1,165 research outputs found
Crustal Deformation and Regional Metamorphism Across a Terrane Boundary, Coast Plutonic Complex, British Columbia
Crustal Deformation and Regional Metamorphism Across a Terrane Boundary, Coast Plutonic Complex, British Columbia
Development of Aluminum LEKIDs for Balloon-Borne Far-IR Spectroscopy
We are developing lumped-element kinetic inductance detectors (LEKIDs)
designed to achieve background-limited sensitivity for far-infrared (FIR)
spectroscopy on a stratospheric balloon. The Spectroscopic Terahertz Airborne
Receiver for Far-InfraRed Exploration (STARFIRE) will study the evolution of
dusty galaxies with observations of the [CII] 158 m and other atomic
fine-structure transitions at , both through direct observations of
individual luminous infrared galaxies, and in blind surveys using the technique
of line intensity mapping. The spectrometer will require large format
(1800 detectors) arrays of dual-polarization sensitive detectors with
NEPs of W Hz. The low-volume LEKIDs are fabricated
with a single layer of aluminum (20 nm thick) deposited on a crystalline
silicon wafer, with resonance frequencies of MHz. The inductor is a
single meander with a linewidth of 0.4 m, patterned in a grid to absorb
optical power in both polarizations. The meander is coupled to a circular
waveguide, fed by a conical feedhorn. Initial testing of a small array
prototype has demonstrated good yield, and a median NEP of
W Hz.Comment: accepted for publication in Journal of Low Temperature Physic
Status of SuperSpec: A Broadband, On-Chip Millimeter-Wave Spectrometer
SuperSpec is a novel on-chip spectrometer we are developing for multi-object,
moderate resolution (R = 100 - 500), large bandwidth (~1.65:1) submillimeter
and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer
employs a filter bank architecture, and consists of a series of half-wave
resonators formed by lithographically-patterned superconducting transmission
lines. The signal power admitted by each resonator is detected by a lumped
element titanium nitride (TiN) kinetic inductance detector (KID) operating at
100-200 MHz. We have tested a new prototype device that is more sensitive than
previous devices, and easier to fabricate. We present a characterization of a
representative R=282 channel at f = 236 GHz, including measurements of the
spectrometer detection efficiency, the detector responsivity over a large range
of optical loading, and the full system optical efficiency. We outline future
improvements to the current system that we expect will enable construction of a
photon-noise-limited R=100 filter bank, appropriate for a line intensity
mapping experiment targeting the [CII] 158 micron transition during the Epoch
of ReionizationComment: 16 pages, 10 figures, Proceedings of the SPIE Astronomical Telescopes
+ Instrumentation 2014 Conference, Vol 9153, Millimeter, Submillimeter, and
Far-Infrared Detectors and Instrumentation for Astronomy VI
Microwave Kinetic Inductance Detector (MKID) Camera Testing for Submillimeter Astronomy
Developing kilopixel focal planes for incoherent submm- and mm-wave detectors remains challenging due to either the large hardware overhead or the complexity of multiplexing standard detectors. Microwave kinetic inductance detectors (MKIDs) provide a efficient means to produce fully lithographic background-limited kilopixel focal planes. We are constructing an MKID-based camera for the Caltech Submillimeter Observatory with 576 spatial pixels each simultaneously sensitive in 4 bands at 230, 300, 350, and 400 GHz. The novelty of MKIDs has required us to develop new techniques for detector characterization. We have measured quasiparticle lifetimes and resonator Qs for detector bath temperatures between 200 mK and 400 mK. Equivalent lifetime measurements were made by coupling energy into the resonators either optically or by driving the third harmonic of the resonator. To determine optical loading, we use both lifetime and internal Q measurements, which range between 15,000 and 30,000 for our resonators. Spectral bandpass measurements confirm the placement of the 230 and 350 GHz bands. Additionally, beam maps measurements conform to expectations. The same device design has been characterized on both sapphire and silicon substrates, and for different detector geometries. We also report on the incorporation of new shielding to reduce detector sensitivity to local magnetic fields
Functional Bone Engineering Using ex Vivo Gene Therapy and Topology-Optimized, Biodegradable Polymer Composite Scaffolds
Bone tissue engineering could provide an alternative to conventional treatments for fracture nonunion, spinal fusion, joint replacement, and pathological loss of bone. However, this approach will require a biocompatible matrix to allow progenitor cell delivery and support tissue invasion. The construct must also support physiological loads as it degrades to allow the regenerated tissue to bear an increasing load. To meet these complex requirements, we have employed topology-optimized design and solid free-form fabrication to manufacture biodegradable poly(propylene fumarate)/ β-tricalcium phosphate composites. These scaffolds were seeded with primary human fibroblasts transduced with an adenovirus expressing bone morphogenetic protein-7 and implanted subcutaneously in mice. Specimens were evaluated by microcomputed tomography, compressive testing, and histological staining. New bone was localized on the scaffold surface and closely followed its designed contours. Furthermore, the total stiffness of the constructs was retained for up to 12 weeks after implantation, as scaffold degradation and tissue invasion took place.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63144/1/ten.2005.11.1589.pd
MKID development for SuperSpec: an on-chip, mm-wave, filter-bank spectrometer
SuperSpec is an ultra-compact spectrometer-on-a-chip for millimeter and
submillimeter wavelength astronomy. Its very small size, wide spectral
bandwidth, and highly multiplexed readout will enable construction of powerful
multibeam spectrometers for high-redshift observations. The spectrometer
consists of a horn-coupled microstrip feedline, a bank of narrow-band
superconducting resonator filters that provide spectral selectivity, and
Kinetic Inductance Detectors (KIDs) that detect the power admitted by each
filter resonator. The design is realized using thin-film lithographic
structures on a silicon wafer. The mm-wave microstrip feedline and spectral
filters of the first prototype are designed to operate in the band from 195-310
GHz and are fabricated from niobium with at Tc of 9.2K. The KIDs are designed
to operate at hundreds of MHz and are fabricated from titanium nitride with a
Tc of 2K. Radiation incident on the horn travels along the mm-wave microstrip,
passes through the frequency-selective filter, and is finally absorbed by the
corresponding KID where it causes a measurable shift in the resonant frequency.
In this proceedings, we present the design of the KIDs employed in SuperSpec
and the results of initial laboratory testing of a prototype device. We will
also briefly describe the ongoing development of a demonstration instrument
that will consist of two 500-channel, R=700 spectrometers, one operating in the
1-mm atmospheric window and the other covering the 650 and 850 micron bands.Comment: As submitted, except that "in prep" references have been update
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