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1. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

Author

Chuss, D. T., Ali, A., Amiri, M., Appel, J., Bennett, C. L., Colazo, F., Denis, K. L., Dünner, R., Essinger-Hileman, T., Eimer, J., Fluxa, P., Gothe, D., Halpern, M., Harrington, K., Hilton, G., Hinshaw, G., Hubmayr, J., Iuliano, J., Marriage, T. A., Miller, N., Moseley, S. H., Mumby, G., Petroff, M., Reintsema, C., Rostem, K., U-Yen, K., Watts, D., Wagner, E., Wollack, E. J., Xu, Z., and Zeng, L.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe $\sim$70% of the sky. A variable-delay polarization modulator (VPM) modulates the polarization at $\sim$10 Hz to suppress the 1/f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that span both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single mode transmission on the chip and prevents stray light from coupling to the detectors., Comment: 7 pages, 5 figures, accepted by the Journal of Low Temperature Physics

Published
2015
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2. The Simons Observatory: A large-diameter truss for a refracting telescope cooled to 1 K

Author

Crowley, K, Dow, P, Shroyer, J, Groh, J, Dober, B, Spisak, J, Galitzki, N, Bhandarkar, T, Devlin, M, Dicker, S, Gallardo, P, Harrington, K, Iuliano, J, Johnson, B, Johnson, D, Kofman, A, Kusaka, A, Lee, A, Limon, M, Nati, F, Orlowski-Scherer, J, Page, L, Randall, M, Teply, G, Tsan, T, Wollack, E, Xu, Z, Zhu, N, Crowley K. D., Dow P., Shroyer J. E., Groh J. C., Dober B., Spisak J., Galitzki N., Bhandarkar T., Devlin M. J., Dicker S., Gallardo P. A., Harrington K., Iuliano J., Johnson B. R., Johnson D., Kofman A. M., Kusaka A., Lee A., Limon M., Nati F., Orlowski-Scherer J., Page L., Randall M., Teply G., Tsan T., Wollack E. J., Xu Z., Zhu N., Crowley, K, Dow, P, Shroyer, J, Groh, J, Dober, B, Spisak, J, Galitzki, N, Bhandarkar, T, Devlin, M, Dicker, S, Gallardo, P, Harrington, K, Iuliano, J, Johnson, B, Johnson, D, Kofman, A, Kusaka, A, Lee, A, Limon, M, Nati, F, Orlowski-Scherer, J, Page, L, Randall, M, Teply, G, Tsan, T, Wollack, E, Xu, Z, Zhu, N, Crowley K. D., Dow P., Shroyer J. E., Groh J. C., Dober B., Spisak J., Galitzki N., Bhandarkar T., Devlin M. J., Dicker S., Gallardo P. A., Harrington K., Iuliano J., Johnson B. R., Johnson D., Kofman A. M., Kusaka A., Lee A., Limon M., Nati F., Orlowski-Scherer J., Page L., Randall M., Teply G., Tsan T., Wollack E. J., Xu Z., and Zhu N.

Abstract

We present the design and measured performance of a new carbon fiber strut design that is used in a cryogenically cooled truss for the Simons Observatory small aperture telescope. The truss consists of two aluminum 6061 rings separated by 24 struts. Each strut consists of a central carbon fiber tube fitted with two aluminum end caps. We tested the performance of the strut and truss by (i) cryogenically cycling and destructively pull-Testing strut samples, (ii) non-destructively pull-Testing the final truss, and (iii) measuring the thermal conductivity of the carbon fiber tubes. We found that the strut strength is limited by the mounting fasteners and the strut end caps, not the epoxy adhesive or the carbon fiber tube. This result is consistent with our numerical predictions. Our thermal measurements suggest that the conductive heat load through the struts (from 4 to 1 K) will be less than 1 mW. This strut design may be a promising candidate for use in other cryogenic support structures.

Published
2022

3. Erratum: The Simons Observatory Large Aperture Telescope Receiver (ApJS (2021) 256: 23 DOI: 10.3847/1538-4365/ac0db7)

Author

Zhu N., Zhu, N, Bhandarkar, T, Coppi, G, Kofman, A, Orlowski-Scherer, J, Xu, Z, Adachi, S, Ade, P, Aiola, S, Austermann, J, Bazarko, A, Beall, J, Bhimani, S, Bond, J, Chesmore, G, Choi, S, Connors, J, Cothard, N, Devlin, M, Dicker, S, Dober, B, Duell, C, Duff, S, Dunner, R, Fabbian, G, Galitzki, N, Gallardo, P, Golec, J, Haridas, S, Harrington, K, Healy, E, Patty Ho, S, Huber, Z, Hubmayr, J, Iuliano, J, Johnson, B, Keating, B, Kiuchi, K, Koopman, B, Lashner, J, Lee, A, Li, Y, Limon, M, Link, M, Lucas, T, Mccarrick, H, Moore, J, Nati, F, Newburgh, L, Niemack, M, Pierpaoli, E, Randall, M, Sarmiento, K, Saunders, L, Seibert, J, Sierra, C, Sonka, R, Spisak, J, Sutariya, S, Tajima, O, Teply, G, Thornton, R, Tsan, T, Tucker, C, Ullom, J, Vavagiakis, E, Vissers, M, Walker, S, Westbrook, B, Wollack, E, Zannoni, M, Zhu N., Bhandarkar T., Coppi G., Kofman A. M., Orlowski-Scherer J. L., Xu Z., Adachi S., Ade P., Aiola S., Austermann J., Bazarko A. O., Beall J. A., Bhimani S., Bond J. R., Chesmore G. E., Choi S. K., Connors J., Cothard N. F., Devlin M., Dicker S., Dober B., Duell C. J., Duff S. M., Dunner R., Fabbian G., Galitzki N., Gallardo P. A., Golec J. E., Haridas S. K., Harrington K., Healy E., Patty Ho S. -P., Huber Z. B., Hubmayr J., Iuliano J., Johnson B. R., Keating B., Kiuchi K., Koopman B. J., Lashner J., Lee A. T., Li Y., Limon M., Link M., Lucas T. J., McCarrick H., Moore J., Nati F., Newburgh L. B., Niemack M. D., Pierpaoli E., Randall M. J., Sarmiento K. P., Saunders L. J., Seibert J., Sierra C., Sonka R., Spisak J., Sutariya S., Tajima O., Teply G. P., Thornton R. J., Tsan T., Tucker C., Ullom J., Vavagiakis E. M., Vissers M. R., Walker S., Westbrook B., Wollack E. J., Zannoni M., Zhu N., Zhu, N, Bhandarkar, T, Coppi, G, Kofman, A, Orlowski-Scherer, J, Xu, Z, Adachi, S, Ade, P, Aiola, S, Austermann, J, Bazarko, A, Beall, J, Bhimani, S, Bond, J, Chesmore, G, Choi, S, Connors, J, Cothard, N, Devlin, M, Dicker, S, Dober, B, Duell, C, Duff, S, Dunner, R, Fabbian, G, Galitzki, N, Gallardo, P, Golec, J, Haridas, S, Harrington, K, Healy, E, Patty Ho, S, Huber, Z, Hubmayr, J, Iuliano, J, Johnson, B, Keating, B, Kiuchi, K, Koopman, B, Lashner, J, Lee, A, Li, Y, Limon, M, Link, M, Lucas, T, Mccarrick, H, Moore, J, Nati, F, Newburgh, L, Niemack, M, Pierpaoli, E, Randall, M, Sarmiento, K, Saunders, L, Seibert, J, Sierra, C, Sonka, R, Spisak, J, Sutariya, S, Tajima, O, Teply, G, Thornton, R, Tsan, T, Tucker, C, Ullom, J, Vavagiakis, E, Vissers, M, Walker, S, Westbrook, B, Wollack, E, Zannoni, M, Zhu N., Bhandarkar T., Coppi G., Kofman A. M., Orlowski-Scherer J. L., Xu Z., Adachi S., Ade P., Aiola S., Austermann J., Bazarko A. O., Beall J. A., Bhimani S., Bond J. R., Chesmore G. E., Choi S. K., Connors J., Cothard N. F., Devlin M., Dicker S., Dober B., Duell C. J., Duff S. M., Dunner R., Fabbian G., Galitzki N., Gallardo P. A., Golec J. E., Haridas S. K., Harrington K., Healy E., Patty Ho S. -P., Huber Z. B., Hubmayr J., Iuliano J., Johnson B. R., Keating B., Kiuchi K., Koopman B. J., Lashner J., Lee A. T., Li Y., Limon M., Link M., Lucas T. J., McCarrick H., Moore J., Nati F., Newburgh L. B., Niemack M. D., Pierpaoli E., Randall M. J., Sarmiento K. P., Saunders L. J., Seibert J., Sierra C., Sonka R., Spisak J., Sutariya S., Tajima O., Teply G. P., Thornton R. J., Tsan T., Tucker C., Ullom J., Vavagiakis E. M., Vissers M. R., Walker S., Westbrook B., Wollack E. J., and Zannoni M.

Abstract

After the publication of the article, it was brought to our attention that the description of Equation (1) may cause potential confusion. Thus, we have decided to provide a newer reference and added a unit for qtot in the description. The updated paragraph should read as the following:.

Published
2021

4. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

Author

Chuss, D. T., Ali, A., Amiri, M., Appel, J., Bennett, C. L., Colazo, F., Denis, K. L., Dünner, R., Essinger-Hileman, T., Eimer, J., Fluxa, P., Gothe, D., Halpern, M., Harrington, K., Hilton, G., Hinshaw, G., Hubmayr, J., Iuliano, J., Marriage, T. A., Miller, N., Moseley, S. H., Mumby, G., Petroff, M., Reintsema, C., Rostem, K., U-Yen, K., Watts, D., Wagner, E., Wollack, E. J., Xu, Z., and Zeng, L.

Published
2016
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5. Simons Observatory: characterizing the Large Aperture Telescope Receiver with radio holography

Author

Chesmore, G, Harrington, K, Sierra, C, Gallardo, P, Sutariya, S, Alford, T, Adler, A, Bhandarkar, T, Coppi, G, Dachlythra, N, Golec, J, Gudmundsson, J, Haridas, S, Johnson, B, Kofman, A, Iuliano, J, Mcmahon, J, Niemack, M, Orlowski-Scherer, J, Perez Sarmiento, K, Puddu, R, Silva-Feaver, M, Simon, S, Robe, J, Wollack, E, Xu, Z, Grace E. Chesmore, Kathleen Harrington, Carlos E. Sierra, Patricio A. Gallardo, Shreya Sutariya, Tommy Alford, Alexandre E. Adler, Tanay Bhandarkar, Gabriele Coppi, Nadia Dachlythra, Joseph Golec, Jon Gudmundsson, Saianeesh K. Haridas, Bradley R. Johnson, Anna M. Kofman, Jeffrey Iuliano, Jeff McMahon, Michael D. Niemack, John Orlowski-Scherer, Karen Perez Sarmiento, Roberto Puddu, Max Silva-Feaver, Sara M. Simon, Julia Robe, Edward J. Wollack, Zhilei Xu, Chesmore, G, Harrington, K, Sierra, C, Gallardo, P, Sutariya, S, Alford, T, Adler, A, Bhandarkar, T, Coppi, G, Dachlythra, N, Golec, J, Gudmundsson, J, Haridas, S, Johnson, B, Kofman, A, Iuliano, J, Mcmahon, J, Niemack, M, Orlowski-Scherer, J, Perez Sarmiento, K, Puddu, R, Silva-Feaver, M, Simon, S, Robe, J, Wollack, E, Xu, Z, Grace E. Chesmore, Kathleen Harrington, Carlos E. Sierra, Patricio A. Gallardo, Shreya Sutariya, Tommy Alford, Alexandre E. Adler, Tanay Bhandarkar, Gabriele Coppi, Nadia Dachlythra, Joseph Golec, Jon Gudmundsson, Saianeesh K. Haridas, Bradley R. Johnson, Anna M. Kofman, Jeffrey Iuliano, Jeff McMahon, Michael D. Niemack, John Orlowski-Scherer, Karen Perez Sarmiento, Roberto Puddu, Max Silva-Feaver, Sara M. Simon, Julia Robe, Edward J. Wollack, and Zhilei Xu

Abstract

We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments.

Published
2022

6. The Simons Observatory Large Aperture Telescope Receiver

Author

Zhu, N, Bhandarkar, T, Coppi, G, Kofman, A, Orlowski-Scherer, J, Xu, Z, Adachi, S, Ade, P, Aiola, S, Austermann, J, Bazarko, A, Beall, J, Bhimani, S, Richard Bond, J, Chesmore, G, Choi, S, Connors, J, Cothard, N, Devlin, M, Dicker, S, Dober, B, Duell, C, Duff, S, Dünner, R, Fabbian, G, Galitzki, N, Gallardo, P, Golec, J, Haridas, S, Harrington, K, Healy, E, Patty Ho, S, Huber, Z, Hubmayr, J, Iuliano, J, Johnson, B, Keatin, B, Kiuchi, K, Koopman, B, Lashner, J, Lee, A, Li, Y, Limon, M, Link, M, J Lucas, T, Mccarrick, H, Moore, J, Nati, F, Newburgh, L, Niemack, M, Pierpaoli, E, Randall, M, Perez Sarmiento, K, Saunders, L, Seibert, J, Sierra, C, Sonka, R, Spisak, J, Sutariya, S, Tajima, O, Teply, G, Thornton, R, Tsan, T, Tucker, C, Ullom, J, Vavagiakis, E, Vissers, M, Walker, S, Westbrook, B, Wollack, E, Zannoni, M, Ningfeng Zhu, Tanay Bhandarkar, Gabriele Coppi, Anna M. Kofman, John L. Orlowski-Scherer, Zhilei Xu, Shunsuke Adachi, Peter Ade, Simone Aiola, Jason Austermann, Andrew O. Bazarko, James A. Beall, Sanah Bhimani, J. Richard Bond, Grace E. Chesmore, Steve K. Choi, Jake Connors, Nicholas F. Cothard, Mark Devlin, Simon Dicker, Bradley Dober, Cody J. Duell, Shannon M. Duff, Rolando Dünner, Giulio Fabbian, Nicholas Galitzki, Patricio A. Gallardo, Joseph E. Golec, Saianeesh K. Haridas, Kathleen Harrington, Erin Healy, Shuay-Pwu Patty Ho, Zachary B. Huber, Johannes Hubmayr, Jeffrey Iuliano, Bradley R. Johnson, Brian Keatin, Kenji Kiuchi, Brian J. Koopman, Jack Lashner, Adrian T. Lee, Yaqiong Li, Michele Limon, Michael Link, Tammy J Lucas, Heather McCarrick, Jenna Moore, Federico Nati, Laura B. Newburgh, Michael D. Niemack, Elena Pierpaoli, Michael J. Randall, Karen Perez Sarmiento, Lauren J. Saunders, Joseph Seibert, Carlos Sierra, Rita Sonka, Jacob Spisak, Shreya Sutariya, Osamu Tajima, Grant P. Teply, Robert J. Thornton, Tran Tsan, Carole Tucker, Joel Ullom, Eve M. Vavagiakis, Michael R. Vissers, Samantha Walker, Benjamin Westbrook, Edward J. Wollack, Mario Zannoni, Zhu, N, Bhandarkar, T, Coppi, G, Kofman, A, Orlowski-Scherer, J, Xu, Z, Adachi, S, Ade, P, Aiola, S, Austermann, J, Bazarko, A, Beall, J, Bhimani, S, Richard Bond, J, Chesmore, G, Choi, S, Connors, J, Cothard, N, Devlin, M, Dicker, S, Dober, B, Duell, C, Duff, S, Dünner, R, Fabbian, G, Galitzki, N, Gallardo, P, Golec, J, Haridas, S, Harrington, K, Healy, E, Patty Ho, S, Huber, Z, Hubmayr, J, Iuliano, J, Johnson, B, Keatin, B, Kiuchi, K, Koopman, B, Lashner, J, Lee, A, Li, Y, Limon, M, Link, M, J Lucas, T, Mccarrick, H, Moore, J, Nati, F, Newburgh, L, Niemack, M, Pierpaoli, E, Randall, M, Perez Sarmiento, K, Saunders, L, Seibert, J, Sierra, C, Sonka, R, Spisak, J, Sutariya, S, Tajima, O, Teply, G, Thornton, R, Tsan, T, Tucker, C, Ullom, J, Vavagiakis, E, Vissers, M, Walker, S, Westbrook, B, Wollack, E, Zannoni, M, Ningfeng Zhu, Tanay Bhandarkar, Gabriele Coppi, Anna M. Kofman, John L. Orlowski-Scherer, Zhilei Xu, Shunsuke Adachi, Peter Ade, Simone Aiola, Jason Austermann, Andrew O. Bazarko, James A. Beall, Sanah Bhimani, J. Richard Bond, Grace E. Chesmore, Steve K. Choi, Jake Connors, Nicholas F. Cothard, Mark Devlin, Simon Dicker, Bradley Dober, Cody J. Duell, Shannon M. Duff, Rolando Dünner, Giulio Fabbian, Nicholas Galitzki, Patricio A. Gallardo, Joseph E. Golec, Saianeesh K. Haridas, Kathleen Harrington, Erin Healy, Shuay-Pwu Patty Ho, Zachary B. Huber, Johannes Hubmayr, Jeffrey Iuliano, Bradley R. Johnson, Brian Keatin, Kenji Kiuchi, Brian J. Koopman, Jack Lashner, Adrian T. Lee, Yaqiong Li, Michele Limon, Michael Link, Tammy J Lucas, Heather McCarrick, Jenna Moore, Federico Nati, Laura B. Newburgh, Michael D. Niemack, Elena Pierpaoli, Michael J. Randall, Karen Perez Sarmiento, Lauren J. Saunders, Joseph Seibert, Carlos Sierra, Rita Sonka, Jacob Spisak, Shreya Sutariya, Osamu Tajima, Grant P. Teply, Robert J. Thornton, Tran Tsan, Carole Tucker, Joel Ullom, Eve M. Vavagiakis, Michael R. Vissers, Samantha Walker, Benjamin Westbrook, Edward J. Wollack, and Mario Zannoni

Abstract

The Simons Observatory is a ground-based cosmic microwave background experiment that consists of three 0.4 m small-aperture telescopes and one 6 m Large Aperture Telescope, located at an elevation of 5300 m on Cerro Toco in Chile. The Simons Observatory Large Aperture Telescope Receiver (LATR) is the cryogenic camera that will be coupled to the Large Aperture Telescope. The resulting instrument will produce arcminute-resolution millimeter-wave maps of half the sky with unprecedented precision. The LATR is the largest cryogenic millimeter-wave camera built to date, with a diameter of 2.4 m and a length of 2.6 m. The coldest stage of the camera is cooled to 100 mK, the operating temperature of the bolometric detectors with bands centered around 27, 39, 93, 145, 225, and 280 GHz. Ultimately, the LATR will accommodate 13 40 cm diameter optics tubes, each with three detector wafers and a total of 62,000 detectors. The LATR design must simultaneously maintain the optical alignment of the system, control stray light, provide cryogenic isolation, limit thermal gradients, and minimize the time to cool the system from room temperature to 100 mK. The interplay between these competing factors poses unique challenges. We discuss the trade studies involved with the design, the final optimization, the construction, and ultimate performance of the system.

Published
2021

7. Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

Author

Chuss, D. T., primary, Ali, A., additional, Amiri, M., additional, Appel, J., additional, Bennett, C. L., additional, Colazo, F., additional, Denis, K. L., additional, Dünner, R., additional, Essinger-Hileman, T., additional, Eimer, J., additional, Fluxa, P., additional, Gothe, D., additional, Halpern, M., additional, Harrington, K., additional, Hilton, G., additional, Hinshaw, G., additional, Hubmayr, J., additional, Iuliano, J., additional, Marriage, T. A., additional, Miller, N., additional, Moseley, S. H., additional, Mumby, G., additional, Petroff, M., additional, Reintsema, C., additional, Rostem, K., additional, U-Yen, K., additional, Watts, D., additional, Wagner, E., additional, Wollack, E. J., additional, Xu, Z., additional, and Zeng, L., additional

Published
2015
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8. The Simons Observatory: Characterizing the Large Aperture Telescope Receiver with Radio Holography

Author

Grace E. Chesmore, Kathleen Harrington, Carlos E. Sierra, Patricio A. Gallardo, Shreya Sutariya, Tommy Alford, Alexandre E. Adler, Tanay Bhandarkar, Gabriele Coppi, Nadia Dachlythra, Joseph Golec, Jon Gudmundsson, Saianeesh K. Haridas, Bradley R. Johnson, Anna M. Kofman, Jeffrey Iuliano, Jeff McMahon, Michael D. Niemack, John Orlowski-Scherer, Karen Perez Sarmiento, Roberto Puddu, Max Silva-Feaver, Sara M. Simon, Julia Robe, Edward J. Wollack, Zhilei Xu, Chesmore, G, Harrington, K, Sierra, C, Gallardo, P, Sutariya, S, Alford, T, Adler, A, Bhandarkar, T, Coppi, G, Dachlythra, N, Golec, J, Gudmundsson, J, Haridas, S, Johnson, B, Kofman, A, Iuliano, J, Mcmahon, J, Niemack, M, Orlowski-Scherer, J, Perez Sarmiento, K, Puddu, R, Silva-Feaver, M, Simon, S, Robe, J, Wollack, E, and Xu, Z

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Electrical and Electronic Engineering, Astrophysics - Instrumentation and Methods for Astrophysics, Engineering (miscellaneous), Instrumentation and Methods for Astrophysics (astro-ph.IM), Atomic and Molecular Physics, and Optics, optics, Astrophysics::Galaxy Astrophysics
Abstract

We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments.

Published
2022

9. The Simons Observatory: A large-diameter truss for a refracting telescope cooled to 1 K

Author

Kevin D. Crowley, Peter Dow, Jordan E. Shroyer, John C. Groh, Bradley Dober, Jacob Spisak, Nicholas Galitzki, Tanay Bhandarkar, Mark J. Devlin, Simon Dicker, Patricio A. Gallardo, Kathleen Harrington, Jeffrey Iuliano, Bradley R. Johnson, Delwin Johnson, Anna M. Kofman, Akito Kusaka, Adrian Lee, Michele Limon, Federico Nati, John Orlowski-Scherer, Lyman Page, Michael Randall, Grant Teply, Tran Tsan, Edward J. Wollack, Zhilei Xu, Ningfeng Zhu, Crowley, K, Dow, P, Shroyer, J, Groh, J, Dober, B, Spisak, J, Galitzki, N, Bhandarkar, T, Devlin, M, Dicker, S, Gallardo, P, Harrington, K, Iuliano, J, Johnson, B, Johnson, D, Kofman, A, Kusaka, A, Lee, A, Limon, M, Nati, F, Orlowski-Scherer, J, Page, L, Randall, M, Teply, G, Tsan, T, Wollack, E, Xu, Z, and Zhu, N

Subjects
Instrumentation, CMB, cosmology, telescopes
Abstract

We present the design and measured performance of a new carbon fiber strut design that is used in a cryogenically cooled truss for the Simons Observatory small aperture telescope. The truss consists of two aluminum 6061 rings separated by 24 struts. Each strut consists of a central carbon fiber tube fitted with two aluminum end caps. We tested the performance of the strut and truss by (i) cryogenically cycling and destructively pull-testing strut samples, (ii) non-destructively pull-testing the final truss, and (iii) measuring the thermal conductivity of the carbon fiber tubes. We found that the strut strength is limited by the mounting fasteners and the strut end caps, not the epoxy adhesive or the carbon fiber tube. This result is consistent with our numerical predictions. Our thermal measurements suggest that the conductive heat load through the struts (from 4 to 1 K) will be less than 1 mW. This strut design may be a promising candidate for use in other cryogenic support structures.

Published
2022

10. The Simons Observatory: the Large Aperture Telescope Receiver (LATR) Integration and Validation Results

Author

Suzanne T. Staggs, Jenna Moore, Jake Connors, John Orlowski-Scherer, Steve K. Choi, Federico Nati, Michael D. Niemack, Erin Healy, Ningfeng Zhu, Joseph Seibert, Bradley Dober, Robert Thornton, Brian J. Koopman, Zhilei Xu, Johannes Hubmayr, Jack Lashner, Tanay Bhandarkar, Christian L. Reichardt, Nicholas F. Cothard, Jason E. Austermann, Giulio Fabbian, Shuay-Pwu Patty Ho, Edward J. Wollack, Gabriele Coppi, Yuhan Wang, Michele Limon, Jeffrey Iuliano, Mark J. Devlin, Kathleen Harrington, Kaiwen Zheng, Shannon M. Duff, Kam Arnold, Heather McCarrick, Samantha Walker, Simon Dicker, Eve M. Vavagiakis, Maximiliano Silva-Feaver, Nicholas Galitzki, A. M. Kofman, Rita Sonka, Michael R. Vissers, Karen Perez Sarmiento, Yaqiong Li, Aamir Ali, Saianeesh K. Haridas, Zmuidzinas J.,Gao J.-R., Xu, Z, Bhandarkar, T, Coppi, G, Kofman, A, Orlowski-Scherer, J, Zhu, N, Ali, A, Arnold, K, Austermann, J, Choi, S, Connors, J, Cothard, N, Devlin, M, Dicker, S, Dober, B, Duff, S, Fabbian, G, Galitzki, N, Haridas, S, Harrington, K, Healy, E, Ho, S, Hubmayr, J, Iuliano, J, Lashner, J, Li, Y, Limon, M, Koopman, B, Mccarrick, H, Moore, J, Nati, F, Niemack, M, Reichardt, C, Sarmiento, K, Seibert, J, Silva-Feaver, M, Sonka, R, Staggs, S, Thornton, R, Vavagiakis, E, Vissers, M, Walker, S, Wang, Y, Wollack, E, and Zheng, K

Subjects
Physics, COSMIC cancer database, Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, Bolometer, Astrophysics::Instrumentation and Methods for Astrophysics, Observa-tional Cosmology, Astronomy, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Radio spectrum, Cryogenic Technology, law.invention, Astronomical Instrumentation, Telescope, law, Observatory, Observational cosmology, Cosmic Microwave Background, Astrophysics::Earth and Planetary Astrophysics, Neutrino, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

The Simons Observatory (SO) will observe the cosmic microwave background (CMB) from Cerro Toco in the Atacama Desert of Chile. The observatory consists of three 0.5 m Small Aperture Telescopes (SATs) and one 6 m Large Aperture Telescope (LAT), covering six frequency bands centering around 30, 40, 90, 150, 230, and 280 GHz. The SO observations will transform the understanding of our universe by characterizing the properties of the early universe, measuring the number of relativistic species and the mass of neutrinos, improving our understanding of galaxy evolution, and constraining the properties of cosmic reionization. As a critical instrument, the Large Aperture Telescope Receiver (LATR) is designed to cool $\sim$ 60,000 transition-edge sensors (TES) to $, Comment: 20 pages, 12 figures, submitted to the 2020 SPIE Astronomical Telescopes + Instrumentation

Published
2020

11. Simons Observatory: characterizing the Large Aperture Telescope Receiver with radio holography.

Author

Chesmore GE, Harrington K, Sierra CE, Gallardo PA, Sutariya S, Alford T, Adler AE, Bhandarkar T, Coppi G, Dachlythra N, Golec J, Gudmundsson J, Haridas SK, Johnson BR, Kofman AM, Iuliano J, McMahon J, Niemack MD, Orlowski-Scherer J, Perez Sarmiento K, Puddu R, Silva-Feaver M, Simon SM, Robe J, Wollack EJ, and Xu Z

Abstract

We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments.

Published
2022
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12. Simons Observatory: broadband metamaterial antireflection cuttings for large-aperture alumina optics.

Author

Golec JE, Sutariya S, Jackson R, Zimmerman J, Dicker SR, Iuliano J, McMahon J, Puglisi G, Tucker C, and Wollack EJ

Abstract

We present the design, fabrication, and measured performance of metamaterial antireflection cuttings (ARCs) for large-format alumina filters operating over more than an octave of bandwidth to be deployed at the Simons Observatory (SO). The ARC consists of subwavelength features diced into the optic's surface using a custom dicing saw with near-micrometer accuracy. The designs achieve percent-level control over reflections at angles of incidence up to 20 ∘ . The ARCs were demonstrated on four 42 cm diameter filters covering the 75 to 170 GHz band and a 50 mm diameter prototype covering the 200 to 300 GHz band. The reflection and transmission of these samples were measured using a broadband coherent source that covers frequencies from 20 GHz to 1.2 THz. These measurements demonstrate percent-level control over reflectance across the targeted pass-bands and a rapid reduction in transmission as the wavelength approaches the length scale of the metamaterial structure where scattering dominates the optical response. The latter behavior enables use of the metamaterial ARC as a scattering filter in this limit.

Published
2022
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13. The Simons Observatory: A large-diameter truss for a refracting telescope cooled to 1 K.

Author

Crowley KD, Dow P, Shroyer JE, Groh JC, Dober B, Spisak J, Galitzki N, Bhandarkar T, Devlin MJ, Dicker S, Gallardo PA, Harrington K, Iuliano J, Johnson BR, Johnson D, Kofman AM, Kusaka A, Lee A, Limon M, Nati F, Orlowski-Scherer J, Page L, Randall M, Teply G, Tsan T, Wollack EJ, Xu Z, and Zhu N

Abstract

We present the design and measured performance of a new carbon fiber strut design that is used in a cryogenically cooled truss for the Simons Observatory small aperture telescope. The truss consists of two aluminum 6061 rings separated by 24 struts. Each strut consists of a central carbon fiber tube fitted with two aluminum end caps. We tested the performance of the strut and truss by (i) cryogenically cycling and destructively pull-testing strut samples, (ii) non-destructively pull-testing the final truss, and (iii) measuring the thermal conductivity of the carbon fiber tubes. We found that the strut strength is limited by the mounting fasteners and the strut end caps, not the epoxy adhesive or the carbon fiber tube. This result is consistent with our numerical predictions. Our thermal measurements suggest that the conductive heat load through the struts (from 4 to 1 K) will be less than 1 mW. This strut design may be a promising candidate for use in other cryogenic support structures.

Published
2022
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14. Mechanism of the AppABLUF Photocycle Probed by Site-Specific Incorporation of Fluorotyrosine Residues: Effect of the Y21 pKa on the Forward and Reverse Ground-State Reactions.

Author

Gil A, Haigney A, Laptenok SP, Brust R, Lukacs A, Iuliano J, Jeng J, Melief E, Zhao RK, Yoon E, Clark I, Towrie M, Greetham GM, Ng A, Truglio J, French J, Meech SR, and Tonge PJ

Subjects
Hydrogen Bonding, Hydrogen-Ion Concentration, Models, Molecular, Molecular Structure, Bacterial Proteins chemistry, Flavoproteins chemistry, Fluorine chemistry, Photochemical Processes, Quantum Theory, Tyrosine analogs & derivatives, Tyrosine chemistry
Abstract

The transcriptional antirepressor AppA is a blue light using flavin (BLUF) photoreceptor that releases the transcriptional repressor PpsR upon photoexcitation. Light activation of AppA involves changes in a hydrogen-bonding network that surrounds the flavin chromophore on the nanosecond time scale, while the dark state of AppA is then recovered in a light-independent reaction with a dramatically longer half-life of 15 min. Residue Y21, a component of the hydrogen-bonding network, is known to be essential for photoactivity. Here, we directly explore the effect of the Y21 pKa on dark state recovery by replacing Y21 with fluorotyrosine analogues that increase the acidity of Y21 by 3.5 pH units. Ultrafast transient infrared measurements confirm that the structure of AppA is unperturbed by fluorotyrosine substitution, and that there is a small (3-fold) change in the photokinetics of the forward reaction over the fluorotyrosine series. However, reduction of 3.5 pH units in the pKa of Y21 increases the rate of dark state recovery by 4000-fold with a Brønsted coefficient of ∼ 1, indicating that the Y21 proton is completely transferred in the transition state leading from light to dark adapted AppA. A large solvent isotope effect of ∼ 6-8 is also observed on the rate of dark state recovery. These data establish that the acidity of Y21 is a crucial factor for stabilizing the light activated form of the protein, and have been used to propose a model for dark state recovery that will ultimately prove useful for tuning the properties of BLUF photosensors for optogenetic applications.

Published
2016
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