We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer ...(DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 µm.
•We present sub-kelvin thermal conductivity data for an artificial graphite, polyimides (3), titanium alloys (3), a shape memory alloy and a bulk metallic glass.•The heat flow along the length of a ...laminated flat cable can be predicted by composing the thermal conductivities of its constituent materials, but heat flow across its thickness cannot be predicted in this way.•Titanium alloys are useful as low thermal conductivity superconducting structural and flat cabling materials.•SCP-5050 VESPEL is a useful insulating structural material due to its very low thermal conductivity, and high strength and dimensional stability.•Structural parts made from bulk metallic glass would have thermal conductivity on par with stainless steel and could be manufactured via injection molding.
We present measurements of the low temperature thermal conductivity for materials useful in the construction of cryogenic supports for scientific instrumentation and in the fabrication of flat flexible cryogenic cabling. The materials we measure have relatively low thermal conductivity. We present a method for measuring the heat transfer coefficient of flat cabling and show, using an example, that the thermal conductivity of a flex cable is reasonably well predicted by composing the thermal conductivities of its constituent material layers. Room temperature physical and mechanical data is given for the materials studied, as well as an overview of relevant materials science and manufacturing details. Materials include Timet Ti 15-3 and Ti 21S, Materion alloy vit105 (LM105) in amorphous state, ATI Metals Nb-47Ti, Johnson Matthey nitinol (NiTi), Mersen graphite grade 2020, DuPont Pyralux coverlay and Vespel SCP-5050, and Fralock Cirlex polyimide sheets. All data is in the temperature range 0.05–2 K, and up to 5 K for SCP-5050.
We propose disk resonators for use as kinetic inductance detectors. Benefits and drawbacks of this design are discussed with consideration for potential detector applications. We have conducted ...electromagnetic simulations of the resonator geometry and will use them to examine the disk resonator properties. We will compare several schemes for coupling these resonators to feed lines and review the effect of a large kinetic inductance on the design equations for the resonant frequency. Additionally, a strategy to reduce the resonator metal volume by meshing is considered, and its effects on the resonator’s current distribution are shown. We find that meshing can significantly alter the resonant frequency of the disk. We conclude by discussing an example disk resonator, gamma-ray microcalorimeter detector design.
We present measurements of the thermal conductivity between 0.05 and 1 K, and radioactive contamination levels, for some thermally isolating materials. TIMET Ti 15-3-3-3, Mersen grade 2020 graphite, ...Vespel SP-1, Vespel SP-22, Vespel SCP-5000, Vespel SCP-5050, Graphlite CFRP, and a Kapton/epoxy composite are all investigated. Thermal conductivities were measured using a single-heater longitudinal heat flow method. Material radioactivity was determined for the materials at a low background counting facility using a high-purity gamma detector and GEANT4 Monte Carlo simulations.
A mummy portrait of a young woman with a golden wreath is part of the archaeological collection of the Allard Pierson Museum in Amsterdam. This portrait is covered by four authors, each from their ...separate perspective, namely provenance research, technical examination, museum presentation, and diversity education. Provenance research is significant not only for tracing the second-life biography of the panel, but also for assessing its bona fide authenticity. Non-invasive examinations can help identify possible underlayers, pigments and modern restorations. Museological aspects concern the contextualization of the portrait, not only as a funerary artefact, but also as an expression of physical appearance. Educational programs can be implemented to illustrate to museum visitors the relevance of ancient artefacts for modern society.
A common challenge in low temperature instrumentation is adequately heat sinking signal wires between room temperature and devices at base temperature. Using cryostat space for adequate heat sinking ...typically comes at the cost of complexity or experimental space. As such, it is useful to know how much heat sinking is adequate given the materials, heat sources and cooling capacities involved. We present a differential equation for modeling the heat flowing out of a flat cable along an interval over which it is adhered to an insulating interface which is bound to a metallic heat sinking surface and numerical results for realistic heat sinks in the Kelvin range. We also present a computational method for solving this differential equation.
•Joint thermal conductance across bolted copper to copper connections has been tested from 60mK to 26K.•Surfaces passivated with citric acid were tested as an alternative to gold plating.•Results of ...joint thermal conductance testing are well fitted with a power law regression.•These results correlate well with data obtained from a literature survey.
Joint thermal conductance testing has been undertaken for bolted copper to copper connections from 60mK to 26K. This testing was performed to validate an initial design basis for the SuperCDMS experiment, where a dilution refrigerator will be coupled to a cryostat via multiple bolted connections. Copper used during testing was either gold plated or passivated with citric acid to prevent surface oxidation. Results obtained are well fit by a power law regression of joint thermal conductance to temperature and match well with data collected during a literature review.
Periprocedural stroke during transcatheter aortic valve replacement (TAVR) is a highly feared adverse event. The TriGUARD 3 cerebral embolic protection device (CEPD) may have the potential benefit of ...reduction of embolic events, but it still remains unclear whether it reduces the incidence of periprocedural stroke or transient ischemic attack (TIA).
We aimed to investigate whether the latest TriGUARD 3 CEPD reduces the incidence of clinically overt stroke within 72 h or at discharge after TAVR.
In this prospective single-center study 117 patients (mean age 80.3 years, 53.8 % male) were included from July 2020 to December 2021.
The primary efficacy endpoint of this study, periprocedural clinically overt stroke or TIA, within 72 h or at discharge after TAVR with the TriGUARD 3 CEPD occurred in 1/117 pts (0.8 %). Secondary endpoints (device related issues such as life-threatening or disabling bleeding, acute kidney injury, major vascular complications) were reported in 4/117 pts (3.4 %).
This study suggests that the use of the latest TriGUARD 3™ CEPD in transfemoral TAVR seems to be associated with a low rate of clinically overt stroke and a low rate of device related adverse events, reflecting “real world” TAVR practice. However these results should be hypothesis generating and confirmed in a large RCT.
•The use of the latest TriGUARD 3™ CEPD in transfemoral TAVR is associated with a low rate of clinically overt stroke•A low rate of device related adverse events occurred post-TAVR with the TriGUARD 3™ CEPD within 72 hours or at discharge•Complete coverage of all the three cerebral arteries with the latest TriGUARD 3™ CEPD was achieved in all patients
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