms in the standard model or magnetic fields in the CMB era.

First Results from BISTRO: A SCUBA-2 Polarimeter Survey of the Gould Belt

NASA Astrophysics Data System (ADS)

Ward-Thompson, Derek; Pattle, Kate; Bastien, Pierre; Furuya, Ray S.; Kwon, Woojin; Lai, Shih-Ping; Qiu, Keping; Berry, David; Choi, Minho; Coudé, Simon; Di Francesco, James; Hoang, Thiem; Franzmann, Erica; Friberg, Per; Graves, Sarah F.; Greaves, Jane S.; Houde, Martin; Johnstone, Doug; Kirk, Jason M.; Koch, Patrick M.; Kwon, Jungmi; Lee, Chang Won; Li, Di; Matthews, Brenda C.; Mottram, Joseph C.; Parsons, Harriet; Pon, Andy; Rao, Ramprasad; Rawlings, Mark; Shinnaga, Hiroko; Sadavoy, Sarah; van Loo, Sven; Aso, Yusuke; Byun, Do-Young; Eswaraiah, Chakali; Chen, Huei-Ru; Chen, Mike C.-Y.; Chen, Wen Ping; Ching, Tao-Chung; Cho, Jungyeon; Chrysostomou, Antonio; Chung, Eun Jung; Doi, Yasuo; Drabek-Maunder, Emily; Eyres, Stewart P. S.; Fiege, Jason; Friesen, Rachel K.; Fuller, Gary; Gledhill, Tim; Griffin, Matt J.; Gu, Qilao; Hasegawa, Tetsuo; Hatchell, Jennifer; Hayashi, Saeko S.; Holland, Wayne; Inoue, Tsuyoshi; Inutsuka, Shu-ichiro; Iwasaki, Kazunari; Jeong, Il-Gyo; Kang, Ji-hyun; Kang, Miju; Kang, Sung-ju; Kawabata, Koji S.; Kemper, Francisca; Kim, Gwanjeong; Kim, Jongsoo; Kim, Kee-Tae; Kim, Kyoung Hee; Kim, Mi-Ryang; Kim, Shinyoung; Lacaille, Kevin M.; Lee, Jeong-Eun; Lee, Sang-Sung; Li, Dalei; Li, Hua-bai; Liu, Hong-Li; Liu, Junhao; Liu, Sheng-Yuan; Liu, Tie; Lyo, A.-Ran; Mairs, Steve; Matsumura, Masafumi; Moriarty-Schieven, Gerald H.; Nakamura, Fumitaka; Nakanishi, Hiroyuki; Ohashi, Nagayoshi; Onaka, Takashi; Peretto, Nicolas; Pyo, Tae-Soo; Qian, Lei; Retter, Brendan; Richer, John; Rigby, Andrew; Robitaille, Jean-François; Savini, Giorgio; Scaife, Anna M. M.; Soam, Archana; Tamura, Motohide; Tang, Ya-Wen; Tomisaka, Kohji; Wang, Hongchi; Wang, Jia-Wei; Whitworth, Anthony P.; Yen, Hsi-Wei; Yoo, Hyunju; Yuan, Jinghua; Zhang, Chuan-Peng; Zhang, Guoyin; Zhou, Jianjun; Zhu, Lei; André, Philippe; Dowell, C. Darren; Falle, Sam; Tsukamoto, Yusuke

2017-06-01

We present the first results from the B-fields In STar-forming Region Observations (BISTRO) survey, using the Sub-millimetre Common-User Bolometer Array 2 camera, with its associated polarimeter (POL-2), on the James Clerk Maxwell Telescope in Hawaii. We discuss the survey’s aims and objectives. We describe the rationale behind the survey, and the questions that the survey will aim to answer. The most important of these is the role of magnetic fields in the star formation process on the scale of individual filaments and cores in dense regions. We describe the data acquisition and reduction processes for POL-2, demonstrating both repeatability and consistency with previous data. We present a first-look analysis of the first results from the BISTRO survey in the OMC 1 region. We see that the magnetic field lies approximately perpendicular to the famous “integral filament” in the densest regions of that filament. Furthermore, we see an “hourglass” magnetic field morphology extending beyond the densest region of the integral filament into the less-dense surrounding material, and discuss possible causes for this. We also discuss the more complex morphology seen along the Orion Bar region. We examine the morphology of the field along the lower-density northeastern filament. We find consistency with previous theoretical models that predict magnetic fields lying parallel to low-density, non-self-gravitating filaments, and perpendicular to higher-density, self-gravitating filaments.

Preliminary status of POLICAN: A near-infrared imaging polarimeter

NASA Astrophysics Data System (ADS)

Devaraj, R.; Luna, A.; Carrasco, L.; Mayya, Y. D.

2015-10-01

POLICAN is a near-infrared (J, H, K) imaging polarimeter developed for the Cananea near infrared camera (CANICA) at the 2.1m telescope of the Guillermo Haro Astrophysical Observatory (OAGH) located at Cananea, Sonora, México. The camera has a 1024 x 1024 HgCdTe detector (HAWAII array) with a plate scale of 0.32 arcsec/pixel providing a field of view of 5.5 x 5.5 arcmin. POLICAN is mounted externally to CANICA for narrow-field (f/12) linear polarimetric observations. It consists of a rotating super achromatic (1-2.7μm) half waveplate and a fixed wire-grid polarizer as the analyzer. The light is modulated by setting the half waveplate at different angles (0°, 22.5°, 45°, 67.5°) and linear combinations of the Stokes parameters (I, Q and U) are obtained. Image reduction and removal of instrumental polarization consist of dark noise subtraction, polarimetric flat fielding and background sky subtraction. Polarimetric calibration is performed by observing polarization standards available in the literature. The astrometry correction is performed by matching common stars with the Two Micron All Sky Survey. POLICAN's bright and limiting magnitudes are approximately 6th and 16th magnitude, which correspond to saturation and photon noise, respectively. POLICAN currently achieves a polarimetric accuracy about 3.0% and polarization angle uncertainties within 3°. Preliminary observations of star forming regions are being carried out in order to study their magnetic field properties.

Calibration method of microgrid polarimeters with image interpolation.

PubMed

Chen, Zhenyue; Wang, Xia; Liang, Rongguang

2015-02-10

Microgrid polarimeters have large advantages over conventional polarimeters because of the snapshot nature and because they have no moving parts. However, they also suffer from several error sources, such as fixed pattern noise (FPN), photon response nonuniformity (PRNU), pixel cross talk, and instantaneous field-of-view (IFOV) error. A characterization method is proposed to improve the measurement accuracy in visible waveband. We first calibrate the camera with uniform illumination so that the response of the sensor is uniform over the entire field of view without IFOV error. Then a spline interpolation method is implemented to minimize IFOV error. Experimental results show the proposed method can effectively minimize the FPN and PRNU.

High-precision polarimetry at the Mont-Mégantic Observatory with the new polarimeter POMM

NASA Astrophysics Data System (ADS)

Bastien, Pierre; Hernandez, Olivier; Albert, Loïc.; Artigau, Étienne; Doyon, René; Drissen, Laurent; Lafrenière, David; Moffat, Antony F. J.; St-Louis, Nicole

2014-07-01

A new polarimeter has been built for the "Observatoire du Mont-Mégantic" (POMM) and is now in commissioning phase. It will allow polarization measurements with a precision of 10-6, an improvement by a factor of 100 over the previous observatory polarimeter. The characteristics of the instrument that allow this goal are briefly discussed and the planned science observations are presented. They include exoplanets near their host star (hot Jupiters), transiting exoplanets, stars with debris disks, young stars with proto-planetary disks, brown dwarfs, massive Wolf-Rayet stars and comets. The details of the optical and mechanical designs are presented in two other papers.

TES Detector Noise Limited Readout Using SQUID Multiplexers

NASA Technical Reports Server (NTRS)

Staguhn, J. G.; Benford, D. J.; Chervenak, J. A.; Khan, S. A.; Moseley, S. H.; Shafer, R. A.; Deiker, S.; Grossman, E. N.; Hilton, G. C.; Irwin, K. D.

2004-01-01

The availability of superconducting Transition Edge Sensors (TES) with large numbers of individual detector pixels requires multiplexers for efficient readout. The use of multiplexers reduces the number of wires needed between the cryogenic electronics and the room temperature electronics and cuts the number of required cryogenic amplifiers. We are using an 8 channel SQUID multiplexer to read out one-dimensional TES arrays which are used for submillimeter astronomical observations. We present results from test measurements which show that the low noise level of the SQUID multiplexers allows accurate measurements of the TES Johnson noise, and that in operation, the readout noise is dominated by the detector noise. Multiplexers for large number of channels require a large bandwidth for the multiplexed readout signal. We discuss the resulting implications for the noise performance of these multiplexers which will be used for the readout of two dimensional TES arrays in next generation instruments.

Power-Combined GaN Amplifier with 2.28-W Output Power at 87 GHz

NASA Technical Reports Server (NTRS)

Fung, King Man; Ward, John; Chattopadhyay, Goutam; Lin, Robert H.; Samoska, Lorene A.; Kangaslahti, Pekka P.; Mehdi, Imran; Lambrigtsen, Bjorn H.; Goldsmith, Paul F.; Soria, Mary M.;

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2009-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Sub-millimeter wave frequency heterodyne detector system

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

2010-01-01

The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

Self-Calibration of CMB Polarimeters

NASA Astrophysics Data System (ADS)

Keating, Brian

2013-01-01

Precision measurements of the polarization of the cosmic microwave background (CMB) radiation, especially experiments seeking to detect the odd-parity "B-modes", have far-reaching implications for cosmology. To detect the B-modes generated during inflation the flux response and polarization angle of these experiments must be calibrated to exquisite precision. While suitable flux calibration sources abound, polarization angle calibrators are deficient in many respects. Man-made polarized sources are often not located in the antenna's far-field, have spectral properties that are radically different from the CMB's, are cumbersome to implement and may be inherently unstable over the (long) duration these searches require to detect the faint signature of the inflationary epoch. Astrophysical sources suffer from time, frequency and spatial variability, are not visible from all CMB observatories, and none are understood with sufficient accuracy to calibrate future CMB polarimeters seeking to probe inflationary energy scales of ~1000 TeV. CMB TB and EB modes, expected to identically vanish in the standard cosmological model, can be used to calibrate CMB polarimeters. By enforcing the observed EB and TB power spectra to be consistent with zero, CMB polarimeters can be calibrated to levels not possible with man-made or astrophysical sources. All of this can be accomplished without any loss of observing time using a calibration source which is spectrally identical to the CMB B-modes. The calibration procedure outlined here can be used for any CMB polarimeter.

Integrated Arrays on Silicon at Terahertz Frequencies

NASA Technical Reports Server (NTRS)

Chattopadhayay, Goutam; Lee, Choonsup; Jung, Cecil; Lin, Robert; Peralta, Alessandro; Mehdi, Imran; Llombert, Nuria; Thomas, Bertrand

2011-01-01

In this paper we explore various receiver font-end and antenna architecture for use in integrated arrays at terahertz frequencies. Development of wafer-level integrated terahertz receiver front-end by using advanced semiconductor fabrication technologies and use of novel integrated antennas with silicon micromachining are reported. We report novel stacking of micromachined silicon wafers which allows for the 3-dimensional integration of various terahertz receiver components in extremely small packages which easily leads to the development of 2- dimensioanl multi-pixel receiver front-ends in the terahertz frequency range. We also report an integrated micro-lens antenna that goes with the silicon micro-machined front-end. The micro-lens antenna is fed by a waveguide that excites a silicon lens antenna through a leaky-wave or electromagnetic band gap (EBG) resonant cavity. We utilized advanced semiconductor nanofabrication techniques to design, fabricate, and demonstrate a super-compact, low-mass submillimeter-wave heterodyne frontend. When the micro-lens antenna is integrated with the receiver front-end we will be able to assemble integrated heterodyne array receivers for various applications such as multi-pixel high resolution spectrometer and imaging radar at terahertz frequencies.

ALMA BAND 8 CONTINUUM EMISSION FROM ORION SOURCE I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirota, Tomoya; Matsumoto, Naoko; Machida, Masahiro N.

2016-12-20

We have measured continuum flux densities of a high-mass protostar candidate, a radio source I in the Orion KL region (Orion Source I) using the Atacama Large Millimeter/Submillimeter Array (ALMA) at band 8 with an angular resolution of 0.″1. The continuum emission at 430, 460, and 490 GHz associated with Source I shows an elongated structure along the northwest–southeast direction perpendicular to the so-called low-velocity bipolar outflow. The deconvolved size of the continuum source, 90 au × 20 au, is consistent with those reported previously at other millimeter/submillimeter wavelengths. The flux density can be well fitted to the optically thick blackbody spectral energy distribution, and the brightness temperaturemore » is evaluated to be 700–800 K. It is much lower than that in the case of proton–electron or H{sup −} free–free radiations. Our data are consistent with the latest ALMA results by Plambeck and Wright, in which the continuum emission was proposed to arise from the edge-on circumstellar disk via thermal dust emission, unless the continuum source consists of an unresolved structure with a smaller beam filling factor.« less

Featured Image: A Molecular Cloud Outside Our Galaxy

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-06-01

What do molecular clouds look like outside of our own galaxy? See for yourself in the images above and below of N55, a molecular cloud located in the Large Magellanic Cloud (LMC). In a recent study led by Naslim Neelamkodan (Academia Sinica Institute of Astronomy and Astrophysics, Taiwan), a team of scientists explore N55 to determine how its cloud properties differ from clouds within the Milky Way. The image above reveals the distribution of infrared-emitting gas and dust observed in three bands by the Spitzer Space Telescope. Overplotted in cyan are observations from the Atacama Submillimeter Telescope Experiment tracing the clumpy, warm molecular gas. Below, new observations from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the sub-parsec-scale molecular clumps in greater detail, showing the correlation of massive clumps with Spitzer-identified young stellar objects (crosses). The study presented here indicates that this cloud in the LMC is the site of massive star formation, with properties similar to equivalent clouds in the Milky Way. To learn more about the authors findings, check out the article linked below.CitationNaslim N. et al 2018 ApJ 853 175. doi:10.3847/1538-4357/aaa5b0

Pure rotational spectra of TiO and TiO2 in VY Canis Majoris

NASA Astrophysics Data System (ADS)

Kamiński, T.; Gottlieb, C. A.; Menten, K. M.; Patel, N. A.; Young, K. H.; Brünken, S.; Müller, H. S. P.; McCarthy, M. C.; Winters, J. M.; Decin, L.

2013-03-01

We report the first detection of pure rotational transitions of TiO and TiO2 at (sub-)millimeter wavelengths towards the red supergiant VY CMa. A rotational temperature, Trot, of about 250 K was derived for TiO2. Although Trot was not well constrained for TiO, it is likely somewhat higher than that of TiO2. The detection of the Ti oxides confirms that they are formed in the circumstellar envelopes of cool oxygen-rich stars and may be the "seeds" of inorganic-dust formation, but alternative explanations for our observation of TiO and TiO2 in the cooler regions of the envelope cannot be ruled out at this time. The observations suggest that a significant fraction of the oxides is not converted to dust, but instead remains in the gas phase throughout the outflow. Based on observations carried out with the Submillimeter Array and IRAM Plateau de Bure Interferometer.Plateau de Bure data (FITS file) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A113

ALMA Observations of the Archetypal “Hot Core” That Is Not: Orion-KL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orozco-Aguilera, M. T.; Zapata, Luis A.; Hirota, Tomoya

We present sensitive high angular resolution (∼0.″1–0.″3) continuum Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the archetypal hot core located in the Orion Kleinmann-Low (KL) region. The observations were made in five different spectral bands (bands 3, 6, 7, 8, and 9) covering a very broad range of frequencies (149–658 GHz). Apart from the well-known millimeter emitting objects located in this region (Orion Source I and BN), we report the first submillimeter detection of three compact continuum sources (ALMA1–3) in the vicinities of the Orion-KL hot molecular core. These three continuum objects have spectral indices between 1.47 and 1.56, andmore » brightness temperatures between 100 and 200 K at 658 GHz, suggesting that we are seeing moderate, optically thick dust emission with possible grain growth. However, as these objects are not associated with warm molecular gas, and some of them are farther out from the molecular core, we thus conclude that they cannot heat the molecular core. This result favors the hypothesis that the hot molecular core in Orion-KL core is heated externally.« less

Millimeter and Sub-millimeter High Resolution Spectroscopy: New Frontiers with ALMA

NASA Astrophysics Data System (ADS)

Ziurys, Lucy M.

2016-06-01

It is becoming increasingly clear that new laboratory data will be critical for the next decade of observations with the Atacama Large Millimeter Array (ALMA). The high spatial resolution offered by ALMA will probe new regions of molecular complexity, including the inner envelopes of evolved stars, regions dominated by UV radiation, and the densest cores of molecular clouds. New molecular lines will be discovered in the wide wavelength range covered by the ALMA bands, and high resolution, gas-phase spectroscopy are needed to provide crucial “rest frequencies.” In particular, highly accurate methods that measure millimeter and sub-millimeter rotational transitions, such as direct absorption and Fourier transform mm-wave techniques, are important, especially when coupled to exotic molecular production schemes. Recent ALMA studies of SH+ and larger organic species have already demonstrated the need for laboratory measurements. New laboratory work will likely be required for circumstellar refractory molecules, radicals and ions generated near photon-dominated regions (PDRs), and large, organic-type species. This talk will give an overview of current contributions of laboratory spectroscopy to ALMA observations, summarize relevant spectroscopic techniques, and provide input into future prospects and directions.

The Millimeter-Wave Spectrum of Propanal

NASA Astrophysics Data System (ADS)

Zingsheim, Oliver; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan

2017-06-01

The microwave spectrum of propanal, also known as propionaldehyde, CH_3CH_2CHO, has been investigated in the laboratory already since 1964^1 and has also been detected in space^2. Recently, propanal was detected with the Atacama Large Millimeter/submillimeter Array (ALMA), Protostellar Interferometric Line Survey (PILS)^3. The high sensitivity and resolution of ALMA indicated small discrepancies between observed and predicted rotational spectra of propanal. As higher accuracies are desired the spectrum of propanal was measured up to 500 GHz with the Cologne (Sub-)Millimeter spectrometer. Propanal has two stable conformers, syn and gauche, which differ mainly in the rotation of the aldehyd group with respect to the rigid C-atom framework of the molecule. We extensively studied both of them. The lower syn-conformer shows small splittings caused by the internal rotation of the methyl group, whereas the spectrum of gauche-propanal is complicated due to the tunneling rotation interaction from two stable degenerate conformers. Additionally, we analyzed vibrationally excited states. ^1 Butcher et al., J. Chem. Phys. 40 6 (1964) ^2 Hollis et al., Astrophys. J. 610 L21 (2004) ^3 Lykke et al., A&A 597 A53 (2017)

Method and apparatus for manufacturing high-accuracy radio telescope reflector panels

NASA Astrophysics Data System (ADS)

Bosma, Marinus B.

1998-07-01

This article covers the manufacturing of aluminum reflector panels for submillimeter radio astronomy. The first part involves the general construction and application of a machine custom designed and built to do this. The second is a discussion of the software and execution of method to actually produce the reflectors for the Smithsonian Astrophysical Observatories Submillimeter Array (SMA). The reflective surface of each panel is contoured both radially and circularly by oscillating a platen supporting the panel about a fixed axis relative to a tool which is fixed during platen oscillation. The tool is repositionable between oscillations along an x axis to achieve the radial contour and along a z axis to achieve the desired parabolic or spherical contour. Contrary to the normal contouring of such a surface with a 5- axis CNC machine, tool positioning along either axis is independent of tool location along the other axis, simplifying the machine structure as well as its computerized operation. A unique hinge is provided to restrain the platen in a radial direction while allowing floating action of the platen on an air cushion during its oscillation. These techniques and the equipment are documented in U.S. Patent No. 5477602.

The SCUBA-2 Cosmology Legacy Survey: Multiwavelength Counterparts to 103 Submillimeter Galaxies in the UKIDSS-UDS Field

NASA Astrophysics Data System (ADS)

Chen, Chian-Chou; Smail, Ian; Ivison, Rob J.; Arumugam, Vinodiran; Almaini, Omar; Conselice, Christopher J.; Geach, James E.; Hartley, Will G.; Ma, Cheng-Jiun; Mortlock, Alice; Simpson, Chris; Simpson, James M.; Swinbank, A. Mark; Aretxaga, Itziar; Blain, Andrew; Chapman, Scott C.; Dunlop, James S.; Farrah, Duncan; Halpern, Mark; Michałowski, Michał J.; van der Werf, Paul; Wilkinson, Aaron; Zavala, Jorge A.

2016-04-01

We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850 μm in the SCUBA-2 Cosmology Legacy Survey study of the UKIRT Infrared Deep Sky Survey-Ultra-Deep Survey (UDS) field. By utilizing an Atacama Large Millimeter Array (ALMA) pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical-near-infrared (OIR) data available in this field, we develop a novel technique, Optical-IR Triple Color (OIRTC), using z - K, K - [3.6], [3.6] - [4.5] colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates for 80% of the Class = 1 ≥ 4σ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be 82% ± 20%, with a completeness of 69% ± 16%, essentially as accurate as the traditional p-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850 μm sources, and we argue that for follow-up observations sensitive to SMGs with S850 ≳ 1 mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be >40% for SCUBA-2 sources at S850 ≳ 4 mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of z = 2.3 ± 0.1. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be z = 2.6 ± 0.1 for SMGs with S850 > 1 mJy. We also use this new large sample to study the clustering of SMGs and the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission.

Infrared and Radio Observations of a Small Group of Protostellar Objects in the Molecular Core, L1251-C

NASA Astrophysics Data System (ADS)

Kim, Jungha; Lee, Jeong-Eun; Choi, Minho; Bourke, Tyler L.; Evans, Neal J., II; Di Francesco, James; Cieza, Lucas A.; Dunham, Michael M.; Kang, Miju

2015-05-01

We present a multi-wavelength observational study of a low-mass star-forming region, L1251-C, with observational results at wavelengths from the near-infrared to the millimeter. Spitzer Space Telescope observations confirmed that IRAS 22343+7501 is a small group of protostellar objects. The extended emission in the east-west direction with its intensity peak at the center of L1251A has been detected at 350 and 850 μm with the Caltech Submillimeter Observatory and James Clerk Maxwell telescopes, tracing dense envelope material around L1251A. The single-dish data from the Korean VLBI Network and TRAO telescopes show inconsistencies between the intensity peaks of several molecular emission lines and that of the continuum emission, suggesting complex distributions of molecular abundances around L1251A. The Submillimeter Array interferometer data, however, show intensity peaks of CO 2-1 and 13CO 2-1 located at the position of IRS 1, which is both the brightest source in the Infrared Array Camera image and the weakest source in the 1.3 mm dust-continuum map. IRS 1 is the strongest candidate for the driving source of the newly detected compact CO 2-1 outflow. Over the entire region (14‧ × 14‧) of L125l-C, 3 Class I and 16 Class II sources have been detected, including three young stellar objects (YSOs) in L1251A. A comparison between the average projected distance among the 19 YSOs in L1251-C and that among the 3 YSOs in L1251A suggests that L1251-C is an example of low-mass cluster formation where protostellar objects form in a small group.

DIRECT DETECTION OF PRECURSORS OF GAS GIANTS FORMED BY GRAVITATIONAL INSTABILITY WITH THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, Lucio; Peters, Thomas; Pineda, Jaime E.

Phases of gravitational instability are expected in the early phases of disk evolution, when the disk mass is still a substantial fraction of the mass of the star. Disk fragmentation into sub-stellar objects could occur in the cold exterior part of the disk. Direct detection of massive gaseous clumps on their way to collapse into gas giant planets would offer an unprecedented test of the disk instability model. Here we use state-of-the-art 3D radiation-hydro simulations of disks undergoing fragmentation into massive gas giants, post-processed with RADMC-3D to produce dust continuum emission maps. These are then fed into the Common Astronomymore » Software Applications (CASA) ALMA simulator. The synthetic maps show that both overdense spiral arms and actual clumps at different stages of collapse can be detected with the Atacama Large Millimeter/submillimeter Array (ALMA) in the full configuration at the distance of the Ophiuchus star forming region (125 pc). The detection of clumps is particularly effective at shorter wavelengths (690 GHz) combining two resolutions with multi-scale clean. Furthermore, we show that a flux-based estimate of the mass of a protoplanetary clump can be comparable to a factor of three higher than the gravitationally bound clump mass. The estimated mass depends on the assumed opacity, and on the gas temperature, which should be set using the input of radiation-hydro simulations. We conclude that ALMA has the capability to detect “smoking gun” systems that are a signpost of the disk instability model for gas giant planet formation.« less

Micro-Spec: an Integrated, Direct-Detection Spectrometer for Far-Infrared and Submillimeter Astronomy

NASA Technical Reports Server (NTRS)

Cataldo, Giuseppe

2014-01-01

The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Our ability to fully explore this rich spectral region has been limited, however, by the size and cost of the cryogenic spectrometers required to carry out such measurements. Micro-Spec (u-Spec) is a high-sensitivity, direct-detection spectrometer concept working in the 450-1000 micromillimeter wavelength range which will enable a wide range of flight missions that would otherwise be challenging due to the large size of current instruments with the required spectral resolution and sensitivity. The spectrometer design utilizes two internal antenna arrays, one for transmitting and one for receiving, superconducting microstrip transmission lines for power division and phase delay, and an array of microwave kinetic inductance detectors (MKIDs) to achieve these goals. The instrument will be integrated on a approximately 10 square cm silicon chip and can therefore become an important capability under the low background conditions accessible via space and high-altitude borne platforms. In this paper, an optical design methodology for Micro-Spec is presented, with particular attention given to its twodimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the maximization of the instrument resolving power and minimization of the RMS phase error on the instrument focal plane. This two-step optimization can generate geometrical configurations given specific requirements on spectrometer size, operating spectral range and performance. A point design with resolving power of 257, an RMS phase error less than 0.1 radians and four stigmatic points was developed for initial demonstration and will be the basis of future instruments with resolving power up to about 1200.

MAPPING THE RELEASE OF VOLATILES IN THE INNER COMAE OF COMETS C/2012 F6 (LEMMON) AND C/2012 S1 (ISON) USING THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cordiner, M. A.; Milam, S. N.; Mumma, M. J.

2014-09-01

Results are presented from the first cometary observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), including measurements of the spatially resolved distributions of HCN, HNC, H{sub 2}CO, and dust within the comae of two comets: C/2012 F6 (Lemmon) and C/2012 S1 (ISON), observed at heliocentric distances of 1.5 AU and 0.54 AU, respectively. These observations (with angular resolution ≈0.''5), reveal an unprecedented level of detail in the distributions of these fundamental cometary molecules, and demonstrate the power of ALMA for quantitative measurements of the distributions of molecules and dust in the inner comae of typical bright comets. In both comets, HCN ismore » found to originate from (or within a few hundred kilometers of) the nucleus, with a spatial distribution largely consistent with spherically symmetric, uniform outflow. By contrast, the HNC distributions are clumpy and asymmetrical, with peaks at cometocentric radii ∼500-1000 km, consistent with release of HNC in collimated outflow(s). Compared to HCN, the H{sub 2}CO distribution in comet Lemmon is very extended. The interferometric visibility amplitudes are consistent with coma production of H{sub 2}CO and HNC from unidentified precursor material(s) in both comets. Adopting a Haser model, the H{sub 2}CO parent scale length is found to be a few thousand kilometers in Lemmon and only a few hundred kilometers in ISON, consistent with the destruction of the precursor by photolysis or thermal degradation at a rate that scales in proportion to the solar radiation flux.« less

Submillimeter array observations of NGC 2264-C: molecular outflows and driving sources

NASA Astrophysics Data System (ADS)

Cunningham, Nichol; Lumsden, Stuart L.; Cyganowski, Claudia J.; Maud, Luke T.; Purcell, Cormac

2016-05-01

We present 1.3 mm Submillimeter Array (SMA) observations at ˜3 arcsec resolution towards the brightest section of the intermediate/massive star-forming cluster NGC 2264-C. The millimetre continuum emission reveals ten 1.3 mm continuum peaks, of which four are new detections. The observed frequency range includes the known molecular jet/outflow tracer SiO (5-4), thus providing the first high-resolution observations of SiO towards NGC 2264-C. We also detect molecular lines of 12 additional species towards this region, including CH3CN, CH3OH, SO, H2CO, DCN, HC3N, and 12CO. The SiO (5-4) emission reveals the presence of two collimated, high-velocity (up to 30 km s-1 with respect to the systemic velocity) bipolar outflows in NGC 2264-C. In addition, the outflows are traced by emission from 12CO, SO, H2CO, and CH3OH. We find an evolutionary spread between cores residing in the same parent cloud. The two unambiguous outflows are driven by the brightest mm continuum cores, which are IR-dark, molecular line weak, and likely the youngest cores in the region. Furthermore, towards the Red MSX Source AFGL 989-IRS1, the IR-bright and most evolved source in NGC 2264-C, we observe no molecular outflow emission. A molecular line rich ridge feature, with no obvious directly associated continuum source, lies on the edge of a low-density cavity and may be formed from a wind driven by AFGL 989-IRS1. In addition, 229 GHz class I maser emission is detected towards this feature.

Multiwavelength Variations of 3C 454.3 during the 2010 November to 2011 January Outburst

NASA Astrophysics Data System (ADS)

Wehrle, Ann E.; Marscher, Alan P.; Jorstad, Svetlana G.; Gurwell, Mark A.; Joshi, Manasvita; MacDonald, Nicholas R.; Williamson, Karen E.; Agudo, Iván; Grupe, Dirk

2012-10-01

We present multiwavelength data of the blazar 3C 454.3 obtained during an extremely bright outburst from 2010 November through 2011 January. These include flux density measurements with the Herschel Space Observatory at five submillimeter-wave and far-infrared bands, the Fermi Large Area Telescope at γ-ray energies, Swift at X-ray, ultraviolet (UV), and optical frequencies, and the Submillimeter Array at 1.3 mm. From this data set, we form a series of 52 spectral energy distributions (SEDs) spanning nearly two months that are unprecedented in time coverage and breadth of frequency. Discrete correlation analysis of the millimeter, far-infrared, and γ-ray light curves show that the variations were essentially simultaneous, indicative of cospatiality of the emission, at these wavebands. In contrast, differences in short-term fluctuations at various wavelengths imply the presence of inhomogeneities in physical conditions across the source. We locate the site of the outburst in the parsec-scale "core," whose flux density as measured on 7 mm Very Long Baseline Array images increased by 70% during the first five weeks of the outburst. Based on these considerations and guided by the SEDs, we propose a model in which turbulent plasma crosses a conical standing shock in the parsec-scale region of the jet. Here, the high-energy emission in the model is produced by inverse Compton scattering of seed photons supplied by either nonthermal radiation from a Mach disk, thermal emission from hot dust, or (for X-rays) synchrotron radiation from plasma that crosses the standing shock. For the two dates on which we fitted the model SED to the data, the model corresponds very well to the observations at all bands except at X-ray energies, where the spectrum is flatter than observed.

VLA and ALMA Imaging of Intense Galaxy-wide Star Formation in z ˜ 2 Galaxies

NASA Astrophysics Data System (ADS)

Rujopakarn, W.; Dunlop, J. S.; Rieke, G. H.; Ivison, R. J.; Cibinel, A.; Nyland, K.; Jagannathan, P.; Silverman, J. D.; Alexander, D. M.; Biggs, A. D.; Bhatnagar, S.; Ballantyne, D. R.; Dickinson, M.; Elbaz, D.; Geach, J. E.; Hayward, C. C.; Kirkpatrick, A.; McLure, R. J.; Michałowski, M. J.; Miller, N. A.; Narayanan, D.; Owen, F. N.; Pannella, M.; Papovich, C.; Pope, A.; Rau, U.; Robertson, B. E.; Scott, D.; Swinbank, A. M.; van der Werf, P.; van Kampen, E.; Weiner, B. J.; Windhorst, R. A.

2016-12-01

We present ≃0.″4 resolution extinction-independent distributions of star formation and dust in 11 star-forming galaxies (SFGs) at z = 1.3-3.0. These galaxies are selected from sensitive blank-field surveys of the 2‧ × 2‧ Hubble Ultra-Deep Field at λ = 5 cm and 1.3 mm using the Karl G. Jansky Very Large Array and Atacama Large Millimeter/submillimeter Array. They have star formation rates (SFRs), stellar masses, and dust properties representative of massive main-sequence SFGs at z ˜ 2. Morphological classification performed on spatially resolved stellar mass maps indicates a mixture of disk and morphologically disturbed systems; half of the sample harbor X-ray active galactic nuclei (AGNs), thereby representing a diversity of z ˜ 2 SFGs undergoing vigorous mass assembly. We find that their intense star formation most frequently occurs at the location of stellar-mass concentration and extends over an area comparable to their stellar-mass distribution, with a median diameter of 4.2 ± 1.8 kpc. This provides direct evidence of galaxy-wide star formation in distant blank-field-selected main-sequence SFGs. The typical galactic-average SFR surface density is 2.5 M ⊙ yr-1 kpc-2, sufficiently high to drive outflows. In X-ray-selected AGN where radio emission is enhanced over the level associated with star formation, the radio excess pinpoints the AGNs, which are found to be cospatial with star formation. The median extinction-independent size of main-sequence SFGs is two times larger than those of bright submillimeter galaxies, whose SFRs are 3-8 times larger, providing a constraint on the characteristic SFR (˜300 M ⊙ yr-1) above which a significant population of more compact SFGs appears to emerge.

Millimeter imaging of HD 163296: probing the disk structure and kinematics

NASA Astrophysics Data System (ADS)

Isella, A.; Testi, L.; Natta, A.; Neri, R.; Wilner, D.; Qi, C.

2007-07-01

We present new multi-wavelength millimeter interferometric observations of the Herbig Ae star HD 163296 obtained with the IRAM/PBI, SMA and VLA arrays both in continuum and in the 12CO, 13CO and C18O emission lines. Gas and dust properties have been obtained comparing the observations with self-consistent disk models for the dust and CO emission. The circumstellar disk is resolved both in the continuum and in CO. We find strong evidence that the circumstellar material is in Keplerian rotation around a central star of 2.6 M_⊙. The disk inclination with respect to the line of sight is 46° ± 4° with a position angle of 128° ± 4°. The slope of the dust opacity measured between 0.87 and 7 mm (β = 1) confirms the presence of mm/cm-size grains in the disk midplane. The dust continuum emission is asymmetric and confined inside a radius of 200 AU while the CO emission extends up to 540 AU. The comparison between dust and CO temperature indicates that CO is present only in the disk interior. Finally, we obtain an increasing depletion of CO isotopomers from 12CO to 13CO and C18O. We argue that these results support the idea that the disk of HD 163296 is strongly evolved. In particular, we suggest that there is a strong depletion of dust relative to gas outside 200 AU; this may be due to the inward migration of large bodies that form in the outer disk or to clearing of a large gap in the dust distribution by a low mass companion. Based on observations carried out with IRAM Plateau de Bure Interferometer, Submillimeter Array and NRAO Very Large Array. IRAM Plateau de Bure Interferometer is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Appendix A and Figs. [see full text]- [see full text] are only available in electronic form at http://www.aanda.org

The population of submillimeter galaxies and its impact on the detection of the Sunyaev-Zel'Dovich Effect

NASA Astrophysics Data System (ADS)

Downes, Thomas Patrick

The population of submillimeter galaxies (SMGs) informs models of the formation of structure in the universe. It is likely that SMGs are the progenitors of systems like the Milky Way because their spectra imply the high star formation rates necessary to form the requisite number of stars. Until recently millimeter/submillimeter experiments did not have the sensitivity to image both wide and deep to distinguish between competing models of galaxy evolution. AzTEC is an array instrument operating at 1.1mm that has the necessary sensitivity and dedicated telescope time and has begun making groundbreaking contributions to the field. Furthermore, SMGs are an expected foreground to the detection of the Sunyaev-Zel'dovich Effect (SZE) in clusters of galaxies. In particular, at wavelengths longer than 1.4mm the positive flux of SMGs below an instrument's sensitivity threshold will counteract the decrement expected from the SZE. The detection of galaxy clusters is a promising approach to understanding the expansion history of the universe and putting constraints on s 8 as well as on the properties the dark energy. We present below the results of an analysis of AzTEC surveys for SMGs in galaxy cluster environments as well as "blank" fields far away from clusters. We compare the two results and those of previous surveys and estimate their implications for the ability of a blind survey at 2mm to detect the SZE in clusters. We find that the noise contributions of SMGs to SZE detection are small compared to the sensitivity of existing surveys, such as that of the South Pole Telescope.

Hyperspectral imaging polarimeter in the infrared

NASA Astrophysics Data System (ADS)

Jensen, Gary L.; Peterson, James Q.

1998-11-01

The Space Dynamics Laboratory at Utah State University is building an infrared Hyperspectral Imaging Polarimeter (HIP). Designed for high spatial and spectral resolution polarimetry of backscattered sunlight from cloud tops in the 2.7 micrometer water band, it will fly aboard the Flying Infrared Signatures Technology Aircraft (FISTA), an Air Force KC-135. It is a proof-of-concept sensor, combining hyperspectral pushbroom imaging with high speed, solid state polarimetry, using as many off-the-shelf components as possible, and utilizing an optical breadboard design for rapid prototyping. It is based around a 256 X 320 window selectable InSb camera, a solid-state Ferro-electric Liquid Crystal (FLC) polarimeter, and a transmissive diffraction grating.

Characterization of the dynamics of surface stabilized ferroelectric liquid crystal under electric field by full optical snapshot matrix Mueller polarimeter

NASA Astrophysics Data System (ADS)

Silva, Vinicius N. H.; Babilotte, Philippe; Rivet, Sylvain; Dubreuil, Mathieu; Le Jeune, Bernard; Dupont, Laurent

2012-12-01

We investigated the layer dynamics of a conventional surface-stabilized ferroelectric liquid crystal (SSFLC) using a full-optical snapshot Mueller matrix polarimeter (SMMP) based on wavelength polarization coding. Time-resolved polarimetric measurements were performed with different SSFLC samples, and a strong correlation between the polarimetric parameters and the SSFLC under electric field at different exposure times was found. It has been shown that the SMMP polarimeter is able to determine the evolution of the trajectory of the liquid crystal director between the two addressed states, the reversible motion of the smectic layer while switching, as well as the irreversible transition from chevron to bookshelf texture.

A New Polarimeter at the Universite de Montreal

NASA Astrophysics Data System (ADS)

Manset, Nadine; Bastien, Pierre

1995-05-01

We present Beauty and The Beast, a new polarimeter of the Universite de Montreal, formerly built for the Canada-France-Hawaii telescope (CFHT) but never commissioned there. This computer-controlled Pockels cell polarimeter has been restored to working order and offers a wide range of possibilities: almost all functions are under remote control, linear or circular polarization observations are both possible, a filter slide provides easy access to up to six different bandpasses, and the Pockels cell and Fabry lenses are kept at a constant temperature. In addition to controlling the instrument, the software allows the use of pre-defined sequences of observation, and does data acquisition and reduction. (SECTION: Astronomical Instrumentation)

Ultraviolet spectrometer and polarimeter (UVSP) catalog of observations. Volume 2: Experiments 30720-63057, April 1985 - February 1988

NASA Technical Reports Server (NTRS)

Henze, William, Jr.

1993-01-01

A catalog of observations (experiments) obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) from Feb. 1980 to Nov. 1989 is presented. The information for each entry includes the time of each observation, the observed position of the Sun, the spacecraft roll angle, the slit used, and instrument parameters such as raster size, pixel spacing, wavelength, polarimeter usage, gate time, etc. The document is split into three volumes: Volume 1 contains experiments 1-30719 (February 1980-April 1985); Volume 2 contains experiments 30720-63057 (April 1985-February 1988); and Volume 3 contains experiments 63058-99771 (February 1988-November 1989).

Ultraviolet spectrometer and polarimeter (UVSP) catalog of observations. Volume 1: Experiments 1-30719, February 1980 - April 1985

NASA Technical Reports Server (NTRS)

Henze, William, Jr.

1993-01-01

A catalog of observations (experiments) obtained by the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission (SMM) from Feb. 1980 to Nov. 1989 is presented. The information for each entry includes the time of each observation, the observed position of the Sun, the spacecraft roll angle, the slit used, and instrument parameters such as raster size, pixel spacing, wavelength, polarimeter usage, gate time, etc. The document is split into three volumes: Volume 1 contains experiments 1-30719 (February 1980-April 1985); Volume 2 contains experiments 30720-63057 (April 1985-February 1988); and Volume 3 contains experiments 63058-99771 (February l988-November 1989).

A Gamma Polarimeter for Neutron Polarization Measurement in a Liquid Deuterium Target for Parity Violation in Polarized Neutron Capture on Deuterium.

PubMed

Komives, A; Sint, A K; Bowers, M; Snow, M

2005-01-01

A measurement of the parity-violating gamma asymmetry in n-D capture would yield information on N-N parity violation independent of the n-p system. Since cold neutrons will depolarize in a liquid deuterium target in which the scattering cross section is much larger than the absorption cross section, it will be necessary to quantify the loss of polarization before capture. One way to do this is to use the large circular polarization of the gamma from n-D capture and analyze the circular polarization of the gamma in a gamma polarimeter. We describe the design of this polarimeter.

Silicon nitride Micromesh Bolometer Array for Submillimeter Astrophysics.

PubMed

Turner, A D; Bock, J J; Beeman, J W; Glenn, J; Hargrave, P C; Hristov, V V; Nguyen, H T; Rahman, F; Sethuraman, S; Woodcraft, A L

2001-10-01

We present the design and performance of a feedhorn-coupled bolometer array intended for a sensitive 350-mum photometer camera. Silicon nitride micromesh absorbers minimize the suspended mass and heat capacity of the bolometers. The temperature transducers, neutron-transmutation-doped Ge thermistors, are attached to the absorber with In bump bonds. Vapor-deposited electrical leads address the thermistors and determine the thermal conductance of the bolometers. The bolometer array demonstrates a dark noise-equivalent power of 2.9 x 10(-17) W/ radicalHz and a mean heat capacity of 1.3 pJ/K at 390 mK. We measure the optical efficiency of the bolometer and feedhorn to be 0.45-0.65 by comparing the response to blackbody calibration sources. The bolometer array demonstrates theoretical noise performance arising from the photon and the phonon and Johnson noise, with photon noise dominant under the design background conditions. We measure the ratio of total noise to photon noise to be 1.21 under an absorbed optical power of 2.4 pW. Excess noise is negligible for audio frequencies as low as 30 mHz. We summarize the trade-offs between bare and feedhorn-coupled detectors and discuss the estimated performance limits of micromesh bolometers. The bolometer array demonstrates the sensitivity required for photon noise-limited performance from a spaceborne, passively cooled telescope.

A photoelectric skylight polarimeter.

PubMed

Hariharan, T A; Sekera, Z

1966-09-01

A photoelectric skylight polarimeter to measure directly the Stokes parameters for plane polarized light is described. The basic principle of the instrument consists in the simultaneous measurement of the intensity of light (in the chosen spectral region) transmitted by polarizers oriented in four specific directions. The main features and performance characteristics of the instrument are briefly discussed.

The Skylab ten color photoelectric polarimeter. [sky brightness

NASA Technical Reports Server (NTRS)

Weinberg, J. L.; Hahn, R. C.; Sparrow, J. G.

1975-01-01

A 10-color photoelectric polarimeter was used during Skylab missions SL-2 and SL-3 to measure sky brightness and polarization associated with zodiacal light, background starlight, and the spacecraft corona. A description is given of the instrument and observing routines together with initial results on the spacecraft corona and polarization of the zodiacal light.

Snapshot imaging polarimeters using spatial modulation

NASA Astrophysics Data System (ADS)

Luo, Haitao

The recent demonstration of a novel snapshot imaging polarimeter using the fringe modulation technique shows a promise in building a compact and moving-parts-free device. As just demonstrated in principle, this technique has not been adequately studied. In the effort of advancing this technique, we build a complete theory framework that can address the key issues regarding the polarization aberrations caused by using the functional elements. With this model, we can have the necessary knowledge in designing, analyzing and optimizing the systems. Also, we propose a broader technique that uses arbitrary modulation instead of sinusoidal fringes, which can give us more engineering freedom and can be the solution of achromatizing the system. In the hardware aspect, several important progresses are made. We extend the polarimeter technique from visible to middle wavelength infrared by using the yttrium vanadate crystals. Also, we incorporate a Savart Plate polarimter into a fundus camera to measure the human eye's retinal retardance, useful information for glaucoma diagnosis. Thirdly, a world-smallest imaging polarimeter is proposed and demonstrated, which may open many applications in security, remote sensing and bioscience.

A Millimeter Polarimeter for the 45-m Telescope at Nobeyama

NASA Astrophysics Data System (ADS)

Shinnaga, Hiroko; Tsuboi, Masato; Kasuga, Takashi

1999-04-01

We have designed and constructed a tunable polarimeter to cover frequencies from 35 GHz to 250 GHz (8.6 mm and 1.2 mm in wavelength) for the 45-m telescope at Nobeyama Radio Observatory. Both circular and linear polarizations can be measured by the polarimeter. The insertion loss was measured to be 0.14 +/- 0.05 dB in the 100-GHz band. The overall instrumental polarization of the system in the 100 GHz band is as low as <= 3%. The performance of the polarimeter in astronomical observations was tested by simultaneously measuring the linear polarization of the J = 2--1 transition of SiO in the v = 0 and 1 states at 86 GHz toward VY Canis Majoris. The observation revealed that the J = 2--1 emission in the v = 0 state of the object is highly linear polarized, which suggests that the emission originates through maser action in the circumstellar region. The details of the design, construction, and tests are presented. Nobeyama Radio Observatory is a branch of the National Astronomical Observatory, operated by the Ministry of Education, Science, Sports and Culture.

A new three-band, two beam astronomical photo-polarimeter

NASA Astrophysics Data System (ADS)

Srinivasulu, G.; Raveendran, A. V.; Muneer, S.; Mekkaden, M. V.; Jayavel, N.; Somashekar, M. R.; Sagayanathan, K.; Ramamoorthy, S.; Rosario, M. J.; Jayakumar, K.

2014-09-01

We designed and built a new astronomical photo-polarimeter that can measure linear polarization simultaneously in three spectral bands. It has a Calcite beam-displacement prism as the analyzer. The ordinary and extra-ordinary emerging beams in each spectral bands are quasi-simultaneously detected by the same photomultiplier by using a high speed rotating chopper. A rotating superachromatic Pancharatnam halfwave plate is used to modulate the light incident on the analyzer. The spectral bands are isolated using appropriate dichroic and glass filters. We show that the reduction of 50% in the efficiency of the polarimeter because of the fact that the intensities of the two beams are measured alternately is partly compensated by the reduced time to be spent on the observation of the sky background. The use of a beam-displacement prism as the analyzer completely removes the polarization of background skylight, which is a major source of error during moonlit nights, especially, in the case of faint stars. The field trials that were carried out by observing several polarized and unpolarized stars show the performance of the polarimeter to be satisfactory.

The ability to use remote polarization studies of Earth from space in the national economy (Project of the onboard filter panoramic polarimeter)

NASA Astrophysics Data System (ADS)

Nevodovskyi, P. V.; Vidmachenko, A. P.; Geraimchuk, M. D.; Ivahiv, O. V.

2016-10-01

Remote polarization studies are a very powerful method of solving of astronomical tasks with the study of the physical properties of the planets and their atmospheres. It allows research of objects as in situ, so in vitro, and has many other advantages. To use this method has already been developed and are continuing the development of many various special instruments called polarimeters. The essence of the space experiment consists in the fact to using the polarimeter installed on board a micro satellite, systematically, during each of its revolutions around the Earth, to monitor a polarization components of a diffusely reflected by atmosphere solar radiation in different, previously stipulated wavelengths. There are a lot of the optical schemes, which are used in devices of measuring and monitoring of parameters of polarized radiation, including those into space experiments of probing of the Earth's atmosphere from orbit of satellites. In this paper we analyze the potential for use of filter-polarimeter to measure the Stokes vector components.

Mott Polarimeter Upgrade at Jefferson Lab

NASA Astrophysics Data System (ADS)

McHugh, M.; Opper, A. K.; Grames, J.; Poelker, M.; Suleiman, R.; Horowitz, C.; Rhodes, S.; Roca Maza, X.; Sinclair, C.

2013-10-01

A Mott polarimeter with a design optimized for 5.5 MeV/c has been in routine use at the CEBAF accelerator for well over a decade, providing polarization measurements approaching 1% accuracy. Measurements with different target elements (Au, Ag, Cu) over decades of target thicknesses (100 - 10,000 angstroms), and beam energies between 2 and 8 MeV allow us to determine the effective analyzing power with a high degree of certainty. Recent and planned improvements in our polarimeter configuration, detectors and data acquisition system, coupled with a low 31 MHz repetition rate beam allow us to distinguish and suppress electrons that do not originate from the target foil. This work coupled with a significant effort to produce a detailed GEANT4 model of the polarimeter is part of an effort to determine systematic uncertainties at the level of the theoretically calculated analyzing power. We describe our activities and a series of planned measurements that will allow us to demonstrate and possibly improve the precision and accuracy of polarization measurements at JLab, as required for future parity violation experiments.

Design study of the PEPSI polarimeter for the LBT

NASA Astrophysics Data System (ADS)

Hofmann, A.; Strassmeier, K. G.; Woche, M.

2002-07-01

We present the conceptual design of the two polarimetric channels of the PEPSI spectropolarimeter for the Large Binocular Telescope (LBT). The two direct Gregorian f/15 focii of the LBT will take up two identical but independent full-Stokes IQUV polarimeters that themselves fiberfeed a high-resolution Echelle spectrograph (see the accompanying paper by Zerbi et al.). The polarizing units will be based on super-achromatic Fresnel-rhomb retarders and Foster prisms. A total of four fibers are foreseen to simultaneously direct two ordinary and two extraordinary light beams to the Echelle spectrograph. Both polarimetric units are layed out in a modular design, each one optimized to the polarization state in which it is used. A number of observing modes can be chosen that are optimized to the type of polarization that is expected from the target, e.g. circularly and linearly polarized light simultaneously, or linearly polarized light in both polarimeters, or integral light from one and polarized light from the other telescope, a.s.o.. Calibration would be provided for each polarimeter separately.

Canadian Led X-ray Polarimeter Mission CXP

NASA Technical Reports Server (NTRS)

Kaspi, V.; Hanna, D.; Weisskopf, M.; Ramsey, B.; Ragan, K.; Vachon, B.; Elsner, R.; Heyl, J.; Pavlov, G.; Cumming, A.;

Noninvasive and Painless Urine Glucose Detection by Using Computer-based Polarimeter

NASA Astrophysics Data System (ADS)

Sutrisno; Laksono, Y. A.; Hidayat, N.

2017-05-01

Diabetes kills millions of people worldwide each year. It challenges us as researchers to give contribution in early diagnosis to ensure a healthy life. As a matter of fact, common glucose testing devices that have been widely used so far are, at least, glucose meter and urine glucose test strip. The glucose meter ordinarily requires blood taken from patient’s finger. The glucose test strip uses patient’s urine but records unspecific urine glucose level, since the strip only provides the glucose level in some particular ranges. Instead of detecting the glucose level in blood and using the non-specific technique, a noninvasive and painless technique that can detect glucose level accurately will provide a more feasible approach for diabetes diagnosis. The noninvasive and painless urine glucose level monitoring by means of computer-based polarimeter is presented in this paper. The instrument consisted of a power source, a sample box, a light sensor, a polarizer, an analyzer, an analog to digital converter (ADC), and a computer. The concentration of urine glucose concentration was evaluated from the curve of the change in detected optical rotation angle and output potential by the computer-based polarimeter. Statistical analyses by means of Gaussian fitting and linear regression were applied to investigate the rotation angle and urine glucose concentration, respectively. From our experiment, the urine glucose level, measured by glucose test strips, of the normal patient was 100 mg/dl, and the diabetic patient was 500 mg/dl. Our polarimeter even read more precise values for the urine glucose concentrations of those normal and diabetic of the same patients, i.e. 50.61 mg/dl and 502.41 mg/dl, respectively. In other words, the results showed that our polarimeter was able to quantitatively measure the urine glucose level more accurate than urine glucose test strips. Hence, this computer-based polarimeter could be used as an alternative for early detection of urine glucose with noninvasive and painless characteristics.

Modeling Intracochlear Magnetic Stimulation: A Finite-Element Analysis.

PubMed

Mukesh, S; Blake, D T; McKinnon, B J; Bhatti, P T

2017-08-01

This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (~100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.

VizieR Online Data Catalog: 340GHz SMA obs. of 50 nearby protoplanetary disks (Tripathi+, 2017)

NASA Astrophysics Data System (ADS)

Tripathi, A.; Andrews, S. M.; Birnstiel, T.; Wilner, D. J.

2018-03-01

A sample of 50 nearby (d<=200pc) disk targets was collated from the archived catalog of ~340GHz (880um) continuum measurements made with the Submillimeter Array (SMA), since the start of science operations in 2004. Of the 50 disks in our survey, 10 were recently observed by us expressly for the purposes of the present study. To our knowledge, the SMA observations of 18 targets have not yet been published elsewhere. Table 1 is a brief SMA observation log, with references for where the data originally appeared (observations span 2005 jun 12 to 2015 Jan 19). (3 data files).

Exploring a possible origin of a 14 deg y-normal spin tilt at RHIC polarimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meot, F.; Huang, H.

2015-06-15

A possible origin of a 14 deg y-normal spin n → 0 tilt at the polarimeter is in snake angle defects. This possible cause is investigated by scanning the snake axis angle µ, and the spin rotation angle at the snake, φ, in the vicinity of their nominal values.

POLICAN: A near-infrared imaging polarimeter at OAGH

NASA Astrophysics Data System (ADS)

Devaraj, R.; Luna, A.; Carrasco, L.; Mayya, Y. D.; Serrano-Bernal, O.

2017-07-01

We present a near-infrared linear imaging polarimeter POLICAN, developed for the Cananea near-infrared camera (CANICA) at the 2.1m telescope of the Guillermo Haro Astrophysical Observatory (OAGH) located at Cananea, Sonora, México. POLICAN reaches a limiting magnitude to about 16th mag with a polarimetric accuracy of about 1% for bright sources.

Polarimeter based on video matrix

NASA Astrophysics Data System (ADS)

Pavlov, Andrey; Kontantinov, Oleg; Shmirko, Konstantin; Zubko, Evgenij

2017-11-01

In this paper we present a new measurement tool - polarimeter, based on video matrix. Polarimetric measure- ments are usefull, for example, when monitoring water areas pollutions and atmosphere constituents. New device is small enough to mount on unmanned aircraft vehicles (quadrocopters) and stationary platforms. Device and corresponding software turns it into real-time monitoring system, that helps to solve some research problems.

Snapshot retinal imaging Mueller matrix polarimeter

NASA Astrophysics Data System (ADS)

Wang, Yifan; Kudenov, Michael; Kashani, Amir; Schwiegerling, Jim; Escuti, Michael

2015-09-01

Early diagnosis of glaucoma, which is a leading cause for visual impairment, is critical for successful treatment. It has been shown that Imaging polarimetry has advantages in early detection of structural changes in the retina. Here, we theoretically and experimentally present a snapshot Mueller Matrix Polarimeter fundus camera, which has the potential to record the polarization-altering characteristics of retina with a single snapshot. It is made by incorporating polarization gratings into a fundus camera design. Complete Mueller Matrix data sets can be obtained by analyzing the polarization fringes projected onto the image plane. In this paper, we describe the experimental implementation of the snapshot retinal imaging Mueller matrix polarimeter (SRIMMP), highlight issues related to calibration, and provide preliminary images acquired from the camera.

POL-2: a polarimeter for the James-Clerk-Maxwell telescope

NASA Astrophysics Data System (ADS)

Friberg, Per; Bastien, Pierre; Berry, David; Savini, Giorgio; Graves, Sarah F.; Pattle, Kate

2016-07-01

The POL-2 polarimeter for the SCUBA-2 10 000 pixel Terahertz camera on the James Clerk Maxwell Telescope (JCMT) in it's late state of commissioning. Proposals have been accepted for POL-2 and general observing will start in August 2016. SCUBA-2 has a field of view of 43 arcmin at both of the 850 and 450 μm focal planes. POL-2 will map the sky in the the 850 μm band. The POL-2 polarimeter utilizes three optical components: a half wave plate and two wire-grid polarizers used as calibrator and analyzer covering the full field of SCUBA-2. We describe the instrument, data acquisition and features/artifacts that have been encountered during the commissioning.

Managing Systematic Errors in a Polarimeter for the Storage Ring EDM Experiment

NASA Astrophysics Data System (ADS)

Stephenson, Edward J.; Storage Ring EDM Collaboration

2011-05-01

The EDDA plastic scintillator detector system at the Cooler Synchrotron (COSY) has been used to demonstrate that it is possible using a thick target at the edge of the circulating beam to meet the requirements for a polarimeter to be used in the search for an electric dipole moment on the proton or deuteron. Emphasizing elastic and low Q-value reactions leads to large analyzing powers and, along with thick targets, to efficiencies near 1%. Using only information obtained comparing count rates for oppositely vector-polarized beam states and a calibration of the sensitivity of the polarimeter to rate and geometric changes, the contribution of systematic errors can be suppressed below the level of one part per million.

Extracting the inclination angle of nerve fibers within the human brain with 3D-PLI independent of system properties

NASA Astrophysics Data System (ADS)

Reckfort, Julia; Wiese, Hendrik; Dohmen, Melanie; Grässel, David; Pietrzyk, Uwe; Zilles, Karl; Amunts, Katrin; Axer, Markus

2013-09-01

The neuroimaging technique 3D-polarized light imaging (3D-PLI) has opened up new avenues to study the complex nerve fiber architecture of the human brain at sub-millimeter spatial resolution. This polarimetry technique is applicable to histological sections of postmortem brains utilizing the birefringence of nerve fibers caused by the regular arrangement of lipids and proteins in the myelin sheaths surrounding axons. 3D-PLI provides a three-dimensional description of the anatomical wiring scheme defined by the in-section direction angle and the out-of-section inclination angle. To date, 3D-PLI is the only available method that allows bridging the microscopic and the macroscopic description of the fiber architecture of the human brain. Here we introduce a new approach to retrieve the inclination angle of the fibers independently of the properties of the used polarimeters. This is relevant because the image resolution and the signal transmission inuence the measured birefringent signal (retardation) significantly. The image resolution was determined using the USAF- 1951 testchart applying the Rayleigh criterion. The signal transmission was measured by elliptical polarizers applying the Michelson contrast and histological slices of the optic tract of a postmortem brain. Based on these results, a modified retardation-inclination transfer function was proposed to extract the fiber inclination. The comparison of the actual and the inclination angles calculated with the theoretically proposed and the modified transfer function revealed a significant improvement in the extraction of the fiber inclinations.

Polarimeter Arrays for Cosmic Microwave Background Measurements

NASA Technical Reports Server (NTRS)

Stevenson, Thomas; Cao, Nga; Chuss, David; Fixsen, Dale; Hsieh, Wen-Ting; Kogut, Alan; Limon, Michele; Moseley, S. Harvey; Phillips, Nicholas; Schneider, Gideon

2006-01-01

We discuss general system architectures and specific work towards precision measurements of Cosmic Microwave Background (CMB) polarization. The CMB and its polarization carry fundamental information on the origin, structure, and evolution of the universe. Detecting the imprint of primordial gravitational radiation on the faint polarization of the CMB will be difficult. The two primary challenges will be achieving both the required sensitivity and precise control over systematic errors. At anisotropy levels possibly as small as a few nanokelvin, the gravity-wave signal is faint compared to the fundamental sensitivity limit imposed by photon arrival statistics, and one must make simultaneous measurements with large numbers, hundreds to thousands, of independent background-limited direct detectors. Highly integrated focal plane architectures, and multiplexing of detector outputs, will be essential. Because the detectors, optics, and even the CMB itself are brighter than the faint gravity-wave signal by six to nine orders of magnitude, even a tiny leakage of polarized light reflected or diffracted from warm objects could overwhelm the primordial signal. Advanced methods of modulating only the polarized component of the incident radiation will play an essential role in measurements of CMB polarization. One promising general polarimeter concept that is under investigation by a number of institutions is to first use planar antennas to separate millimeter-wave radiation collected by a lens or horn into two polarization channels. Then the signals can be fed to a pair of direct detectors through a planar circuit consisting of superconducting niobium microstrip transmission lines, hybrid couplers, band-pass filters, and phase modulators to measure the Stokes parameters of the incoming radiation.

Development of a dedicated readout ASIC for TPC based X-ray polarimeter

NASA Astrophysics Data System (ADS)

Zhang, Hongyan; Deng, Zhi; Li, Hong; Liu, Yinong; Feng, Hua

2016-07-01

X-ray polarimetry with time projection chambers was firstly proposed by JK Black in 2007 and has been greatly developed since then. It measured two dimensional photoelectron tracks with one dimensional strip and the other dimension was estimated by the drift time from the signal waveforms. A readout ASIC, APV25, originally developed for CMS silicon trackers was used and has shown some limitations such as waveform sampling depth. A dedicated ASIC was developed for TPC based X-ray polarimeters in this paper. It integrated 32 channel circuits and each channel consisted of an analog front-end and a waveform sampler based on switched capacitor array. The analog front-end has a charge sensitive preamplifier with a gain of 25 mV/fC, a CR-RC shaper with a peaking time of 25 ns, a baseline holder and a discriminator for self-triggering. The SCA has a buffer latency of 3.2 μs with 64 cells operating at 20 MSPS. The ASIC was fabricated in a 0.18 μm CMOS process. The equivalent noise charge (ENC) of the analog front-end was measured to be 274.8 e+34.6 e/pF. The effective resolution of the SCA was 8.8 bits at sampling rate up to 50 MSPS. The total power consumption was 2.8 mW per channel. The ASIC was also tested with real TPC detectors and two dimensional photoelectron tracks have been successfully acquired. More tests and analysis on the sensitivity to the polarimetry are undergoing and will be presented in this paper.

First Light for Mimir, a Near-Infrared Wide-Field Imager, Spectrometer, and Polarimeter for the Perkins Telescope

NASA Astrophysics Data System (ADS)

Clemens, D. P.; Sarcia, D.; Tollestrup, E. V.; Grabau, A.; Bosh, A.; Buie, M.; Taylor, B.; Dunham, E.

2004-12-01

The Mimir instrument completed its 5-year development in our Boston University lab and was delivered this past July to Flagstaff, Arizona and the Perkins telescope for commissioning. Mimir is a "facility-class" multi-function near-infrared imager, spectrometer, and polarimeter developed under a joint program by Boston University and Lowell Observatory scientists, staff, and engineers. It fully covers the wavelength range 1-5 microns onto its 1024x1024 Aladdin III InSb array detector. In its wide-field imaging mode, a 10x10 arcmin field is sampled at 0.6 arcsec per pixel. In its narrow-field mode, the field is 3x3 arcmin, sampled at 0.2 arcsec per pixel. A full complement of JHKsL'M' broad-band filters are present in its four filter wheels. Spectroscopy is accomplished using a matched slit-plate and selector system, three grisms, and special spectroscopy filters (for order suppression). Polarimetry is accomplished using rotating half-wave plates and a fixed wire grid. All of these modes were certified in the lab; all have been certified at the Perkins telescope during the August/September commissioning run. Mode switches are accomplished in a matter of only seconds, making Mimir exceedingly versatile. The poster highlights the designs and components of Mimir as well as examples of images, spectra, and polarimetry from the commissioning telescope runs this past fall. Internal, shared-risk observations with Mimir begin this quarter. Mimir design and development has been funded by NASA, NSF, and the W.M. Keck Foundation.

Characterization of Detectors and Instrument Systematics for the SPIDER CMB Polarimeter

NASA Astrophysics Data System (ADS)

Tucker, Rebecca Suzanne

We know from the CMB and observations of large-scale structure that the universe is extremely flat, homogenous, and isotropic. The current favored mechanism for generating these characteristics is inflation, a theorized period of exponential expansion of the universe that occurred shortly after the Big Bang. Most theories of inflation generically predict a background of stochastic gravitational waves. These gravitational waves should leave their unique imprint on the polarization of the CMB via Thompson scattering. Scalar perturbations of the metric will cause a pattern of polarization with no curl (E-mode). Tensor perturbations (gravitational waves) will cause a unique pattern of polarization on the CMB that includes a curl component (B-mode). A measurement of the ratio of the tensor to scalar perturbations (r ) tells us the energy scale of inflation. Recent measurements by the BICEP2 team detect the B-mode spectrum with a tensor-to-scalar ratio of r=0.2 (+0.05, -0.07). An independent confirmation of this result is the next step towards understanding the inflationary universe. This thesis describes my work on a balloon-borne polarimeter called SPIDER, which is designed to illuminate the physics of the early universe through measurements of the cosmic microwave background polarization. SPIDER consists of six single-frequency, on-axis refracting telescopes contained in a shared-vacuum liquid-helium cryostat. Its large format arrays of millimeter-wave detectors and tight control of systematics will give it unprecedented sensitivity. This thesis describes how the SPIDER detectors are characterized and calibrated for flight, as well as how the systematics requirements for the SPIDER system are simulated and measured.

Performances and first science results with the VEGA/CHARA visible instrument

NASA Astrophysics Data System (ADS)

Mourard, D.; Tallon, M.; Bério, Ph.; Bonneau, D.; Chesneau, O.; Clausse, J. M.; Delaa, O.; Nardetto, N.; Perraut, K.; Spang, A.; Stee, Ph.; Tallon-Bosc, I.; McAlister, H.; ten Brummelaar, T.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

2010-07-01

This paper presents the current status of the VEGA (Visible spEctroGraph and polArimeter) instrument installed at the coherent focus of the CHARA Array, Mount Wilson CA. Installed in september 2007, the first science programs have started during summer 2008 and first science results are now published. Dedicated to high angular (0.3mas) and high spectral (R=30000) astrophysical studies, VEGA main objectives are the study of circumstellar environments of hot active stars or interactive binary systems and a large palette of new programs dedicated to fundamental stellar parameters. We will present successively the main characteristics of the instrument and its current performances in the CHARA environment, a short summary of two science programs and finally we will develop some studies showing the potential and difficulties of the 3 telescopes mode of VEGA/CHARA.

ACTPol: Status and preliminary CMB polarization results from the Atacama Cosmology Telescope

NASA Astrophysics Data System (ADS)

Koopman, Brian

2014-03-01

The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive upgrade for the Atacama Cosmology Telescope, located at an elevation of 5190 m on Cerro Toco in Chile. In summer 2013, ACTPol achieved first light with one third of the final detector configuration. The remaining two thirds of the detector array will be installed during spring 2014, enabling full sensitivity, high resolution, observations at both 90 GHz and 150 GHz. Using approximately 3,000 transition-edge sensor bolometers, ACTPol will enable measurements of small angular scale polarization anisotropies in the Cosmic Microwave Background (CMB). I will present a status update for the ACTPol receiver and some preliminary results. ACTPol measurements will allow us to probe the spectral index of inflation as well as to constrain early dark energy and the sum of neutrino masses.

Recent Progress of the HL-2A Multi-Channel HCOOH Laser Interferometer/Polarimeter

NASA Astrophysics Data System (ADS)

Li, Yonggao; Zhou, Yan; Deng, Zhongchao; Li, Yuan; Yi, Jiang; Wang, Haoxi

2015-05-01

A multichannel methanoic acid (HCOOH, λ = 432.5 μm) laser interferometer/polarimeter is being developed from the previous eight-channel hydrogen cyanide (HCN, λ = 337 μm) laser interferometer in the HL-2A tokamak. A conventional Michelson-type interometer is used for the electron density measurement, and a Dodel-Kunz-type polarimeter is used for the Faraday rotation effect measurement, respectively. Each HCOOH laser can produce a linearly polarized radiation at a power lever of ˜30 mW, and a power stability <10% in 50 min. A beam waist (diameter d0 ≈12.0 mm, about 200 mm away from the outlet) is finally determined through a chopping modulation technique. The latest optical layout of the interferometer/polarimeter has been finished, and the hardware data processing system based on the fast Fourier transform phase-comparator technique is being explored. In order to demonstrate the feasibility of the diagnostic scheme, two associated bench simulation experiments were carried out in the laboratory, in which the plasma was simulated by a piece of polytetrafluoroethene plate, and the Faraday rotation effect was simulated by a rotating half-wave plate. Simulation results agreed well with the initial experimental conditions. At present, the HCOOH laser interferometer/polarimeter system is being assembled on HL-2A, and is planned to be applied in the 2014-2015 experimental campaign. supported by the National Magnetic Confinement Fusion Science Programs of China (Nos. 2010GB101002 and 2014GB109001), and National Natural Science Foundation of China (Nos. 11075048 and 11275059)

Multiparameter measurement utilizing poloidal polarimeter for burning plasma reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

2014-08-21

The authors have made the basic and applied research on the polarimeter for plasma diagnostics. Recently, the authors have proposed an application of multiparameter measurement (magnetic field, B, electron density, n{sub e}, electron temperature, T{sub e}, and total plasma current, I{sub p}) utilizing polarimeter to future fusion reactors. In this proceedings, the brief review of the polarimeter, the principle of the multiparameter measurement and the progress of the research on the multiparameter measurement are explained. The measurement method that the authors have proposed is suitable for the reactor for the following reasons; multiparameters can be obtained from a small numbermore » of diagnostics, the proposed method does not depend on time-history, and far-infrared light utilized by the polarimeter is less sensitive to degradation of of optical components. Taking into account the measuring error, performance assessment of the proposed method was carried. Assuming that the error of Δθ and Δε were 0.1° and 0.6°, respectively, the error of reconstructed j{sub φ}, n{sub e} and T{sub e} were 12 %, 8.4 % and 31 %, respectively. This study has shown that the reconstruction error can be decreased by increasing the number of the wavelength of the probing laser and by increasing the number of the viewing chords. For example, By increasing the number of viewing chords to forty-five, the error of j{sub φ}, n{sub e} and T{sub e} were reduced to 4.4 %, 4.4 %, and 17 %, respectively.« less

On the possibility of space objects invasion observations into the Earth's atmosphere with the help of a multifunctional polarimeter

NASA Astrophysics Data System (ADS)

Nevodovskyi, P. V.; Steklov, A. F.; Vidmachenko, A. P.

2018-05-01

Relevance of the tasks associated with the observation of the invasion of space objects into the Earth's atmosphere increases with each passing year. We used astronomical panoramic polarimeter for carrying out of polarimetric observations of objects, that flying into the atmosphere of the Earth from the surrounding outer space.

Panoramic Stokes-polarimeter

NASA Astrophysics Data System (ADS)

Syniavskyi, I. I.; Ivanov, Yu. S.; Vidmachenko, A. P.; Karpov, N. V.

2013-12-01

This article proposes optical layout of the imaging polarimeter based on the polarization films to measure the linear polarization of point and extended celestial objects. The spectral range of device is 420-850 nm, field of view 0.25°x0.25°. The device is designed to equip the telescope with a diameter of primary mirror about 400 mm and aperture f/12.

PIMACS (Polarimeter and improved modular anti-coincidence system): an effective instrument concept for x-, gamma-ray monitoring, and polarimetry measurements on the International Space Station

NASA Astrophysics Data System (ADS)

Stuffler, Timo; Graue, Roland; Bird, Antony J.; Dean, Antony; Staubert, Rüdiger

2018-04-01

This paper, "PIMACS (Polarimeter and improved modular anti-coincidence system): an effective instrument concept for x-, gamma-ray monitoring, and polarimetry measurements on the International Space Station," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.

The Polarimeter for Relativistic Astrophysical X-ray Sources

NASA Astrophysics Data System (ADS)

Jahoda, Keith; Kallman, Timothy R.; Kouveliotou, Chryssa; Angelini, Lorella; Black, J. Kevin; Hill, Joanne E.; Jaeger, Theodore; Kaaret, Philip E.; Markwardt, Craig B.; Okajima, Takashi; Petre, Robert; Schnittman, Jeremy; Soong, Yang; Strohmayer, Tod E.; Tamagawa, Toru; Tawara, Yuzuru

2016-07-01

The Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) is one of three Small Explorer (SMEX) missions selected by NASA for Phase A study, with a launch date in 2020. The PRAXyS Observatory exploits grazing incidence X-ray mirrors and Time Projection Chamber Polarimeters capable of measuring the linear polarization of cosmic X-ray sources in the 2-10 keV band. PRAXyS combines well-characterized instruments with spacecraft rotation to ensure low systematic errors. The PRAXyS payload is developed at the Goddard Space Flight Center with the Johns Hopkins University Applied Physics Laboratory, University of Iowa, and RIKEN (JAXA) collaborating on the Polarimeter Assembly. The LEOStar-2 spacecraft bus is developed by Orbital ATK, which also supplies the extendable optical bench that enables the Observatory to be compatible with a Pegasus class launch vehicle. A nine month primary mission will provide sensitive observations of multiple black hole and neutron star sources, where theory predicts polarization is a strong diagnostic, as well as exploratory observations of other high energy sources. The primary mission data will be released to the community rapidly and a Guest Observer extended mission will be vigorously proposed.

Polarization-direction correlation measurement --- Experimental test of the PDCO methods

NASA Astrophysics Data System (ADS)

Starosta, K.; Morek, T.; Droste, Ch.; Rohoziński, S. G.; Srebrny, J.; Bergstrem, M.; Herskind, B.

1998-04-01

Information about spins and parities of excited states is crucial for nuclear structure studies. In ``in-beam" gamma ray spectroscopy the directional correlation (DCO) or angular distribution measurements are widely used tools for multipolarity assignment; although, it is known that neither of these methods is sensitive to electric or magnetic character of gamma radiation. Multipolarity of gamma rays may be determined when the results of the DCO analysis are combined with the results of linear polarization measurements. The large total efficiency of modern multidetector arrays allows one to carry out coincidence measurements between the polarimeter and the remaining detectors. The aim of the present study was to test experimentally the possibility of polarization-direction correlation measurements using the EUROGAM II array. The studied nucleus was ^164Yb produced in the ^138Ba(^30Si,4n) reaction at beam energies of 150 and 155 MeV. The angular correlation, linear polarization and direction-polarization correlation were measured for the strong transitions in yrast and non yrast cascades. Application of the PDCO analysis to a transition connecting a side band with the yrast band allowed one to rule out most of the ambiguities in multipolarity assignment occuring if one used angular correlations only.

Physical studies of Centaurs and Trans-Neptunian Objects with the Atacama Large Millimeter Array

NASA Astrophysics Data System (ADS)

Moullet, Arielle; Lellouch, Emmanuel; Moreno, Raphael; Gurwell, Mark

2011-05-01

Once completed, the Atacama Large Millimeter Array (ALMA) will be the most powerful (sub)millimeter interferometer in terms of sensitivity, spatial resolution and imaging. This paper presents the capabilities of ALMA applied to the observation of Centaurs and Trans-Neptunian Objects, and their possible output in terms of physical properties. Realistic simulations were performed to explore the performances of the different frequency bands and array configurations, and several projects are detailed along with their feasibility, their limitations and their possible targets. Determination of diameters and albedos via the radiometric method appears to be possible on ˜500 objects, while sampling of the thermal lightcurve to derive the bodies' ellipticity could be performed at least 30 bodies that display a significant optical lightcurve. On a limited number of objects, the spatial resolution allows for direct measurement of the size or even surface mapping with a resolution down to 13 milliarcsec. Finally, ALMA could separate members of multiple systems with a separation power comparable to that of the HST. The overall performance of ALMA will make it an invaluable instrument to explore the outer Solar System, complementary to space-based telescopes and spacecrafts.

The HERSCHEL/PACS early Data Products

NASA Astrophysics Data System (ADS)

Wieprecht, E.; Wetzstein, M.; Huygen, R.; Vandenbussche, B.; De Meester, W.

2006-07-01

ESA's Herschel Space Observatory to be launched in 2007, is the first space observatory covering the full far-infrared and submillimeter wavelength range (60 - 670 microns). The Photodetector Array Camera & Spectrometer (PACS) is one of the three science instruments. It contains two Ge:Ga photoconductor arrays and two bolometer arrays to perform imaging line spectroscopy and imaging photometry in the 60 - 210 micron wavelength band. The HERSCHEL ground segment (Herschel Common Science System - HCSS) is implemented using JAVA technology and written in a common effort by the HERSCHEL Science Center and the three instrument teams. The PACS Common Software System (PCSS) is based on the HCSS and used for the online and offline analysis of PACS data. For telemetry bandwidth reasons PACS science data are partially processed on board, compressed, cut into telemetry packets and transmitted to the ground. These steps are instrument mode dependent. We will present the software model which allows to reverse the discrete on board processing steps and evaluate the data. After decompression and reconstruction the detector data and instrument status information are organized in two main PACS Products. The design of these JAVA classes considers the individual sampling rates, data formats, memory and performance optimization aspects and comfortable user interfaces.

The Intricate Role of Cold Gas and Dust in Galaxy Evolution at Early Cosmic Epochs

NASA Astrophysics Data System (ADS)

Riechers, Dominik A.; Capak, Peter L.; Carilli, Christopher L.

Cold molecular and atomic gas plays a central role in our understanding of early galaxy formation and evolution. It represents the component of the interstellar medium (ISM) that stars form out of, and its mass, distribution, excitation, and dynamics provide crucial insight into the physical processes that support the ongoing star formation and stellar mass buildup. We here present results that demonstrate the capability of the Atacama Large (sub-)Millimeter Array (ALMA) to detect the cold ISM and dust in ``normal'' galaxies at redshifts z=5-6. We also show detailed studies of the ISM in massive, dust-obscured starburst galaxies out to z>6 with ALMA, the Combined Array for Research in Millimeter-wave Astronomy (CARMA), the Plateau de Bure Interferometer (PdBI), and the Karl G. Jansky Very Large Array (VLA). These observations place some of the most direct constraints on the dust-obscured fraction of the star formation history of the universe at z>5 to date, showing that ``typical'' galaxies at these epochs have low dust content, but also that highly-enriched, dusty starbursts already exist within the first billion years after the Big Bang.

Instrumentation and Future Missions in the Upcoming Era of X-ray Polarimetry

NASA Astrophysics Data System (ADS)

Fabiani, Sergio

2018-05-01

The maturity of current detectors based on technologies that range from solid state to gases renewed the interest for X-ray polarimetry, raising the enthusiasm of a wide scientific community to improve the performance of polarimeters as well as to produce more detailed theoretical predictions. We will introduce the basic concepts about measuring the polarization of photons, especially in the X-rays, and we will review the current state of the art of polarimeters in a wide energy range from soft~to hard X-rays, from solar flares to distant astrophysical sources. We will introduce relevant examples of polarimeters developed from the recent past up to the panorama of upcoming space missions to show how the recent development of the technology is allowing reopening the observational window of X-ray polarimetry.

Calibration of Passive Microwave Polarimeters that Use Hybrid Coupler-Based Correlators

NASA Technical Reports Server (NTRS)

Piepmeier, J. R.

2003-01-01

Four calibration algorithms are studied for microwave polarimeters that use hybrid coupler-based correlators: 1) conventional two-look of hot and cold sources, 2) three looks of hot and cold source combinations, 3) two-look with correlated source, and 4) four-look combining methods 2 and 3. The systematic errors are found to depend on the polarimeter component parameters and accuracy of calibration noise temperatures. A case study radiometer in four different remote sensing scenarios was considered in light of these results. Applications for Ocean surface salinity, Ocean surface winds, and soil moisture were found to be sensitive to different systematic errors. Finally, a standard uncertainty analysis was performed on the four-look calibration algorithm, which was found to be most sensitive to the correlated calibration source.

Strategy for Realizing High-Precision VUV Spectro-Polarimeter

NASA Astrophysics Data System (ADS)

Ishikawa, R.; Narukage, N.; Kubo, M.; Ishikawa, S.; Kano, R.; Tsuneta, S.

2014-12-01

Spectro-polarimetric observations in the vacuum ultraviolet (VUV) range are currently the only means to measure magnetic fields in the upper chromosphere and transition region of the solar atmosphere. The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) aims to measure linear polarization at the hydrogen Lyman- α line (121.6 nm). This measurement requires a polarization sensitivity better than 0.1 %, which is unprecedented in the VUV range. We here present a strategy with which to realize such high-precision spectro-polarimetry. This involves the optimization of instrument design, testing of optical components, extensive analyses of polarization errors, polarization calibration of the instrument, and calibration with onboard data. We expect that this strategy will aid the development of other advanced high-precision polarimeters in the UV as well as in other wavelength ranges.

A Cryogenic Half-Wave Plate Module to Measure Polarization at Multiple FIR Passbands

NASA Technical Reports Server (NTRS)

Rennick, Timothy S.; Vaillancourt, John E.; Hildebrand, Roger H.; Heimsath, Stephen J.

2002-01-01

One of the key components in a far-infrared polarimeter that is being designed at the University of Chicago is a locally-powered half-wave plate module. This compact, lightweight, and reliable module will operate at cryogenic temperatures, rotating a half-wave plate about its axis within the optical path. By doing so, polarization measurements can be made. Further, by utilizing multiple half-wave plate modules within the polarimeter, multiple wavelengths or passbands can be studied. In this paper, we describe the design and performance of a relatively inexpensive prototype module that was assembled and tested successfully, outline the difficulties that had to be overcome, and recommend improvements to future modules. This effort now lays some of the groundwork for a next-generation polarimeter for far-infrared astronomy.

Imaging proportional counters for the stellar X-ray polarimeter. [on Soviet Spectrum X-Gamma mission

NASA Technical Reports Server (NTRS)

Watkins, R. B., Jr.; Kaaret, P.

1990-01-01

The xenon-filled IPCs being developed for the Stellar X-ray Polarimeter are described. The requirements placed on the IPCs by the design of the polarimeter are discussed and results on the performance of prototype counters are presented. The design of a prototype of the IPCs is described. Finally, the performance of the prototype is reported. Due to the extremely low count rates encountered in X-ray polarimetry, efficient background rejection is the most critical parameter of the IPCs. Using a background rejection scheme employing anticoincidence and pulse shape discrimination, a rejection efficiency of 99 percent has been achieved for Co-60-induced events over an energy range of 2 to 15 keV while retaining more than 80 percent of the X-ray efficiency.

Development of land based radar polarimeter processor system

NASA Technical Reports Server (NTRS)

Kronke, C. W.; Blanchard, A. J.

1983-01-01

The processing subsystem of a land based radar polarimeter was designed and constructed. This subsystem is labeled the remote data acquisition and distribution system (RDADS). The radar polarimeter, an experimental remote sensor, incorporates the RDADS to control all operations of the sensor. The RDADS uses industrial standard components including an 8-bit microprocessor based single board computer, analog input/output boards, a dynamic random access memory board, and power supplis. A high-speed digital electronics board was specially designed and constructed to control range-gating for the radar. A complete system of software programs was developed to operate the RDADS. The software uses a powerful real time, multi-tasking, executive package as an operating system. The hardware and software used in the RDADS are detailed. Future system improvements are recommended.

The development of the imaging polarimeter's polarizer on the basis of the polarizing film

NASA Astrophysics Data System (ADS)

Vidmachenko, A. P.; Ivanov, Yu. S.; Syniavskyi, I. I.

2015-07-01

Work has begun on the developing of the scientific equipment "Spectrometer polarimeter", which is planned as one of five devices that form part of the Russian-Ukrainian space experiment "Planetary Monitoring". The devices are designed to form images of celestial objects in the focal plane of a planetary telescope (PT-600) and to register spectral and polarimetric information on gas and aerosol composition of the atmospheres of planets and physics and chemical properties of the surface layers of atmosphereless astronomical bodies. A model of a polarizer based on the use of polarizing films has been designed. This model can be used in the spectrometer-polarimeter. The results of the investigation of the polarizer in the spectral range 420-850 nm are given.

An Interferometric Spectral Line and Imaging Survey of VY Canis Majoris in the 345 GHz Band

NASA Astrophysics Data System (ADS)

Kamiński, T.; Gottlieb, C. A.; Young, K. H.; Menten, K. M.; Patel, N. A.

2013-12-01

A spectral line survey of the oxygen-rich red supergiant VY Canis Majoris was made between 279 and 355 GHz with the Submillimeter Array (SMA). Two hundred twenty-three spectral features from 19 molecules (not counting isotopic species of some of them) were observed, including the rotational spectra of TiO, TiO2, and AlCl for the first time in this source. The parameters and an atlas of all spectral features are presented. Observations of each line with a synthesized beam of ~0.''9, reveal the complex kinematics and morphology of the nebula surrounding VY CMa. Many of the molecules are observed in high-lying rotational levels or in excited vibrational levels. From these, it was established that the main source of the submillimeter-wave continuum (dust) and the high-excitation molecular gas (the star) are separated by about 0.''15. Apparent coincidences between the molecular gas observed with the SMA, and some of the arcs and knots observed at infrared wavelengths and in the optical scattered light by the Hubble Space Telescope are identified. The observations presented here provide important constraints on the molecular chemistry in oxygen-dominated circumstellar environments and a deeper picture of the complex circumstellar environment of VY CMa.

Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

NASA Technical Reports Server (NTRS)

Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.;

Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

NASA Technical Reports Server (NTRS)

Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.;

ALMA Observations of a Misaligned Binary Protoplanetary Disk System in Orion

NASA Astrophysics Data System (ADS)

Williams, Jonathan P.; Mann, Rita K.; Di Francesco, James; Andrews, Sean M.; Hughes, A. Meredith; Ricci, Luca; Bally, John; Johnstone, Doug; Matthews, Brenda

2014-12-01

We present Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a wide binary system in Orion, with projected separation 440 AU, in which we detect submillimeter emission from the protoplanetary disks around each star. Both disks appear moderately massive and have strong line emission in CO 3-2, HCO+ 4-3, and HCN 3-2. In addition, CS 7-6 is detected in one disk. The line-to-continuum ratios are similar for the two disks in each of the lines. From the resolved velocity gradients across each disk, we constrain the masses of the central stars, and show consistency with optical-infrared spectroscopy, both indicative of a high mass ratio ~9. The small difference between the systemic velocities indicates that the binary orbital plane is close to face-on. The angle between the projected disk rotation axes is very high, ~72°, showing that the system did not form from a single massive disk or a rigidly rotating cloud core. This finding, which adds to related evidence from disk geometries in other systems, protostellar outflows, stellar rotation, and similar recent ALMA results, demonstrates that turbulence or dynamical interactions act on small scales well below that of molecular cores during the early stages of star formation.

Submillimeter Spectroscopy of the R Coronae Australis Molecular Cloud Region

NASA Astrophysics Data System (ADS)

Dunn, Marina Madeline; Walker, Christopher K.; Pat, Terrance; Sirsi, Siddhartha; Swift, Brandon J.; Peters, William L.

2018-01-01

The Interstellar Medium is comprised of large amounts of gas and dust which coalesce to form stars. Observing in the Terahertz regime of the electromagnetic spectrum, approximately 0.3 -300 microns, allows astronomers to study the ISM in unprecedented detail. Using the high spectral resolution imaging system of the SuperCam receiver, a 64-pixel array previously installed on the Submillimeter Telescope on Mt. Graham, AZ, we have begun a 500 square degree survey of the galactic plane. This instrument was designed to do a complete survey of the Milky Way from the ground, with the main focus being to observe two specific transitions of the carbon monoxide molecule, 12CO(3-2) and 13CO(3-2), at 345 GHz. In this work, we present results from these observations for the R Coronae Australis (R Cr A) complex, a region in the southern hemisphere of the sky, using spectroscopic data from a portion of the survey to gain better insight into the life cycle of the ISM. The majority of stars being formed here are similar to the stellar class of the Sun, making it an excellent area of observing interest. Using these results, we attempt to better ascertain the large-scale structure and kinematics inside of the molecular cloud.

Lumped element kinetic inductance detectors based on two-gap MgB2 thin films

NASA Astrophysics Data System (ADS)

Yang, C.; Niu, R. R.; Guo, Z. S.; Cai, X. W.; Chu, H. M.; Yang, K.; Wang, Y.; Feng, Q. R.; Gan, Z. Z.

2018-01-01

Lumped element kinetic inductance detectors (LEKIDs) are made from a single layer superconducting thin film. Because of their low noise and highly multiplexibility, LEKIDs provide a sensitive technology for the detection of millimeter and submillimeter waves. In this work, a 5-pixel 50-nm-thick MgB2 array is made. The microwave properties of the array are measured under dark conditions. We show that the loaded quality factor Q of the resonant circuit is 30 000 at 7.5 K, which is comparable to that of lower-operating-temperature (usually several hundred mK) LEKIDs made from superconductors such as Al and Nb. Moreover, the temperature dependence of resonance frequency gives the two-gap character of MgB2, Δπ (0) = 2.58 meV and Δσ (0) = 8.26 meV. The gap frequency (f = 2Δ/h) indicates that MgB2 LEKIDs have a promising application on terahertz detection.

News and Views: Diamond is new head of SKA; Did you read our `A&G' mobile issue? BBC writer wins astro journalism prize; Kavli prize recognizes work on Kuiper Belt objects

NASA Astrophysics Data System (ADS)

2012-10-01

Philip Diamond will become director general of the Square Kilometre Array this month, moving from Australia to the new SKA headquarters at Jodrell Bank Radio Observatory. Technology writer Katia Moskvitch has won the first European Astronomy Journalism Prize for her series of articles on the Very Large Telescope at Paranal, Chile. Moskvitch will be the guest of the ESO at the inauguration of the Atacama Large Millimeter/submillimeter Array (ALMA) in the Atacama desert in March 2013. The 2012 Kavli Prize in Astrophysics is shared between David C Jewitt (University of California, USA), Jane X Luu (Massachusetts Institute of Technology, Lincoln Laboratory, USA), and Michael E Brown (California Institute of Technology, USA) “for discovering and characterizing the Kuiper Belt and its largest members, work that led to a major advance in the understanding of the history of our planetary system”.

Planetary submillimeter spectroscopy

NASA Technical Reports Server (NTRS)

Klein, M. J.

1988-01-01

The aim is to develop a comprehensive observational and analytical program to study solar system physics and meterology by measuring molecular lines in the millimeter and submillimeter spectra of planets and comets. A primary objective is to conduct observations with new JPL and Caltech submillimeter receivers at the Caltech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. A secondary objective is to continue to monitor the time variable planetary phenomena (e.g., Jupiter and Uranus) at centimeter wavelength using the NASA antennas of the Deep Space Network (DSN).

A Disconnect between Staff and Student Perceptions of Learning: An ACELL Educational Analysis of the First Year Undergraduate Chemistry Experiment "Investigating Sugar Using a Home Made Polarimeter"

ERIC Educational Resources Information Center

Crisp, Michael G.; Kable, Scott H.; Read, Justin R.; Buntine, Mark A.

2011-01-01

This paper describes an educational analysis of a first year university chemistry practical called "Investigating sugar using a home made polarimeter". The analysis follows the formalism of the Advancing Chemistry by Enhancing Learning in the Laboratory (ACELL) project, which includes a statement of education objectives, and an analysis…

GDx-MM: An imaging Mueller matrix retinal polarimeter

NASA Astrophysics Data System (ADS)

Twietmeyer, Karen Marie

2007-12-01

Retinal diseases are a major cause of blindness worldwide. Although widely studied, disease mechanisms are not completely understood, and diagnostic tests may not detect disease early enough for timely intervention. The goal of this research is to contribute to research for more sensitive diagnostic tests that might use the interaction of polarized light with retinal tissue to detect subtle changes in the microstructure. This dissertation describes the GDx-MM, a scanning laser polarimeter which measures a complete 16-element Mueller matrix image of the retina. This full polarization signature may provide new comparative information on the structure of healthy and diseased retinal tissue by highlighting depolarizing structures as well as structures with varying magnitudes and orientations of retardance and diattenuation. The three major components of this dissertation are: (1) Development of methods for polarimeter optimization and error analysis; (2) Design, optimization, assembly, calibration, and validation of the GDx-MM polarimeter; and (3) Analysis of data for several human subjects. Development involved modifications to a Laser Diagnostics GDx, a commercially available scanning laser ophthalmoscope with incomplete polarization capability. Modifications included installation of polarization components, development of a data acquisition system, and implementation of algorithms to convert raw data into polarization parameter images. Optimization involved visualization of polarimeter state trajectories on the Poincare sphere and a condition number analysis of the instrument matrix. Retinal images are collected non-invasively at 20 mum resolution over a 15° visual field in four seconds. Validation of the polarimeter demonstrates a polarimetric measurement accuracy of approximately +/- 5%. Retinal polarization data was collected on normal human subjects at the University of Arizona and at Indiana University School of Optometry. Calculated polarization parameter images reveal properties of the tissue microstructure. For example, retardance images indicate nerve fiber layer thickness and orientation, and depolarization images (uniform for these normal subjects), are predicted to indicate regions of disease-related tissue disruption. This research demonstrates a method for obtaining a full polarization signature of the retina in one measurement using a polarimetrically optimized instrument, and provides a step toward the use of complete retinal imaging polarimetry in the diagnosis and monitoring of retinal disease.

Cryogenic Amplifier Based Receivers at Submillimeter Wavelengths

NASA Technical Reports Server (NTRS)

Chattopadhyay, Goutam; Reck, Theodore and; Schlecht, Erich; Lin, Robert; Deal, William

2012-01-01

The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with usable gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown substantial improvement in their noise temperature. This has opened up the real possibility of cryogenic amplifier based heterodyne receivers at submillimeter wavelengths for ground-based, air-borne, and space-based instruments for astrophysics, planetary, and Earth science applications. This paper provides an overview of the science applications at submillimeter wavelengths that will benefit from this technology. It also describes the current state of the InP HEMT based cryogenic amplifier receivers at submillimeter wavelengths.

U.S. and European ALMA Partners Sign Agreement Green Light for World's Most Powerful Radio Observatory

NASA Astrophysics Data System (ADS)

2003-02-01

Dr. Rita Colwell, director of the U.S. National Science Foundation (NSF), and Dr. Catherine Cesarsky, director general of the European Southern Observatory (ESO), today signed a historic agreement jointly to construct and operate ALMA, the Atacama Large Millimeter Array, the world's largest and most powerful radio telescope operating at millimeter and sub-millimeter wavelengths. "With this agreement, we usher in a new age of research in astronomy," said Dr. Colwell. "By working together in this truly global partnership, the international astronomy community will be able to ensure the research capabilities needed to meet the long-term demands of our scientific enterprise, and we will be able to study and understand our Universe in ways that have previously been beyond our vision." ALMA Array Artist's Conception of ALMA Array in Compact Configuration (Click on Image for Larger Version) Other Images Available: Artist's conception of the antennas for the Atacama Large Millimeter Array Moonrise over ALMA test equipment near Cerro Chajnantor, Chile VertexRSI antenna at the VLA test site Dr. Cesarsky also commented, "This agreement signifies the start of a great project of contemporary astronomy and astrophysics. Representing Europe, and in collaboration with many laboratories and institutes on this continent, we together look forward toward wonderful research projects. With ALMA, we may learn how the earliest galaxies in the Universe really looked like, to mention but one of the many eagerly awaited opportunities with this marvelous facility." When complete in 2011, ALMA will be an array of 64, 12-meter radio antennas that will work together as one telescope to study millimeter and sub-millimeter wavelength light from space. These wavelengths of the electromagnetic spectrum, which cross the critical boundary between infrared and microwave radiation, hold the key to understanding such processes as planet and star formation, the formation of early galaxies and galaxy clusters, and the detection of organic and other molecules in space. The ALMA partners will construct the telescope at an altitude of 16,500 feet in the Atacama Desert in the Chilean Andes. This unique site is perhaps the best location on Earth to study millimeter and sub-millimeter light because these wavelengths are absorbed by moisture in the atmosphere. "Astronomers will have a pristine view of that portion of the electromagnetic spectrum from the ALMA site," said Colwell. ALMA is a joint project between Europe and North America. In Europe, ESO is leading on behalf of its ten member countries and Spain. In North America, the NSF executes the project through the National Radio Astronomy Observatory (NRAO), which is operated under cooperative agreement by Associated Universities, Inc. (AUI). The National Research Council of Canada will partner with the NSF in the North American endeavor. "The NRAO is very pleased to have the leading role in this project on behalf of the North American partners," said Dr. Fred K.Y. Lo, director of the NRAO in Charlottesville, Virginia. "ALMA will be one of astronomy's premier tools for studying the Universe," said Nobel Laureate Riccardo Giacconi, president of AUI. "The entire astronomical community is anxious to have the unprecedented power and resolution that ALMA will provide." The President of the ESO Council, Professor Piet van der Kruit, agrees: "ALMA heralds a breakthrough in sub-millimeter and millimeter astronomy, allowing some of the most penetrating studies of the Universe ever made. It is safe to predict that there will be exciting scientific surprises when ALMA enters into operation." By signing this agreement, ESO and the NSF give the green light for the joint construction of the ALMA telescope, which will cost approximately $552 million U.S. (in FY 2000 dollars). To oversee the construction and management of ALMA, a joint ALMA Board has been established by the partners. This board met for the first time on February 24-25, 2003, and witnessed the signing at the NSF headquarters in Arlington, Virginia. Dr. Joseph Bordogna, deputy director of the NSF, represented Dr. Colwell at the actual ceremony. Chile, the host country for ALMA, has shown its support for the telescope by issuing a Presidential decree granting AUI permission to work on the ALMA project, and by signing an agreement between ESO and the government of the Republic of Chile. These actions by the government of Chile were necessary formal steps to secure the telescope site in that country. ESO is an intergovernmental, European organization for astronomical research. It has ten member countries. ESO operates astronomical observatories in Chile and has its headquarters in Garching, near Munich, Germany. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

HerMES: ALMA Imaging of Herschel-selected Dusty Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Bussmann, R. S.; Riechers, D.; Fialkov, A.; Scudder, J.; Hayward, C. C.; Cowley, W. I.; Bock, J.; Calanog, J.; Chapman, S. C.; Cooray, A.; De Bernardis, F.; Farrah, D.; Fu, Hai; Gavazzi, R.; Hopwood, R.; Ivison, R. J.; Jarvis, M.; Lacey, C.; Loeb, A.; Oliver, S. J.; Pérez-Fournon, I.; Rigopoulou, D.; Roseboom, I. G.; Scott, Douglas; Smith, A. J.; Vieira, J. D.; Wang, L.; Wardlow, J.

2015-10-01

The Herschel Multi-tiered Extragalactic Survey (HerMES) has identified large numbers of dusty star-forming galaxies (DSFGs) over a wide range in redshift. A detailed understanding of these DSFGs is hampered by the limited spatial resolution of Herschel. We present 870 μm 0.″45 resolution imaging obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of a sample of 29 HerMES DSFGs that have far-infrared (FIR) flux densities that lie between the brightest of sources found by Herschel and fainter DSFGs found via ground-based surveys in the submillimeter region. The ALMA imaging reveals that these DSFGs comprise a total of 62 sources (down to the 5σ point-source sensitivity limit in our ALMA sample; σ ≈ 0.2 {mJy}). Optical or near-infrared imaging indicates that 36 of the ALMA sources experience a significant flux boost from gravitational lensing (μ \\gt 1.1), but only six are strongly lensed and show multiple images. We introduce and make use of uvmcmcfit, a general-purpose and publicly available Markov chain Monte Carlo visibility-plane analysis tool to analyze the source properties. Combined with our previous work on brighter Herschel sources, the lens models presented here tentatively favor intrinsic number counts for DSFGs with a break near 8 {mJy} at 880 μ {{m}} and a steep fall-off at higher flux densities. Nearly 70% of the Herschel sources break down into multiple ALMA counterparts, consistent with previous research indicating that the multiplicity rate is high in bright sources discovered in single-dish submillimeter or FIR surveys. The ALMA counterparts to our Herschel targets are located significantly closer to each other than ALMA counterparts to sources found in the LABOCA ECDFS Submillimeter Survey. Theoretical models underpredict the excess number of sources with small separations seen in our ALMA sample. The high multiplicity rate and small projected separations between sources seen in our sample argue in favor of interactions and mergers plausibly driving both the prodigious emission from the brightest DSFGs as well as the sharp downturn above {S}880=8 {mJy}. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

THE SCUBA-2 COSMOLOGY LEGACY SURVEY: MULTIWAVELENGTH COUNTERPARTS TO 10{sup 3} SUBMILLIMETER GALAXIES IN THE UKIDSS-UDS FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Chian-Chou; Smail, Ian; Ma, Cheng-Jiun

We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850 μm in the SCUBA-2 Cosmology Legacy Survey study of the UKIRT Infrared Deep Sky Survey-Ultra-Deep Survey (UDS) field. By utilizing an Atacama Large Millimeter Array (ALMA) pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical–near-infrared (OIR) data available in this field, we develop a novel technique, Optical–IR Triple Color (OIRTC), using z − K, K − [3.6], [3.6] − [4.5] colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates formore » 80% of the Class = 1 ≥ 4σ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be 82% ± 20%, with a completeness of 69% ± 16%, essentially as accurate as the traditional p-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850 μm sources, and we argue that for follow-up observations sensitive to SMGs with S{sub 850} ≳ 1 mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be >40% for SCUBA-2 sources at S{sub 850} ≳ 4 mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of z = 2.3 ± 0.1. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be z = 2.6 ± 0.1 for SMGs with S{sub 850} > 1 mJy. We also use this new large sample to study the clustering of SMGs and the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission.« less

The speckle polarimeter of the 2.5-m telescope: Design and calibration

NASA Astrophysics Data System (ADS)

Safonov, B. S.; Lysenko, P. A.; Dodin, A. V.

2017-05-01

The speckle polarimeter is a facility instrument of the 2.5-mSAIMSU telescope that combines the features of a speckle interferometer and a polarimeter. The speckle polarimeter is designed for observations in several visible bands in the following modes: speckle interferometry, polarimetry, speckle polarimetry, and polaroastrometry. In this paper we describe the instrument design and the procedures for determining the angular scale of the camera and the position angle of the camera and the polarimeter. Our measurements of the parameters for the binary star HD 9165 are used as an example to demonstrate the technique of speckle interferometry. For bright objects the accuracy of astrometry is limited by the error of the correction for the distortion caused by the atmospheric dispersion compensator. At zenith distances less than 45◦ the additional relative measurement error of the separation is 0.7%, while the additional error of the position angle is 0.3°. In the absence of a dispersion compensator the accuracy of astrometry is limited by the uncertainty in the scale and position angle of the camera, which are 0.15% and 0.06°, respectively. We have performed polarimetric measurements of unpolarized stars and polarization standards. The instrumental polarization at the Cassegrain focus in the V band does not exceed 0.01%. The instrumental polarization for the Nasmyth focus varies between 2 and 4% within the visible range; we have constructed its model and give a method for its elimination from the measurements. For stars with an intrinsic polarization of less than 0.2% during observations at the Cassegrain focus the error is determined mainly by the photon and readout noises and can reach 5 × 10-5.

First Local Ties from Data of the Wettzell Triple Radio Telescope Array

NASA Astrophysics Data System (ADS)

Schüler, T.; Plötz, C.; Mähler, S.; Klügel, T.; Neidhardt, A.; Bertarini, A.; Halsig, S.; Nothnagel, A.; Lösler, M.; Eschelbach, C.; Anderson, J.

2016-12-01

The Geodetic Observatory Wettzell features three radio telescopes. Local ties between the reference points are available from terrestrial precision surveying with an expected accuracy below 0.7 mm. In addition, local VLBI data analysis is currently investigated to provide independent vectors and to provide quality feedback to the engineers. The preliminary results presented in this paper show a deviation from the local survey at the level of one millimeter with a clear systematic component. Sub-millimeter precision is reached after removal of this bias. This systematic effect is likely caused by omission of thermal expansion and gravity deformation, which is not yet implemented in our local VLBI analysis software.

High resolution, wide field of view, real time 340GHz 3D imaging radar for security screening

NASA Astrophysics Data System (ADS)

Robertson, Duncan A.; Macfarlane, David G.; Hunter, Robert I.; Cassidy, Scott L.; Llombart, Nuria; Gandini, Erio; Bryllert, Tomas; Ferndahl, Mattias; Lindström, Hannu; Tenhunen, Jussi; Vasama, Hannu; Huopana, Jouni; Selkälä, Timo; Vuotikka, Antti-Jussi

2017-05-01

The EU FP7 project CONSORTIS (Concealed Object Stand-Off Real-Time Imaging for Security) is developing a demonstrator system for next generation airport security screening which will combine passive and active submillimeter wave imaging sensors. We report on the development of the 340 GHz 3D imaging radar which achieves high volumetric resolution over a wide field of view with high dynamic range and a high frame rate. A sparse array of 16 radar transceivers is coupled with high speed mechanical beam scanning to achieve a field of view of 1 x 1 x 1 m3 and a 10 Hz frame rate.

Bulk and integrated acousto-optic spectrometers for radio astronomy

NASA Technical Reports Server (NTRS)

Chin, G.; Buhl, D.; Florez, J. M.

1981-01-01

The development of sensitive heterodyne receivers (front end) in the centimeter and millimeter range, and the construction of sensitive RF spectrometers (back end) enable the spectral lines of interstellar molecules to be detected and identified. A technique was developed which combines acoustic bending of a collimated coherent light beam by a Bragg cell followed by detection by a sensitive array of photodetectors (thus forming an RF acousto-optic spectrometer (AOS). An AOS has wide bandwidth, large number of channels, and high resolution, and is compact, lightweight, and energy efficient. The thrust of receiver development is towards high frequency heterodyne systems, particularly in the millimeter, submillimeter, far infrared, and 10 micron spectral ranges.

Exploring the Sun with ALMA

NASA Astrophysics Data System (ADS)

Bastian, T. S.; Bárta, M.; Brajša, R.; Chen, B.; Pontieu, B. D.; Gary, D. E.; Fleishman, G. D.; Hales, A. S.; Iwai, K.; Hudson, H.; Kim, S.; Kobelski, A.; Loukitcheva, M.; Shimojo, M.; Skokić, I.; Wedemeyer, S.; White, S. M.; Yan, Y.

2018-03-01

The Atacama Large Millimeter/submillimeter Array (ALMA) Observatory opens a new window onto the Universe. The ability to perform continuum imaging and spectroscopy of astrophysical phenomena at millimetre and submillimetre wavelengths with unprecedented sensitivity opens up new avenues for the study of cosmology and the evolution of galaxies, the formation of stars and planets, and astrochemistry. ALMA also allows fundamentally new observations to be made of objects much closer to home, including the Sun. The Sun has long served as a touchstone for our understanding of astrophysical processes, from the nature of stellar interiors, to magnetic dynamos, non-radiative heating, stellar mass loss, and energetic phenomena such as solar flares. ALMA offers new insights into all of these processes.

ORAC-DR: One Pipeline for Multiple Telescopes

NASA Astrophysics Data System (ADS)

Cavanagh, B.; Hirst, P.; Jenness, T.; Economou, F.; Currie, M. J.; Todd, S.; Ryder, S. D.

ORAC-DR, a flexible and extensible data reduction pipeline, has been successfully used for real-time data reduction from UFTI and IRCAM (infrared cameras), CGS4 (near-infrared spectrometer), Michelle (mid-infrared imager and echelle spectrometer), at UKIRT; and SCUBA (sub-millimeter bolometer array) at JCMT. We have now added the infrared imaging spectrometers IRIS2 at the Anglo-Australian Telescope and UIST at UKIRT to the list of officially supported instruments. We also present initial integral field unit support for UIST, along with unofficial support for the imager and multi-object spectrograph GMOS at Gemini. This paper briefly describes features of the pipeline along with details of adopting ORAC-DR for other instruments on telescopes around the world.

Array of Bolometers for Submillimeter- Wavelength Operation

NASA Technical Reports Server (NTRS)

Bock, James; Turner, Anthony

2007-01-01

A feed-horn-coupled monolithic array of micromesh bolometers is undergoing development for use in a photometric camera. The array is designed for conducting astrophysical observations in a wavelength band centered at 350 m. The bolometers are improved versions of previously developed bolometers comprising metalized Si3N4 micromesh radiation absorbers coupled with neutron- transmutation-doped Ge thermistors. Incident radiation heats the absorbers above a base temperature, changing the electrical resistance of each thermistor. In the present array of improved bolometers (see figure), the thermistors are attached to the micromesh absorbers by indium bump bonds and are addressed by use of lithographed, vapor-deposited electrical leads. This architecture reduces the heat capacity and minimizes the thermal conductivity to 1/20 and 1/300, respectively, of earlier versions of these detectors, with consequent improvement in sensitivity and speed of response. The micromesh bolometers, intended to operate under an optical background set by thermal emission from an ambient-temperature space-borne telescope, are designed such that the random arrival of photons ("photon noise") dominates the noise sources arising from the detector and readout electronics. The micromesh is designed to be a highly thermally and optically efficient absorber with a limiting response time of about 100 s. The absorber and thermistor heat capacity are minimized in order to give rapid speed of response. Due to the minimization of the absorber volume, the dominant source of heat capacity arises from the thermistor.

Large size GEM for Super Bigbite Spectrometer (SBS) polarimeter for Hall A 12GeV program at JLab

DOE PAGES

Gnanvo, Kondo; Liyanage, Nilanga; Nelyubin, Vladimir; ...

2015-05-01

We report on the R&D effort in the design and construction of a large size GEM chamber for the Proton Polarimeter of the Super Bigbite Spectrometer (SBS) in Hall A at Thomas Jefferson National Laboratory (JLab). The SBS Polarimeter trackers consist of two sets of four large chambers of size 200 cm x 60 cm 2. Each chamber is a vertical stack of four GEM modules with an active area of 60 cm x 50 cm. We have built and tested several GEM modules and we describe in this paper the design and construction of the final GEM as wellmore » as the preliminary results on performances from tests carried out in our detector lab and with test beams at (Fermilab).« less

SOUTH POL: Revealing the Polarized Southern Sky

NASA Astrophysics Data System (ADS)

Magalhães, A. M.

2014-10-01

SOUTH POL will be a survey of the Southern sky in optical polarized light. It will use a newly designed polarimeter for an 80cm Robotic Telescope. Telescope and polarimeter will be installed at CTIO, Chile. The initial goal is to cover the sky south of declination -15° in about two years of observing time, aiming at a polarimetric accuracy ≤ 0.1% down to V=15, with a camera covering a field of about 2.0 square degrees. SOUTH POL will impact areas such as Cosmology, Extragalactic Astronomy, Interstellar Medium of the Galaxy and Magellanic Clouds, Star Formation, Stellar Envelopes, Stellar Explosions and Solar System, among others. The polarimeter is currently being built and its optics and electronics assembled. We will describe the current status of the project. This project is supported by FAPESP. AMM is also supported by CNPq.

Quantitative performance of a polarization diffraction grating polarimeter encoded onto two liquid-crystal-on-silicon displays

NASA Astrophysics Data System (ADS)

Cofré, Aarón; Vargas, Asticio; Torres-Ruiz, Fabián A.; Campos, Juan; Lizana, Angel; del Mar Sánchez-López, María; Moreno, Ignacio

2017-11-01

We present a quantitative analysis of the performance of a complete snapshot polarimeter based on a polarization diffraction grating (PDGr). The PDGr is generated in a common path polarization interferometer with a Z optical architecture that uses two liquid-crystal on silicon (LCoS) displays to imprint two different phase-only diffraction gratings onto two orthogonal linear states of polarization. As a result, we obtain a programmable PDGr capable to act as a simultaneous polarization state generator (PSG), yielding diffraction orders with different states of polarization. The same system is also shown to operate as a polarization state analyzer (PSA), therefore useful for the realization of a snapshot polarimeter. We analyze its performance using quantitative metrics such as the conditional number, and verify its reliability for the detection of states of polarization.

Earth Observing Scanning Polarimeter (EOSP), phase B

NASA Technical Reports Server (NTRS)

1990-01-01

Evaluations performed during a Phase B study directed towards defining an optimal design for the Earth Observing Scanning Polarimeter (EOSP) instrument is summarized. An overview of the experiment approach is included which provides a summary of the scientific objectives, the background of the measurement approach, and the measurement method. In the instrumentation section, details of the design are discussed starting with the key instrument features required to accomplish the scientific objectives and a system characterization in terms of the Stokes vector/Mueller matrix formalism. This is followed by a detailing of the instrument design concept, the design of the individual elements of the system, the predicted performance, and a summary of appropriate instrument testing and calibration. The selected design makes use of key features of predecessor polarimeters and is fully compatible with the Earth Observing System spacecraft requirements.

Optimal reference polarization states for the calibration of general Stokes polarimeters in the presence of noise

NASA Astrophysics Data System (ADS)

Mu, Tingkui; Bao, Donghao; Zhang, Chunmin; Chen, Zeyu; Song, Jionghui

2018-07-01

During the calibration of the system matrix of a Stokes polarimeter using reference polarization states (RPSs) and pseudo-inversion estimation method, the measurement intensities are usually noised by the signal-independent additive Gaussian noise or signal-dependent Poisson shot noise, the precision of the estimated system matrix is degraded. In this paper, we present a paradigm for selecting RPSs to improve the precision of the estimated system matrix in the presence of both types of noise. The analytical solution of the precision of the system matrix estimated with the RPSs are derived. Experimental measurements from a general Stokes polarimeter show that accurate system matrix is estimated with the optimal RPSs, which are generated using two rotating quarter-wave plates. The advantage of using optimal RPSs is a reduction in measurement time with high calibration precision.

An upgraded interferometer-polarimeter system for broadband fluctuation measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parke, E., E-mail: eparke@ucla.edu; Ding, W. X.; Brower, D. L.

2016-11-15

Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°–0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibriummore » and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.« less

New View of Distant Galaxy Reveals Furious Star Formation

NASA Astrophysics Data System (ADS)

2007-12-01

A furious rate of star formation discovered in a distant galaxy shows that galaxies in the early Universe developed either much faster or in a different way from what astronomers have thought. "This galaxy is forming stars at an incredible rate," said Wei-Hao Wang, an astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. The galaxy, Wang said, is forming the equivalent of 4,000 Suns a year. This is a thousand times more violent than our own Milky Way Galaxy. Location of Distant Galaxy Visible-light, left (from HST) and Infrared, right, (from Spitzer) Images: Circles indicate location of GOODS 850-5. CREDIT: Wang et al., STScI, Spitzer, NASA, NRAO/AUI/NSF Click on image for high-resolution file (1 MB) The galaxy, called GOODS 850-5, is 12 billion light-years from Earth, and thus is seen as it was only about 1.5 billion years after the Big Bang. Wang and his colleagues observed it using the Smithsonian Astrophysical Observatory's Submillimeter Array (SMA) on Mauna Kea in Hawaii. Young stars in the galaxy were enshrouded in dust that was heated by the stars and radiated infrared light strongly. Because of the galaxy's great distance from Earth, the infrared light waves have been stretched out to submillimeter-length radio waves, which are seen by the SMA. The waves were stretched or "redshifted," as astronomers say, by the ongoing expansion of the Universe. "This evidence for prolific star formation is hidden by the dust from visible-light telescopes," Wang explained. The dust, in turn, was formed from heavy elements that had to be built up in the cores of earlier stars. This indicates, Wang said, that significant numbers of stars already had formed, then spewed those heavy elements into interstellar space through supernova explosions and stellar winds. "Seeing the radiation from this heated dust revealed star formation we could have found in no other way," Wang said. Similar dusty galaxies in the early Universe may contain most of the star formation at those times. "This means that future telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA) can reveal many more such galaxies and give us a much more complete picture of star formation in the early Universe," he added. Lennox Cowie of the University of Hawaii said, "We found out in the last decade that most of the recent star formation in the Universe occurs in large dusty galaxies, but we had always expected that early star formation would be dominated by smaller and less obscured galaxies. Now it seems that even at very early times it may be the same big dusty star formers that are the sites of most of the star formation. That's quite a surprise." Astronomers believe that large galaxies originally formed through mergers of smaller objects. Seeing a large galaxy such as GOODS 850-5 forming stars so rapidly at such an early time in the history of the Universe is a surprise. "Either the mergers that formed the galaxy happened much faster than we thought or some other process altogether produced the galaxy," Wang said. Wang and Cowie worked with Jennifer van Saders of Rutgers University and NRAO, Amy Barger of the University of Wisconsin-Madison, and Jonathan Williams of the University of Hawaii. The scientists published their findings in the December 1 edition of the Astrophysical Journal. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.The Submillimeter Array is an 8-element interferometer located atop Mauna Kea in Hawaii. It is a collaboration between the Smithsonian Astrophysical Observatory and the Institute of Astronomy and Astrophysics of the Academia Sinica of Taiwan.

Polarization Techniques for Mitigation of Low Grazing Angle Sea Clutter

DTIC Science & Technology

2017-01-01

Lincoln Laboratory funded an experimental data collection using a fully polarimetic X-band radar assembled largely from COTS components. The Point de Chene...applications and environments in which experimental polarimet- ric radar has proven invaluable. Most notably, the imaging and mapping applications of synthetic...polarimetric analysis, as discussed in Chapter 1. Another part is due to the experimental SAR community’s collective recognition of polarimetry’s value

Developments of a multi-wavelength spectro-polarimeter on the Domeless Solar Telescope at Hida Observatory

NASA Astrophysics Data System (ADS)

Anan, Tetsu; Huang, Yu-Wei; Nakatani, Yoshikazu; Ichimoto, Kiyoshi; UeNo, Satoru; Kimura, Goichi; Ninomiya, Shota; Okada, Sanetaka; Kaneda, Naoki

2018-05-01

To obtain full Stokes spectra in multi-wavelength windows simultaneously, we developed a new spectro-polarimeter on the Domeless Solar Telescope at Hida Observatory. The new polarimeter consists of a 60 cm aperture vacuum telescope on an altazimuth mounting, an image rotator, a high-dispersion spectrograph, and a polarization modulator and an analyzer composed of a continuously rotating waveplate with a retardation that is nearly constant at around 127° in 500-1100 nm. There are also a polarizing beam splitter located close behind the focus of the telescope, fast and large format CMOS cameras, and an infrared camera. A slit spectrograph allows us to obtain spectra in as many wavelength windows as the number of cameras. We characterized the instrumental polarization of the entire system and established a polarization calibration procedure. The cross-talks among the Stokes Q, U, and V have been evaluated to be about 0.06%-1.2%, depending on the degree of the intrinsic polarizations. In a typical observing setup, a sensitivity of 0.03% can be achieved in 20-60 seconds for 500-1100 nm. The new polarimeter is expected to provide a powerful tool for diagnosing the 3D magnetic field and other vector physical quantities in the solar atmosphere.

Fast Solar Polarimeter: First Light Results

NASA Astrophysics Data System (ADS)

Krishnappa, N.; Feller, A.; Iglesia, F. A.; Solanki, S.

2013-12-01

Accurate measurements of magnetic fields on the Sun are crucial to understand various physical processes that take place in the solar atmosphere such as solar eruptions, coronal heating, solar wind acceleration, etc. The Fast Solar Polarimeter (FSP) is a new instrument that is being developed to probe magnetic fields on the Sun. One of the main goals of this polarimeter is to carry out high precision spectropolarimetric observations with spatial resolution close to the telescope diffraction limit. The polarimeter is based on pnCCD technology with split frame transfer and simultaneous multi-channel readout, resulting in frame rate upto 1 kHz. The FSP prototype instrument uses a small format pnCCD of 264x264 pixels which has been developed by PNSensor and by the semiconductor lab of the Max Planck Society. The polarization modulator is based on two ferro-electric liquid crystals (FLCs) interlaced between two static retarders. The first solar observations have been carried out with this prototype during May-June, 2013 at German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands, Spain. Here we present the instrument performance assessments and the first results on the magnetic field measurements. Further, we briefly discuss about the next phase of FSP which will be a dual beam system with 1k x 1k CCDs.

An integrated thermo-structural model to design a polarimeter for the GTC

NASA Astrophysics Data System (ADS)

Di Varano, I.; Strassmeier, K. G.; Woche, M.; Laux, U.

2016-07-01

The GTC (Gran Telescopio Canarias), with an equivalent aperture of 10.4 m, effective focal length of 169.9 m, located at the Observatorio del Roque de los Muchachos , in La Palma, Canary Islands, will host on its Cassegrain focus the GRAPE polarimeter (GRAntecan PolarimEter). At such focus the plate scale is 1.21 arcsec/mm and the unvignetted FOV 8 arcmin. The instrument will provide full Stokes polarimetry in the spectral range 380-1500 nm, feeding simultaneously up to two spectrographs. At the moment an interface to HORS (High Optical Resolution Spectrograph) is being defined, located on the Nasmyth platform, it has a FWHM resolving power of about 25,000 (5 pixel) within a spectral range of 400-680 nm. The rotator and instrumental flanges for the Cassegrain focus are currently under definition. Hereafter I present the state of art of the mechanical design of the polarimeter, whose strategy is based on an integrated model of Zemax design into ANSYS FEM static and dynamic analyses with thermal loads applied, in order to retrieve tip-tilt, decentering errors and other significant parameters to be looped back to the Zemax model. In such a way it is possible to compare and refine the results achieved through the tolerance analysis.

Development of a Hydrogen Møller Polarimeter for Precision Parity-Violating Electron Scattering

NASA Astrophysics Data System (ADS)

Gray, Valerie M.

2013-10-01

Parity-violating electron scattering experiments allow for testing the Standard Model at low energy accelerators. Future parity-violating electron scattering experiments, like the P2 experiment at the Johannes Gutenberg University, Mainz, Germany, and the MOLLER and SoLID experiments at Jefferson Lab will measure observables predicted by the Standard Model to high precision. In order to make these measurements, we will need to determine the polarization of the electron beam to sub-percent precision. The present way of measuring the polarization, with Møller scattering in iron foils or using Compton laser backscattering, will not easily be able to reach this precision. The novel Hydrogen Møller Polarimeter presents a non-invasive way to measure the electron polarization by scattering the electron beam off of atomic hydrogen gas polarized in a 7 Tesla solenoidal magnetic trap. This apparatus is expected to be operational by 2016 in Mainz. Currently, simulations of the polarimeter are used to develop the detection system at College of William & Mary, while the hydrogen trap and superconducting solenoid magnet are being developed at the Johannes Gutenberg University, Mainz. I will discuss the progress of the design and development of this novel polarimeter system. This material is based upon work supported by the National Science Foundation under Grant No. PHY-1206053.

Imaging Spectropolarimeter for the Multi-Application Solar Telescope at Udaipur Solar Observatory: Characterization of Polarimeter and Preliminary Observations

NASA Astrophysics Data System (ADS)

Tiwary, Alok Ranjan; Mathew, Shibu K.; Bayanna, A. Raja; Venkatakrishnan, P.; Yadav, Rahul

2017-04-01

The Multi-Application Solar Telescope (MAST) is a 50 cm off-axis Gregorian telescope that has recently become operational at the Udaipur Solar Observatory (USO). An imaging spectropolarimeter is being developed as one of the back-end instruments of MAST to gain a better understanding of the evolution and dynamics of solar magnetic and velocity fields. This system consists of a narrow-band filter and a polarimeter. The polarimeter includes a linear polarizer and two sets of liquid crystal variable retarders (LCVRs). The instrument is intended for simultaneous observations in the spectral lines 6173 Å and 8542 Å, which are formed in the photosphere and chromosphere, respectively. In this article, we present results from the characterization of the LCVRs for the spectral lines of interest and the response matrix of the polarimeter. We also present preliminary observations of an active region obtained using the spectropolarimeter. For verification purposes, we compare the Stokes observations of the active region obtained from the Helioseismic Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) with that of MAST observations in the spectral line 6173 Å. We find good agreement between the two observations, considering the fact that MAST observations are limited by seeing.

GEMS X-ray Polarimeter Performance Simulations

NASA Technical Reports Server (NTRS)

Baumgartner, Wayne H.; Strohmayer, Tod; Kallman, Tim; Black, J. Kevin; Hill, Joanne; Swank, Jean

2012-01-01

The Gravity and Extreme Magnetism Small explorer (GEMS) is an X-ray polarization telescope selected as a NASA small explorer satellite mission. The X-ray Polarimeter on GEMS uses a Time Projection Chamber gas proportional counter to measure the polarization of astrophysical X-rays in the 2-10 keV band by sensing the direction of the track of the primary photoelectron excited by the incident X-ray. We have simulated the expected sensitivity of the polarimeter to polarized X-rays. We use the simulation package Penelope to model the physics of the interaction of the initial photoelectron with the detector gas and to determine the distribution of charge deposited in the detector volume. We then model the charge diffusion in the detector,and produce simulated track images. Within the track reconstruction algorithm we apply cuts on the track shape and focus on the initial photoelectron direction in order to maximize the overall sensitivity of the instrument, using this technique we have predicted instrument modulation factors nu(sub 100) for 100% polarized X-rays ranging from 10% to over 60% across the 2-10 keV X-ray band. We also discuss the simulation program used to develop and model some of the algorithms used for triggering, and energy measurement of events in the polarimeter.

Design and Fabrication of the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter

NASA Technical Reports Server (NTRS)

Hoover, Richard B.; Johnson, R. Barry; Fineschi, Silvano; Walker, Arthur B. C., Jr.; Baker, Phillip C.; Zukic , Muamer; Kim, Jongmin

1993-01-01

We have designed, analyzed, and are now fabricating an All-Reflecting H-Lyman alpha Coronagraph/Polarimeter for solar research. This new instrument operates in a narrow bandpass centered at lambda 1215.7 A-the neutral hydrogen Lyman alpha (Ly-alpha) line. It is shorter and faster than the telescope which produced solar Ly-alpha images as a part of the MSSTA payload that was launched on May 13, 1991. The Ly-alpha line is produced and linearly polarized in the solar corona by resonance scattering, and the presence of a magnetic field modifies this polarization according to the Hanle effect. The Lyman alpha Coronagraph/Polarimeter instrument has been designed to measure coronal magnetic fields by interpreting, via the Hanle effect, the measured linear polarization of the coronal Ly-alpha line. Ultrasmooth mirrors, polarizers, and filters are being flow-polished for this instrument from CVD silicon carbide substrates. These optical components will be coated using advanced induced transmission and absorption thin film multilayer coatings, to optimize the reflectivity and polarization properties at 1215.7 A. We describe some of the solar imaging results obtained with the MSSTA Lyman alpha coronagraph. We also discuss the optical design parameters and fabrication plans for the All-Reflecting H-Lyman alpha Coronagraph/Polarimeter.

The Atacama Cosmology Telescope: Two-season spectrum and parameters

NASA Astrophysics Data System (ADS)

Hlozek, Renée; Louis, Thibaut; Grace, Emily; Hasselfield, Matthew; Lungu, Marius; Maurin, Loic; Atacama Cosmology Telescope

2017-01-01

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope polarimeter (ACTPol) over 548 deg^2 of sky on the celestial Equator, from nighttime data collected during 2013-14 using two kilo-detector arrays at 146 GHz. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with Planck and WMAP satellite data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature power spectrum, including the baryon density and the acoustic peak position angle, and the derived Hubble constant. Adding the new data to Planck temperature data tightens the limits on damping tail parameters, which we present here.

Polarimetric receiver in the forty gigahertz band: new instrument for the Q-U-I joint Tenerife experiment

NASA Astrophysics Data System (ADS)

Villa, Enrique; Cano, Juan L.; Aja, Beatriz; Terán, J. Vicente; de la Fuente, Luisa; Mediavilla, Ángel; Artal, Eduardo

2018-03-01

This paper describes the analysis, design and characterization of a polarimetric receiver developed for covering the 35 to 47 GHz frequency band in the new instrument aimed at completing the ground-based Q-U-I Joint Tenerife Experiment. This experiment is designed to measure polarization in the Cosmic Microwave Background. The described high frequency instrument is a HEMT-based array composed of 29 pixels. A thorough analysis of the behaviour of the proposed receiver, based on electronic phase switching, is presented for a noise-like linearly polarized input signal, obtaining simultaneously I, Q and U Stokes parameters of the input signal. Wideband subsystems are designed, assembled and characterized for the polarimeter. Their performances are described showing appropriate results within the 35-to-47 GHz frequency band. Functionality tests are performed at room and cryogenic temperatures with adequate results for both temperature conditions, which validate the receiver concept and performance.

Measurements of vector fields with diode array

NASA Technical Reports Server (NTRS)

Wiehr, E. J.; Scholiers, W.

1985-01-01

A polarimeter was designed for high spatial and spectral resolution. It consists of a quarter-wave plate alternately operating in two positions for Stoke-V measurements and an additional quarter-wave plate for Stokes-U and -Q measurements. The spatial range covers 75 arcsec, the spectral window of about 1.8 a allows the simultaneous observations of neighboring lines. The block diagram of the data processing and acquisition system consists of five memories each one having a capacity of 10 to the 4th power 16-bit words. The total time to acquire profiles of Stokes parameters can be chosen by selecting the number of successive measurements added in the memories, each individual measurement corresponding to an integration time of 0.5 sec. Typical values range between 2 and 60 sec depending on the brightness of the structure, the amount of polarization and a compromise between desired signal-to-noise ratio and spatial resolution.

Data Analysis for the E and B EXperiment and Instrumentation Development for Cosmic Microwave Background Polarimetry

NASA Astrophysics Data System (ADS)

Araujo, Derek C.

The E and B EXperiment (EBEX) was a balloon-borne instrument designed to measure the polarization of the cosmic microwave background (CMB) while simultaneously characterizing Galactic dust emission. The instrument was based on a two-mirror ambient temperature Gregorian-Dragone telescope coupled with cooled refractive optics to a kilo-pixel array of transition edge sensor (TES) bolometeric detectors. To achieve sensitivity to both the CMB signal and Galactic foregrounds, EBEX observed in three signal bands centered on 150, 250, and 410 GHz. Polarimetry was achieved via a stationary wire-grid polarizer and a continuously rotating achromatic half-wave plate (HWP) based on a superconducting magnetic bearing (SMB). EBEX launched from McMurdo station, Antarctica on December 29, 2012 and collected 1.3 TB of data during 11 days of observation. This thesis is presented in two Parts. Part I reviews the data analysis we performed to transform the raw EBEX data into maps of temperature and polarization sky signals, with a particular focus on post-flight pointing reconstruction; time stream cleaning and map making; the generation of model sky maps of the expected signal for each of the three EBEX signal bands; removal of the HWP-synchronous signal from the detector time streams; and our attempts to identify, characterize, and correct for non-linear detector responsivity. In Part II we present recent developments in instrumentation for the next generation of CMB polarimeters. The developments we describe, including advances in lumped-element kinetic inductance detector (LEKID) technology and the development of a hollow-shaft SMB-based motor for use in HWP polarimetry, were motivated in part by the design for a prospective ground-based CMB polarimeter based in Greenland.

A LEKID-based CMB instrument design for large-scale observations in Greenland

NASA Astrophysics Data System (ADS)

Araujo, D. C.; Ade, P. A. R.; Bond, J. R.; Bradford, K. J.; Chapman, D.; Che, G.; Day, P. K.; Didier, J.; Doyle, S.; Eriksen, H. K.; Flanigan, D.; Groppi, C. E.; Hillbrand, Seth N.; Johnson, B. R.; Jones, G.; Limon, Michele; Miller, A. D.; Mauskopf, P.; McCarrick, H.; Mroczkowski, T.; Reichborn-Kjennerud, B.; Smiley, B.; Sobrin, Joshua; Wehus, I. K.; Zmuidzinas, J.

2014-08-01

We present the results of a feasibility study, which examined deployment of a ground-based millimeter-wave polarimeter, tailored for observing the cosmic microwave background (CMB), to Isi Station in Greenland. The instrument for this study is based on lumped-element kinetic inductance detectors (LEKIDs) and an F/2.4 catoptric, crossed-Dragone telescope with a 500 mm aperture. The telescope is mounted inside the receiver and cooled to < 4 K by a closed-cycle 4He refrigerator to reduce background loading on the detectors. Linearly polarized signals from the sky are modulated with a metal-mesh half-wave plate that is rotated at the aperture stop of the telescope with a hollow-shaft motor based on a superconducting magnetic bearing. The modular detector array design includes at least 2300 LEKIDs, and it can be configured for spectral bands centered on 150 GHz or greater. Our study considered configurations for observing in spectral bands centered on 150, 210 and 267 GHz. The entire polarimeter is mounted on a commercial precision rotary air bearing, which allows fast azimuth scan speeds with negligible vibration and mechanical wear over time. A slip ring provides power to the instrument, enabling circular scans (360 degrees of continuous rotation). This mount, when combined with sky rotation and the latitude of the observation site, produces a hypotrochoid scan pattern, which yields excellent cross-linking and enables 34% of the sky to be observed using a range of constant elevation scans. This scan pattern and sky coverage combined with the beam size (15 arcmin at 150 GHz) makes the instrument sensitive to 5 < ` < 1000 in the angular power spectra.

ESO and NSF Sign Agreement on ALMA

NASA Astrophysics Data System (ADS)

2003-02-01

Green Light for World's Most Powerful Radio Observatory On February 25, 2003, the European Southern Observatory (ESO) and the US National Science Foundation (NSF) are signing a historic agreement to construct and operate the world's largest and most powerful radio telescope, operating at millimeter and sub-millimeter wavelength. The Director General of ESO, Dr. Catherine Cesarsky, and the Director of the NSF, Dr. Rita Colwell, act for their respective organizations. Known as the Atacama Large Millimeter Array (ALMA), the future facility will encompass sixty-four interconnected 12-meter antennae at a unique, high-altitude site at Chajnantor in the Atacama region of northern Chile. ALMA is a joint project between Europe and North America. In Europe, ESO is leading on behalf of its ten member countries and Spain. In North America, the NSF also acts for the National Research Council of Canada and executes the project through the National Radio Astronomy Observatory (NRAO) operated by Associated Universities, Inc. (AUI). The conclusion of the ESO-NSF Agreement now gives the final green light for the ALMA project. The total cost of approximately 650 million Euro (or US Dollars) is shared equally between the two partners. Dr. Cesarsky is excited: "This agreement signifies the start of a great project of contemporary astronomy and astrophysics. Representing Europe, and in collaboration with many laboratories and institutes on this continent, we together look forward towards wonderful research projects. With ALMA we may learn how the earliest galaxies in the Universe really looked like, to mention but one of the many eagerly awaited opportunities with this marvellous facility". "With this agreement, we usher in a new age of research in astronomy" says Dr. Colwell. "By working together in this truly global partnership, the international astronomy community will be able to ensure the research capabilities needed to meet the long-term demands of our scientific enterprise, and that we will be able to study and understand our universe in ways that have previously been beyond our vision". The recent Presidential decree from Chile for AUI and the agreement signed in late 2002 between ESO and the Government of the Republic of Chile (cf. ESO PR 18/02) recognize the interest that the ALMA Project has for Chile, as it will deepen and strengthen the cooperation in scientific and technological matters between the parties. A joint ALMA Board has been established which oversees the realisation of the ALMA project via the management structure. This Board meets for the first time on February 24-25, 2003, at NSF in Washington and will witness this historic event. ALMA: Imaging the Light from Cosmic Dawn ESO PR Photo 06a/03 ESO PR Photo 06a/03 [Preview - JPEG: 588 x 400 pix - 52k [Normal - JPEG: 1176 x 800 pix - 192k] [Hi-Res - JPEG: 3300 x 2244 pix - 2.0M] ESO PR Photo 06b/03 ESO PR Photo 06b/03 [Preview - JPEG: 502 x 400 pix - 82k [Normal - JPEG: 1003 x 800 pix - 392k] [Hi-Res - JPEG: 2222 x 1773 pix - 3.0M] ESO PR Photo 06c/03 ESO PR Photo 06c/03 [Preview - JPEG: 474 x 400 pix - 84k [Normal - JPEG: 947 x 800 pix - 344k] [Hi-Res - JPEG: 2272 x 1920 pix - 2.0M] ESO PR Photo 06d/03 ESO PR Photo 06d/03 [Preview - JPEG: 414 x 400 pix - 69k [Normal - JPEG: 828 x 800 pix - 336k] [HiRes - JPEG: 2935 x 2835 pix - 7.4k] Captions: PR Photo 06a/03 shows an artist's view of the Atacama Large Millimeter Array (ALMA), with 64 12-m antennae. PR Photo 06b/03 is another such view, with the array arranged in a compact configuration at the high-altitude Chajnantor site. The ALMA VertexRSI prototype antennae is shown in PR Photo 06c/03 on the Antenna Test Facility (ATF) site at the NRAO Very Large Array (VLA) site near Socorro (New Mexico, USA). The future ALMA site at Llano de Chajnantor at 5000 metre altitude, some 40 km East of the village of San Pedro de Atacama (Chile) is seen in PR Photo 06d/03 - this view was obtained at 11 hrs in the morning on a crisp and clear autumn day (more views of this site are available at the Chajnantor Photo Gallery). The Atacama Large Millimeter Array (ALMA) will be one of astronomy's most powerful telescopes - providing unprecedented imaging capabilities and sensitivity in the corresponding wavelength range, many orders of magnitude greater than anything of its kind today. ALMA will be an array of 64 antennae that will work together as one telescope to study millimeter and sub-millimeter wavelength radiation from space. This radiation crosses the critical boundary between infrared and microwave radiation and holds the key to understanding such processes as planet and star formation, the formation of early galaxies and galaxy clusters, and the formation of organic and other molecules in space. "ALMA will be one of astronomy's premier tools for studying the universe" says Nobel Laureate Riccardo Giacconi, President of AUI (and former ESO Director General (1993-1999)). "The entire astronomical community is anxious to have the unprecedented power and resolution that ALMA will provide". The President of the ESO Council, Professor Piet van der Kruit, agrees: "ALMA heralds a break-through in sub-millimeter and millimeter astronomy, allowing some of the most penetrating studies the Universe ever made. It is safe to predict that there will be exciting scientific surprises when ALMA enters into operation". What is millimeter and sub-millimeter wavelength astronomy? Astronomers learn about objects in space by studying the energy emitted by those objects. Our Sun and the other stars throughout the Universe emit visible light. But these objects also emit other kinds of light waves, such as X-rays, infrared radiation, and radio waves. Some objects emit very little or no visible light, yet are strong sources at other wavelengths in the electromagnetic spectrum. Much of the energy in the Universe is present in the sub-millimeter and millimeter portion of the spectrum. This energy comes from the cold dust mixed with gas in interstellar space. It also comes from distant galaxies that formed many billions of years ago at the edges of the known universe. With ALMA, astronomers will have a uniquely powerful facility with access to this remarkable portion of the spectrum and hence, new and wonderful opportunities to learn more about those objects. Current observatories simply do not have anywhere near the necessary sensitivity and resolution to unlock the secrets that abundant sub-millimeter and millimeter wavelength radiation can reveal. It will take the unparalleled power of ALMA to fully study the cosmic emission at this wavelength and better understand the nature of the universe. Scientists from all over the world will use ALMA. They will compete for observing time by submitting proposals, which will be judged by a group of their peers on the basis of scientific merit. ALMA's unique capabilities ALMA's ability to detect remarkably faint sub-millimeter and millimeter wavelength emission and to create high-resolution images of the source of that emission gives it capabilities not found in any other astronomical instruments. ALMA will therefore be able to study phenomena previously out of reach to astronomers and astrophysicists, such as: * Very young galaxies forming stars at the earliest times in cosmic history; * New planets forming around young stars in our galaxy, the Milky Way; * The birth of new stars in spinning clouds of gas and dust; and * Interstellar clouds of gas and dust that are the nurseries of complex molecules and even organic chemicals that form the building blocks of life. How will ALMA work? All of ALMA's 64 antennae will work in concert, taking quick "snapshots" or long-term exposures of astronomical objects. Cosmic radiation from these objects will be reflected from the surface of each antenna and focussed onto highly sensitive receivers cooled to just a few degrees above absolute zero in order to suppress undesired "noise" from the surroundings. There the signals will be amplified many times, digitized, and then sent along underground fiber-optic cables to a large signal processor in the central control building. This specialized computer, called a correlator - running at 16,000 million-million operations per second - will combine all of the data from the 64 antennae to make images of remarkable quality. The extraordinary ALMA site Since atmospheric water vapor absorbs millimeter and (especially) sub-millimeter waves, ALMA must be constructed at a very high altitude in a very dry region of the earth. Extensive tests showed that the sky above the Atacama Desert of Chile has the excellent clarity and stability essential for ALMA. That is why ALMA will be built there, on Llano de Chajnantor at an altitude of 5,000 metres in the Chilean Andes. A series of views of this site, also in high-resolution suitable for reproduction, is available at the Chajnantor Photo Gallery. Timeline for ALMA June 1998: Phase 1 (Research and Development) June 1999: European/American Memorandum of Understanding February 2003: Signature of the bilateral Agreement 2004: Tests of the Prototype System 2007: Initial scientific operation of a partially completed array 2011: End of construction of the array

InP HEMT Integrated Circuits for Submillimeter Wave Radiometers in Earth Remote Sensing

NASA Technical Reports Server (NTRS)

Deal, William R.; Chattopadhyay, Goutam

2012-01-01

The operating frequency of InP integrated circuits has pushed well into the Submillimeter Wave frequency band, with amplification reported as high as 670 GHz. This paper provides an overview of current performance and potential application of InP HEMT to Submillimeter Wave radiometers for earth remote sensing.

Submillimeter detection of stratospheric OH and further line assignments in the stratospheric emission spectrum

NASA Technical Reports Server (NTRS)

Carli, B.; Mencaraglia, F.; Bonetti, A.; Dinelli, B. M.; Forni, F.

1983-01-01

Hydroxyl radical has been identified in submillimeter stratospheric emission spectra measured with an unapodized resolution of 0.0033 per cm. Many features due to vibrationally excited ozone have also been detected. The contribution to the submillimeter atmospheric spectrum of NO, NO2, and HBr is discussed.

Preliminary submillimeter spectroscopic measurements using a submillimeter heterodyne radiometer

NASA Technical Reports Server (NTRS)

Safren, H. G.; Stabnow, W. R.; Bufton, J. L.; Peruso, C. J.; Rossey, C. E.; Walker, H. E.

1982-01-01

A submillimeter heterodyne radiometer uses a submillimeter laser, pumped by a CO2 laser, as a local oscillator and a room temperature Schottky barrier diode as the first IF mixer. The radiometer can resolve spectral lines in the submillimeter region of the spectrum (arising from pure rotational molecular transitions) to within 0.3 MHz, using acousto-optic spectrum analyzer which measures the power spectrum by simultaneously sampling 0.3 MHz wide channels over a 100 MHz bandwidth spanning the line. Preliminary observations of eight spectral lines of H2O2, CO, NH3 and H2O, all lying in the 434-524 micrometer wavelength range are described. All eight lines were observed using two local oscillator frequencies obtained by operating the submillimeter laser with either methyl fluoride (CH3F) or formic acid (HCOOH) as the lasing gas. Sample calculations of line parameters from the observed data show good agreement with established values. One development goal is the size and weight reduction of the package to make it suitable for balloon or shuttle experiments to detect trace gases in the upper atmosphere.

Evidence for a Major Merger Origin of High-Redshift Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Conselice, Christopher J.; Chapman, Scott C.; Windhorst, Rogier A.

2003-10-01

Submillimeter-detected galaxies located at redshifts z>1 host a major fraction of the bolometric luminosity at high redshifts due to thermal emission from heated dust grains, yet the nature of these objects remains a mystery. The major problem in understanding their origin is whether the dust-heating mechanism is predominantly caused by star formation or active galactic nuclei and what triggered this activity. We address this issue by examining the structures of 11 submillimeter galaxies imaged with STIS on the Hubble Space Telescope. We argue that ~61%+/-21% of these submillimeter sources are undergoing an active major merger using the CAS (concentration, asymmetry, clumpiness) quantitative morphological system. We rule out at ~5 σ confidence that these submillimeter galaxies are normal Hubble types at high redshift. This merger fraction appears to be higher than for Lyman break galaxies undergoing mergers at similar redshifts. Using reasonable constraints on the stellar masses of Lyman break galaxies and these submillimeter sources, we further argue that at redshifts z~2-3, systems with high stellar masses are more likely than lower mass galaxies to be involved in major mergers.

A MASSIVE MOLECULAR GAS RESERVOIR IN THE z = 5.3 SUBMILLIMETER GALAXY AzTEC-3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riechers, Dominik A.; Scoville, Nicholas Z.; Capak, Peter L.

2010-09-10

We report the detection of CO J = 2{yields}1, 5{yields}4, and 6{yields}5 emission in the highest-redshift submillimeter galaxy (SMG) AzTEC-3 at z = 5.298, using the Expanded Very Large Array and the Plateau de Bure Interferometer. These observations ultimately confirm the redshift, making AzTEC-3 the most submillimeter-luminous galaxy in a massive z {approx_equal} 5.3 protocluster structure in the COSMOS field. The strength of the CO line emission reveals a large molecular gas reservoir with a mass of 5.3 x 10{sup 10}({alpha}{sub CO}/0.8) M {sub sun}, which can maintain the intense 1800 M {sub sun} yr{sup -1} starburst in this systemmore » for at least 30 Myr, increasing the stellar mass by up to a factor of six in the process. This gas mass is comparable to 'typical' z {approx} 2 SMGs and constitutes {approx_gt}80% of the baryonic mass (gas+stars) and 30%-80% of the total (dynamical) mass in this galaxy. The molecular gas reservoir has a radius of <4 kpc and likely consists of a 'diffuse', low-excitation component, containing (at least) 1/3 of the gas mass (depending on the relative conversion factor {alpha}{sub CO}), and a 'dense', high-excitation component, containing {approx}2/3 of the mass. The likely presence of a substantial diffuse component besides highly excited gas suggests different properties between the star-forming environments in z > 4 SMGs and z > 4 quasar host galaxies, which perhaps trace different evolutionary stages. The discovery of a massive, metal-enriched gas reservoir in an SMG at the heart of a large z = 5.3 protocluster considerably enhances our understanding of early massive galaxy formation, pushing back to a cosmic epoch where the universe was less than 1/12 of its present age.« less

Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies

NASA Astrophysics Data System (ADS)

Hodge, J. A.; Swinbank, A. M.; Simpson, J. M.; Smail, I.; Walter, F.; Alexander, D. M.; Bertoldi, F.; Biggs, A. D.; Brandt, W. N.; Chapman, S. C.; Chen, C. C.; Coppin, K. E. K.; Cox, P.; Dannerbauer, H.; Edge, A. C.; Greve, T. R.; Ivison, R. J.; Karim, A.; Knudsen, K. K.; Menten, K. M.; Rix, H.-W.; Schinnerer, E.; Wardlow, J. L.; Weiss, A.; van der Werf, P.

2016-12-01

We present high-resolution (0.″16) 870 μm Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous ({L}{IR}˜ 4× {10}12 {L}⊙ ) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these z˜ 2.5 galaxies on ˜1.3 kpc scales. The emission has a median effective radius of R e = 0.″24 ± 0.″02, corresponding to a typical physical size of {R}e= 1.8 ± 0.2 kpc. We derive a median Sérsic index of n = 0.9 ± 0.2, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0.″12 (˜1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate signal-to-noise ratio interferometric data. We compare our maps to comparable-resolution Hubble Space Telescope {H}160-band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the z˜ 0 descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive ({M}* ˜ 1-2 × 1011 {M}⊙ ) early-type galaxies observed locally.

A reinterpretation of millimeter observations of nearby IRAS excess stars

NASA Technical Reports Server (NTRS)

Weintraub, David A.; Stern, S. Alan

1994-01-01

We analyze new and previously published 1300, 870, and 800 micrometers, single-element bolometer observations of Vega (alpha Lyr), Formalhaut (alpha PsA), epsilon Eri, tau(sup1) Eri, and Beta Leo. We show that these data are consistent with models in which the dust disks around these stars are larger than the radio telescope beams with which they were observed; thus, these disks may be many hundreds of AU in radius or larger. Our interpretation of submillimeter/millimeter measurements of these stars also indicates that for some Infrared Astronomy Satellite (IRAS) IR excess stars the assumption that there is no astrophysical flux in the OFF beams, when using the standard ON-minus-OFF chopping technique and the chop distance is less than 1000AU, may be incorrect. Therefore, for IRAS IR excess stars within approximately 20 pc, virtually all submillimeter/millimeter chopping observations with chop throws less than 100" may have subtracted away some or most of the flux associated with their circumstellar disks. Finally, we present new 1300 micrometers continuum observations of Vega made with chop throws of 500 and 1000 AU. These data are consistent with an interpretation in which Vega has a disk that is at least 1000AU in radius; this disk could have a region with much less material per beam area near 500 AU than at both 100 AU and 1000 AU, corresponding to a gap at the orbital distance of alpha Lyr B. The observations of Vega are also consistent with the assumption that the circumVega dust structure is unresolved. Thus, these new data very effectively illustrate that the 'standard' model of small, unresolved, dust structures around main-sequence IRAS IR excess stars is not unique. Maps of IRAS IR excess stars, which soon will be available from submillimeter/millimeter array detectors, will determine whether the paradigm shift we propose will occur.

Submillimeter Remote Sensing of Planetary and Cometary Atmospheres and LRO/LCROSS Observations of the Moon

NASA Technical Reports Server (NTRS)

Chin, Gordon

2011-01-01

Submillimeter remote sensing of planetary and cometary atmospheres have been proposed for Venus and Mars while MIRO on Rosetta will observe the coma of Comet 67P/Churyumov - Cierasimenko in December 2015, UARS and AURA MLS have observed millimeter and submillimeter molecule emissions in the Earth's stratosphere for many decades, Observations of submillimeter wave molecular emissions provide a wealth of information not obtainable by alternative techniques. Submillimeter line emissions exhibit linear temperature dependence, insensitivity to aerosol scattering, extinction, and have separated transitions with well determined line-shapes. These observations have high sensitivities to trace chemical species and can; 1) Fully resolve the line profiles of molecules with high resolution, 2) Provide deterministic retrievals of species abundance, temperature, and pressure, and 3) Measure Doppler shifts of detected molecules for wind velocities.

Development of an infrared polarimeter

NASA Technical Reports Server (NTRS)

Coffeen, D. L.

1972-01-01

AEROPOL infrared polarimeter was built for measurements microns between 1.1 and 3.5 microns, with a 1.5 degree field of view, using a wire grid polarization analyzer. A PbS detector is cooled by condensed Freon-13. The instrument operates under minicomputer control, giving a polarization least squares solution each 2.5 seconds. AEROPOL was flown on the NASA CV-990 aircraft, in a remote-sensing study of terrestrial cloud particle sizes and shapes.

The polarization phase difference of orchard trees

NASA Technical Reports Server (NTRS)

Wang, James R.; Mo, Tsan

1990-01-01

An image obtained by the Jet Propulsion Laboratory's airborne L-band polarimeter (SAR) over an agricultural area near Fresno, California, was analyzed for the signatures of polarization phase difference (PPD). The PPD of orchard trees was found to be distinctly different from that of bare fields or fields covered with other crops. Thus the PPD signatures obtained from a polarimeter may be useful in the understanding of the radar remote sensing of the earth's surface.

Chromospheric LAyer SpectroPolarimeter (CLASP2)

NASA Technical Reports Server (NTRS)

Narukage, Noriyuki; Cirtain, Jonathan W.; Ishikawa, Ryoko; Trujillo-Bueno, Javier; De Pontieu, Bart; Kubo, Masahito; Ishikawa, Shinnosuke; Kano, Ryohei; Suematsu, Yoshinori; Yoshida, Masaki;

Analysis of Data from the Balloon Borne Gamma RAy Polarimeter Experiment (GRAPE)

NASA Astrophysics Data System (ADS)

Wasti, Sambid K.; Bloser, Peter F.; Legere, Jason S.; McConnell, Mark L.; Ryan, James M.

2016-04-01

The Gamma Ray Polarimeter Experiment (GRAPE), a balloon borne polarimeter for 50~300 keV gamma rays, successfully flew in 2011 and 2014. The main goal of these balloon flights was to measure the gamma ray polarization of the Crab Nebula. Analysis of data from the first two balloon flights of GRAPE has been challenging due to significant changes in the background level during each flight. We have developed a technique based on the Principle Component Analysis (PCA) to estimate the background for the Crab observation. We found that the background depended mostly on the atmospheric depth, pointing zenith angle and instrument temperatures. Incorporating Anti-coincidence shield data (which served as a surrogate for the background) was also found to improve the analysis. Here, we present the calibration data and describe the analysis done on the GRAPE 2014 flight data.

Low cost ellipsometer using a standard commercial polarimeter

NASA Astrophysics Data System (ADS)

Velosa, F.; Abreu, M.

2017-08-01

Ellipsometry is an optical technique to characterize materials or phenomena that occurs at an interface or thin film between two different media. In this paper, we present an experimental low-cost version of a photometric ellipsometer, assembled with commonly found material at every Optics laboratory. The polarization parameters measurement was performed using a Thorlabs PAX5710 polarimeter. The uncertainty computed using the Guide to the Expression of Uncertainty in Measurement (GUM) procedures. With the assembled ellipsometer we were able to measure the thickness of a 10 nm thick SiO2 thin film deposited upon Si, and the complex refractive index of Gold and Tantalum samples. The SiO2 thickness we achieved had an experimental deviation of 4.5% with 2.00 nm uncertainty. The value complex refractive index of Gold and Tantalum measured agrees with the different values found in several references. The uncertainty values were found to be mostly limited by the polarimeter's uncertainty.

Results from the First Two Observing Seasons of PIQUE

NASA Astrophysics Data System (ADS)

Gundersen, Joshua; Barkats, Denis; Hedman, Matt; Staggs, Suzanne; Winstein, Bruce

2001-04-01

We report on the first two seasons of the Princeton IQU Experiment (PIQUE). PIQUE is a ground-based telescope designed to measure the polarization of the Cosmic Microwave Background (CMB). During the first season (1/19/00-4/2/00), PIQUE measured the Q Stokes parameter on a ring at declination of 89 degrees from the roof of the Physics Department at Princeton University using a 90 GHz correlation polarimeter with a full-width-half maximum beam of 0.24 degrees. PIQUE's observations from the first season yielded a new limit on the polarization of the CMB in the multipole range 100

A novel comparison of Møller and Compton electron-beam polarimeters

DOE PAGES

Magee, J. A.; Narayan, A.; Jones, D.; ...

2017-01-19

We have performed a novel comparison between electron-beam polarimeters based on Moller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (more » $<$ 5 $$\\mu$$A) during the $$Q_{\\rm weak}$$ experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 $$\\mu$$A) operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Moller measurements made at low beam currents to physics experiments performed at higher beam currents. Here, the agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.« less

Improvements of the target lifetime in the RHIC polarimeter

NASA Astrophysics Data System (ADS)

Steski, D. B.; Huang, H.; Kewisch, J.; Sukhanova, L.; Zelenski, A.

2018-05-01

The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is the only collider in the world to collide polarized protons. It is critical to the RHIC experimental program that the polarization of the proton beam is measured. This is accomplished with the Coulomb Nuclear Interference (CNI) polarimeter. The targets used in the RHIC CNI polarimeter are 50 nm thick, 25 mm long and <10 µm wide. As the beam intensity in RHIC has increased and the beam size has decreased, the lifetime of these targets has decreased dramatically. During the 2013 polarized proton experimental run, the targets needed to be replaced twice. This resulted in additional work and lost beam time. Before the 2015 experimental run, metal shields were installed around the ends of the targets which greatly improved the target lifetime. The results from the 2015 experimental run and plans for the 2017 experimental run will be discussed.

The Bragg Reflection Polarimeter On the Gravity and Extreme Magnetism Small Explorer Mission

NASA Astrophysics Data System (ADS)

Allured, Ryan; Griffiths, S.; Daly, R.; Prieskorn, Z.; Marlowe, H.; Kaaret, P.; GEMS Team

2011-09-01

The strong gravity associated with black holes warps the spacetime outside of the event horizon, and it is predicted that this will leave characteristic signatures on the polarization of X-ray emission originating in the accretion disk. The Gravity and Extreme Magnetism Small Explorer (GEMS) mission will be the first observatory with the capability to make polarization measurements with enough sensitivity to quantitatively test this prediction. Students at the University of Iowa are currently working on the development of the Bragg Reflection Polarimeter (BRP), a soft X-ray polarimeter sensitive at 500 eV, that is the student experiment on GEMS. The BRP will complement the main experiment by making a polarization measurement from accreting black holes below the main energy band (2-10 keV). This measurement will constrain the inclination of the accretion disk and tighten measurements of black hole spin.

Design of a dispersion interferometer combined with a polarimeter to increase the electron density measurement reliability on ITER

NASA Astrophysics Data System (ADS)

Akiyama, T.; Sirinelli, A.; Watts, C.; Shigin, P.; Vayakis, G.; Walsh, M.

2016-11-01

A dispersion interferometer is a reliable density measurement system and is being designed as a complementary density diagnostic on ITER. The dispersion interferometer is inherently insensitive to mechanical vibrations, and a combined polarimeter with the same line of sight can correct fringe jump errors. A proof of the principle of the CO2 laser dispersion interferometer combined with the PEM polarimeter was recently conducted, where the phase shift and the polarization angle were successfully measured simultaneously. Standard deviations of the line-average density and the polarization angle measurements over 1 s are 9 × 1016 m-2 and 0.19°, respectively, with a time constant of 100 μs. Drifts of the zero point, which determine the resolution in steady-state operation, correspond to 0.25% and 1% of the phase shift and the Faraday rotation angle expected on ITER.

Design of a dispersion interferometer combined with a polarimeter to increase the electron density measurement reliability on ITER.

PubMed

Akiyama, T; Sirinelli, A; Watts, C; Shigin, P; Vayakis, G; Walsh, M

2016-11-01

A dispersion interferometer is a reliable density measurement system and is being designed as a complementary density diagnostic on ITER. The dispersion interferometer is inherently insensitive to mechanical vibrations, and a combined polarimeter with the same line of sight can correct fringe jump errors. A proof of the principle of the CO 2 laser dispersion interferometer combined with the PEM polarimeter was recently conducted, where the phase shift and the polarization angle were successfully measured simultaneously. Standard deviations of the line-average density and the polarization angle measurements over 1 s are 9 × 10 16 m -2 and 0.19°, respectively, with a time constant of 100 μs. Drifts of the zero point, which determine the resolution in steady-state operation, correspond to 0.25% and 1% of the phase shift and the Faraday rotation angle expected on ITER.

A novel comparison of Møller and Compton electron-beam polarimeters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magee, J. A.; Narayan, A.; Jones, D.

We have performed a novel comparison between electron-beam polarimeters based on Moller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (more » $<$ 5 $$\\mu$$A) during the $$Q_{\\rm weak}$$ experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 $$\\mu$$A) operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Moller measurements made at low beam currents to physics experiments performed at higher beam currents. Here, the agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.« less

Double-wedged Wollaston-type polarimeter design and integration to RTT150-TFOSC

NASA Astrophysics Data System (ADS)

Helhel, Selcuk; Kirbiyik, Halil; Bayar, Cevdet; Khamitov, Irek; Kahya, Gizem; Okuyan, Oguzhan

2016-07-01

Photometric and spectroscopic observation capabilities of 1.5-m Russian- Turkish Telescope RTT150 has been broadened with the integration of presented polarimeter. The well-known double-wedged Wollaston-type dual-beam technique was preferred and applied to design and produce it. The designed polarimeter was integrated into the telescope detector TFOSC, and called TFOSC-WP. Its capabil- ities and limitations were attempted to be determined by a number of observation sets. Non-polarized and strongly polarized stars were observed to determine its limi- tations as well as its linearity. An instrumental intrinsic polarization was determined for the 1×5 arcmin field of view in equatorial coordinate system, the systematic error of polarization degree as 0.2% %, and position angle as 1.9°. These limitations and capabilities are denoted as good enough to satisfy telescopes' present and future astrophysical space missions related to GAIA and SRG projects.

Double-wedged Wollaston-type polarimeter design and integration to RTT150-TFOSC; initial tests, calibration, and characteristics

NASA Astrophysics Data System (ADS)

Helhel, S.; Khamitov, I.; Kahya, G.; Bayar, C.; Kaynar, S.; Gumerov, R.

2015-10-01

Photometric and spectroscopic observation capabilities of 1.5-m Russian-Turkish Telescope RTT150 has been broadened with the integration of presented polarimeter. The well-known double-wedged Wollaston-type dual-beam technique was preferred and applied to design and produce it. The designed polarimeter was integrated into the telescope detector TFOSC, and called TFOSC-WP. Its capabilities and limitations were attempted to be determined by a number of observation sets. Non-polarized and strongly polarized stars were observed to determine its limitations as well as its linearity. An instrumental intrinsic polarization was determined for the 1 × 5 arcmin field of view in equatorial coordinate system, the systematic error of polarization degree as 0.2 %, and position angle as 1.9∘. These limitations and capabilities are denoted as good enough to satisfy telescopes' present and future astrophysical space missions related to GAIA and SRG projects.

About study of radiation flux carried out on the stand, which is designed for testing of space ultraviolet polarimeter

NASA Astrophysics Data System (ADS)

Nevodovskiy, P. V.; Vidmachenko, A. P.; Geraimchuk, M. D.; Ivahiv, O. V.

2016-08-01

In the Main Astronomical Observatory of NAS of Ukraine, National Technical University of Ukraine "KPI" and National University "Lviv Polytechnic" over the many years has accumulated considerable experience of work on the design and development of polarimeters, and created a working model of compact an onboard ultraviolet polarimeter (UFP) [1-6]. For debugging, research and testing as the entire layout of UFP and its individual parts we have created a special stand with complex equipment that allows carrying the following works. The structural construction of the stand allows obtaining characteristics as a whole unit, and its individual parts; obtaining spectral dependences and counting characteristics signal of the light radiation, and of dark signal; carry out the polarization measurements and more. For this stand developed a number of special techniques to study various parameters of all UFP appliance and its individual parts. Thus, for control - characteristics and calibration of elements of photo-detector system of electro-optical equipment, must use the reference emitters. But they are complicated and expensive. Therefore for simplified calibration and configuration of optical devices, it is expedient to use cheap and small in size, but specially selected LEDs. For this, developed for testing of UFP stand, has been modernized. Thus, the selection was carried out, and then carefully studied the sources of radiation, that will be used for calibration of polarimeters. More information on this work expounded in the report. References. 1. P. Nevodovskyi, O. Morozhenko, A. Vidmachenko, O. Ivakhiv, M. Geraimchuk, O. Zbrutskyi. Tiny Ultraviolet Polarimeter for Earth Stratosphere from Space Investigation // Proceedings of 8th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS'2015). 24-26 September 2015, Proceedings. Warsaw, Poland. Vol.81, p. 28-32. 2. Nevodovsksiy P. V., Morozhenko A. V. Studies of stratospheric ozone layer from near-earth orbit utilizing ultraviolet polarimeter // Acta Astronautica. 2009, vol. 64, no. 1, p. 54-58. 3. Nevodovskij P. V. Kvantakons and optimization of their parameters for astronomical observations // Kinematika i Fizika Nebesnykh Tel. 2001, vol. 17, no. 3, p. 279-288. 4. A. P. Vid'machenko, P. V. Nevodovsky. A cooled photomultiplier with an InGaAs photocathode developed for the spectropolarimetry observations // Kinematika i Fizika Nebesnykh Tel. 2000, Suppl. 3, p. 283-285. 5. P. Nevodovsky! i, A. Morozhenko, A. Vidmachenko, M. Geraimchuk, A. Zbrutskyi,! Yu. Kur eniov, V. Sergunin, Yu. Hirniak, O. Ivakhiv. Ultraviolet Polarimeter for Studying the Aerosol Component in the Earth Atmosphere // International Symposium on Atmospheric Radiation and Dynamics. Session 1. "Satellite sounding of atmosphere and surface". ISARD - 2013. June 24-27 2013. Peterhof, St Petersburg, Russia. P. 21.

Phonon Recycling for Ultrasensitive Kinetic Inductance Detectors

NASA Astrophysics Data System (ADS)

Zmuidzinas, Jonas

Initially proposed (Day et al. 2003; Zmuidzinas 2012) in 1999 by our Caltech/JPL group, and thanks to strong support from NASA, the superconducting (microwave) kinetic inductance detector (MKID or KID) technology continues to develop rapidly as it transitions into applications. The development effort worldwide is intensifying and NASA's continued support of KID development is essential in order to keep pace. Here we propose to investigate and demonstrate a new, low-TRL concept, which we call phonon recycling, that promises to open broad new avenues in KID design and performance. Briefly, phonon recycling allows the detector designer to tailor the responsivity and sensitivity of a KID to match the needs of the application by using geometry to restrict the rate at which recombination phonons are allowed to escape from the detector. In particular, phonon recycling should allow very low noise-equivalent power (NEP) to be achieved without requiring very low operating tem- peratures. Phonon recycling is analogous to the use of micromachined suspension legs to control the flow of heat in a bolometer, as measured by the thermal conductivity G. However, phonon recycling exploits the non-thermal distribution of recombination phonons as well as their very slow decay in crystals at low temperatures. These properties translate to geometrical and mechanical requirements for a phonon-recycled KID that are considerably more relaxed than for a bolometer operating at the same temperature and NEP. Our ultimate goal is to develop detector arrays suitable for a far-infrared (FIR) space mission, which will impose strict requirements on the array sensitivity, yield, uniformity, multiplexing density, etc. Through previous NASA support under the Strategic Astrophysics Technology (SAT) program, we have successfully demonstrated the MAKO submillimeter camera at the Caltech Submillimeter Observatory and have become familiar with these practical issues. If our demonstration of phonon recycling is successful, we will have a path for continuously adapting the high-background, high-NEP detectors we have demonstrated on the ground to the ultralow-NEP detectors needed for space.

Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): Fast-Scan Single-Dish Mapping

NASA Astrophysics Data System (ADS)

White, S. M.; Iwai, K.; Phillips, N. M.; Hills, R. E.; Hirota, A.; Yagoubov, P.; Siringo, G.; Shimojo, M.; Bastian, T. S.; Hales, A. S.; Sawada, T.; Asayama, S.; Sugimoto, M.; Marson, R. G.; Kawasaki, W.; Muller, E.; Nakazato, T.; Sugimoto, K.; Brajša, R.; Skokić, I.; Bárta, M.; Kim, S.; Remijan, A. J.; de Gregorio, I.; Corder, S. A.; Hudson, H. S.; Loukitcheva, M.; Chen, B.; De Pontieu, B.; Fleishmann, G. D.; Gary, D. E.; Kobelski, A.; Wedemeyer, S.; Yan, Y.

2017-07-01

The Atacama Large Millimeter/submillimeter Array (ALMA) radio telescope has commenced science observations of the Sun starting in late 2016. Since the Sun is much larger than the field of view of individual ALMA dishes, the ALMA interferometer is unable to measure the background level of solar emission when observing the solar disk. The absolute temperature scale is a critical measurement for much of ALMA solar science, including the understanding of energy transfer through the solar atmosphere, the properties of prominences, and the study of shock heating in the chromosphere. In order to provide an absolute temperature scale, ALMA solar observing will take advantage of the remarkable fast-scanning capabilities of the ALMA 12 m dishes to make single-dish maps of the full Sun. This article reports on the results of an extensive commissioning effort to optimize the mapping procedure, and it describes the nature of the resulting data. Amplitude calibration is discussed in detail: a path that uses the two loads in the ALMA calibration system as well as sky measurements is described and applied to commissioning data. Inspection of a large number of single-dish datasets shows significant variation in the resulting temperatures, and based on the temperature distributions, we derive quiet-Sun values at disk center of 7300 K at λ = 3 mm and 5900 K at λ = 1.3 mm. These values have statistical uncertainties of about 100 K, but systematic uncertainties in the temperature scale that may be significantly larger. Example images are presented from two periods with very different levels of solar activity. At a resolution of about 25'', the 1.3 mm wavelength images show temperatures on the disk that vary over about a 2000 K range. Active regions and plages are among the hotter features, while a large sunspot umbra shows up as a depression, and filament channels are relatively cool. Prominences above the solar limb are a common feature of the single-dish images.

VLA AND ALMA IMAGING OF INTENSE GALAXY-WIDE STAR FORMATION IN z ∼ 2 GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rujopakarn, W.; Silverman, J. D.; Dunlop, J. S.

2016-12-10

We present ≃0.″4 resolution extinction-independent distributions of star formation and dust in 11 star-forming galaxies (SFGs) at z  = 1.3–3.0. These galaxies are selected from sensitive blank-field surveys of the 2′ × 2′ Hubble Ultra-Deep Field at λ  = 5 cm and 1.3 mm using the Karl G. Jansky Very Large Array and Atacama Large Millimeter/submillimeter Array. They have star formation rates (SFRs), stellar masses, and dust properties representative of massive main-sequence SFGs at z  ∼ 2. Morphological classification performed on spatially resolved stellar mass maps indicates a mixture of disk and morphologically disturbed systems; half of the sample harbor X-ray active galactic nuclei (AGNs),more » thereby representing a diversity of z  ∼ 2 SFGs undergoing vigorous mass assembly. We find that their intense star formation most frequently occurs at the location of stellar-mass concentration and extends over an area comparable to their stellar-mass distribution, with a median diameter of 4.2 ± 1.8 kpc. This provides direct evidence of galaxy-wide star formation in distant blank-field-selected main-sequence SFGs. The typical galactic-average SFR surface density is 2.5 M {sub ⊙} yr{sup −1} kpc{sup −2}, sufficiently high to drive outflows. In X-ray-selected AGN where radio emission is enhanced over the level associated with star formation, the radio excess pinpoints the AGNs, which are found to be cospatial with star formation. The median extinction-independent size of main-sequence SFGs is two times larger than those of bright submillimeter galaxies, whose SFRs are 3–8 times larger, providing a constraint on the characteristic SFR (∼300 M {sub ⊙} yr{sup −1}) above which a significant population of more compact SFGs appears to emerge.« less

RESOLVING GIANT MOLECULAR CLOUDS IN NGC 300: A FIRST LOOK WITH THE SUBMILLIMETER ARRAY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faesi, Christopher M.; Lada, Charles J.; Forbrich, Jan

2016-04-20

We present the first high angular resolution study of giant molecular clouds (GMCs) in the nearby spiral galaxy NGC 300, based on observations from the Submillimeter Array (SMA). We target eleven 500 pc sized regions of active star formation within the galaxy in the {sup 12}CO( J = 2-1) line at 40 pc spatial and 1 km s{sup −1} spectral resolution and identify 45 individual GMCs. We characterize the physical properties of these GMCs, and find that they are similar to GMCs in the disks of the Milky Way and other nearby spiral galaxies. For example, the GMC mass spectrummore » in our sample has a slope of 1.80 ± 0.07. Twelve clouds are spatially resolved by our observations, of which ten have virial mass estimates that agree to within a factor of two with mass estimates derived directly from {sup 12}CO integrated intensity, suggesting that the majority of these GMCs are bound. The resolved clouds show consistency with Larson’s fundamental relations between size, linewidth, and mass observed in the Milky Way. We find that the linewidth scales with the size as Δ V ∝ R {sup 0.52±0.20}, and the median surface density in the subsample is 54 M {sub ⊙} pc{sup −2}. We detect {sup 13}CO in four GMCs and find a mean {sup 12}CO/{sup 13}CO flux ratio of 6.2. Our interferometric observations recover between 30% and 100% of the integrated intensity from the APEX single dish {sup 12}CO observations of Faesi et al., suggesting the presence of low-mass GMCs and/or diffuse gas below our sensitivity limit. The fraction of APEX emission recovered increases with the SMA total intensity, as well as with the star formation rate.« less

The Digital Motion Control System for the Submillimeter Array Antennas

NASA Astrophysics Data System (ADS)

Hunter, T. R.; Wilson, R. W.; Kimberk, R.; Leiker, P. S.; Patel, N. A.; Blundell, R.; Christensen, R. D.; Diven, A. R.; Maute, J.; Plante, R. J.; Riddle, P.; Young, K. H.

2013-09-01

We describe the design and performance of the digital servo and motion control system for the 6-meter parabolic antennas of the Submillimeter Array (SMA) on Mauna Kea, Hawaii. The system is divided into three nested layers operating at a different, appropriate bandwidth. (1) A rack-mounted, real-time Unix system runs the position loop which reads the high resolution azimuth and elevation encoders and sends velocity and acceleration commands at 100 Hz to a custom-designed servo control board (SCB). (2) The microcontroller-based SCB reads the motor axis tachometers and implements the velocity loop by sending torque commands to the motor amplifiers at 558 Hz. (3) The motor amplifiers implement the torque loop by monitoring and sending current to the three-phase brushless drive motors at 20 kHz. The velocity loop uses a traditional proportional-integral-derivative (PID) control algorithm, while the position loop uses only a proportional term and implements a command shaper based on the Gauss error function. Calibration factors and software filters are applied to the tachometer feedback prior to the application of the servo gains in the torque computations. All of these parameters are remotely adjustable in the software. The three layers of the control system monitor each other and are capable of shutting down the system safely if a failure or anomaly occurs. The Unix system continuously relays the antenna status to the central observatory computer via reflective memory. In each antenna, a Palm Vx hand controller displays the complete system status and allows full local control of the drives in an intuitive touchscreen user interface. The hand controller can also be connected outside the cabin, a major convenience during the frequent reconfigurations of the interferometer. Excellent tracking performance ( 0.3‧‧ rms) is achieved with this system. It has been in reliable operation on 8 antennas for over 10 years and has required minimal maintenance.

Optical and Radio Observations of the T Tauri Binary KH 15D (V582 Mon): Stellar Properties, Disk Mass Limit, and Discovery of a CO Outflow

NASA Astrophysics Data System (ADS)

Aronow, Rachel A.; Herbst, William; Hughes, A. Meredith; Wilner, David J.; Winn, Joshua N.

2018-01-01

We present VRIJHK photometry of the KH 15D T Tauri binary system for the 2015/2016 and 2016/2017 observing seasons. For the first time in the modern (CCD) era, we are seeing Star B fully emerge from behind the trailing edge of the precessing circumbinary ring during each apastron passage. We are, therefore, able to measure its luminosity and color. Decades of photometry on the system now allow us to infer the effective temperature, radius, mass, and age of each binary component. We find our values to be in good agreement with previous studies, including archival photographic photometry from the era when both stars were fully visible, and they set the stage for a full model of the system that can be constructed once radial velocity measurements are available. We also present the first high-sensitivity radio observations of the system, taken with the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array. The respective 2.0 and 0.88 mm observations provide an upper limit on the circumbinary (gas and dust) disk mass of 1.7 M Jup and reveal an extended CO outflow, which overlaps with the position, systemic velocity, and orientation of the KH 15D system and is certainly associated with it. The low velocity, tight collimation, and extended nature of the emission suggest that the outflow is inclined nearly orthogonal to the line of sight, implying it is also orthogonal to the circumbinary ring. The position angle of the radio outflow also agrees precisely with the direction of polarization of the optical emission during the faint phase. A small offset between the optical image of the binary and the central line of the CO outflow remains a puzzle and possible clue to the jet launching mechanism.

Submillimeter wave detection with superconducting tunnel diodes

NASA Technical Reports Server (NTRS)

Wengler, Michael J.

1992-01-01

Superconductor-Insulator-Superconductor (SIS) diodes are the detector elements in the most sensitive heterodyne receivers available from 100 to 500 GHz. SIS mixers are the front end of radio astronomical systems around the world. SIS mixer technology is being extended to 1 THz and higher frequencies for eventual use on spaceborne astronomical experiments. Here is a short review of submillimeter SIS mixers. The role of impedance matching in the proper design of an SIS mixer is described. A variety of methods for achieving good impedance match at submillimeter frequencies are presented. The experimental state of the submillimeter SIS mixer art is described and summarized.

A stable submillimeter laser local oscillator for heterodyne radiometry and spectroscopy

NASA Technical Reports Server (NTRS)

Koepf, G. A.; Fetterman, H. R.; Mcavoy, N.

1980-01-01

A submillimeter laser with off-axis pump beam injection is described. This design concept achieves complete isolation of the pump laser with respect to the pump radiation reflected from the submillimeter resonator. Active line independent stabilization of the pump laser is obtained by the use of an external tunable etalon as a frequency reference. The submillimeter output power is constant to within 4% over periods of hours. Mean frequency drifts of less than 2 parts in 100 million per minute were measured by mixing with very high harmonics of an X-band synthesizer in a planar Schottky diode.

Angular and Polarization Response of Multimode Sensors with Resistive-Grid Absorbers

NASA Technical Reports Server (NTRS)

Kusaka, Akito; Wollack, Edward J.; Stevenson, Thomas R.

2014-01-01

High sensitivity receiver systems with near ideal polarization sensitivity are highly desirable for development of millimeter and sub-millimeter radio astronomy. Multimoded bolometers provide a unique solution to achieve such sensitivity, for which hundreds of single-mode sensors would otherwise be required. The primary concern in employing such multimoded sensors for polarimetery is the control of the polarization systematics. In this paper, we examine the angular- and polarization- dependent absorption pattern of a thin resistive grid or membrane, which models an absorber used for a multimoded bolometer. The result shows that a freestanding thin resistive absorber with a surface resistivity of eta/2, where eta is the impedance of free space, attains a beam pattern with equal E- and H-plane responses, leading to zero cross polarization. For a resistive-grid absorber, the condition is met when a pair of grids is positioned orthogonal to each other and both have a resistivity of eta/2. When a reflective backshort termination is employed to improve absorption efficiency, the cross-polar level can be suppressed below -30 dB if acceptance angle of the sensor is limited to < or approx. 60deg. The small cross-polar systematics have even-parity patterns and do not contaminate the measurements of odd-parity polarization patterns, for which many of recent instruments for cosmic microwave background are designed. Underlying symmetry that suppresses these cross-polar systematics is discussed in detail. The estimates and formalism provided in this paper offer key tools in the design consideration of the instruments using the multimoded polarimeters.

The ArTéMiS wide-field sub-millimeter camera: preliminary on-sky performance at 350 microns

NASA Astrophysics Data System (ADS)

Revéret, Vincent; André, Philippe; Le Pennec, Jean; Talvard, Michel; Agnèse, Patrick; Arnaud, Agnès.; Clerc, Laurent; de Breuck, Carlos; Cigna, Jean-Charles; Delisle, Cyrille; Doumayrou, Eric; Duband, Lionel; Dubreuil, Didier; Dumaye, Luc; Ercolani, Eric; Gallais, Pascal; Groult, Elodie; Jourdan, Thierry; Leriche, Bernadette; Maffei, Bruno; Lortholary, Michel; Martignac, Jérôme; Rabaud, Wilfried; Relland, Johan; Rodriguez, Louis; Vandeneynde, Aurélie; Visticot, François

2014-07-01

ArTeMiS is a wide-field submillimeter camera operating at three wavelengths simultaneously (200, 350 and 450 μm). A preliminary version of the instrument equipped with the 350 μm focal plane, has been successfully installed and tested on APEX telescope in Chile during the 2013 and 2014 austral winters. This instrument is developed by CEA (Saclay and Grenoble, France), IAS (France) and University of Manchester (UK) in collaboration with ESO. We introduce the mechanical and optical design, as well as the cryogenics and electronics of the ArTéMiS camera. ArTeMiS detectors consist in Si:P:B bolometers arranged in 16×18 sub-arrays operating at 300 mK. These detectors are similar to the ones developed for the Herschel PACS photometer but they are adapted to the high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4 sub-arrays at 200 μm and 2×8 sub-arrays at 350 and 450 μm. We show preliminary lab measurements like the responsivity of the instrument to hot and cold loads illumination and NEP calculation. Details on the on-sky commissioning runs made in 2013 and 2014 at APEX are shown. We used planets (Mars, Saturn, Uranus) to determine the flat-field and to get the flux calibration. A pointing model was established in the first days of the runs. The average relative pointing accuracy is 3 arcsec. The beam at 350 μm has been estimated to be 8.5 arcsec, which is in good agreement with the beam of the 12 m APEX dish. Several observing modes have been tested, like "On- The-Fly" for beam-maps or large maps, spirals or raster of spirals for compact sources. With this preliminary version of ArTeMiS, we concluded that the mapping speed is already more than 5 times better than the previous 350 μm instrument at APEX. The median NEFD at 350 μm is 600 mJy.s1/2, with best values at 300 mJy.s1/2. The complete instrument with 5760 pixels and optimized settings will be installed during the first half of 2015.

Integrated Lens Antennas for Multi-Pixel Receivers

NASA Technical Reports Server (NTRS)

Lee, Choonsup; Chattopadhyay, Goutam

2011-01-01

Future astrophysics and planetary experiments are expected to require large focal plane arrays with thousands of detectors. Feedhorns have excellent performance, but their mass, size, fabrication challenges, and expense become prohibitive for very large focal plane arrays. Most planar antenna designs produce broad beam patterns, and therefore require additional elements for efficient coupling to the telescope optics, such as substrate lenses or micromachined horns. An antenna array with integrated silicon microlenses that can be fabricated photolithographically effectively addresses these issues. This approach eliminates manual assembly of arrays of lenses and reduces assembly errors and tolerances. Moreover, an antenna array without metallic horns will reduce mass of any planetary instrument significantly. The design has a monolithic array of lens-coupled, leaky-wave antennas operating in the millimeter- and submillimeter-wave frequencies. Electromagnetic simulations show that the electromagnetic fields in such lens-coupled antennas are mostly confined in approximately 12 15 . This means that one needs to design a small-angle sector lens that is much easier to fabricate using standard lithographic techniques, instead of a full hyper-hemispherical lens. Moreover, this small-angle sector lens can be easily integrated with the antennas in an array for multi-pixel imager and receiver implementation. The leaky antenna is designed using double-slot irises and fed with TE10 waveguide mode. The lens implementation starts with a silicon substrate. Photoresist with appropriate thickness (optimized for the lens size) is spun on the substrate and then reflowed to get the desired lens structure. An antenna array integrated with individual lenses for higher directivity and excellent beam profile will go a long way in realizing multi-pixel arrays and imagers. This technology will enable a new generation of compact, low-mass, and highly efficient antenna arrays for use in multi-pixel receivers and imagers for future planetary and astronomical instruments. These antenna arrays can also be used in radars and imagers for contraband detection at stand-off distances. This will be enabling technology for future balloon-borne, smaller explorer class mission (SMEX), and other missions, and for a wide range of proposed planetary sounders and radars for planetary bodies.

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

NASA Technical Reports Server (NTRS)

Ishikawa, Shin-nosuke; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N..; Ishikawa, R.; Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Hara, H.;

Development of absorber coupled TES polarimeter at millimeter wavelengths.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G.; Yefremenko, V.; Novosad, V.

2009-06-01

We report an absorber coupled TES bolometric polarimeter, consisting of an absorptive metal grid and a Mo/Au bi-layer TES on a suspended silicon nitride membrane disk. The electromagnetic design of the polarization sensitive absorbers, the heat transport modeling of the detector, the thermal response of the TES, and the micro-fabrication processes are presented. We also report the results of laboratory tests of a single pixel prototype detector, and compare with theoretical expectations.

X-Ray Spectro-Polarimetry with Photoelectric Polarimeters

NASA Technical Reports Server (NTRS)

Strohmayer, T. E.

2017-01-01

We derive a generalization of forward fitting for X-ray spectroscopy to include linear polarization of X-ray sources, appropriate for the anticipated next generation of space-based photoelectric polarimeters. We show that the inclusion of polarization sensitivity requires joint fitting to three observed spectra, one for each of the Stokes parameters, I(E), U(E), and Q(E). The equations for StokesI (E) (the total intensity spectrum) are identical to the familiar case with no polarization sensitivity, and for which the model-predicted spectrum is obtained by a convolution of the source spectrum, F (E), with the familiar energy response function,(E) R(E,E), where (E) and R(E,E) are the effective area and energy redistribution matrix, respectively. In addition to the energy spectrum, the two new relations for U(E) and Q(E) include the source polarization fraction and position angle versus energy, a(E), and 0(E), respectively, and the model-predicted spectra for these relations are obtained by a convolution with the modulated energy response function, (E)(E) R(E,E), where(E) is the energy-dependent modulation fraction that quantifies a polarimeters angular response to 100 polarized radiation. We present results of simulations with response parameters appropriate for the proposed PRAXyS Small Explorer observatory to illustrate the procedures and methods, and we discuss some aspects of photoelectric polarimeters with relevance to understanding their calibration and operation.

A cryogenic waveplate rotator for polarimetry at mm and submm wavelengths

NASA Astrophysics Data System (ADS)

Salatino, M.; de Bernardis, P.; Masi, S.

2011-04-01

Context. Polarimetry at mm and submm wavelengths is the new frontier of research in cosmic microwave background and interstellar dust studies. Polarimeters working in the IR to MM range need to be operated at cryogenic temperatures to limit the systematic effects related to the emission of the polarization analyzer. Aims: We study the effect of the temperature of the different components of a waveplate polarimeter and describe a system able to rotate a birefringent crystal at 4 K in a completely automated way. Methods: We simulate the main systematic effects related to the temperature and non-ideality of the optical components in a Stokes polarimeter. To limit these effects, a cryogenic implementation of the polarimeter is mandatory. In our system, the rotation produced by a step motor running at room temperature is transmitted down to cryogenic temperatures by means of a long shaft and gears running on custom cryogenic bearings. Results: Our system is able to rotate a birefringent crystal at 4 K in a completely automated way and dissipates only a few mW in the cold environment. A readout system based on optical fibers allows us to control the rotation of the crystal to better than 0.1°. Conclusions: This device fulfills the stringent requirements for operations in cryogenic space experiments, such as the forthcoming PILOT, BOOMERanG and LSPE.

Deep IR imaging of Submillimeter Galaxies detected by SMA: Unambiguously Identifying SMGs at High Redshifts

NASA Astrophysics Data System (ADS)

Huang, Jiasheng; Aretxaga, Itziar; Ashby, Mat; Fazio, Giovanni; Hughes, David; Ilbert, Olivier; Le Floc'h, Emeric; Lowenthal, James; Sanders, David; Scoville, Nick; Webb, Tracy; Wilner, David; Wilson, Grant; Yan, Lin; Younger, Joshua; Yun, Min

2007-05-01

In 2007 January, we detected no fewer than five AzTEC 1.1 mm galaxies via high-resolution interferometric imaging with the Sub-Millimeter Array (SMA) atop Mauna Kea at 890 microns. Despite the fact that these sources are all radio-quiet SMGs, with the high S/N SMA detections in the narrow SMA beam we unambiguously determine the position of the AzTEC galaxies with subarcsecond accuracy. All the counterparts, which lie in the SCOSMOS survey, are detected by IRAC at 3.6 and 4.5 microns in the existing SCOSMOS mosaics. Only two are detected at the longer IRAC wavelengths, however, and none are detected in the existing 24 micron data. Furthermore, only two are detected at optical wavelengths. These sources thus present (incomplete) SEDs that appear consistent with their being either 1. deeply dust-enshrouded galaxies at z=2, or 2. a distant z=4 population of very luminous objects. Because they are so optically faint, only broadband imaging such as Spitzer can provide will permit construction of their rest-frame optical-near-IR SEDs. This appears to be the only way to discriminate between the two possibilities for the origin of SMGs that are radio-quiet. Accordingly, we ask for 37.4 h to carry out a very deep imaging program utilizing all three Spitzer instruments to construct the SEDs for the four SMGs in our sample.

Characterization of a sub-assembly of 3D position sensitive cadmium zinc telluride detectors and electronics from a sub-millimeter resolution PET system.

PubMed

Abbaszadeh, Shiva; Gu, Yi; Reynolds, Paul D; Levin, Craig S

2016-09-21

Cadmium zinc telluride (CZT) offers key advantages for small animal positron emission tomography (PET), including high spatial and energy resolution and simple metal deposition for fabrication of very small pixel arrays. Previous studies have investigated the intrinsic spatial, energy, and timing resolution of an individual sub-millimeter resolution CZT detector. In this work we present the first characterization results of a system of these detectors. The 3D position sensitive dual-CZT detector module and readout electronics developed in our lab was scaled up to complete a significant portion of the final PET system. This sub-system was configured as two opposing detection panels containing a total of twelve [Formula: see text] mm monolithic CZT crystals for proof of concept. System-level characterization studies, including optimizing the trigger threshold of each channel's comparators, were performed. 68 Ge and 137 Cs radioactive isotopes were used to characterize the energy resolution of all 468 anode channels in the sub-system. The mean measured global 511 keV photopeak energy resolution over all anodes was found to be [Formula: see text]% FWHM after correction for photon interaction depth-dependent signal variation. The measured global time resolution was 37 ns FWHM, a parameter to be further optimized, and the intrinsic spatial resolution was 0.76 mm FWHM.

The South Pole Telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruhl, J.E.; Ade, P.A.R.; Carlstrom, J.E.

2004-11-04

A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope willmore » be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.« less

Subaru Imaging of Asymmetric Features in a Transitional Disk in Upper Scorpius

NASA Technical Reports Server (NTRS)

Mayama, S.; Hashimoto, J.; Muto, T.; Tsukagoshi, T.; Kusakabe, N.; Kuzuhara, M.; Takahashi, Y.; Kudo, T.; Dong, R.; Fukagawa, M.;

Subaru Imaging of Asymmetric Features in a Transitional Disk in a Transitional Disk in Upper Scorpius

NASA Technical Reports Server (NTRS)

Mayama, S.; Hashimoto, J.; Muto, T.; Tsukagoshi, T.; Kusakabe, N.; Kuzuhara, M.; Takahashi, Y.; Kudo, T.; Dong, R.; Fukagawa, M.;

A Multiwavelength Characterization of Proto-brown-dwarf Candidates in Serpens

NASA Astrophysics Data System (ADS)

Riaz, B.; Vorobyov, E.; Harsono, D.; Caselli, P.; Tikare, K.; Gonzalez-Martin, O.

2016-11-01

We present results from a deep submillimeter survey in the Serpens Main and Serpens/G3-G6 clusters, conducted with the Submillimetre Common-User Bolometer Array (SCUBA-2) at the James Clerk Maxwell Telescope. We have combined near- and mid-infrared spectroscopy, Herschel PACS far-infrared photometry, submillimeter continuum, and molecular gas line observations, with the aim of conducting a detailed multiwavelength characterization of “proto-brown-dwarf” (proto-BD) candidates in Serpens. We have performed continuum and line radiative transfer modeling and have considered various classification schemes to understand the structure and the evolutionary stage of the system. We have identified four proto-BD candidates, of which the lowest-luminosity source has an L bol ˜ 0.05 L ⊙. Two of these candidates show characteristics consistent with Stage 0/I systems, while the other two are Stage I-T/Class Flat systems with tenuous envelopes. Our work has also revealed a ˜20% fraction of misidentified Class 0/I/Flat sources that show characteristics consistent with Class II edge-on disk systems. We have set constraints on the mass of the central object using the measured bolometric luminosities and numerical simulations of stellar evolution. Considering the available gas+dust mass reservoir and the current mass of the central source, three of these candidates are likely to evolve into BDs.

A MULTIWAVELENGTH CHARACTERIZATION OF PROTO-BROWN-DWARF CANDIDATES IN SERPENS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riaz, B.; Caselli, P.; Vorobyov, E.

2016-11-10

We present results from a deep submillimeter survey in the Serpens Main and Serpens/G3–G6 clusters, conducted with the Submillimetre Common-User Bolometer Array (SCUBA-2) at the James Clerk Maxwell Telescope. We have combined near- and mid-infrared spectroscopy, Herschel PACS far-infrared photometry, submillimeter continuum, and molecular gas line observations, with the aim of conducting a detailed multiwavelength characterization of “proto-brown-dwarf” (proto-BD) candidates in Serpens. We have performed continuum and line radiative transfer modeling and have considered various classification schemes to understand the structure and the evolutionary stage of the system. We have identified four proto-BD candidates, of which the lowest-luminosity source hasmore » an L {sub bol} ∼ 0.05 L {sub ☉}. Two of these candidates show characteristics consistent with Stage 0/I systems, while the other two are Stage I-T/Class Flat systems with tenuous envelopes. Our work has also revealed a ∼20% fraction of misidentified Class 0/I/Flat sources that show characteristics consistent with Class II edge-on disk systems. We have set constraints on the mass of the central object using the measured bolometric luminosities and numerical simulations of stellar evolution. Considering the available gas+dust mass reservoir and the current mass of the central source, three of these candidates are likely to evolve into BDs.« less

BLAST: The Balloon-Borne Large Aperture Submillimeter Telescope

NASA Technical Reports Server (NTRS)

Devlin, Mark; Ade, Peter; Bock, Jamie; Dicker, Simon; Griffin, Matt; Gunderson, Josh; Halpern, Mark; Hargrave, Peter; Hughes, David; Klein, Jeff

2004-01-01

BLAST is the Balloon-borne Large-Aperture Sub-millimeter Telescope. It will fly from a Long Duration Balloon (LDB) platform from Antarctica. The telescope design incorporates a 2 m primary mirror with large-format bolometer arrays operating at 250, 350 and 500 microns. By providing the first sensitive large-area (10 sq. deg.) sub-mm surveys at these wavelengths, BLAST will address some of the most important galactic and cosmological questions regarding the formation and evolution of stars, galaxies and clusters. Galactic and extragalactic BLAST surveys will: (1) identify large numbers of high-redshift galaxies; (2) measure photometric redshifts, rest-frame FIR luminosities and star formation rates thereby constraining the evolutionary history of the galaxies that produce the FIR and sub-mm background; (3) measure cold pre-stellar sources associated with the earliest stages of star and planet formation; (4) make high-resolution maps of diffuse galactic emission over a wide range of galactic latitudes. In addition to achieving the above scientific goals, the exciting legacy of the BLAST LDB experiment will be a catalogue of 3000-5000 extragalactic sub-mm sources and a 100 sq. deg. sub-mm galactic plane survey. Multi-frequency follow-up observations from SIRTF, ASTRO-F, and Herschel, together with spectroscopic observations and sub-arcsecond imaging from ALMA are essential to understand the physical nature of the BLAST sources.

Molecular Gas Content of an Extremely Star-forming Herschel Observed Lensed Dusty Galaxy at z=2.685

NASA Astrophysics Data System (ADS)

Nayyeri, Hooshang; Cooray, Asantha R.; H-ATLAS

2017-01-01

We present the results of combined deep near-infrared, far infrared and millimeter observations of an extremely star forming lensed dusty star-forming galaxy (DSFG) identified from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). The high redshift DSFG is gravitationally lensed by a massive WISE identified cluster at z~1 (spectroscopically confirmed with Keck/DEIMOS and Gemini/GMOS) producing multiply lensed images and arcs observed in the optical. The DSFG is spectroscopically confirmed at z=2.685 from CO(1-0) observations by GBT and separately from CO(3-2) observations by CARMA. We use the combined spectroscopic and imaging observations to construct a detailed lens model of the background DSFG which allowed us to study the sources plane properties of the target. Multi-band data from Keck/NIRC2, HST/WFC3 and Herschel yields star formation rate and stellar mass well above the main sequence. Observations of the dust continuum by the Sub-millimeter Array yields an observed total ISM mass of 6.5E+11 M* which is responsible for the intense observed star formation rates. Comparing the measured SFR with molecular gas measurements from CO(1-0) observations reveals that this system has relatively short gas depletion time scale which is consistent with the starburst phase observed in high redshift sub-millimeter galaxies.

ALMA Observations of SMM11 Reveal an Extremely Young Protostar in Serpens Main Cluster

NASA Astrophysics Data System (ADS)

Aso, Yusuke; Ohashi, Nagayoshi; Aikawa, Yuri; Machida, Masahiro N.; Saigo, Kazuya; Saito, Masao; Takakuwa, Shigehisa; Tomida, Kengo; Tomisaka, Kohji; Yen, Hsi-Wei; Williams, Jonathan P.

2017-11-01

We report the discovery of an extremely young protostar, SMM11, located in the associated submillimeter condensation in the Serpens Main cluster using the Atacama Large Millimeter/submillimeter Array (ALMA) during its Cycle 3 at 1.3 mm and an angular resolution of ˜ 0\\buildrel{\\prime\\prime}\\over{.} 5˜ 210 {AU}. SMM11 is a Class 0 protostar without any counterpart at 70 μm or shorter wavelengths. The ALMA observations show 1.3 mm continuum emission associated with a collimated 12CO bipolar outflow. Spitzer and Herschel data show that SMM11 is extremely cold ({T}{bol} = 26 K) and faint ({L}{bol} ≲ 0.9 {L}⊙ ). We estimate the inclination angle of the outflow to be ˜ 80^\\circ , almost parallel to the plane of the sky, from simple fitting using a wind-driven-shell model. The continuum visibilities consist of Gaussian and power-law components, suggesting a spherical envelope with a radius of ˜600 au around the protostar. The estimated low C18O abundance, X(C18O) = 1.5-3 × {10}-10, is also consistent with its youth. The high outflow velocity, a few 10 {km} {{{s}}}-1 at a few 1000 au, is much higher than theoretical simulations of first hydrostatic cores, and we suggest that SMM11 is a transitional object right after the second collapse of the first core.

VizieR Online Data Catalog: 89 Her interferometric study (Hillen+, 2013)

NASA Astrophysics Data System (ADS)

Hillen, M.; Verhoelst, T.; van Winckel, H.; Chesneau, O.; Hummel, C. A.; Monnier, J. D.; Farrington, C.; Tycner, C.; Mourard, D.; Ten Brummelaar, T.; Banerjee, D. P. K.; Zavala, R. T.

2013-08-01

89 Herculis was observed with the AMBER instrument on the VLTI using the Auxiliary Telescopes (ATs) in 2007, 2008, and 2012, all in the low-spectral-resolution (R=30) mode covering the H and K bands with detector integration times (DITs) of 25 and 50ms and without the use of the fringe tracker FINITO. Both the CLASSIC and CLIMB beam combiners on the Georgia State University CHARA Array interferometer were used to conduct observations in the H and K bands.In May 2012 observations were performed with the sensitive two-beam CLASSIC beam combiner in both H and K band. Three-beam CLIMB observations, in H and K band, were also obtained during three nights in July 2012. We retrieved and calibrated observations from the PTI archive. 89 Her was observed during 30 nights between 1999 and 2003, equally spread over the H and K bands. Eight and 15 observations of 89 Her were obtained at the IOTA interferometer on 2003 June 15 and 16, respectively. Observations of 89 Her were carried out in October 2011 with the NPOI. Two observations were performed in June and August 2011 with the Visible spEctroGraph And Polarimeter (VEGA instrument) integrated within the CHARA Array. (2 data files).

International Conference on Infrared and Millimeter Waves, 16th, Ecole Polytechnique Federale de Lausanne, Switzerland, Aug. 26-30, 1991, Conference Digest

NASA Astrophysics Data System (ADS)

Siegrist, M. R.; Tran, T. M.; Tran, M. Q.

1991-10-01

Consideration is given to millimeter waves (MMW), submillimeter waves, materials properties, and gyrotrons/FEL. Particular attention is given to MMW sources, detectors and mixers; MMW systems, devices and antennas; guided propagation; high Tc superconductors; semiconductors; MMW astronomy and atmospheric physics; lasers, submillimeter devices, and plasma diagnostics; and submillimeter detectors.

Report of the Asilomar 3 LDR Workshop

NASA Technical Reports Server (NTRS)

Mahoney, M. J. (Editor)

1988-01-01

The conclusions and recommendations of the workshop held to study technology development issues critical to the Large Deployable Reflector (LDR) are summarized. LDR is to be a dedicated, orbiting, astronomical observatory, operating at wavelengths from 30 to 1000 microns, a spectral region where the Earth's atmosphere is almost completely opaque. Because it will have a large, segmented, passively cooled aperture, LDR addresses a wide range of technology areas. These include lightweight, low cost, structural composite reflector panels, primary support structures, wavefront sensing and adaptive optics, thermal background management, and integrated vibration and pointing control systems. The science objectives for LDR present instrument development challenges for coherent and direct arrayed detectors which can operate effectively at far infrared and submillimeter wavelengths, and for sub-Kelvin cryogenic systems.

Patterning of oxide-hardened gold black by photolithography and metal lift-off

NASA Astrophysics Data System (ADS)

Panjwani, Deep; Yesiltas, Mehmet; Nath, Janardan; Maukonen, D. E.; Rezadad, Imen; Smith, Evan M.; Peale, R. E.; Hirschmugl, Carol; Sedlmair, Julia; Wehlitz, Ralf; Unger, Miriam; Boreman, Glenn

2014-01-01

A method to pattern infrared-absorbing gold black by conventional photolithography and lift-off is described. A photo-resist pattern is developed on a substrate by standard photolithography. Gold black is deposited over the whole by thermal evaporation in an inert gas at ˜1 Torr. SiO2 is then deposited as a protection layer by electron beam evaporation. Lift-off proceeds by dissolving the photoresist in acetone. The resulting sub-millimeter size gold black patterns that remain on the substrate retain high infrared absorption out to ˜5 μm wavelength and exhibit good mechanical stability. This technique allows selective application of gold black coatings to the pixels of thermal infrared imaging array detectors.

Heat trap - An optimized far infrared field optics system. [for astronomical sources

NASA Technical Reports Server (NTRS)

Harper, D. A.; Hildebrand, R. H.; Winston, R.; Stiening, R.

1976-01-01

The article deals with the design and performance of a heat trap IR system designed to maximize the concentration and efficient reception of far IR and submillimeter wavelength radiation. The test object is assumed to be extended and/or viewed at wavelengths much longer than the detector, and the entrance aperture is limited to the size of the telescope Airy diffraction disk. The design of lenses, cavity, bolometers, light collectors, and mirrors for the system is discussed. Advantages and feasibility of arrays of heat traps are considered. Beam patterns, flux concentration, and performance variation with wavelength are dealt with. The heat trap is recommended for sensing all types of far IR sources and particularly for extended far IR sources.-

Predicting Complex Organic Molecule Emission from TW Hya

NASA Astrophysics Data System (ADS)

Vissapragada, Shreyas; Walsh, Catherine

2017-01-01

The Atacama Large Millimeter/submillimeter Array (ALMA) has significantly increased our ability to observe the rich chemical inventory of star and planet formation. ALMA has recently been used to detect CH3OH (methanol) and CH3CN (methyl cyanide) in protoplanetary disks; these molecules may be vital indicators of the complex organic ice reservoir in the comet-forming zone. We have constructed a physiochemical model of TW Hya, a well-studied protoplanetary disk, to explore the different formation mechanisms of complex ices. By running our model through a radiative transfer code and convolving with beam sizes appropriate for ALMA, we have obtained synthetic observations of methanol and methyl cyanide. Here, we compare and comment on these synthetic observations, and provide astrochemical justification for their spatial distributions.

Polarimetric survey of main-belt asteroids. V. The unusual polarimetric behavior of V-type asteroids

NASA Astrophysics Data System (ADS)

Gil-Hutton, R.; López-Sisterna, C.; Calandra, M. F.

2017-03-01

Aims: We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the CASPROF and CASPOL polarimeters at the 2.15 m telescope. The CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation and CASPOL is a polarimeter based on a CCD detector, which allows us to observe fainter objects with better signal-to-noise ratio. Results: The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We obtained 55 polarimetric measurements for 28 V-type main belt asteroids, all of them polarimetrically observed for the first time. The data obtained in this survey let us find polarimetric parameters for (1459) Magnya and for a group of 11 small V-type objects with similar polarimetric behavior. These polarization curves are unusual since they show a shallow minimum and a small inversion angle in comparison with (4) Vesta, although they have a steeper slope at α0. This polarimetric behavior could be explained by differences in the regoliths of these asteroids. The observations of (2579) Spartacus, and perhaps also (3944) Halliday, indicate a inversion angle larger than 24-25°. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

Radiometric and Polarimetric Accuracy Assessment and Calibration of the Hyper-Angular Rainbow Polarimeter (HARP) Instrument

NASA Astrophysics Data System (ADS)

McBride, B.; Martins, J. V.; Fernandez Borda, R. A.; Barbosa, H. M.

2017-12-01

The Laboratory for Aerosols, Clouds, and Optics (LACO) at the University of Maryland, Baltimore County (UMBC) present a novel, wide FOV, hyper-angular imaging polarimeter for the microphysical sampling of clouds and aerosols from aircraft and space. The instrument, the Hyper-Angular Rainbow Polarimeter (HARP), is a precursor to the multi-angle imaging polarimeter solicited by the upcoming NASA Aerosols, Clouds, and Ecosystems (ACE) mission. HARP currently operates in two forms: a spaceborne CubeSat slated for a January 2018 launch to the ISS orbit, and an identical aircraft platform that participated in the Lake Michigan Ozone Study (LMOS) and Aerosol Characterization from Polarimeter and Lidar (ACEPOL) NASA campaigns in 2017. To ensure and validate the instrument's ability to produce high quality Level 2 cloud and aerosol microphysical products, a comprehensive calibration scheme that accounts for flatfielding, radiometry, and all optical interference processes that contribute to the retrieval of Stokes parameters I, Q, and U, is applied across the entirety of HARP's 114° FOV. We present an innovative calibration algorithm that convolves incident polarization from a linear polarization state generator with intensity information observed at three distinct linear polarizations. The retrieved results are pixel-level, modified Mueller matrices that characterize the entire HARP optical assembly, without the need to characterize every individual element or perform ellipsometric studies. Here we show results from several pre- and post- LMOS campaign radiometric calibrations at NASA GSFC and polarimetric calibration using a "polarization dome" that allows for full-FOV characterization of Stokes parameters I, Q, and U. The polarization calibration is verified by passing unpolarized light through partially-polarized, tilted glass plates with well-characterized degree of linear polarization (DoLP). We apply this calibration to a stratocumulous cloud deck case observed during the LMOS campaign on June 19 2017, and assess the polarized cloudbow for cloud droplet effective radius and variance information at 0.67µm.

A Specialized Multi-Transmit Head Coil for High Resolution fMRI of the Human Visual Cortex at 7T.

PubMed

Sengupta, Shubharthi; Roebroeck, Alard; Kemper, Valentin G; Poser, Benedikt A; Zimmermann, Jan; Goebel, Rainer; Adriany, Gregor

2016-01-01

To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using [Formula: see text] mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil. The performance of the coil was further evaluated with human subjects through functional MRI (fMRI) studies at standard and submillimeter resolutions of upto 0.8mm isotropic. The transmit and receive sections were characterized using bench tests and showed good interelement decoupling, preamplifier decoupling and sample loading. SNR for the 16 channel coil was ∼ 1.5 times that of the commercial coil in the human occipital lobe, and showed better g-factor values for accelerated imaging. fMRI tests conducted showed better response to Blood Oxygen Level Dependent (BOLD) activation, at resolutions of 1.2mm and 0.8mm isotropic. The 4 channel phased array transmit coil provides homogeneous excitation across the visual cortex, which, in combination with the dual row 16 channel receive array, makes for a valuable research tool for high resolution anatomical and functional imaging of the visual cortex at 7T.

NASA Tech Briefs, February 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics covered include: Calibration Test Set for a Phase-Comparison Digital Tracker; Wireless Acoustic Measurement System; Spiral Orbit Tribometer; Arrays of Miniature Microphones for Aeroacoustic Testing; Predicting Rocket or Jet Noise in Real Time; Computational Workbench for Multibody Dynamics; High-Power, High-Efficiency Ka-Band Space Traveling-Wave Tube; Gratings and Random Reflectors for Near-Infrared PIN Diodes; Optically Transparent Split-Ring Antennas for 1 to 10 GHz; Ice-Penetrating Robot for Scientific Exploration; Power-Amplifier Module for 145 to 165 GHz; Aerial Videography From Locally Launched Rockets; SiC Multi-Chip Power Modules as Power-System Building Blocks; Automated Design of Restraint Layer of an Inflatable Vessel; TMS for Instantiating a Knowledge Base With Incomplete Data; Simulating Flights of Future Launch Vehicles and Spacecraft; Control Code for Bearingless Switched- Reluctance Motor; Machine Aided Indexing and the NASA Thesaurus; Arbitrating Control of Control and Display Units; Web-Based Software for Managing Research; Driver Code for Adaptive Optics; Ceramic Paste for Patching High-Temperature Insulation; Fabrication of Polyimide-Matrix/Carbon and Boron-Fiber Tape; Protective Skins for Aerogel Monoliths; Code Assesses Risks Posed by Meteoroids and Orbital Debris; Asymmetric Bulkheads for Cylindrical Pressure Vessels; Self-Regulating Water-Separator System for Fuel Cells; Self-Advancing Step-Tap Drills; Array of Bolometers for Submillimeter- Wavelength Operation; Delta-Doped CCDs as Detector Arrays in Mass Spectrometers; Arrays of Bundles of Carbon Nanotubes as Field Emitters; Staggering Inflation To Stabilize Attitude of a Solar Sail; and Bare Conductive Tether for Decelerating a Spacecraft.

5 MeV Mott polarimeter for rapid precise electron beam polarization measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, J.S.; Poelker, B.M.; Sinclair, C.K.

1997-11-01

Low energy (E{sub k} = 100 keV) Mott scattering polarimeters are ill-suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections; measured rates scale to 1 kHz/{mu}A with a 1 {mu}m thick gold target foil.

Survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range

NASA Technical Reports Server (NTRS)

Caux, Emmanuel; Serra, Guy

1987-01-01

The first almost complete survey of the galactic disk from 1 = -150 deg to 1 = 82 deg in the submillimeter range (effective wavelength = 380 microns), performed with the AGLAE balloon-borne instrument modified to include a submillimeter channel, is reported. The instrumentation and observational procedures are described, as are the signal processing and calibration. The results are presented as a profile of the submillimeter brightness of the galactic disk displayed as a function of the galactic longitude. This profile exhibits diffuse emission all along the disk with bright peaks associated with resolved sources. The averaged galactic spectrum is in agreement with a temperature distribution of the interstellar cold dust.

Sub-millimeter science with the Heinrich-Hertz-Telescope

NASA Astrophysics Data System (ADS)

Dumke, Michael

The Heinrich-Hertz-Telescope on Mt. Graham, Arizona, is a state-of-the-art single-dish radio telescope for observations in the sub-millimeter wavelength range. It is operated by the Sub-Millimeter Telescope Observatory (SMTO), which is a collaboration between the University of Arizona, Tucson, and the Max-Planck-Institut für Radioastronomie, Bonn. In this talk I give an overview over the telescope and its instrumentation, and show some examples of forefront research performed by astronomers from both the U.S. and Europe using this instrument. The telescope is located on Mt. Graham, Arizona, at an altitude of 3178 m, which ensures sub-mm weather conditions during a significant amount of available observing time. It has a primary reflector of 10 m diameter, mounted on a carbon fiber backup structure, and is equipped with a corotating enclosure. The surface accuracy of the primary reflector is 12 microns rms, what makes the HHT the most accurate radio telescope ever built. For spectral line observations, SIS receivers covering the frequency range from 200 to 500 GHz are available. Furthermore, a Hot-Electron-Bolometer, developed at the CfA, can be used for spectral line observations above 800 GHz. The continuum receivers are a 4-color bolometer, observing at 1300, 870, 450, and 350 microns, and a 19-channel bolometer array, developed at the MPIfR, which is sensitive around 850 microns. In the last few years, the HHT has been used by several groups to perform astronomical research. The most notable result was the measurement of the CO(9--8) line in Orion at 1.037 THz with the Hot-Electron Bolometer -- the first radioastronomical observation above 1 THz from a ground-based telescope. Several galactic molecular line sources have been mapped in the CO(7--6) line at 806 GHz, and in two fine-structure lines of atomic carbon. A continuum map of the galactic center at 850 microns could be produced using the new 19-channel bolometer array. Even external galaxies, where molecular line emission can be observed at much smaller brightness temperatures, could be mapped in the higher CO transitions. While CO(7--6) studies have been restricted to starburst galaxies like M 82 in the past, the CO(4--3) and especially the CO(3--2) line could be mapped also in fairly normal galaxies, showing that the warmer and denser gas is distributed throughout the galactic disks. Recently several nearby galaxies of different types could be mapped also in the continuum emission at 850 microns, allowing the determination of dust properties in various environments. Some interesting results following from observations with the Heinrich-Hertz-Telescope will be shown in this talk, with some emphasis on extragalactic astronomy.

Retrievals of cloud microphysical properties from the Research Scanning Polarimeter measurements made during PODEX field campaign

NASA Astrophysics Data System (ADS)

Alexandrov, M. D.; Cairns, B.; Sinclair, K.

2013-12-01

We present the retrievals of cloud droplet size distribution parameters (effective radius and variance) from the Research Scanning Polarimeter (RSP) measurements made during NASA's POlarimeter Definition EXperiment (PODEX), which was based in Palmdale, California in January - February 2013. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS), which was built for the NASA Glory Mission project. This instrument measures both polarized and total reflectances in 9 spectral channels with center wavelengths of 410, 470, 555, 670, 865, 960, 1590, 1880 and 2250 nm. The RSP is a push broom scanner making samples at 0.8 degree intervals within 60 degrees from nadir in both forward and backward directions. The data from actual RSP scans is aggregated into "virtual" scans, each consisting of all reflectances (at a variety of scattering angles) from a single point on the ground or at the cloud top. In the case of water clouds the rainbow is observed in the polarized reflectances in the scattering angle range between 135 and 170 degrees. It has a unique signature that is being used to accurately determine the droplet size and is not affected by cloud morphology. Simple parametric fitting algorithm applied to these polarized reflectances provides retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT), which allows to retrieve the droplet size distribution a parametric model. Of particular interest is the information contained in droplet size distribution width, which is indicative of cloud life cycle. The absorbing band method is also applied to RSP total reflectance observations. The difference in the retrieved droplet size between polarized and absorbing band techniques is expected to reflect the strength of the vertical gradient in cloud liquid water content. In addition to established retrieval techniques, we will use the campaign data to evaluate a new theoretical concept allowing to estimate cloud physical thickness and droplet number concentration using both polarized and total reflectances. During the PODEX campaign the RSP was onboard the NASA's long-range high-altitude ER-2 aircraft together with an array of other remote sensing instrumentation. Correlative sampling measurements from another aircraft were also available. The data obtained during the campaign provides a good opportunity to study cloud properties and to test retrieval algorithms in a variety of locations and atmospheric conditions.