Prof. Bradley R. Johnson Profile

Prof. Bradley R. Johnson

at Univ of Virginia

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Author

Publications (14)

Proceedings Article | 11 September 2024 Poster + Paper

The Simons Observatory: laboratory beam characterization for the first small aperture telescope

Remington Gerras, Thomas Alford, Michael Randall, Joseph Seibert, Grace Chesmore, Kevin Crowley, Nicholas Galitzki, Jon Gudmundsson, Kathleen Harrington, Bradley Johnson, J. Lloyd, Amber Miller, Max Silva-Feaver

Proceedings Volume 13094, 130945M (2024) https://doi.org/10.1117/12.3019416

KEYWORDS: Optical simulations, Holography, Near field, Telescopes, Sensors, Near field optics, Optical testing, Signal detection, Beam analyzers, Staring arrays

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The Simons Observatory is a ground-based telescope array located at an elevation of 5200 meters, in the Atacama Desert in Chile, designed to measure the temperature and polarization of the cosmic microwave background. It comprises four telescopes: three 0.42-meter small aperture telescopes (SATs), focused on searching for primordial gravitational waves, and one 6-meter large aperture telescope, focused on studying small-scale perturbations. Each of the SATs will field over 12,000 TES bolometers, with two SATs sensitive to both 90 and 150GHz frequency bands (SAT-MF1, and SAT-MF2), while the third SAT is sensitive to 220 and 280GHz frequency bands. Prior to its deployment in 2023, the optical properties of SAT-MF1 were characterized in the laboratory. We report here on measurements of beam maps acquired using a thermal source on SAT-MF1, along with measurements of near-field beam maps using a holographic method that enables characterization of both the amplitude and phase of the beam response, yielding an estimate of the far-field radiation pattern received by the telescope. We find that the near-field half-width-half-maximum (HWHM) requirements are met across the focal plane array for the 90GHz frequency band, and through most of the focal plane array for the 150GHz frequency band. Namely, the mean of the bandpass averaged HWHM of the edge-detector universal focal plane modules match the simulated HWHM to 10.4%, with the discrepancy caused by fringing in the simulation. The measured radial profile of the beams matches simulations to within 2dB from the beam center to at least the -10dB level. Holography estimates of the far-field 90GHz beams match the full-width-half-maximum from simulation within 1%, and the beam radial profiles deviate by less than 2dB inside the central lobe. The success of the holography and thermal beam map experiments confirmed the optical performance were sufficient to meet the science requirements. SAT-MF1 was deployed to Chile in June, 2023. On-site observations are currently underway.

Proceedings Article | 17 August 2024 Poster

The Simons Observatory: in-lab optical testing and validation for the first small aperture telescope

Michael Randall, Thomas Alford, Remington Gerras, JB Lloyd, Joseph Seibert, Kevin Crowley, Shannon Duff, Nicholas Galitzki, Kathleen Harrington, Johannes Hubmayr, Bradley Johnson, Brian Keating, Max Silva-Feaver, Yuhan Wang, Kaiwen Zheng

Proceedings Volume PC13102, PC131021E (2024) https://doi.org/10.1117/12.3020265

Proceedings Article | 16 August 2024 Poster + Paper

The Simons Observatory: calibration and characterization of the first small-aperture telescope

Kevin Crowley, Kam Arnold, Nicholas Galitzki, Remington Gerras, Bradley Johnson, Brian Keating, Akito Kusaka, Adrian Lee, Hironobu Nakata, Michael Randall, Elle Shaw, Tomoki Terasaki

Proceedings Volume 13102, 1310219 (2024) https://doi.org/10.1117/12.3020564

KEYWORDS: Sensors, Calibration, Bolometers, Telescopes, Polarization, Cosmic microwave background

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Proceedings Article | 16 August 2024 Poster + Paper

The Simons Observatory: studies of detector yield and readout noise from the first large-scale deployment of microwave multiplexing at the large aperture telescope

Thomas Satterthwaite, Zeeshan Ahmed, Kyuyoung Bae, Mark Devlin, Simon Dicker, Shannon Duff, Daniel Dutcher, Saianeesh Haridas, Shawn Henderson, Johannes Hubmayr, Bradley Johnson, Anna Kofman, Jack Lashner, Michael Link, Tammy Lucas, Alex Manduca, Michael Niemack, John Orlowski-Scherer, Tristan Pinsonneault-Marotte, Max Silva-Feaver, Suzanne Staggs, Eve Vavagiakis, Yuhan Wang, Kaiwen Zheng

Proceedings Volume 13102, 1310223 (2024) https://doi.org/10.1117/12.3019196

KEYWORDS: Sensors, Observatories, Telescopes, Microwave radiation, Multiplexing, Superconducting detectors, Superconductors, Physics

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Proceedings Article | 16 August 2024 Poster + Paper

The Simons Observatory: dark characterization of the large aperture telescope

Saianeesh Haridas, Zeeshan Ahmed, Tanay Bhandarkar, Mark Devlin, Simon Dicker, Shannon Duff, Daniel Dutcher, Kathleen Harrington, Shawn Henderson, Johannes Hubmayr, Bradley Johnson, Anna Kofman, Alex Manduca, Michael Niemack, Michael Randall, Thomas Satterthwaite, John Orlowski-Scherer, Benjamin Schmitt, Carlos Sierra, Max Silva-Feaver, Robert Thornton, Yuhan Wang, Kaiwen Zheng

Proceedings Volume 13102, 131022S (2024) https://doi.org/10.1117/12.3019247

KEYWORDS: Sensors, Telescopes, Tunable filters, Singular value decomposition, Physics, Observatories, Interference (communication), Resonators, Principal component analysis, Optical character recognition

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Proceedings Article | 16 August 2024 Poster + Paper

The Simons Observatory: design, fabrication, and characterization of low-frequency detectors

Bhoomija Prasad, Benjamin Westbrook, Shawn Beckman, Aashrita Mangu, Christopher Raum, Adrian Lee, Aritoki Suzuki, Daniel Dutcher, Kaiwen Zheng, Susanne Staggs, Bradley Johnson, Yuhan Wang

Proceedings Volume 13102, 131020X (2024) https://doi.org/10.1117/12.3020813

KEYWORDS: Semiconducting wafers, Etching, Sensors, Niobium, Fabrication, Bolometers, Photography, Optical alignment, Design, Detector arrays

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Proceedings Article | 31 August 2022 Poster + Paper

The Simons Observatory: development and validation of the large aperture telescope receiver

Tanay Bhandarkar, Sanah Bhimani, Gabriele Coppi, Simon Dicker, Saianeesh Haridas, Kathleen Harrington, Jeffrey Iuliano, Bradley Johnson, Anna Kofman, Jack Lashner, Jenna Moore, David Nguyen, John Orlowski-Scherer, Karen Sarmiento, Julia Robe, Maximiliano Silva-Feaver, Robert Thornton, Yuhan Wang, Zhilei Xu

Proceedings Volume 12190, 1219012 (2022) https://doi.org/10.1117/12.2629557

KEYWORDS: Sensors, Telescopes, Receivers, Cryogenics, Optical filters, Copper, Observatories, Temperature metrology, Physics, Resonators

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Proceedings Article | 31 August 2022 Poster + Paper

Simons Observatory focal-plane module: detector re-biasing with bias-step measurements

Yuhan Wang, Tanay Bhandarkar, Steve Choi, Kevin Crowley, Shannon Duff, Daniel Dutcher, John Groh, Kathleen Harrington, Erin Healy, Bradley Johnson, Jack Lashner, Yaqiong Li, Max Silva-Feaver, Rita Sonka, Suzanne Staggs, Samantha Walker, Kaiwen Zheng

Proceedings Volume 12190, 121901I (2022) https://doi.org/10.1117/12.2630135

KEYWORDS: Sensors, Semiconducting wafers, Bolometers, Telescopes, Superconductors, Resistors, Receivers, Copper, Tellurium, Physics

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Proceedings Article | 31 August 2022 Poster + Paper

The Simons Observatory: mechanical and electrical robustness of the universal focal-plane modules

Erin Healy, James Beall, Shannon Duff, Daniel Dutcher, Bradley Johnson, Rita Sonka, Suzanne Staggs, Yuhan Wang, Kaiwen Zheng

Proceedings Volume 12190, 1219013 (2022) https://doi.org/10.1117/12.2629583

KEYWORDS: Sensors, Multiplexers, Resistance, Semiconducting wafers, Silicon, Microwave radiation, Observatories, Multiplexing, Telescopes, Prototyping

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Proceedings Article | 29 August 2022 Poster

Laboratory measurements of horn-coupled and antenna-coupled microwave kinetic inductance detector (MKID) arrays

Jordan Shroyer, Jeremy Meinke, Bradley Johnson, Philip Mauskopf

Proceedings Volume PC12190, PC121901E (2022) https://doi.org/10.1117/12.2630355

KEYWORDS: Sensors, Microwave radiation, Inductance, Detector arrays, Polarization, Waveguides, Transducers, Bandpass filters, Antennas

Proceedings Article | 18 December 2020 Poster + Presentation + Paper

Simons Observatory Small Aperture Telescope overview

Kenji Kiuchi, Shunsuke Adachi, Aamir Ali, Kam Arnold, Peter Ashton, Jason Austermann, Andrew Bazako, James Beall, Yuji Chinone, Gabriele Coppi, Kevin Crowley, Simon Dicker, Bradley Dober, Shannon Duff, Giulio Fabbian, Nicholas Galitzki, Joseph Golec, Jon Gudmundsson, Kathleen Harrington, Masaya Hasegawa, Makoto Hattori, Charles Hill, Shuay-Pwu Patty Ho, Johannes Hubmayr, Bradley Johnson, Daisuke Kaneko, Nobuhiko Katayama, Brian Keating, Akito Kusaka, Jack Lashner, Adrian Lee, Frederick Matsuda, Heather McCarrick, Masaaki Murata, Federico Nati, Yume Nishinomiya, Lyman Page, Mayuri Sathyanarayana Rao, Christian Reichardt, Kana Sakaguri, Yuki Sakurai, Joseph Sibert, Jacob Spisak, Osamu Tajima, Grant Teply, Tomoki Terasaki, Tran Tsan, Samantha Walker, Edward Wollack, Zhilei Xu, Kyohei Yamada, Mario Zannoni, Ningfeng Zhu

Proceedings Volume 11445, 114457L (2020) https://doi.org/10.1117/12.2562016

KEYWORDS: Telescopes, Observatories, Polarization, Cryogenics, Atmospheric optics, Microwave radiation, Sensors, Bolometers, Singular optics, Optical systems

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Proceedings Article | 14 December 2020 Presentation + Paper

Assembly development for the Simons Observatory focal plane readout module

Erin Healy, Aamir Ali, Kam Arnold, Jason Austermann, James Beall, Sarah Marie Bruno, Steve Choi, Jake Connors, Nicholas Cothard, Bradley Dober, Shannon Duff, Nicholas Galitzki, Gene Hilton, Shuay-Pwu Patty Ho, Johannes Hubmayr, Bradley Johnson, Yaqiong Li, Michael Link, Tammy Lucas, Heather McCarrick, Michael Niemack, Maximiliano Silva-Feaver, Rita Sonka, Suzanne Staggs, Eve Vavagiakis, Michael Vissers, Yuhan Wang, Edward Wollack, Zhilei Xu, Benjamin Westbrook, Kaiwen Zheng

Proceedings Volume 11453, 1145317 (2020) https://doi.org/10.1117/12.2561743

KEYWORDS: Observatories, Microwave radiation, Telescopes, Sensors, Bolometers, Multiplexing, Electronics, Receivers, Antennas, Transducers

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Proceedings Article | 13 December 2020 Presentation

A four kilopixel 150 GHz KID imager paired with a 1.5 m crossed Dragone telescope

Jack Sayers, Peter Day, Daniel Cunnane, Byeong Ho Eom, Henry LeDuc, Roger O'Brient, Marcus Runyan, Sean Bryan, Samuel Gordon, Philip Mauskopf, Bradley Johnson, Heather McCarrick, Tanay Bhandarkar

Proceedings Volume 11453, 114531C (2020) https://doi.org/10.1117/12.2561647

KEYWORDS: Telescopes, Imaging systems, Aluminum, Sensors, Waveguides, Cameras, Inductance, Crystals, Silicon, Polarization

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Proceedings Article | 18 May 2020 Presentation + Paper

A millimeter-wave kinetic inductance detector camera for long-range imaging through optical obscurants

Jack Sayers, Peter Day, Daniel Cunnane, Byeong Ho Eom, Henry LeDuc, Roger O'Brient, Marcus Runyan, Sean Bryan, Samuel Gordon, Philip Mauskopf, Bradley Johnson, Heather McCarrick, Tanay Bhandarkar

Proceedings Volume 11411, 114110H (2020) https://doi.org/10.1117/12.2557428

KEYWORDS: Sensors, Signal attenuation, Quasiparticles, Imaging systems, Superconductors, Photons, Inductance, Resonators, Absorption

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Showing 5 of 14 publications

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