arXiv subjects

Ricardo R. Rodriguez

Publications and source records attributed to Ricardo R. Rodriguez.

4 recordsLinked to original sources

arXiv2026

picoMUX: microcontroller based time-domain multiplexing readout for kilopixel TES arrays

Advances in cryogenic SQUID-based time-domain multiplexing (TDM) have outpaced their warm readout electronics. Next generation CMB telescopes are baselining kilopixel TES arrays with few viable electronic options. We present picoMUX, a new TDM readout electronics architecture that replaces the FPGA typically used in such systems with a complement of modern microcontrollers. Designed around the current generation NIST multiplexer, it fully exploits its differential nature and two-level switching. The system achieves the desired timing metrics (sub μs row dwell time) while reducing cost, complexity, and power consumption over a comparable FPGA solution. Preliminary noise measurements are consistent with expectations and show no evidence that the novel architecture introduces excess noise. picoMUX demonstrates how recent advances in microcontrollers enable simpler, low-power, low-cost TDM readouts for kilopixel TES arrays.

astro-ph.IM↗

arXiv2026

Sub-Kelvin Cryogenics for a Super-Pressure Balloon-Borne CMB Polarimeter: Taurus

Taurus is a balloon-borne cosmic microwave background (CMB) experiment designed to operate more than 10,000 transition-edge sensor bolometers at a base temperature near 100 mK during a multi-week stratospheric balloon flight. This platform provides near-space observing conditions while imposing stringent constraints on mass, power, and system robustness, driving the need for a lightweight and highly reliable cryogenic system. To meet these requirements, Taurus employs a multi-stage cryogenic architecture. A 660 L liquid helium tank provides a stable 4 K reservoir, with vapor-cooled shields establishing intermediate stages at approximately 40 K and 80 K. A superfluid helium tank provides an approximately 1.5 K takeoff point for the sub-Kelvin cooling systems. Each of the instrument's three receivers is supported by an independent sub-Kelvin cooling chain that includes closed-cycle 3He sorption refrigerators that cool to 300 mK. These provide the thermal intercept and takeoff for a Chase Research Cryogenics miniature dilution refrigerator that cools the detectors to approximately 100 mK. Here we discuss the requirements and challenges of the Taurus sub-Kelvin cryogenic system and present results of early performance tests.

astro-ph.IM↗

arXiv2025

$τ$HK: a modular housekeeping system for cryostats and balloon payloads

$τ$HK is a versatile experiment housekeeping (HK) system designed to perform cryogenic temperature readout and heater control on the upcoming Taurus balloon experiment. $τ$HK, more broadly, is also suitable for ambient-temperature applications and general-purpose experiment input and output. It is built around an IEEE Eurocard subrack capable of housing up to 16 interchangeable daughter cards, allowing a fully populated system to support as many as 256 independent channels while drawing under 7.5\,W. This modular architecture allows experiments to expand on the existing daughter cards with ones tailored to their specific needs. There are currently three flavors of daughter cards: Resistive Temperature Device (RTD) readout, general purpose thermometer bias and readout, and load driver. The RTD board consists of a low noise lock-in amplifier that is limited only by device sensitivity over all temperature ranges. The general-purpose bias and readout board with chopping capability is primarily designed for thermometer diodes, but flexible enough to accommodate room temperature thermistors, Wheatstone bridges, optical encoders, and other devices. Finally, the load driver card can output an analog voltage for precise cryogenic heaters or it can be used to pulse width modulate high power loads. $τ$HK is a power efficient solution for experimental housekeeping needs that is suited for the the harsh environment of stratospheric ballooning.

physics.ins-det↗

arXiv2025

Intensity Interferometer Results on Sirius with 0.25 m Telescopes

We present the successful measurement of the squared visibility of Sirius at a telescope separation of 3.3 m using small 0.25 m Newtonian-style telescopes in an urban backyard setting. The primary science goal for small-scale intensity interferometers has been to measure the angular diameters of stars. Recent advances in low jitter time-tagging equipment and Single Photon Avalanche Detectors have made the detection of second-order photon correlation signals feasible with small low-cost telescopes. Using Sirius as a target star, we observe a photon count rate of $\sim$1.9 Mcps per detector with matched 1.2 nm wide filters at 589.3 nm and measured the spatial squared visibility at a telescope separation of 3.3 m to be $|V_{12}(3.3\text{m})|^2 = 0.94\pm0.16$. The measured detection significance is $\sim7 σ$ after 13.55 h of integration. The uncertainty in the measured visibility includes uncertainty in the instrument response function.The squared visibility agrees closely with the expected value of $0.94\pm0.01$. These results demonstrate that using small low-cost telescopes is feasible for intensity interferometry of bright stars. This enables a simple scaling in sensitivity by further realistic improvements in the instrument response jitter as well as increasing both the number of spectral bands and the number of telescopes towards systems capable of resolving objects such as quasars, white dwarfs, and galactic Cepheid variable stars.

astro-ph.IM↗