arXiv subjects

J. A. B. Mates

Publications and source records attributed to J. A. B. Mates.

15 recordsLinked to original sources

arXiv2026

A microwave SQUID multiplexing concept for macro-cryogenic calorimeter arrays

Massive cryogenic calorimeters read out by transition-edge sensors (TES) can reach eV-scale baseline resolution, but the single-channel dc-SQUID readout conventionally used in rare-event searches, with one amplifier chain and several wires per detector, limits practical arrays to a few tens of channels. We propose to apply microwave SQUID multiplexing ($μ$MUX), developed for fast X-ray and neutrino-mass microcalorimeters, to massive BGO (Bi$_4$Ge$_3$O$_{12}$) calorimeters operated at $\simeq 20$~mK; sapphire and TeO$_2$ absorbers are covered by the same framework. Using the established thermal and noise model for massive TES calorimeters, we derive a noise model for the multiplexed readout, including the HEMT, two-level-system and SQUID contributions, and its scaling with the multiplexing factor $N_{\rm mux}$. Since the slow thermal signals require only about a kHz of sampling per channel, the limiting requirement is not bandwidth but an input-coil sensitivity of $( 0.1$ to $1)\,μ$A$/Φ_0$, a factor of $10$ to $30$ beyond current $μ$MUX devices, matched to the detector current noise of ($9$ to $10$)~pA$/\sqrt{\rm Hz}$, which is independent of the absorber mass. With a total flux noise of $\simeq$$1.2\,μΦ_0/\sqrt{\rm Hz}$, the readout degrades the baseline resolution by less than $2\%$ up to $N_{\rm mux}=1000$, negligible compared with the TES-limited resolution. These results are implemented in a single-tower design: 52 BGO crystals of 100~g each and one HEMT amplifier. The tower is the unit of a multi-tower array of several kilograms aimed at CE$ν$NS and dark matter searches.

physics.ins-det↗

arXiv2026

Phenomenological Modeling of the $^{163}$Ho Calorimetric Electron Capture Spectrum from the HOLMES Experiment

We present a comprehensive phenomenological analysis of the calorimetric electron capture (EC) decay spectrum of $^{163}$Ho as measured by the HOLMES experiment. Using high-statistics data, we unfold the instrumental energy resolution from the measured spectrum and model it as a sum of Breit-Wigner resonances and shake-off continua, providing a complete set of parameters for each component. Our approach enables the identification and tentative interpretation of all observed spectral features, including weak and overlapping structures, in terms of atomic de-excitation processes. We compare our phenomenological model with recent ab initio theoretical calculations, finding good agreement for both the main peaks and the spectral tails, despite the limitations of current theoretical and experimental precision. The model delivers an accurate description of the endpoint region, which is crucial for neutrino mass determination, and allows for a realistic treatment of backgrounds such as pile-up and tails of low-energy components. Furthermore, our decomposition facilitates the generation of Monte Carlo toy spectra for sensitivity studies and provides a framework for investigating systematic uncertainties related to solid-state and detector effects. This work establishes a robust foundation for future calorimetric neutrino mass experiments employing $^{163}$Ho, supporting both data analysis and experimental design.

nucl-ex↗

arXiv2025

Demonstration of a 1820 channel multiplexer for transition-edge sensor bolometers

The scalability of most transition-edge sensor arrays is limited by the multiplexing technology which combines their signals over a reduced number of wires and amplifiers. In this Letter, we present and demonstrate a multiplexer design optimized for transition-edge sensor bolometers with 1820 sensors per readout unit, a factor of two more than the previous state-of-the-art. The design is optimized for cosmic microwave background imaging applications, and it builds on previous microwave superconducting quantum interference device multiplexers by doubling the available readout bandwidth to the full 4-8 GHz octave. Evaluating the key performance metrics of yield, sensitivity, and crosstalk through laboratory testing, we find an end-to-end operable detector yield of 78%, a typical nearest-neighbor crosstalk amplitude of ~0.4%, and a median white noise level of 83 pA/rtHz due to the multiplexer, corresponding to an estimated contribution of 4% to the total system noise for a ground-based cosmic microwave background telescope. Additionally, we identify a possible path toward reducing resonator loss for future designs with reduced noise. We expect these developments to alleviate the system complexity, cryogenic requirements, and cost of future large arrays of low temperature detectors.

physics.ins-det↗

arXiv2025

Most stringent bound on electron neutrino mass obtained with a scalable low temperature microcalorimeter array

The determination of the absolute neutrino mass scale remains a fundamental open question in particle physics, with profound implications for both the Standard Model and cosmology. Direct kinematic measurements, independent of model-dependent assumptions, provide the most robust approach to address this challenge. In this Letter, we present the most stringent upper bound on the effective electron neutrino mass ever obtained with a calorimetric measurement of the electron capture decay of $^{163}$Ho. The HOLMES experiment employs an array of ion-implanted transition-edge sensor (TES) microcalorimeters, achieving an average energy resolution of 6 eV FWHM with a scalable, multiplexed readout technique. With a total of $7\times10^7$ decay events recorded over two months and a Bayesian statistical analysis, we derive an upper limit of $m_β<27$ eV/c$^2$ at 90% credibility. These results validate the feasibility of $^{163}$Ho calorimetry for next-generation neutrino mass experiments and demonstrate the potential of a scalable TES-based microcalorimetric technique to push the sensitivity of direct neutrino mass measurements beyond the current state of the art.

hep-ex↗

arXiv2024

New Experimentally Observable Gamma-ray Emissions from 241Am Nuclear Decay

With the high resolution of microcalorimeter detectors, previously unresolvable gamma-ray lines are now clearly resolvable. A careful measurement of Am-241 decay with a large array of gamma-ray microcalorimeters has revealed never before seen or predicted gamma lines at 207.72 +/- 0.02 keV and 208.21 +/- 0.01 keV. These results were made possible by new microwave-multiplexing readout to increase the array size and improved analysis algorithms to eliminate spectral artifacts. We suggest nuclear levels from which these gamma-rays might originate and calculate branching ratios for these transitions from measurements of both mixed Pu-Am standards and a pure Am-241 source. These results have implications for nuclear material safeguards and accounting, particularly for microcalorimeter gamma spectrometers, which are now being adopted in nuclear safeguards analytical laboratories.

nucl-ex↗

arXiv2023

Improved microwave SQUID multiplexer readout using a kinetic-inductance traveling-wave parametric amplifier

We report on the use of a kinetic-inductance traveling-wave parametric amplifier (KITWPA) as the first amplifier in the readout chain of a microwave superconducting quantum interference device (SQUID) multiplexer (umux). This umux is designed to multiplex signals from arrays of low temperature detectors such as superconducting transition-edge sensor microcalorimeters. When modulated with a periodic flux-ramp to linearize the SQUID response, the flux noise improves, on average, from $1.6$ $μΦ_0/\sqrt{\mathrm{Hz}}$ with the KITWPA off, to $0.77$ $μΦ_0/\sqrt{\mathrm{Hz}}$ with the KITWPA on. When statically biasing the umux to the maximally flux-sensitive point, the flux noise drops from $0.45$ $μΦ_0/\sqrt{\mathrm{Hz}}$ to $0.2$ $μΦ_0/\sqrt{\mathrm{Hz}}$. We validate this new readout scheme by coupling a transition-edge sensor microcalorimeter to the umux and detecting background radiation. The combination of umux and KITWPA provides a variety of new capabilities including improved detector sensitivity and more efficient bandwidth utilization.

astro-ph.IM↗

arXiv2022

Signal readout for Transition-Edge Sensor X-ray imaging spectrometers

Arrays of low-temperature microcalorimeters provide a promising technology for X-ray astrophysics: the imaging spectrometer. A camera with at least several thousand pixels, each of which has an energy-resolving power ($E/ΔE\urss{FWHM}$) of a few thousand across a broad energy range (200~eV to 10~keV or higher), would be a revolutionary instrument for the study of energetic astrophysical objects and phenomena. Signal readout is a critical enabling technology. Multiplexed readout, in which signals from multiple pixels are combined into a single amplifier channel, allows a kilo pixel-scale microcalorimeter array to meet the stringent requirements for power consumption, mass, volume, and cooling capacity in orbit. This chapter describes three different multiplexed-readout technologies for transition-edge-sensor microcalorimeters: time-division multiplexing, frequency-domain multiplexing, and microwave-SQUID multiplexing. For each multiplexing technique, we present the basic method, discuss some design considerations and parameters, and show the state of the art. The chapter concludes with a brief discussion of future prospects.

astro-ph.IM↗

arXiv2021

Observations of compact sources in galaxy clusters using MUSTANG2

Compact sources can cause scatter in the scaling relationships between the amplitude of the thermal Sunyaev-Zel'dovich Effect (tSZE) in galaxy clusters and cluster mass. Estimates of the importance of this scatter vary - largely due to limited data on sources in clusters at the frequencies at which tSZE cluster surveys operate. In this paper we present 90 GHz compact source measurements from a sample of 30 clusters observed using the MUSTANG2 instrument on the Green Bank Telescope. We present simulations of how a source's flux density, spectral index, and angular separation from the cluster's center affect the measured tSZE in clusters detected by the Atacama Cosmology Telescope (ACT). By comparing the MUSTANG2 measurements with these simulations we calibrate an empirical relationship between 1.4 GHz flux densities from radio surveys and source contamination in ACT tSZE measurements. We find 3 per cent of the ACT clusters have more than a 20 per cent decrease in Compton-y but another 3 per cent have a 10 per cent increase in the Compton-y due to the matched filters used to find clusters. As sources affect the measured tSZE signal and hence the likelihood that a cluster will be detected, testing the level of source contamination in the tSZE signal using a tSZE selected catalog is inherently biased. We confirm this by comparing the ACT tSZE catalog with optically and X-ray selected cluster catalogs. There is a strong case for a large, high resolution survey of clusters to better characterize their source population.

astro-ph.CO↗

arXiv2021

The Simons Observatory microwave SQUID multiplexing detector module design

Advances in cosmic microwave background (CMB) science depend on increasing the number of sensitive detectors observing the sky. New instruments deploy large arrays of superconducting transition-edge sensor (TES) bolometers tiled densely into ever larger focal planes. High multiplexing factors reduce the thermal loading on the cryogenic receivers and simplify their design. We present the design of focal-plane modules with an order of magnitude higher multiplexing factor than has previously been achieved with TES bolometers. We focus on the novel cold readout component, which employs microwave SQUID multiplexing ($μ$mux). Simons Observatory will use 49 modules containing 60,000 bolometers to make exquisitely sensitive measurements of the CMB. We validate the focal-plane module design, presenting measurements of the readout component with and without a prototype detector array of 1728 polarization-sensitive bolometers coupled to feedhorns. The readout component achieves a $95\%$ yield and a 910 multiplexing factor. The median white noise of each readout channel is 65 $\mathrm{pA/\sqrt{Hz}}$. This impacts the projected SO mapping speed by $< 8\%$, which is less than is assumed in the sensitivity projections. The results validate the full functionality of the module. We discuss the measured performance in the context of SO science requirements, which are exceeded.

astro-ph.IM↗

arXiv2021

A Microwave SQUID Multiplexer Optimized for Bolometric Applications

A microwave SQUID multiplexer ($μ$MUX) has been optimized for coupling to large arrays of superconducting transition-edge sensor (TES) bolometers. We present the scalable cryogenic multiplexer chip design in a 1820-channel multiplexer configuration for the 4-8 GHz rf band. The key metrics of yield, sensitivity, and crosstalk are determined through measurements of 455 readout channels, which span 4-5 GHz. The median white-noise level is 45 pA/$\sqrt{\textrm{Hz}}$, evaluated at 2 Hz, with a 1/f knee $\leq$ 20 mHz after common-mode subtraction. The white-noise level decreases the sensitivity of a TES bolometer optimized for detection of the cosmic microwave background at 150 GHz by only 3%. The measured crosstalk between any channel pair is $\leq$ 0.3%.

astro-ph.IM↗

arXiv2021

Progress in the development of TES microcalorimeter detectors suitable for neutrino mass measurement

The HOLMES experiment will perform a precise calorimetric measurement of the end point of the Electron Capture (EC) decay spectrum of 163Ho in order to extract information on neutrino mass with a sensitivity below 2 eV. In its final configuration, HOLMES will deploy 1000 detectors of low-temperature microcalorimeters with implanted 163Ho nuclei. The baseline sensors for HOLMES are Mo/Cu TESs (Transition Edge Sensors) on SiNx membrane with gold absorbers. Considering the large number of pixels and an event rate of about 300 Hz/pixel, a large multiplexing factor and a large bandwidth are needed. To fulfill this requirement, HOLMES will exploit recent advances in microwave multiplexing. In this contribution, we present the status of the activities in development, the performances of the developed microwave-multiplexed readout system, and the results obtained with the detectors specifically designed for HOLMES in terms of noise, time, and energy resolutions

physics.ins-det↗

arXiv2018

SLAC Microresonator Radio Frequency (SMuRF) Electronics for Read Out of Frequency-Division-Multiplexed Cryogenic Sensors

Large arrays of cryogenic sensors for various imaging applications ranging across x-ray, gamma-ray, Cosmic Microwave Background (CMB), mm/sub-mm, as well as particle detection increasingly rely on superconducting microresonators for high multiplexing factors. These microresonators take the form of microwave SQUIDs that couple to Transition-Edge Sensors (TES) or Microwave Kinetic Inductance Detectors (MKIDs). In principle, such arrays can be read out with vastly scalable software-defined radio using suitable FPGAs, ADCs and DACs. In this work, we share plans and show initial results for SLAC Microresonator Radio Frequency (SMuRF) electronics, a next-generation control and readout system for superconducting microresonators. SMuRF electronics are unique in their implementation of specialized algorithms for closed-loop tone tracking, which consists of fast feedback and feedforward to each resonator's excitation parameters based on transmission measurements. Closed-loop tone tracking enables improved system linearity, a significant increase in sensor count per readout line, and the possibility of overcoupled resonator designs for enhanced dynamic range. Low-bandwidth prototype electronics were used to demonstrate closed-loop tone tracking on twelve 300-kHz-wide microwave SQUID resonators, spaced at $\sim$6 MHz with center frequencies $\sim$5-6 GHz. We achieve multi-kHz tracking bandwidth and demonstrate that the noise floor of the electronics is subdominant to the noise intrinsic in the multiplexer.

astro-ph.IM↗

arXiv2017

Microwave SQUID Multiplexer demonstration for Cosmic Microwave Background Imagers

Key performance characteristics are demonstrated for the microwave SQUID multiplexer ($μ$MUX) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the $μ$MUX produces a white, input referred current noise level of 29~pA$/\sqrt{\mathrm{Hz}}$ at -77~dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure 98~pA$/\sqrt{\mathrm{Hz}}$ in the TES-coupled channels biased at 65% of the sensor normal resistance. This noise level is consistent with that predicted from bolometer thermal fluctuation (i.e., phonon) noise. Furthermore, the power spectral density exhibits a white spectrum at low frequencies ($\sim$~100~mHz), which enables CMB mapping on large angular scales that constrain the physics of inflation. Additionally, we report cross-talk measurements that indicate a level below 0.3%, which is less than the level of cross-talk from multiplexed readout systems in deployed CMB imagers. These measurements demonstrate the $μ$MUX as a viable readout technique for future CMB imaging instruments.

astro-ph.IM↗

arXiv2010

Time-division SQUID multiplexers with reduced sensitivity to external magnetic fields

Time-division SQUID multiplexers are used in many applications that require exquisite control of systematic error. One potential source of systematic error is the pickup of external magnetic fields in the multiplexer. We present measurements of the field sensitivity figure of merit, effective area, for both the first stage and second stage SQUID amplifiers in three NIST SQUID multiplexer designs. These designs include a new variety with improved gradiometry that significantly reduces the effective area of both the first and second stage SQUID amplifiers.

astro-ph.IM↗

arXiv2010

Strongly quadrature-dependent noise in superconducting micro-resonators measured at the vacuum-noise limit

We measure frequency- and dissipation-quadrature noise in superconducting lithographed microwave resonators with sensitivity near the vacuum noise level using a Josephson parametric amplifier. At an excitation power of 100~nW, these resonators show significant frequency noise caused by two-level systems. No excess dissipation-quadrature noise (above the vacuum noise) is observed to our measurement sensitivity. These measurements demonstrate that the excess dissipation-quadrature noise is negligible compared to vacuum fluctuations, at typical readout powers used in micro-resonator applications. Our results have important implications for resonant readout of various devices such as detectors, qubits and nano-mechanical oscillators.

cond-mat.supr-con↗