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12 results on '"Bhandarkar T"'

1. Witnessing the intracluster medium assembly at the cosmic noon in JKCS041

Author

Andreon, S., Romero, C., Aussel, H., Bhandarkar, T., Devlin, M., Dicker, S., Ladjelate, B., Lowe, I., Mason, B., Mroczkowski, T., Raichoor, A., Sarazin, C., and Trinchieri, G.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

In this work we study the intracluster medium of a galaxy cluster at the cosmic noon: JKCS041 at z=1.803. A 28h long Sunyaev-Zel'dovich (SZ) observation using MUSTANG-2 allows us to detect JKCS041, even if intrinsically extremely faint compared to other SZ-detected clusters. We found that the SZ peak is offset from the X-ray center by about 220 kpc in the direction of the brightest cluster galaxy, which we interpret as due to the cluster being observed just after first passage of a major merger. JKCS041 has a low central pressure and a low Compton Y compared to local clusters selected by their intracluster medium (ICM), likely because the cluster is still in the process of assembly but also in part because of a hard-to-quantify bias in current local ICM-selected samples. JKCS041 has a 0.5 dex fainter Y signal than another less massive z~1.8 cluster, exemplifying how much different weak-lensing mass and SZ mass can be at high redshift. The observations we present provide us with the measurement of the most distant resolved pressure profile of a galaxy cluster. Comparison with a library of plausibly descendants shows that JKCS041 pressure profile will likely increase by about 0.7 dex in the next 10 Gyr at all radii., Comment: MNRAS, in press

Published
2023
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2. Linking the dust and chemical evolution: Taurus and Perseus -- New collisional rates for HCN, HNC, and their C, N, and H isotopologues

Author

Navarro-Almaida, D., Bop, C. T., Lique, F., Esplugues, G., Rodríguez-Baras, M., Kramer, C., Romero, C. E., Fuente, A., Caselli, P., Riviére-Marichalar, P., Kirk, J. M., Chacón-Tanarro, A., Roueff, E., Mroczkowski, T., Bhandarkar, T., Devlin, M., Dicker, S., Lowe, I., Mason, B., Sarazin, C. L., and Sievers, J.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

HCN, HNC, and their isotopologues are ubiquitous molecules that can serve as chemical thermometers and evolutionary tracers to characterize star-forming regions. Despite their importance in carrying information that is vital to studies of the chemistry and evolution of star-forming regions, the collision rates of some of these molecules have not been available for rigorous studies in the past. We perform an up-to-date gas and dust chemical characterization of two different star-forming regions, TMC 1-C and NGC 1333-C7, using new collisional rates of HCN, HNC, and their isotopologues. We investigated the possible effects of the environment and stellar feedback in their chemistry and their evolution. With millimeter observations, we derived their column densities, the C and N isotopic fractions, the isomeric ratios, and the deuterium fractionation. The continuum data at 3 mm and 850 $\mu$m allowed us to compute the emissivity spectral index and look for grain growth as an evolutionary tracer. The H$^{13}$CN/HN$^{13}$C ratio is anticorrelated with the deuterium fraction of HCN, thus it can readily serve as a proxy for the temperature. The spectral index $(\beta\sim 1.34-2.09)$ shows a tentative anticorrelation with the H$^{13}$CN/HN$^{13}$C ratio, suggesting grain growth in the evolved, hotter, and less deuterated sources. Unlike TMC 1-C, the south-to-north gradient in dust temperature and spectral index observed in NGC 1333-C7 suggests feedback from the main NGC 1333 cloud. With this up-to-date characterization of two star-forming regions, we found that the chemistry and the physical properties are tightly related. The dust temperature, deuterium fraction, and the spectral index are complementary evolutionary tracers. The large-scale environmental factors may dominate the chemistry and evolution in clustered star-forming regions., Comment: 25 pages, 20 figures

Published
2022
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3. Atacama Cosmology Telescope: High-resolution component-separated maps across one third of the sky

Author

Coulton, W, Madhavacheril, M, Duivenvoorden, A, Hill, J, Abril-Cabezas, I, Ade, P, Aiola, S, Alford, T, Amiri, M, Amodeo, S, An, R, Atkins, Z, Austermann, J, Battaglia, N, Battistelli, E, Beall, J, Bean, R, Beringue, B, Bhandarkar, T, Biermann, E, Bolliet, B, Bond, J, Cai, H, Calabrese, E, Calafut, V, Capalbo, V, Carrero, F, Chesmore, G, Cho, H, Choi, S, Clark, S, Rosado, R, Cothard, N, Coughlin, K, Crowley, K, Devlin, M, Dicker, S, Doze, P, Duell, C, Duff, S, Dunkley, J, Dünner, R, Fanfani, V, Fankhanel, M, Farren, G, Ferraro, S, Freundt, R, Fuzia, B, Gallardo, P, Garrido, X, Givans, J, Gluscevic, V, Golec, J, Guan, Y, Halpern, M, Han, D, Hasselfield, M, Healy, E, Henderson, S, Hensley, B, Hervías-Caimapo, C, Hilton, G, Hilton, M, Hincks, A, Hložek, R, Ho, S, Huber, Z, Hubmayr, J, Huffenberger, K, Hughes, J, Irwin, K, Isopi, G, Jense, H, Keller, B, Kim, J, Knowles, K, Koopman, B, Kosowsky, A, Kramer, D, Kusiak, A, La Posta, A, Lakey, V, Lee, E, Li, Z, Li, Y, Limon, M, Lokken, M, Louis, T, Lungu, M, Maccrann, N, Macinnis, A, Maldonado, D, Maldonado, F, Mallaby-Kay, M, Marques, G, Van Marrewijk, J, Mccarthy, F, Mcmahon, J, Mehta, Y, Menanteau, F, Coulton W., Madhavacheril M. S., Duivenvoorden A. J., Hill J. C., Abril-Cabezas I., Ade P. A. R., Aiola S., Alford T., Amiri M., Amodeo S., An R., Atkins Z., Austermann J. E., Battaglia N., Battistelli E. S., Beall J. A., Bean R., Beringue B., Bhandarkar T., Biermann E., Bolliet B., Bond J. R., Cai H., Calabrese E., Calafut V., Capalbo V., Carrero F., Chesmore G. E., Cho H. M., Choi S. K., Clark S. E., Rosado R. C., Cothard N. F., Coughlin K., Crowley K. T., Devlin M. J., Dicker S., Doze P., Duell C. J., Duff S. M., Dunkley J., Dünner R., Fanfani V., Fankhanel M., Farren G., Ferraro S., Freundt R., Fuzia B., Gallardo P. A., Garrido X., Givans J., Gluscevic V., Golec J. E., Guan Y., Halpern M., Han D., Hasselfield M., Healy E., Henderson S., Hensley B., Hervías-Caimapo C., Hilton G. C., Hilton M., Hincks A. D., HloŽek R., Ho S. P. P., Huber Z. B., Hubmayr J., Huffenberger K. M., Hughes J. P., Irwin K., Isopi G., Jense H. T., Keller B., Kim J., Knowles K., Koopman B. J., Kosowsky A., Kramer D., Kusiak A., La Posta A., Lakey V., Lee E., Li Z., Li Y., Limon M., Lokken M., Louis T., Lungu M., Maccrann N., Macinnis A., Maldonado D., Maldonado F., Mallaby-Kay M., Marques G. A., Van Marrewijk J., McCarthy F., McMahon J., Mehta Y., Menanteau F., Coulton, W, Madhavacheril, M, Duivenvoorden, A, Hill, J, Abril-Cabezas, I, Ade, P, Aiola, S, Alford, T, Amiri, M, Amodeo, S, An, R, Atkins, Z, Austermann, J, Battaglia, N, Battistelli, E, Beall, J, Bean, R, Beringue, B, Bhandarkar, T, Biermann, E, Bolliet, B, Bond, J, Cai, H, Calabrese, E, Calafut, V, Capalbo, V, Carrero, F, Chesmore, G, Cho, H, Choi, S, Clark, S, Rosado, R, Cothard, N, Coughlin, K, Crowley, K, Devlin, M, Dicker, S, Doze, P, Duell, C, Duff, S, Dunkley, J, Dünner, R, Fanfani, V, Fankhanel, M, Farren, G, Ferraro, S, Freundt, R, Fuzia, B, Gallardo, P, Garrido, X, Givans, J, Gluscevic, V, Golec, J, Guan, Y, Halpern, M, Han, D, Hasselfield, M, Healy, E, Henderson, S, Hensley, B, Hervías-Caimapo, C, Hilton, G, Hilton, M, Hincks, A, Hložek, R, Ho, S, Huber, Z, Hubmayr, J, Huffenberger, K, Hughes, J, Irwin, K, Isopi, G, Jense, H, Keller, B, Kim, J, Knowles, K, Koopman, B, Kosowsky, A, Kramer, D, Kusiak, A, La Posta, A, Lakey, V, Lee, E, Li, Z, Li, Y, Limon, M, Lokken, M, Louis, T, Lungu, M, Maccrann, N, Macinnis, A, Maldonado, D, Maldonado, F, Mallaby-Kay, M, Marques, G, Van Marrewijk, J, Mccarthy, F, Mcmahon, J, Mehta, Y, Menanteau, F, Coulton W., Madhavacheril M. S., Duivenvoorden A. J., Hill J. C., Abril-Cabezas I., Ade P. A. R., Aiola S., Alford T., Amiri M., Amodeo S., An R., Atkins Z., Austermann J. E., Battaglia N., Battistelli E. S., Beall J. A., Bean R., Beringue B., Bhandarkar T., Biermann E., Bolliet B., Bond J. R., Cai H., Calabrese E., Calafut V., Capalbo V., Carrero F., Chesmore G. E., Cho H. M., Choi S. K., Clark S. E., Rosado R. C., Cothard N. F., Coughlin K., Crowley K. T., Devlin M. J., Dicker S., Doze P., Duell C. J., Duff S. M., Dunkley J., Dünner R., Fanfani V., Fankhanel M., Farren G., Ferraro S., Freundt R., Fuzia B., Gallardo P. A., Garrido X., Givans J., Gluscevic V., Golec J. E., Guan Y., Halpern M., Han D., Hasselfield M., Healy E., Henderson S., Hensley B., Hervías-Caimapo C., Hilton G. C., Hilton M., Hincks A. D., HloŽek R., Ho S. P. P., Huber Z. B., Hubmayr J., Huffenberger K. M., Hughes J. P., Irwin K., Isopi G., Jense H. T., Keller B., Kim J., Knowles K., Koopman B. J., Kosowsky A., Kramer D., Kusiak A., La Posta A., Lakey V., Lee E., Li Z., Li Y., Limon M., Lokken M., Louis T., Lungu M., Maccrann N., Macinnis A., Maldonado D., Maldonado F., Mallaby-Kay M., Marques G. A., Van Marrewijk J., McCarthy F., McMahon J., Mehta Y., and Menanteau F.

Abstract

Observations of the millimeter sky contain valuable information on a number of signals, including the blackbody cosmic microwave background (CMB), Galactic emissions, and the Compton-y distortion due to the thermal Sunyaev-Zel'dovich (tSZ) effect. Extracting new insight into cosmological and astrophysical questions often requires combining multiwavelength observations to spectrally isolate one component. In this work, we present a new arc-minute-resolution Compton-y map, which traces out the line-of-sight-integrated electron pressure, as well as maps of the CMB in intensity and E-mode polarization, across a third of the sky (around 13,000 deg2). We produce these through a joint analysis of data from the Atacama Cosmology Telescope (ACT) data release 4 and 6 at frequencies of roughly 93, 148, and 225 GHz, together with data from the Planck satellite at frequencies between 30 and 545 GHz. We present detailed verification of an internal linear combination pipeline implemented in a needlet frame that allows us to efficiently suppress Galactic contamination and account for spatial variations in the ACT instrument noise. These maps provide a significant advance, in noise levels and resolution, over the existing Planck component-separated maps and will enable a host of science goals including studies of cluster and galaxy astrophysics, inferences of the cosmic velocity field, primordial non-Gaussianity searches, and gravitational lensing reconstruction of the CMB.

Published
2024

4. 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

5. The Atacama Cosmology Telescope: Systematic Transient Search of 3 Day Maps

Author

Li, Y, Biermann, E, Naess, S, Aiola, S, An, R, Battaglia, N, Bhandarkar, T, Calabrese, E, Choi, S, Crowley, K, Devlin, M, Duell, C, Duff, S, Dunkley, J, Dünner, R, Gallardo, P, Guan, Y, Hervias-Caimapo, C, Hincks, A, Hubmayr, J, Huffenberger, K, Hughes, J, Kosowsky, A, Louis, T, Mallaby-Kay, M, Mcmahon, J, Nati, F, Niemack, M, Orlowski-Scherer, J, Page, L, Salatino, M, Sifón, C, Staggs, S, Vargas, C, Vavagiakis, E, Wang, Y, Wollack, E, Li, YQ, Choi, SK, Crowley, KT, Duell, CJ, Duff, SM, Gallardo, PA, Guan, YL, Hincks, AD, Huffenberger, KM, Hughes, JP, Niemack, MD, Staggs, ST, Vavagiakis, EM, Wang, YH, Wollack, EJ, Li, Y, Biermann, E, Naess, S, Aiola, S, An, R, Battaglia, N, Bhandarkar, T, Calabrese, E, Choi, S, Crowley, K, Devlin, M, Duell, C, Duff, S, Dunkley, J, Dünner, R, Gallardo, P, Guan, Y, Hervias-Caimapo, C, Hincks, A, Hubmayr, J, Huffenberger, K, Hughes, J, Kosowsky, A, Louis, T, Mallaby-Kay, M, Mcmahon, J, Nati, F, Niemack, M, Orlowski-Scherer, J, Page, L, Salatino, M, Sifón, C, Staggs, S, Vargas, C, Vavagiakis, E, Wang, Y, Wollack, E, Li, YQ, Choi, SK, Crowley, KT, Duell, CJ, Duff, SM, Gallardo, PA, Guan, YL, Hincks, AD, Huffenberger, KM, Hughes, JP, Niemack, MD, Staggs, ST, Vavagiakis, EM, Wang, YH, and Wollack, EJ

Abstract

We conduct a systematic search for transients in 3 yr of data (2017-2019) from the Atacama Cosmology Telescope (ACT). ACT covers 40% of the sky at three bands spanning from 77-277 GHz. Analysis of 3 day mean-subtracted sky maps, which were match filtered for point sources, yielded 29 transient detections. Eight of these transients are due to known asteroids, and three others were previously published. Four of these events occur in areas with poor noise models and thus we cannot be confident they are real transients. We are left with 14 new transient events occurring at 11 unique locations. All of these events are associated with either rotationally variable stars or cool stars. Ten events have flat or falling spectra indicating radiation from synchrotron emission. One event has a rising spectrum indicating a different engine for the flare.

Published
2023

7. Linking the dust and chemical evolution: Taurus and Perseus

Author

Navarro-Almaida, D., primary, Bop, C. T., additional, Lique, F., additional, Esplugues, G., additional, Rodríguez-Baras, M., additional, Kramer, C., additional, Romero, C. E., additional, Fuente, A., additional, Caselli, P., additional, Rivière-Marichalar, P., additional, Kirk, J. M., additional, Chacón-Tanarro, A., additional, Roueff, E., additional, Mroczkowski, T., additional, Bhandarkar, T., additional, Devlin, M., additional, Dicker, S., additional, Lowe, I., additional, Mason, B., additional, Sarazin, C. L., additional, and Sievers, J., additional

Published
2023
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9. 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

10. 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

11. 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
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12. 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
Full Text
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