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Lee, Adrian

Publications and source records attributed to Lee, Adrian.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Deployment of POLARBEAR-2b

POLARBEAR-2b (PB-2b) is the second receiver in the Simons Array, a cosmic microwave background (CMB) polarization experiment. The Simons Array uses dichroic polarization sensitive lenslet-coupled sinuous antennas and transition-edge sensor (TES) bolometers made of superconducting films. These bolometers are read out with frequency multiplexing electronics. PB-2b contains ~7500 detectors in two bands at 90 and 150 GHz with arcminute resolution. The polarization of these detectors is modulated by a cryogenic continuously rotating half-wave plate. PB-2b was installed on its telescope in 2022 in the Atacama Desert at an altitude of 5.2 km. This paper will detail initial readout commissioning, test of a new loopgain monitoring method, and focusing the optics. Work is ongoing to commission the remaining ambient temperature readout electronics, measure detector time constants, and observe with the cryogenic half-wave plate spinning.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Intensity-coupled Polarization in Instruments with a Continuously Rotating Half-wave Plate

In this work, we discuss a systematic effect associated with measuring polarization with a continuously rotating half-wave plate (HWP). The effect was identified with the data from the E and B Experiment, which was a balloon-borne instrument designed to measure the polarization of the cosmic microwave background (CMB) as well as that from Galactic dust. The data show polarization fractions larger than 10%, while less than 3% were expected from instrumental polarization. We give evidence that the excess polarization is due to detector nonlinearity in the presence of a continuously rotating HWP. The nonlinearity couples intensity signals to polarization. We develop a map-based method to remove the excess polarization. Applying this method to the 150 (250) GHz band data, we find that 81% (92%) of the excess polarization was removed. Finally, characterization and mitigation of this effect are important for future experiments aiming to measure the CMB B-modes with a continuously rotating HWP.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

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. Additionally, 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. Finally, we discuss the design and fabrication of these devices and present measurements of the standalone resonators.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

The EBEX Balloon-borne Experiment—Optics, Receiver, and Polarimetry

The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background (CMB) polarimeter that flew over Antarctica in 2012. We describe the experiment's optical system, receiver, and polarimetric method and discuss their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410 GHz. To make effective use of limited mass and space, we created a 115 cm 2 sr high-throughput optical system that had two ambient temperature mirrors and four antireflection-coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). This is the first use of an SMB in astrophysics. Rotation stability was 0.45% over a period of 10 hr, and angular position accuracy was 0$^{°}_{.}$1. The measured modulation efficiency was above 90% for all bands. To our knowledge the 109% fractional bandwidth of the AHWP was the broadest implemented to date. The receiver, composed of one lens and the AHWP at a temperature of 4 K, the polarizing grid and other lenses at 1 K, and the two focal planes at 0.25 K, performed according to specifications, giving focal plane temperature stability with a fluctuation power spectrum that had a 1/f knee at 2 mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters, including high-throughput optical systems, and large arrays of transition edge sensor bolometric detectors with multiplexed readouts.

polarization↗
DOE OSTI2018

The EBEX Balloon-borne Experiment—Gondola, Attitude Control, and Control Software

The E and B Experiment (EBEX) was a long-duration balloon-borne instrument created to measure the polarization of the cosmic microwave background (CMB) radiation. EBEX was the first balloon-borne instrument to implement a kilopixel array of transition edge sensor (TES) bolometric detectors and the first CMB experiment to use the digital version of the frequency domain multiplexing system for readout of the TES array. The scan strategy relied on 40 s peak-to-peak constant-velocity azimuthal scans. We report on the unique demands on the design and operation of the payload that resulted from these new technologies and the scan strategy. We describe the solutions implemented, including the development of a power system designed to provide a total of at least 2.3 kW, a cooling system to dissipate 590 W consumed by the detectors' readout system, software to manage and handle the data of the kilopixel array, and specialized attitude reconstruction software. We demonstrate flight performance data reflecting faultless management of the TES array, adequate powering and cooling of the readout electronics, and constraint of attitude reconstruction errors such that the spurious B-modes they induced were less than 10% of the CMB B-mode power spectrum with r = 0.05.

polarization↗
DOE OSTI2018

The EBEX Balloon-borne Experiment—Detectors and Readout

EBEX was a long-duration balloon-borne experiment to measure the polarization of the cosmic microwave background. The experiment had three frequency bands centered at 150, 250, and 410 GHz and was the first to use a kilopixel array of transition edge sensor bolometers aboard a balloon platform. We determine the design and characterization of the array and the readout system. From the lowest to highest frequency, the median measured detectors' average thermal conductances were 39, 53, and 63 pW/K, the medians of transition temperatures were 0.45, 0.48, and 0.47 K, and the medians of normal resistances were 1.9, 1.5, and 1.4 Ω; moreover, we give the measured distributions. With the exception of the thermal conductance at 150 GHz, all measured values are within 30% of their design. We measure median low-loop-gain time constants τ 0 = 88, 46, and 57 ms. Two measurements of bolometer absorption efficiency gave results consistent within 10% and showing high (~0.9) efficiency at 150 GHz and medium (~0.35 and ~0.25) efficiency at the two higher bands. We calculate a median total optical power absorbed of 3.6, 5.3, and 5.0 pW. EBEX pioneered the use of the digital version of the frequency domain multiplexing system. We multiplexed the bias and readout of 16 bolometers onto two wires. The median per-detector noise-equivalent temperatures are 400, 920, and 14,500 $\mu {{\rm{K}}}_{{\rm{cmb}}}\sqrt{{\rm{s}}}$. We compare these values to our preflight predictions and to a previous balloon payload. We report on the sources of excess noise and the path for a future payload to make full use of the balloon environment.

instrumentation: polarimeters↗
DOE OSTI2018

Year 2 instrument status from the SPT-3G cosmic microwave background receiver (Conference Presentation)

The South Pole Telescope (SPT) is a millimeter-wavelength telescope surveying the cosmic microwave background (CMB). The SPT measures both the temperature and polarization of the CMB with a large aperture, resulting in high-resolution maps sensitive to signals across a wide range of angular scales on the sky. With these capabilities, the SPT has the potential to constrain inflationary gravitational waves as well as the effect of massive neutrinos on large-scale structure formation. The SPT was upgraded in late 2016 with a new receiver (SPT-3G) containing 16,0000 polarization-sensitive transition-edge sensor bolometers. Several key technological developments have enabled this large-format focal, including advances in detectors, readout electronics, and large millimeter-wavelength optics. We will discuss the implementation of these technologies in the SPT-3G receiver as well as the challenges they presented. In late 2017 the implementations of all three of these technologies were iterated to optimize total performance. Here, we present the current instrument status of the SPT-3G receiver.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗