Transition Edge Sensor Detectors Research Articles

Background studies for the HOLMES experiment

Determining the mass of neutrinos is one of the most compelling topics in particle physics. HOLMES, an experiment for a direct measurement of the neutrino mass, is addressing this subject through a calorimetric approach, exploiting arrays of Low-Temperature Transition-Edge Sensor Detectors (TESs) loaded with 163\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{163}$$\\end{document}Ho. The experiment has entered its first phase in 2023, implanting approximately 1 Bq per pixel in an array of 64 detectors. In this work, I present the measurement made before this stage, in order to determine the expected background arising from natural radioactivity and cosmic rays. The significance of this background depends on the activity per pixel, which has yet to be defined based on the result of the first phase.

Design and Fabrication of Two-stage SQUID for Transition Edge Sensor

The X-ray transition edge sensor (TES) modeled by calorimeter is extremely sensitive to temperature changes when operating at a voltage bias in the temperature region, and is widely used for the detection of particles and photons from submicron frequency to gamma rays. Superconducting quantum interference device (SQUID) is the key to TES current signal readout, we have designed a two-stage SQUID amplifier circuit. First-stage sensor SQUID uses first-grade gradiometer with high input mutual inductance about 176.2 , it increases the coupling sensitivity with the TES detector and has stronger resistance to external interference. Second-stage SQUID array(SSA) adopts 32 single SQUIDs in series, which has low magnetic flux noise and high magnification. We have verified the characteristics of this two-stage circuit and demonstrated that it has a lower magnetic flux noise.

Event Detection and Reconstruction Using Neural Networks in TES Devices: a Case Study for Athena/X-IFU

Transition Edge Sensors detector devices, like the core of the X-IFU instrument that will be on-board the Athena X-ray Observatory, produce current pulses as a response to the incident X-ray photons. The reconstruction of these pulses has been traditionally performed by means of a triggering algorithm based on the derivative signal overcoming a threshold (detection) followed by an optimal filtering (to retrieve the energy of each event). However, when the arrival of the photons is very close in time, the triggering algorithm is incapable of detecting all the individual pulses which are thus piled-up. In order to improve the efficiency of the detection and energy-retrieval process, we study here an alternative approach based on Machine Learning techniques to process the pulses. For this purpose, we construct and train a series of Neural Networks (NNs) not only for the detection but also for the recovering of the arrival time and the energy of simulated X-ray pulses. The data set used to train the NNs consists of simulations performed with the sixte/xifusim software package, the Athena/X-IFU official simulator. The performance of our NN classification clearly surpasses the detection performance of the classical triggering approach for the full range of photon energy combinations, showing excellent metrics and very competitive computing efficiency. However, the precision obtained for the recovery of the energy of the photons cannot currently compete with the standard optimal filtering algorithm, despite its much better computing efficiency.

Direct Search for Low Energy Nuclear Isomeric Transition of Th-229m With TES Detector

Precise knowledge of the energy and lifetime of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state has notable importance as a basis for a nuclear clock. Such a clock would be capable to extend precision on the oscillator frequency by up to four orders of magnitude compared to the presently best atomic clocks. However, the technique proposed for the clock requires that the isomeric state energy is accessible with existing laser systems. Previous measurement placed this state at ∼8 eV (150 nm), in the Vacuum Ultra Violet (VUV) range of the electromagnetic spectrum. A precise direct measurement of the energy of this state is necessary to determine whether the nuclear clock can be made using existing laser technology. We are developing a cryogenic microcalorimeter to measure the energy and lifetime of the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state directly. The experiment will use a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">233</sup> U source whose alpha-decay will populate the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state with 2% probability. The subsequent decay of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th will be measured by a Transition Edge Sensor (TES) with <1 eV resolution. Such a technique will allow to observe all possible types of decays of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th in the range of energy from 3 to 50 eV and lifetimes >5 microseconds. The single-photon TES has sufficient resolving power combined with high efficiency in the whole energy band for this experiment. Here we present a prototype of TES based on a 200 nm thick iridium-gold (Ir/Au) film which was tested with a pulsed laser source and demonstrated ∼0.8 eV energy resolution and 5.8 ± 2.1 μs signal recovery time.

A second-order gradiometric superconducting quantum interference device current sensor with cross-coupled structure

Superconducting quantum interference device (SQUID) has extremely high magnetic field sensitivity, current sensitivity, and can detect a low-noise weak current signal. The SQUID current sensor has become the only option of the readout of low-noise detector, such as transition-edge sensor (TES). In this paper, a second-order gradiometric cross-coupled SQUID current sensor for TES application is developed. According to the requirements for TES detectors, the structure and various parameters of SQUID current sensor are designed. The SQUID loop, input coil and feedback coil of the SQUID current sensor all use the second-order gradiometric structure. All the couple ways between SQUID loop and input coil or feedback coil adopt cross-coupling mode in different planes, which can effectively weaken the parasitic capacitance. A second-order gradiometric cross-coupled SQUID current sensor based on Nb/Al-AlO&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;/Nb Josephson junction is successfully fabricated on a silicon wafer by optimizing the process. The properties of the second-order gradiometric cross-coupled SQUID current sensor are measured at liquid helium temperature. The bias current of SQUID is 215 μA when the modulation depth of &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;Φ&lt;/i&gt; modulation curve is maximum. The maximum modulation peak of SQUID is 31 μV. The flux-to-voltage transfer coefficient of SQUID is 108 μV/&lt;i&gt;Φ&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;. The input coil current sensitivity is 17 μA/&lt;i&gt;Φ&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;, the mutual inductance between SQUID loop and input coil is 117 pH. The current sensitivity of feedback coil is 86 μA/&lt;i&gt;Φ&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;, the mutual inductance between SQUID loop and feedback coil is 23 pH. The second-order gradiometric cross-coupled SQUID current sensor has a white flux noise of 2 μ&lt;i&gt;Φ&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/&lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$ \sqrt{{\rm{H}}{\rm{z}}} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20201816_M3.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20201816_M3.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; and a white current noise of 34 pA/&lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$ \sqrt{{\rm{H}}{\rm{z}}} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20201816_M4.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20201816_M4.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; with 1/&lt;i&gt;f&lt;/i&gt; corner frequency around 200 Hz. The result of noise level under the condition without magnetic shielding shows that the SQUID current sensor with second-order gradiometric cross-coupled structure has an excellent capability of weakening the environmental electromagnetic interference. In the future, we will further improve the mutual inductance of the second-order gradiometric cross-coupled SQUID current sensor between SQUID loop and input coil, optimize the size and critical current of Josephson junction, in order to improve the input sensitivity of SQUID device, reduce the current noise level and the 1/&lt;i&gt;f&lt;/i&gt; corner frequency, and meet more requirements for TES applications.

Electroplated Tin Absorbers in Microcalorimeter Detectors for Ionizing Radiation

State-of-the-art microcalorimeter gamma-ray detectors 1, 2 show promise for nuclear material characterization because their spectral resolution is substantially better than high purity germanium sensors. Microcalorimeter detectors have been fabricated and tested by National Institute of Standards and Technology (NIST) and Los Alamos National Laboratory (LANL) by combining microfabricated transition edge sensors (TESs) with bulk tin gamma-ray absorbers. The ability to integrate the tin electroplating into the microfabrication process has potential benefits for performance, scalability, reliability, and ease of manufacturing.This work investigates a commercially available tin/silver chemistry traditionally used for 3-D semiconductor packaging. Samples were electroplated on a sacrificial substrate changing chemistry makeup, current density, and time to realize pure tin deposition at thicknesses of 380-400 micron. Characterization was performed using SEM, EDS, XRF, and XPS and compared to bulk tin properties used in past microcalorimeter devices. The electroplated tin samples were diced into individual 1.3x1.3 mm sizes and integrated with TES detectors at NIST and LANL. The assembled devices were tested with gamma radiation sources to evaluate performance. This work will provide an overview of the project, current progress, and future ideas for realizing a fully integrated microcalorimeter fabrication process. D. A. Bennett, R. D. Horansky, D. R. Schmidt, A. S. Hoover, R. Winkler, B. K. Alpert, J. A. Beall, W. B. Doriese, J. W. Fowler, C. P. Fitzgerald, G. C. Hilton, K. D. Irwin, V. Kotsubo, J. A. B. Mates, G. C. O'Neil, M. W. Rabin, C. D. Reintsema, F. J. Schima, D. S. Swetz, L. R. Vale, and J. N. Ullom, Rev Sci Instrum, 83 (9), (2012).D. T. Becker, B. K. Alpert, D. A. Bennett, M. P. Croce, J. W. Fowler, J. D. Gard, A. S. Hoover, Y. I. Joe, K. E. Koehler, J. A. B. Mates, G. C. O'Neil, M. W. Rabin, C. D. Reintsema, D. R. Schmidt, D. S. Swetz, P. Szypryt, L. R. Vale, A. L. Wessels, and J. N. Ullom, Ieee T Nucl Sci, 66 (12), 2355-2363 (2019). Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525, SAND2020-5481 A . The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Resonant Soft X-Ray Scattering from Stripe-Ordered La2−xBaxCuO4 Detected by a Transition-Edge Sensor Array Detector

Resonant soft x-ray scattering (RSXS) is a leading probe of valence band order in materials best known for detecting charge density wave order in the copper-oxide superconductors. One of the biggest limitations on the RSXS technique is the presence of a severe fluorescence background which, like the RSXS cross section itself, is enhanced under resonant conditions. This background prevents the study of weak signals such as diffuse scattering from glassy or fluctuating order that is spread widely over momentum space. Recent advances in superconducting transition edge sensor (TES) detectors have led to major improvements in energy resolution and detection efficiency in the soft x-ray range. Here, we perform a RSXS study of stripe-ordered La$_{2-x}$Ba$_x$CuO$_4$ at the Cu $L_{3/2}$ edge (932.2 eV) using a TES detector with 1.5 eV resolution, to evaluate its utility for mitigating the fluorescence background problem. We find that, for suitable degree of detuning from the resonance, the TES rejects the fluorescence background, leading to a 5 to 10 times improvement in the statistical quality of the data compared to an equivalent, energy-integrated measurement. We conclude that a TES presents a promising approach to reducing background in RSXS studies and may lead to new discoveries in materials exhibiting valence band order that is fluctuating or glassy.

Study of TES Detector Transition Curve to Optimize the Pixel Design for Frequency-Division Multiplexing Readout

Superconducting transition-edge sensors (TESs) are highly sensitive detectors. Based on the outstanding performance on spectral resolution, the X-ray integral field unit (X-IFU) instrument on-board athena will be equipped with a large array of TES-based microcalorimeters. For optimal performance in terms of the energy resolution, it is essential to limit undesirable nonlinearity effects in the TES detector. Weak-link behavior induced on the TES by superconducting leads is such a nonlinearity effect. We designed and fabricated smart test structures to study the effect of the superconducting leads on the intrinsic transition curve of our TiAu-based TES bilayer. We measured and analyzed the resistance versus temperature transition curves of the test structures. We found relations of long-distance proximity effects with TES length and different lead materials. Based on these results, we can redesign and further optimize our TES-based X-ray detectors.

Optical Characterization of the Keck Array and BICEP3 CMB Polarimeters from 2016 to 2019

The BICEP/Keck experiment (BK) is a series of small-aperture refracting telescopes observing degree-scale Cosmic Microwave Background (CMB) polarization from the South Pole in search of a primordial $B$-mode signature. This $B$-mode signal arises from primordial gravitational waves interacting with the CMB, and has amplitude parametrized by the tensor-to-scalar ratio $r$. Since 2016, BICEP3 and the Keck Array have been observing with 4800 total antenna-coupled transition-edge sensor detectors, with frequency bands spanning 95, 150, 220, and 270 GHz. Here we present the optical performance of these receivers from 2016 to 2019, including far-field beams measured in situ with an improved chopped thermal source and instrument spectral response measured with a field-deployable Fourier Transform Spectrometer. As a pair differencing experiment, an important systematic that must be controlled is the differential beam response between the co-located, orthogonally polarized detectors. We generate per-detector far-field beam maps and the corresponding differential beam mismatch that is used to estimate the temperature-to-polarization leakage in our CMB maps and to give feedback on detector and optics fabrication. The differential beam parameters presented here were estimated using improved low-level beam map analysis techniques, including efficient removal of non-Gaussian noise as well as improved spatial masking. These techniques help minimize systematic uncertainty in the beam analysis, with the goal of constraining the bias on $r$ induced by temperature-to-polarization leakage to be subdominant to the statistical uncertainty. This is essential as we progress to higher detector counts in the next generation of CMB experiments.

LiteBIRD Cryogenic Chain: 100 mK Cooling with Mechanical Coolers and ADRs

LiteBIRD is a JAXA-led L-Class mission aimed at the study of B-mode polarization of the cosmic microwave background. Measurements on 15 bandwidth from 34 to 448 GHz are made on two instruments, low-frequency telescope and medium- and high-frequency telescope. To reach the desired sensitivities, more than 4500 transition edge sensors detectors, used on both instruments, will be continuously cooled to 100 mK. The cryogenic design based on shield cooling and mechanical coolers is presented in this paper. Shield cooling will be done with passive cooling and 15 K pulse tube coolers. A single cryogenic chain will cool both instruments. A 4 K stage is cooled by a 4He Joule–Thomson cooler from Japanese Aerospace Exploration Agency, pre-cooled by Stirling coolers. Multistage adiabatic demagnetization refrigerator will be optimized to provide continuous cooling at 1.75 K, 300 mK and 100 mK with 2.2 µW of cooling power on the latter stage. Seven ADR stages provided by NASA (USA) and CEA (France) are required. Details on the thermal design, preliminary sizing and expected performance are presented.

A finite element simulation of transition-edge sensor for measuring kinetic energy of fission fragments

It is necessary to accurately measure the kinetic energy of fission fragments when using the Time-Of-Flight method to determine the mass of fission fragments. The ionization chamber and the Au-Si surface barrier detector are conventional kinetic-energy detectors, but their energy resolution is not sufficient to achieve a mass resolution of 1 amu. The Transition-Edge Sensor (TES) is a cryogenic calorimeter that can be used to measure the kinetic energy by measuring the temperature variation induced by the energy of the incident particle, with a typical resolution of 0.02% of TES detector can be achieved[1]. In this article, we designed a TES to measure the kinetic energy of fission fragments, and the signals of this TES with different incident particle positions, kinetic energy, and thermal conductivity were simulated using ANSYS. Therefore, we verified the feasibility of the TES and improved the count rate of the TES to 100cps.

Commercially Fabricated Low Loss Superconducting Resonators Integrated With Detectors for Frequency Domain Multiplexing Readout of Future Cosmic Microwave Background Experiments

Planned Stage-IV cosmic microwave background (CMB) experiments call for telescopes with the order of 500 000 transition edge sensor (TES) bolometers. Such large arrays would benefit from detector multiplexing, as well as miniaturization and integration of readout components. In addition, fabrication of micro-fabricated devices at a commercial foundry could potentially boost production rate and reduce overall cost. To this end, HYPRES, Inc., LBNL, and U.C. Berkeley are developing low loss, superconducting LC resonators integrated with antenna coupled TES bolometers for frequency multiplexing readout. The resonators are fabricated on the same wafer and are in the same process flow as the TES detectors, reducing size, weight, and wiring complexity of a detector module compared to the conventional design, where each component is fabricated separately. We have fabricated and tested resonators from 0.6 to 70 MHz, both as standalone devices and integrated with TES bolometers, all fabricated on 150- mm wafers. We discuss the design and fabrication of these devices and present measurements of the standalone resonators.

Probing primordial gravitational waves: Ali CMB Polarization Telescope.

In this paper, we will give a general introduction to the Ali CMB Polarization Telescope (AliCPT) project, which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background (CMB) polarization experiment in China and an integral part of China's Gravitational-wave Program. The main scientific goal of the AliCPT project is to probe the primordial gravitational waves (PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope (AliCPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years' observation. Besides the PGWs, AliCPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years' observation will improve the current limit by two orders of magnitude.

Parametric Characterization of TES Detectors Under DC Bias

The X-ray integrated field unit (X-IFU) in European Space Agency's (ESA's) Athena mission will be the first high-resolution X-ray spectrometer in space using a large-format transition-edge sensor microcalorimeter array. Motivated by optimization of detector performance for X-IFU, we have conducted an extensive campaign of parametric characterization on transition-edge sensor (TES) detectors with nominal geometries and physical properties in order to establish sensitivity trends relative to magnetic field, dc bias on detectors, operating temperature, and to improve our understanding of detector behavior relative to its fundamental properties such as thermal conductivity, heat capacity, and transition temperature. These results were used for validation of a simple linear detector model in which a small perturbation can be introduced to one or multiple parameters to estimate the error budget for X-IFU. We will show here results of our parametric characterization of TES detectors and briefly discuss the comparison with the TES model.

Development of microwave-multiplexed superconductive detectors for the HOLMES experiment

In recent years, the progress on low temperature detector technologies has allowed design of large scale experiments aiming at pushing down the sensitivity on the neutrino mass below 1 eV. Even with outstanding performances in both energy (~eV on keV) and time resolution (~ 1 μs) on the single channel, a large number of detectors working in parallel is required to reach a sub-eV sensitivity. HOLMES is a new experiment to directly measure the neutrino mass with a sensitivity as low as 2eV. HOLMES will perform a calorimetric measurement of the energy released in the electron capture (EC) decay of 163 Ho. In its final configuration, HOLMES will deploy 1000 detectors of low temperature microcalorimeters with implanted 163 Ho nuclei. The baseline sensors for HOLMES are Mo/Cu TESs (Transition Edge Sensors) on SiNx membrane with gold absorbers. The readout is based on the use of rf-SQUIDs as input devices with flux ramp modulation for linearization purposes; the rf-SQUID is then coupled to a superconducting lambda/4-wave resonator in the GHz range, and the modulated signal is finally read out using the homodyne technique. The TES detectors have been designed with the aim of achieving an energy resolution of a few eV at the spectrum endpoint and a time resolution of a few micro-seconds, in order to minimize pile-up artifacts.

Development of the Next Generation of Multi-chroic Antenna-Coupled Transition Edge Sensor Detectors for CMB Polarimetry

We present the development of the next generation of multi-chroic sinuous antenna-coupled transition edge sensor (TES) bolometers optimized for precision measurements of polarization of the cosmic microwave background (CMB) and cosmic foreground. These devices employ a polarization sensitive broadband self-complementary sinuous antenna to feed on-chip band defining filters before delivering the power to load resistors coupled to a TES on a released bolometer island. This technology was originally developed by UC Berkeley and will be deployed by POLARBEAR-2 and SPT-3G in the next year and half. In addition, it is a candidate detector for the LiteBIRD mission which will make all sky CMB and cosmic foreground polarization observations from a satellite platform in the early 2020’s. This works focuses on expanding both the bandwidth and band count per pixel of this technology in order to meet the needs of future CMB missions. This work demonstrates that these devices are well suited for observations between 20 and 380 GHz. This proceeding describes the design, fabrication, and the characterization of three new pixel types: a low-frequency triplexing pixel (LFTP) with bands centered on 40, 60, and 90 GHz, a high-frequency triplexing pixel (HFTP) with bands centered on 220, 280, and 350 GHz, and a mid-frequency tetraplexing pixel with bands (MFTP) centered on 90, 150, 220, and 280 GHz. The average fractional bandwidth of these pixels designs was 36.7, 34.5, and 31.4 % respectively. In addition we found that the polarization modulation efficiency of each band was between 1 and 3 % which is consistent with the polarization efficiency of the wire grid used to take the measurement. Finally, we find that the beams have $${\sim }$$ 1 % ellipticity for each pixel type. The thermal properties of the bolometers where tuned for characterization in our lab so we do not report on G and noise values as they would be unsuitable for modern CMB experiments.

Fabrication of Low-Noise TES Arrays for the SAFARI Instrument on SPICA

Ultra-low-noise transition edge sensors (TES) with noise equivalent power lower than 2 $$\times $$ 10 $$^{-19}$$ W/Hz $$^{1/2 }$$ have been fabricated by SRON, which meet the sensitivity requirements for the far-infrared SAFARI instrument on space infrared telescope for cosmology and astrophysics. Our TES detector is based on a titanium/gold (Ti/Au) thermistor on a silicon nitride (SiN) island. The island is thermally linked with SiN legs to a silicon support structure at the bath temperature. The SiN legs are very thin (250 nm), narrow (500 nm), and long (above 300 $${\upmu } $$ m); these dimensions are needed in leg-isolated bolometers to achieve the required level of sensitivity. In this paper, we describe the latest fabrication process for our TES bolometers with improved sensitivity.

Design and Fabrication of TES Detector Modules for the TIME-Pilot [CII] Intensity Mapping Experiment

We are developing a series of close-packed modular detector arrays for TIME-Pilot, a new mm-wavelength grating spectrometer array that will map the intensity fluctuations of the redshifted 157.7 μm emission line of singly ionized carbon ([CII]) from redshift z∼5 to 9. TIME-Pilot’s two banks of 16 parallel-plate waveguide spectrometers (one bank per polarization) will have a spectral range of 183–326 GHz and a resolving power of R∼100. The spectrometers use a curved diffraction grating to disperse and focus the light on a series of output arcs, each sampled by 60 transition edge sensor (TES) bolometers with gold micro-mesh absorbers. These low-noise detectors will be operated from a 250 mK base temperature and are designed to have a background-limited NEP of ∼10^(−17) W/Hz^(1/2). This proceeding presents an overview of the detector design in the context of the TIME-Pilot instrument. Additionally, a prototype detector module produced at the Microdevices Laboratory at JPL is shown.

Tomography of photon-number resolving continuous-output detectors

We report a comprehensive approach to analysing continuous-output photon detectors. We employ principal component analysis to maximize the information extracted from output signals, followed by a novel noise-tolerant parameterized approach to the tomography of photon-number resolving detectors. We further propose a measure for rigorously quantifying a detector’s photon-number-resolving capability. Our approach applies to all detectors with continuous-output signals. We illustrate our methods by applying them to experimental data obtained from a transition-edge sensor detector.

Application of optimum digital filter based on genetic algorithms for transition edge sensor detector

We propose a new signal processing method to improve the energy resolution of superconducting tunnel junction X-ray detectors. An optimum FIR (Finite Impulse Response) filter design tool based on fast Fourier transform was developed using genetic algorithms. The fast Fourier transform is perhaps one of the most used algorithms today in the analysis and manipulation of digital or discrete data. The main feature of this tool is that it needs a minimum number of parameters to specify the FIR filter specifications. This tool was applied successfully on transition edge sensor detector.