Transition Edge Research Articles

Frequency division multiplexing readout of a transition edge sensor bolometer array with microstrip-type electrical bias lines.

We demonstrate multiplexed readout of 43 transition edge sensor (TES) bolometers operating at 90 mK using a frequency division multiplexing (FDM) readout chain with bias frequencies ranging from 1 to 3.5MHz and a typical frequency spacing of 32kHz. We improve the previously reported performance of our FDM system by two important steps. First, we replace the coplanar wires with microstrip wires, which minimize the cross talk from mutual inductance. From the measured electrical cross talk (ECT) map, the ECT of all pixels is carrier leakage dominated. Only five pixels show an ECT level higher than 1%. Second, we reduce the thermal response speed of the TES detectors by a factor of 20 by increasing the heat capacity of the TES, which allows us to bias all TES detectors below 50% in transition without oscillations. We compare the current-voltage curves and noise spectra of the TESs measured in single-pixel mode and multiplexing mode. We also compare the noise equivalent power (NEP) and the saturation power of the bolometers in both modes, where 38 pixels show less than 10% difference in NEP and 5% difference in saturation power when measured in the two different modes. The measured noise spectrum is in good agreement with the simulated noise based on measured parameters from an impedance measurement, confirming that our TES is dominated by phonon noise.

Memory can induce oscillations of microparticles in nonlinear viscoelastic media and cause a giant enhancement of driven diffusion

We investigate analytically and numerically a basic model of driven Brownian motion with a velocity-dependent friction coefficient in nonlinear viscoelastic media featured by a stress plateau at intermediate shear velocities and profound memory effects. For constant force driving, we show that nonlinear oscillations of a microparticle velocity and position emerge by a Hopf bifurcation at a small critical force (first dynamical phase transition), where the friction's nonlinearity seems to be wholly negligible. They also disappear by a second Hopf bifurcation at a much larger force value (second dynamical phase transition). The bifurcation diagram is found in an analytical form confirmed by numerics. Surprisingly, the particles' inertial and the medium's nonlinear properties remain crucial even in a parameter regime where they were earlier considered entirely negligible. Depending on the force and other parameters, the amplitude of oscillations can significantly exceed the size of the particles, and their period can span several time decades, primarily determined by the memory time of the medium. Such oscillations can also be thermally excited near the edges of dynamical phase transitions. The second dynamical phase transition combined with thermally induced stochastic limit cycle oscillations leads to a giant enhancement of diffusion over the limit of vast driving forces, where an effective linearization of stochastic dynamics occurs.

A SQUID controller unit for space-based TES sensor readout

We have developed a Superconducting Quantum Interference Device (SQUID) controller unit for Transition Edge Sensors (TES) readout, designed to be used in a space mission. The unit is made of 8 boards and each board can condition four SQUID array amplifiers. The board design is inspired by a similar one developed for ground based experiments, but specific changes have been made to adopt Components Off The Shelf (COTS) with space grade equivalents, to implement redundancy and cross-strapping capabilities. The design also includes the thermal path to lift the heat off the boards towards an in-house designed monolithic aluminum rack.

Unveiling quaternary GeSbSeEr chalcogenides as photocatalyst: Degradation of cationic and anionic pollutant in visible light

This article presents the photo-catalytic dye-degradation from pure and doped multi-component Ge17Sb8Se75-xErx(x = 0, 0.2, 0.4, 0.6, 0.8, 1) chalcogenides system has been established in visible light (orange ∼590 nm) for the first time. Band-gap shifting, suitable band position and higher absorption of visible range radiation have been accounted for Er doping to realize the improvement in electron-hole pair production. The improvement in the photo-catalytic activity dye degradation efficiency of 89% in 90 min for methylene blue and 76% for methyl orange has been achieved for certain compositions of chalcogenides glass which were synthesized by traditional melt quench approach. Further, SEM-EDX Photoluminescence and Raman spectroscopy measurements of these samples are supplemented to deliberate the composition, band edge transitions and chemical signatures of Ge17Sb8Se75-xErx. Overall, the presence of Er ions as well as the band to band transition (∼664 nm) in the chalcogenides system is found to play a decisive role in the photo catalytically process involved for competitive dye degradation to replace conventional dyes working in the UV range.

Low-threshold sapphire detector for rare event searches

Low mass nuclear recoil dark matter and coherent-elastic-neutrino-nucleus-scattering (CEνNS) searches confront similar challenges in choosing ultra-low threshold and large-mass detectors. We report experimental results from a 100 g single-crystal sapphire detector design with a diameter of 76 mm and thickness of 4 mm instrumented with transition edge sensors (TES). Sapphire is a crystal of aluminum oxide (Al2O3) and has been found to be a good candidate for light mass dark matter search experiments due to its lower atomic mass compared to other detector materials such as germanium and silicon. This new phonon-assisted sapphire detector was characterized to yield a baseline recoil energy resolution of 28.4 ± 0.4 eV. The detector is designed to be sensitive to low-energy rare interactions with an intention to investigate the low-mass region of dark matter phase-space and search for CEνNS at the reactor site.

Piecewise-linear embeddings of decussate extended θ graphs and tetrahedra.

An nθ graph is an n-valent graph with two vertices. From symmetry considerations, it has vertex-edge transitivity 1 1. Here, they are considered extended with divalent vertices added to the edges to explore the simplest piecewise-linear tangled embeddings with straight, non-intersecting edges (sticks). The simplest tangles found are those with 3n sticks, transitivity 2 2, and with 2⌊(n - 1)/2⌋ ambient-anisotopic tangles. The simplest finite and 1-, 2- and 3-periodic decussate structures (links and tangles) are described. These include finite cubic and icosahedral and 1- and 3-periodic links, all with minimal transitivity. The paper also presents the simplest tangles of extended tetrahedra and their linkages to form periodic polycatenanes. A vertex- and edge-transitive embedding of a tangled srs net with tangled and polycatenated θ graphs and vertex-transitive tangled diamond (dia) nets are described.

Environmental DNA (eDNA) detects temporal and habitat effects on community composition and endangered species in ephemeral ecosystems: A case study in vernal pools

AbstractVernal pools are temporary wetlands that can form during a rainy season, often in Mediterranean climates, and serve as ideal testing grounds to understand species detection using eDNA and how biological communities may shift across time and spatial and environmental heterogeneity. Most vernal pools exhibit high plant and animal diversity and endemism, but due to their ephemeral nature, they are understudied, especially their microorganisms. Habitat destruction and fragmentation creates an urgent need to monitor their biodiversity, but traditional species surveys require time and taxonomic expertise. We conducted a community science‐enabled examination of soil environmental DNA (eDNA) in California's Great Central Valley and assessed the capacity of eDNA to aid biomonitoring. We used metabarcoding of16S,ITS1,CO1,18S, andITS2marker regions to quantify and compare differences in pool communities across two sampling periods (during years with disparate precipitation) and to estimate variation among pools and inundation zones (vernal pool bottom, transitional edge, and grassland upland). We found differences in beta diversity among sampling periods, pools, and inundation zones; alpha diversity was mainly affected by sampling period and zone, but this differed by marker. Numerous taxonomic families varied in abundance and composition among samples, yet vernal pool communities remained distinct from upland grass communities, even between sampling periods differing by 1 year. Turnover in ecologically co‐occurring taxon pairs varied by over 90% between sampling periods in all metabarcodes but plants, which were more stable. Finally, we confirmed substantial concordance between eDNA and traditional inventories of the reserve's plants and presented a case in which we detected one endangered plant species, Colusa grass (Neostapfia colusana), in advance of its emergence. This initial study adds hundreds of new taxon records for California vernal pools and discusses benefits and challenges of using eDNA for biomonitoring within stressful, temporary, or otherwise challenging ecosystems.

The TES detector of the ALPS II experiment

The Any Light Particle Search II (ALPS II) experiment is a Light-Shining-through-a-Wall experiment under construction at DESY, Hamburg. Its goal is to probe the existence of Axion Like Particles (ALPs), a possible candidate for dark matter. The expected small rate of reconverted photons requires a sensor capable of measuring low-energetic photons (1.165 eV) with high efficiency and a low dark count rate. A first science run in 2022 will be based on a heterodyne detection scheme. For a second run, a Transition Edge Sensor (TES) system is envisioned as a photon-counting detector. The TES reacts to the change in temperature produced by the absorption of a single photon by operating in the transition between the superconducting and normal conducting phases. Due to its high sensitivity, the TES is susceptible to the influence of electronic noise and background events. In this work, we perform analyses in time and frequency domain and compare these results with simulations to understand the detector’s energy resolution. The setup of the TES is presented, along with the proposed design to measure its efficiency and linearity.

Study on the repair parameters for trailing‐edge bonding failure of wind turbine blade in service

AbstractA numerical analysis method of trailing edge deboning is proposed in this paper. Using this method, multiple repair parameters can be quantified by analyzing aerodynamic responses and structural characteristics of the trailing edge. This method can be applied to three types of trailing edge, including blunt trailing edge, transitional trailing edge, and pointed trailing edge. In this study, the repair parameters are divided into two types, including the internal parameters that can affect the bonding strength and the external parameters that can affect the stiffness and aerodynamic shape. The main research steps are as follows: First, a repair structure shell‐body model was developed. Second, static tensile tests were carried out using 49 specimens, covering two lap joint types and seven bonding thicknesses. Finally, nine different repaired trailing edge models were developed using Ansys/Fluent for each two two‐dimensional airfoil. A 30–40 m section of a 71 m blade was used to develop a three‐dimensional (3D) rotating model with the repaired trailing edge. The simulation results show that the two internal parameters, overlap length and the slope of adhesive joints, are the key to improving the bonding performance of the pointed trailing edge. In addition, the bonding thickness range of 1–10 mm is proved by the experiment results and numerical analysis to be sufficient for good bonding performance. Besides this, the influence of the repair height on the aerodynamic pressure distribution and lift coefficient is much greater than the repair width, and the torque and power of the repaired 3D blade model are 1.91% higher than that of the original blade. This should further help provide an effective theoretical basis for determining the repair plan for a wind turbine blade.

Low Noise Frequency-Domain Multiplexing of TES Bolometers Using SQUIDs at Sub-Kelvin Temperature

Digital Frequency-Domain Multiplexing (DfMux) is a technique that uses MHz superconducting resonators and Superconducting Quantum Interference Device (SQUID) arrays to read out sets of transition edge sensors. DfMux has been used by several Cosmic Microwave Background experiments, including most recently POLARBEAR-2 and SPT-3 G with multiplexing factors as high as 68, and is the baseline readout technology for the planned satellite mission LiteBIRD. Here, we present recent work focused on improving DfMux readout noise, reducing parasitic impedance, and improving sensor operation. We have achieved a substantial reduction in stray impedance by integrating the sensors, resonators, and SQUID array onto a single-carrier board operated at 250 mK. This also drastically simplifies the packaging of the cryogenic components and leads to better-controlled crosstalk. We demonstrate a low readout noise level of 8.6 mathrm{pA/Hz}1^{1/2}, which was made possible by operating the SQUID array at a reduced temperature and with a low dynamic impedance. This is a factor of two improvement compared to the achieved readout noise level in currently operating Cosmic Microwave Background experiments using DfMux and represents a critical step toward maturation of the technology for the next generation of instruments.

First measurements of remoTES cryogenic calorimeters: Easy-to-fabricate particle detectors for a wide choice of target materials

Low-temperature calorimeters based on a readout via Transition Edge Sensors (TESs) and operated below 100mK are well suited for rare event searches with outstanding resolution and low thresholds. We present first experimental results from two detector prototypes using a novel design of the thermometer coupling denoted remoTES, which further extends the applicability of the TES technology by including a wider class of potential absorber materials. In particular, this design facilitates the use of materials whose physical and chemical properties, as e.g. hygroscopicity, low hardness and low melting point, prevent the direct fabrication of the TES onto their surface. This is especially relevant in the context of the COSINUS experiment (Cryogenic Observatory for SIgnals seen in Next-Generation Underground Searches), where sodium iodide (NaI) is used as absorber material.With two remoTES detector prototypes operated in an above-ground R&D facility, we achieve baseline energy resolutions of σ=87.8eV for a 2.33g silicon absorber and σ=193.5eV for a 2.27g α-TeO2 absorber, respectively. RemoTES calorimeters offer – besides the wider choice of absorber materials – a simpler production process combined with a higher reproducibility for large detector arrays.

Device Parameters Based Analytical Modeling of Ground-Bounce Induced Jitter in CMOS Inverters

This article presents an analytical approach to estimate jitter in CMOS inverters in the presence of ground-bounce noise (GBN). The relationships between output and input, considering the effect of ground noise, are derived in terms of device parameters for modeling the timing variations. The deviation of each transition edge from the ideal transition edge is modeled using analytical equations to obtain peak-to-peak ground noise induced jitter. To examine the proposed modeling, five case studies are considered for covering the time domain as well as frequency domain estimations. The results obtained using the proposed methodology have a close match with those obtained from the simulations using the electronic design automation (EDA) tool. To claim the independence of proposed modeling with respect to a particular technology, the results are verified at 40, 65, and 180 nm technology nodes of United Microelectronics Corporation (UMC).

Search for sub-GeV dark matter via the Migdal effect with an EDELWEISS germanium detector with NbSi transition-edge sensors

The EDELWEISS collaboration reports on the search for Dark Matter (DM) particle interactions via Migdal effect with masses between $32$ MeV$\cdot$c$^{-2}$ to $2$ GeV$\cdot$c$^{-2}$ using a $200$ g cryogenic Ge detector sensitive to simultaneously heat and ionization signals and operated underground at the Laboratoire Souterrain de Modane in France. The phonon signal was read out using a Transition Edge Sensor made of a NbSi thin film. The detector was biased at $66$ V in order to benefit from the Neganov-Trofimov-Luke amplification and resulting in a resolution on the energy of electron recoils of $4.46$ eV$_{ee}$ (RMS) and an analysis threshold of $30$ eV$_{ee}$. The sensitivity is limited by a dominant background not associated to charge creation in the detector. The search constrains a new region of parameter space for cross-sections down to $10^{-29}$ cm$^2$ and masses between $32$ and $100$ MeV$\cdot$c$^{-2}$. The achieved low threshold with the NbSi sensor shows the relevance of its use for athermal-phonon sensitive devices for low-mass DM searches.

Modeling a Three-Stage SQUID System in Space with the First Micro-X Sounding Rocket Flight

The Micro-X sounding rocket is a NASA funded X-ray telescope payload that completed its first flight on July 22, 2018. This event marked the first operation of Transition Edge Sensors (TESs) and their SQUID-based multiplexing readout system in space. Unfortunately, due to an ACS pointing failure, the rocket was spinning during its five minute observation period and no scientific data was collected. However, data collected from the internal calibration source marked a partial success for the payload and offers a unique opportunity to study the response of TESs and SQUIDs in space. Of particular interest is the magnetic field response of the NIST MUX06a SQUID readout system to tumbling through Earth's magnetic field. We present a model to explain the baseline response of the SQUIDs, which lead to a subset of pixels failing to "lock" for the full observational period. Future flights of the Micro-X rocket will include the NIST MUX18b SQUID system with dramatically reduced magnetic susceptibility.

Gamma-Ray Spectroscopy for $$^{237}$$Np Using a Transition-Edge Sensor with a Thick-Trilayer Membrane

AbstractGamma-ray transition edge sensors (TESs) are intensively studied not only to measure isotopic composition of nuclear materials but to monitor transuranic radionuclides inside the human body. We have recently proposed a thick-trilayer membrane as an alternative to silicon-nitride (Si$$_{x}$$ x N$$_{y}$$ y ) single-layer ones. It consists of silicon dioxide (SiO$$_2$$ 2 ), Si$$_{x}$$ x N$$_{y}$$ y , and SiO$$_2$$ 2 layers. Their total thickness is 6.9 $$\upmu $$ μ m and exhibits almost the same thermal conductance as conventional Si$$_{x}$$ x N$$_{y}$$ y ones with 1-$$\upmu $$ μ m thickness. The thick-trilayer membrane is expected to have better mechanical strength against implementing heavy-bulk absorbers. In this paper, the gamma-ray TES with the thick-trilayer membrane is used to carry out the spectroscopy for the nuclear radiation source. Neptunium-237 and its decay product Protactinium-233 emit 86.5 and 86.6-keV lines, respectively, and they are clearly resolved by four pixels with the full-width-half-maximum (FWHM) resolution of ($$43.7\pm 0.9$$ 43.7 ± 0.9 ) eV. Furthermore, their intensity ratio agrees with the radioactive equilibrium between the two nuclides. Our experimental results predict that a vast array of pixel formats will reduce the statistical uncertainty in less measuring time.

AP Shadow Net: A Remote Sensing Shadow Removal Network Based on Atmospheric Transport and Poisson's Equation.

Shadow is one of the fundamental indicators of remote sensing image which could cause loss or interference of the target data. As a result, the detection and removal of shadow has already been the hotspot of current study because of the complicated background information. In the following passage, a model combining the Atmospheric Transport Model (hereinafter abbreviated as ATM) with the Poisson Equation, AP ShadowNet, is proposed for the shadow detection and removal of remote sensing images by unsupervised learning. This network based on a preprocessing network based on ATM, A Net, and a network based on the Poisson Equation, P Net. Firstly, corresponding mapping between shadow and unshaded area is generated by the ATM. The brightened image will then enter the Confrontation identification in the P Net. Lastly, the reconstructed image is optimized on color consistency and edge transition by Poisson Equation. At present, most shadow removal models based on neural networks are significantly data-driven. Fortunately, by the model in this passage, the unsupervised shadow detection and removal could be released from the data source restrictions from the remote sensing images themselves. By verifying the shadow removal on our model, the result shows a satisfying effect from a both qualitative and quantitative angle. From a qualitative point of view, our results have a prominent effect on tone consistency and removal of detailed shadows. From the quantitative point of view, we adopt the non-reference evaluation indicators: gradient structure similarity (NRSS) and Natural Image Quality Evaluator (NIQE). Combining various evaluation factors such as reasoning speed and memory occupation, it shows that it is outstanding among other current algorithms.

A Testbed for Modeling Validation and Characterization of Quasi-optical Elements in Microwave Receivers

We describe the setup for the broadband millimeter/submillimeter characterization of the quasi-optical elements and the dielectric materials commonly used in microwave receivers operated in microwave astronomy. The setup is made of a large aperture (100 mm) Fourier transform spectrometer coupled to a transition edge superconducting detector. The system has been assembled and characterized in different configurations and operation modes for the acquisition of interferograms from various kinds of samples. After the initial test runs, the configuration is now being updated to ensure a broader range of measurements, including reflectance and scattering. We plan to first use this testbed for the characterization of the dielectric materials used in the LSPE/SWIPE experiment, devoted to the study the polarization of the Cosmic Microwave Background.

Operation of an Archaeological Lead PbWO_4 Crystal to Search for Neutrinos from Astrophysical Sources with a Transition Edge Sensor

The experimental detection of the CEnuNS allows the investigation of neutrinos and neutrino sources with all-flavor sensitivity. Given its large content in neutrons and stability, Pb is a very appealing choice as target element. The presence of the radioisotope ^{210}Pb (T_{1/2}sim22 yrs) makes natural Pb unsuitable for low-background, low-energy event searches. This limitation can be overcome employing Pb of archaeological origin, where several half-lives of ^{210}Pb have gone by. We present results of a cryogenic measurement of a 15 g PbWO_4 crystal, grown with archaeological Pb (older than sim2000 yrs) that achieved a sub-keV nuclear recoil detection threshold. A ton-scale experiment employing such material, with a detection threshold for nuclear recoils of just 1 keV would probe the entire Milky Way for SuperNovae, with equal sensitivity for all neutrino flavors, allowing the study of the core of such exceptional events.

Distance–transitive digraphs: Descendant-homogeneity, property [formula omitted] and reachability

A digraph is distance–transitive if for every integer s≥0, the automorphism group of the digraph is transitive on pairs (u,v) of vertices for which there is a directed path of length s from u to v, but no directed path of length t<s. This implies vertex and edge transitivity but is weaker than being highly-arc-transitive. A digraph is said to have property Z if it has a homomorphism onto the two-way infinite directed path. In a digraph D, an edge e′ is reachable from an edge e if there exists an alternating walk in D whose initial and terminal edges are e and e′. Reachability is an equivalence relation on the edge set of D and if D is transitive on edges, then this relation is either universal or all of its equivalence classes induce isomorphic bipartite digraphs.We investigate the class of infinite distance–transitive digraphs of finite out-valency. First, we show that earlier results, proved in the context of highly-arc-transitive digraphs, hold for the class of distance–transitive digraphs. Second, we show that if D is a weakly descendant–homogeneous digraph in our class then either (1) D has property Z and the reachability relation is not universal; or (2) D does not have property Z, the reachability relation is universal and D has infinite in-valency. Finally, we describe some distance–transitive, weakly descendant–homogeneous digraphs for which the reachability relation is not universal.

Mitigation of the Magnetic Field Susceptibility of Transition-Edge Sensors Using a Superconducting Groundplane

Transition edge sensor (TES) microcalorimeters and bolometers are used for a variety of applications. The sensors are based on the steep temperature-dependent resistance of the normal-to-superconducting transition, and are thus intrinsically sensitive to magnetic fields. Conventionally the detectors are shielded from stray magnetic fields using external magnetic shields. However, in particular for applications with strict limits on the available space and mass of an instrument, external magnetic shields might not be enough to obtain the required shielding factors or field homogeneity. Additionally, these shields are only effective for magnetic fields generated external to the TES array, and are ineffective to mitigate the impact of internally generated magnetic fields. Here we present an alternative shielding method based on a superconducting groundplane deposited directly on the backside of the silicon nitride membrane on which the TESs are located. We demonstrate that this local shielding for external magnetic fields has a shielding factor of at the least ~ 75, and is also effective at reducing internal self-induced magnetic fields, as demonstrated by measurements and simulation of the eddy current losses in our AC biased detectors. Measurements of 5.9 keV X-ray photons show that our shielded detectors have a high resilience to external magnetic fields, showing no degradation of the energy resolution or shifts of the energy scale calibration for fields of several microTesla, values higher than expected in typical real-world applications.