186 research outputs found
Hybrid metamaterial lenslet arrays for millimeter and submillimeter imaging
No full textWe are developing broadband metamaterial planar lenslet arrays for millimeter and submillimeter imaging using stacked silicon wafers patterned with subwavelength copper squares, deep reactive ion etched (DRIE) holes, or a hybrid combination of the two. Beam-forming is accomplished through spatial variation in refractive index within each pixel created by these subwavelength features, a gradient-index (GRIN) design. However, the optical properties of both the metal mesh and DRIE metamaterials exhibit dependence on polarization orientation and wavelength, posing challenges for lens design. We combine metal mesh and DRIE GRIN sections to leverage the contrasting polarization- and frequency-dependent properties of the two material types. Here we present measurements of our most recent prototype metamaterial GRIN lens on sinuous antenna-coupled TES detectors from 88 to 225 GHz. We also present design studies extending to higher frequencies and optimizing for different pixel pitches
Planar silicon metamaterial lenslet arrays for millimeter-wavelength imaging
No full textWe are developing planar lenslet arrays for millimeter-wavelength imaging using metamaterials microlithically fabricated using silicon wafers. We describe the design process for a gradient-index (GRIN) metamaterial lenslet using metal-mesh patterned on silicon and a combination of metal-mesh and etched-hole metamaterial anti-reflection layers. We optimize the design using a bulk-material model to rapidly simulate and iterate on the lenslet design. We fabricated prototype GRIN metamaterial lenslet array and mounted it on a Polarbear/Simons Array 90/150 GHz band transition edge sensor (TES) bolometer detector array with sinuous planar antennas. Beam measurements of a prototype lenslet array agree reasonably well with the model simulations. We plan to further optimize the design and combine it with a broadband anti-reflection coating to achieve operation over 70–350 GHz bandwidth. Applications include measurements of the Cosmic Microwave Background (CMB) and sub millimeter astrophysics
Design and experimental investigation of a planar metamaterial Silicon based lenslet
No full textThe next generations of ground-based cosmic microwave background experiments will require polarisation sensitive, multichroic pixels of large focal planes comprising several thousand detectors operating at the photon noise limit. One approach to achieve this goal is to couple light from the telescope to a polarisation sensitive antenna structure connected to a superconducting diplexer network where the desired frequency bands are filtered before being fed to individual ultra-sensitive detectors such as Transition Edge Sensors. Traditionally, arrays constituted of horn antennas, planar phased antennas or anti-reflection coated micro-lenses have been placed in front of planar antenna structures to achieve the gain required to couple efficiently to the telescope optics. In this paper are presented the design concept and a preliminary analysis of the measured performances of a phase-engineered metamaterial flat-lenslet. The flat lens design is inherently matched to free space, avoiding the necessity of an anti-reflection coating layer. It can be fabricated lithographically, making scaling to large format arrays relatively simple. Furthermore, this technology is compatible with the fabrication process required for the production of large-format lumped element kinetic inductance detector arrays which have already demonstrated the required sensitivity along with multiplexing ratios of order 1000 detectors/channel
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The AzTEC Millimeter-wave Camera: Design, Integration, Performance, and the Characterization of the (sub-)millimeter Galaxy Population
No full textOne 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.AstronomyDoctor of Philosophy (Ph.D.
Plutonides Hicks 1895
No full textGenus Plutonides Hicks, 1895 Plutonides Hicks, 1895: 230, 231. — Type species: Plutonia sedgwickii Hicks, 1871, designated by Whittington et al. (1997). Plutonia Hicks, 1869: 69. — Type species: Plutonia sedgwickii Hicks, 1871, by monotypy. Paradoxides (Mawddachites) Fletcher, 2007: 47. — Type species: Paradoxides hicksii Salter, 1866b, by original designation (Fletcher 2007). DIAGNOSIS. — Surface ornamented; glabella widest at S4 furrow, frontal margin bluntly pointed; S2 to S4 present; palpebral lobes oblique, extending from S1 to S4; posterior section of facial suture sigmoidal; thorax with 19 segments; pygidium with one axial ring (based on Hicks 1869; Whittington et al. 1997, with modifications). REMARKS Plutonia was first described by Hicks (1869) but the name Plutonia was used by Stabile (1864) for a genus of Mollusca. Therefore, Hicks (1895) renamed the genus Plutonides which is still recognized today. Fletcher (2007) introduced the subgenus Paradoxides (Mawddachites) based on ‘ Paradoxides hicksii ’ as type species. His diagnosis only includes Pl. hicksii. Diagnostic characteristics presented by the author included a glabella widest at S4, deep S1 to S4 furrows, palpebral lobes extending from the base of L5 to S1, a pygidium almost circular in outline and an exoskeleton ornamented with fine anastomosing venation or granulation. These characteristics match those given byWhittington et al. (1997) for Plutonides, e.g. the characteristic glabella widening to L4, well defined S2 to S4 furrows, palpebral lobes from L1 or S1 to S4, pygidium subhexagonal and a coarsely granulose surface with meshlike pattern of fine, anastomosing ridges. We therefore interpret Paradoxides (Mawddachites) as a synonym of Plutonides. The distinctly narrow occipital ring and the relatively narrow librigena extending backward into a long curving spine, as mentioned by Fletcher (2007) for Pa. (Mawddachites), are here considered not to be diagnostic. Hicks (1869) already mentioned a close relationship between Plutonides and Paradoxides, but the author still referred to Plutonides as differing by its ornamentation of tubercles, unusual position of the eye suture and straight thoracic pleurae. Fletcher et al. (2005) ranked Plutonides as subgenus of Paradoxides, but this view is not followed here. Plutonides does not have a transglabellar S2 furrow, which is characteristic for Paradoxides. Other diagnostic differences in Plutonides are a shorter palpebral lobe and a bluntly pointed frontal margin compared to a rounded in Paradoxides. They clearly mark the separation of the genus Plutonides from Paradoxides.Published as part of Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, pp. 1051-1087 in Geodiversitas 44 (33) on page 1070, DOI: 10.5252/geodiversitas2022v44a33, http://zenodo.org/record/747765
Agraulos Hawle & Corda 1847
No full textGenus Agraulos Hawle & Corda, 1847 Agraulos Hawle & Corda, 1847: 26, 27. — Type species: Arion ceticephalus Barrande, 1846, designated by Miller (1889). Arion Barrande, 1846: 12, 13. — Type species: Arion ceticephalus Barrande, 1846, by monotypy (Barrande 1846). Arionides – Barrande 1847: 391. Herse Hawle & Corda, 1847: 19. — Type species: Herse neubergii Hawle & Corda, 1847, by monotypy (Hawle & Corda 1847). Arionellus – Barrande 1852b: 404. DIAGNOSIS. — Cranidium parabolic and domed; exoskeleton thick; glabella domed, equal-sided to trapezoidal; preglabellar field long; thorax of 16 segments (based onLake 1932; Harrington et al. 1959; Fletcher 2017, with modifications). REMARKS The genus was first described by Barrande (1846) as Arion. As the name Arion was occupied by a genus of gastropods, Hawle & Corda (1847) renamed the trilobite Arion to Agraulos. Barrande (1847) corrected his mistake and renamed the genus to Arionides. Barrande (1852b) re-renamed the genus to Arionellus, as in his opinion Arionides might still be challenged by other authors. He rejected Agraulos Hawle & Corda (1847) as he found the name too similar to Agraulis, a genus of butterflies. Nevertheless, Pompeckj (1896) and Lake (1932) stated that a similarity of names, i.e. Agraulos and Agraulis, was not an adequate reason to reject the name given by Hawle & Corda (1947). Therefore, Agraulos is now the name established for this genus. Lake (1932) mentioned that Hawle & Corda (1847) described juvenile forms of Agraulos as the new genus Herse. The genus Agraulos is closely related to Skreiaspis Růžička, 1946, but differs by a longer preglabellar field (Harrington et al. 1959). Agraulos is here included in the family Agraulidae Howell, 1937, following e.g., Harrington et al. (1959), Martin & Dean (1988), Jell & Adrain (2002), Bentley & Jago (2004) and Weidner & Nielsen (2014). The limiting of Agraulidae to a subfamily of the family Solenopleuridae Angelin, 1854, as proposed by Fletcher (2017), is not followed herein. This latter author suggested that the same characters that support Agraulidae, as defined by Bentley & Jago (2004), are also seen in Parasolenopleura aculeata (Angelin, 1851), the reference species of the Solenopleuridae.However, the Solenopleuridae has a deep occipital furrow and a narrow border (Harrington et al. 1959), which differ from a weakly to effaced occipital furrow and presence of a preglabellar field, as characteristically seen in the Agraulidae (Harrington et al. 1959; Bentley & Jago 2004).Published as part of Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, pp. 1051-1087 in Geodiversitas 44 (33) on pages 1055-1056, DOI: 10.5252/geodiversitas2022v44a33, http://zenodo.org/record/747765
Simultaneous Millimeter-wave, Gamma-Ray, and Optical Monitoring of the Blazar PKS 2326-502 during a Flaring State
No full text
Including millimeter-wave data in multiwavelength studies of the variability of active galactic nuclei (AGN) can provide insights into AGN physics that are not easily accessible at other wavelengths. We demonstrate in this work the potential of cosmic microwave background (CMB) telescopes to provide long-term, high-cadence millimeter-wave AGN monitoring over large fractions of sky. We report on a pilot study using data from the SPTpol instrument on the South Pole Telescope (SPT), which was designed to observe the CMB at arcminute and larger angular scales. Between 2013 and 2016, SPTpol was used primarily to observe a single 500 deg2 field, covering the entire field several times per day with detectors sensitive to radiation in bands centered at 95 and 150 GHz. We use SPT 150 GHz observations to create AGN light curves, and we compare these millimeter-wave light curves to those at other wavelengths, in particular γ-ray and optical. In this Letter, we focus on a single source, PKS 2326-502, which has extensive, day-timescale monitoring data in gamma-ray, optical, and now millimeter-wave between 2013 and 2016. We find PKS 2326-502 to be in a flaring state in the first 2 yr of this monitoring, and we present a search for evidence of correlated variability between millimeter-wave, optical R-band, and γ-ray observations. This pilot study is paving the way for AGN monitoring with current and upcoming CMB experiments such as SPT-3G, Simons Observatory, and CMB-S4, including multiwavelength studies with facilities such as Vera C. Rubin Observatories Large Synoptic Survey Telescope.
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Meneviella venulosa
No full textMeneviella venulosa (Hicks, 1872) (Fig. 10) Erinnys venulosa Hicks, 1872: 177, pl. 6, figs 1-6. — Salter 1873: 5. — Illing 1915: 426. Erinnys (Harpides) venulosa – Salter 1866a: 285 (?), nomen nudum. Salteria venulosa – Walcott 1884: 31, 32. Erinnys breviceps – Matthew 1899: 91-95, pl. 4, fig. 9. Conocoryphe (Erinnys) venulosa – Grönwall 1902: 94-96, pl. 1, fig. 23. Bailiella venulosa – Howell 1925: 30, 31 (?). Menevia venulosa – Lake 1938: 272, pl. 39, figs 4-9; 1940: 273, 274. — Harrington et al. 1959: O244, fig. 181.10. Menevia cf. venulosa; Kindle & Whittington 1959: fig. 3i (?). Meneviella venulosa – Hutchinson 1962: 108, pl. 16, figs 2-7 (?). — Shaw 1966: 855, pl. 99, fig. 17. — Korobov 1973: 124- 126, pl. 12, fig. 1. — Egorova et al. 1982: 110, pl. 3, fig. 10; pl. 9, fig. 10 (?). — Kindle 1982: pl. 1.2, fig. 7. — Morris & Fortey 1985: pl. 1, fig. 10. — Buchholz 1991: 222, pl. 2, fig. 2; 1997: 251, pl. 20, figs 7, 8. — Rudolph 1994: 197, 198, pl. 22, fig. 8 (?). — Cotton 2001: text.fig. 1A, pl. 3, figs 1-4. — Young et al. 2002:, pl. 4, fig. xiii (?). — Fletcher 2006: pl. 34, fig. 37. — Weidner & Nielsen 2014: 75, 76, figs 44A-E. — Bushuev & Makarova 2016: 15, 16, pl. 1, fig. 4. Meneviella viatrix Shergold, 1973: 21-25, pl. 10, fig. 1; pl. 11, figs 1-4; pl. 12, figs 1-8. Dasometopus groenlandicus – Babcock 1994: 87, 88, fig. 7.3. LECTOTYPE. — Specimen no. SM A1033, Sedgwick Museum of Earth Sciences, Cambridge, United Kingdom, originally figured in Hicks (1872) and designated as lectotype by Stubblefield (1951), from the Menevian of Port-y-rhaw, St. David’s, Wales. DIAGNOSIS. — Cranidium with wide border; glabella two thirds of cranidial length with three pairs of furrows, S1 curves back to occipital furrow axially, S2 and S3 short; occipital furrow arching forward axially; occipital ring with node; fixigena divided by ridges that run out from eye ridges, tapering backwards and spread out to anterior part by splitting into venulose markings, posterior part granulated. MATERIAL EXAMINED. — 16 cranidia of Meneviella venulosa (for NFM numbers seeAppendix 1). All specimens range between 10.00 and 16.55 m (Fig. 2) of the Manuels River Formation, type locality, Conception Bay South, Newfoundland, Canada. OCCURRENCE. — Meneviella venulosa has a wide middle Cambrian distribution and has been documented from southeastern Canada, eastern Newfoundland, in the upper Paradoxides hicksi to Paradoxides davidis zones (Hutchinson, 1962). It has also been reported from western Newfoundland (Tomagnostus fissus and Ptychagnostus atavus bearing Zone 3; Kindle 1982), United States of America in Vermont (Paradoxides davidis Zone; Shaw 1966), Greenland (Ptychagnostus atavus Zone; Babcock 1994), United Kingdom in Wales (Hypagnostus parvifrons to Ptychagnostus punctuosus zones; Thomas et al. 1984; Young et al. 2002) and England (Paradoxides davidis Zone; Illing 1915), Denmark in Bornholm (Ptychagnostus punctuosus Zone; Buchholz 1991; Grönwall 1902; Rudolph 1994), Russia in Siberia (Tomagnostus fissus to Paradoxides hicksi zones and Anapolenus henrici Zone; e.g., Egorova et al. 1982) and Australia in Queensland (Ptychagnostus punctuosus and Goniagnostus nathorsti zones; Shergold 1973). DESCRIPTION The cranidia range from 11.0 mm to 17.0 mm width and from 4.5 mm to 8.0 mm length. They are well-preserved as internal casts and moulds. Some are broken along the dorsal furrow on one side of the glabella. In smaller specimens the venulose markings are less prominent and granulation covers the whole cranidium. Cranidia from stratigraphically lower beds (three cranidia from 10.00 m) have a more prominent granulation than those from stratigraphically higher beds (12 cranidia above 15.73 m). One internal cast has a white surface (NFM F-3655). REMARKS Salter (1866a) first reported Erinnys (Harpides) venulosa as a nomen nudum. He doubted that it could be distinguished from Harpides Beyrich, 1846, but without supporting this view by additional information, e.g. descriptions or figures. Thus, the assignment is questionable and Hicks (1872) is the author who first described the species. Matthew (1899) distinguished Erinnys breviceps from Erinnys venulosa based on the marginal furrow and border of the former, which, according to him, does not border the entire cranidium of E. breviceps. Matthew’s plate 4, fig. 9 (Matthew 1899) illustrates a cranidium attached to the anterior portion of the thorax with a marginal furrow and border surrounding the whole cranidium. Therefore, the illustrated specimen is here assigned to M. venulosa. Howell (1925) repported specimens of Salter’s Erinnys venulosa and named them Bailiella venulosa without providing a description or illustrations. The assignment of his unfigured specimens is questionable. Kindle & Whittington (1959) illustrated one cranidium of Menevia venulosa which does not show the characteristic vein-like markings of the cephalon. Hence, the assignment is questionable. Note that Kindle & Whittington (1959) used Menevia in the figure description and Meneviella in the written text. Hutchinson (1962) described and illustrated different growth stages of M. venulosa, reporting that meraspid specimens (described as younger specimens by Hutchinson (1962)) show a more prominent granulation and less venulose markings than meraspid to holaspid specimens. The assumption that the specimen figured on Hutchinson’s plate 16, figure 2 (Hutchinson 1962), is a young specimen of M. venulosa cannot be assigned with certainty due to the low resolution of the image. Shergold (1973) described the new species Meneviella viatrix. According to the author, it differs from M. venulosa by a smaller size, fewer axial rings, more pygidial segments, and weaker geniculation in the posterior cranidial margin. The body size is a questionable taxonomic characteristic (Müller 1994). In combination with the fewer axial rings, Shergold’s (1973) almost completely articulated specimens may represent a late meraspis stage. Cephala figured by Shergold (1973) are indistinguishable from M. venulosa, especially as no weaker geniculation (diagnostic character introduced by Shergold [1973]) is seen in the posterior cranidial margin. The different number of axial rings may represent a different ontogenetic stage or represent a possible variation within M. venulosa. Shergold (1973) only figured one disarticulated and two slightly deformed pygidia, all three attached to the thorax. The material is preserved and illustrated insufficiently to determine the number of pygidial axial rings. Therefore, M. viatrix is here interpreted to be a synonym of M. venulosa. One cranidium of M. venulosa figured by Egorova et al. (1982: pl. 3, fig. 10) is illustrated insufficiently. Therefore, the assignment is here considered questionable. Babcock (1994) defined the new species Dasometopus groenlandicus. The illustrated fragment in his figure 7.3 shows the vein-like markings of the cephalon characteristic for M. venulosa and was attributed to this species by Weidner & Nielsen (2014). Their suggestion is followed here. A small cranidium with a disarticulated glabella was illustrated as M. venulosa by Rudolph (1994: pl. 22, fig. 8), whose material includes several juvenile cranidida. The illustrated specimen does not show the characteristic vein-like markings of the cephalon. The case is similar to the incomplete cranidium illustrated by Young et al. (2002: pl. 4, fig. xiii). The illustrated specimen does not show the characteristic venulose markings, possibly due to the resolution of the illustration. In both cases, the assignment to M. venulosa is therefore questionable.Published as part of Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, pp. 1051-1087 in Geodiversitas 44 (33) on pages 1065-1066, DOI: 10.5252/geodiversitas2022v44a33, http://zenodo.org/record/747765
An Open Source, FPGA-Based LeKID Readout for BLAST-TNG: Pre-Flight Results
No full textWe present a highly frequency multiplexed readout for large-format superconducting detector arrays intended for use in the next generation of balloon-borne and space-based sub-millimeter and far-infrared missions. We will demonstrate this technology on the upcoming NASA Next Generation Balloon-borne Large Aperture Sub-millimeter Telescope (BLAST-TNG) to measure the polarized emission of Galactic dust at wavelengths of 250, 350 and 500 microns. The BLAST-TNG receiver incorporates the first arrays of Lumped Element Kinetic Inductance Detectors (LeKID) along with the first microwave multiplexing readout electronics to fly in a space-like environment and will significantly advance the TRL for these technologies. After the flight of BLAST-TNG, we will continue to improve the performance of the detectors and readout electronics for the next generation of balloon-borne instruments and for use in a future FIR Surveyor.
Read More: http://www.worldscientific.com/doi/abs/10.1142/S225117171641003
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