Browsing by Author "Mcmahon, Jeff"

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    Freeform three-mirror anastigmatic large-aperture telescope and receiver optics for CMB-S4
    (2024) Gallardo, Patricio A.; Puddu, Roberto; Harrington, Kathleen; Benson, Bradford; Carlstrom, John E.; Dicker, Simon R.; Emerson, Nick; Gudmundsson, Jon E.; Limon, Michele; Mcmahon, Jeff; Nagy, Johanna M.; Natoli, Tyler; Niemack, Michael D.; Padin, Stephen; Ruhl, John; Simon, Sara M.
    CMB-S4, the next-generation ground-based cosmic microwave background (CMB) observatory, will provide detailed maps of the CMB at millimeter wavelengths to dramatically advance our understanding of the origin and evolution of the universe. CMB-S4 will deploy large- and small-aperture telescopes with hundreds of thousands of detectors to observe the CMB at arcminute and degree resolutions at millimeter wavelengths. Inflationary science benefits from a deep delensing survey at arcminute resolutions capable of observing a large field of view at millimeter wavelengths. This kind of survey acts as a complement to a degree angular resolution survey. The delensing survey requires a nearly uniform distribution of cameras per frequency band across the focal plane. We present a large-throughput (9.4 degrees field of view), large-aperture (5-m diameter) freeform three-mirror anastigmatic telescope and an array of 85 cameras for CMB observations at arcminute resolutions, which meets the needs of the delensing survey of CMB-S4. A detailed prescription of this three-mirror telescope and cameras is provided, with a series of numerical calculations that indicates expected optical performance and mechanical tolerance.
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    Simons Observatory: characterizing the Large Aperture Telescope Receiver with radio holography
    (2022) Chesmore, Grace E.; Harrington, Kathleen; Sierra, Carlos E.; Gallardo, Patricio A.; Sutariya, Shreya; Alford, Tommy; Adler, Alexandre E.; Bhandarkar, Tanay; Coppi, Gabriele; Dachlythra, Nadia; Golec, Joseph; Gudmundsson, Jon; Haridas, Saianeesh K.; Johnson, Bradley R.; Kofman, Anna M.; Iuliano, Jeffrey; Mcmahon, Jeff; Niemack, Michael D.; Orlowski-Scherer, John; Sarmiento, Karen Perez; Puddu, Roberto; Silva-Feaver, Max; Simon, Sara M.; Robe, Julia; Wollack, Edward J.; Xu, Zhilei
    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. (c) 2022 Optica Publishing Group
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    The Atacama cosmology telescope : CMB polarization at 200 < l < 9000
    (2014) Naess, Sigurd; Hasselfield, Matthew; Mcmahon, Jeff; Niemack, Michael D.; Addison, Graeme E.; Dünner Planella, Rolando; Gallardo, Patricio; Infante Lira, Leopoldo; Maurin, Loïc Benjamin; Rojas, Felipe
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    The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters
    (2024) Madhavacheril, Mathew S.; Qu, Frank J.; Sherwin, Blake D.; Maccrann, Niall; Li, Yaqiong; Abril-Cabezas, Irene; Ade, Peter A. R.; Aiola, Simone; Alford, Tommy; Amiri, Mandana; Amodeo, Stefania; An, Rui; Atkins, Zachary; Austermann, Jason E.; Battaglia, Nicholas; Battistelli, Elia Stefano; Beall, James A.; Bean, Rachel; Beringue, Benjamin; Bhandarkar, Tanay; Biermann, Emily; Bolliet, Boris; Bond, J. Richard; Cai, Hongbo; Calabrese, Erminia; Calafut, Victoria; Capalbo, Valentina; Carrero, Felipe; Challinor, Anthony; Chesmore, Grace E.; Cho, Hsiao-mei; Choi, Steve K.; Clark, Susan E.; Rosado, Rodrigo Cordova; Cothard, Nicholas F.; Coughlin, Kevin; Coulton, William; Crowley, Kevin T.; Dalal, Roohi; Darwish, Omar; Devlin, Mark J.; Dicker, Simon; Doze, Peter; Duell, Cody J.; Duff, Shannon M.; Duivenvoorden, Adriaan J.; Dunkley, Jo; Duenner, Rolando; Fanfani, Valentina; Fankhanel, Max; Farren, Gerrit; Ferraro, Simone; Freundt, Rodrigo; Fuzia, Brittany; Gallardo, Patricio A.; Garrido, Xavier; Givans, Jahmour; Gluscevic, Vera; Golec, Joseph E.; Guan, Yilun; Hall, Kirsten R.; Halpern, Mark; Han, Dongwon; Harrison, Ian; Hasselfield, Matthew; Healy, Erin; Henderson, Shawn; Hensley, Brandon; Hervias-Caimapo, Carlos; Hill, J. Colin; Hilton, Gene C.; Hilton, Matt; Hincks, Adam D.; Hlozek, Renee; Ho, Shuay-Pwu Patty; Huber, Zachary B.; Hubmayr, Johannes; Huffenberger, Kevin M.; Hughes, John P.; Irwin, Kent; Isopi, Giovanni; Jense, Hidde T.; Keller, Ben; Kim, Joshua; Knowles, Kenda; Koopman, Brian J.; Kosowsky, Arthur; Kramer, Darby; Kusiak, Aleksandra; La Posta, Adrien; Lague, Alex; Lakey, Victoria; Lee, Eunseong; Li, Zack; Limon, Michele; Lokken, Martine; Louis, Thibaut; Lungu, Marius; Macinnis, Amanda; Maldonado, Diego; Maldonado, Felipe; Mallaby-Kay, Maya; Marques, Gabriela A.; Mcmahon, Jeff; Mehta, Yogesh; Menanteau, Felipe; Moodley, Kavilan; Morris, Thomas W.; Mroczkowski, Tony; Naess, Sigurd; Namikawa, Toshiya; Nati, Federico; Newburgh, Laura; Nicola, Andrina; Niemack, Michael D.; Nolta, Michael R.; Orlowski-Scherer, John; Page, Lyman A.; Pandey, Shivam; Partridge, Bruce; Prince, Heather; Puddu, Roberto; Radiconi, Federico; Robertson, Naomi; Rojas, Felipe; Sakuma, Tai; Salatino, Maria; Schaan, Emmanuel; Schmitt, Benjamin L.; Sehgal, Neelima; Shaikh, Shabbir; Sierra, Carlos; Sievers, Jon; Sifon, Cristobal; Simon, Sara; Sonka, Rita; Spergel, David N.; Staggs, Suzanne T.; Storer, Emilie; Switzer, Eric R.; Tampier, Niklas; Thornton, Robert; Trac, Hy; Treu, Jesse; Tucker, Carole; Ullom, Joel; Vale, Leila R.; Van Engelen, Alexander; Van Lanen, Jeff; van Marrewijk, Joshiwa; Vargas, Cristian; Vavagiakis, Eve M.; Wagoner, Kasey; Wang, Yuhan; Wenzl, Lukas; Wollack, Edward J.; Xu, Zhilei; Zago, Fernando; Zheng, Kaiwen
    We present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg(2). reconstructed from CMB measurements made by the Atacama Cosmology Telescope (ACT) from 2017 to 2021. In combination with BAO measurements (from SDSS and 6dF), we obtain the amplitude of matter fluctuations sigma(8)=0.819 +/- 0.015 at 1.8% precision, S-8 equivalent to sigma(8)(Omega(m)/0.3)(0.5)=0.840 +/- 0.028 and the Hubble constant H-0=(68.3 +/- 1.1)kms(-1)Mpc(-1) at 1.6% precision. A joint constraint with CMB lensing measured by the Planck satellite yields even more precise values: sigma(8)=0.812 +/- 0.013, S-8 equivalent to sigma(8)(Omega m/0.3)(0.5)=0.831 +/- 0.023 and H-0=(68.1 +/- 1.0)kms(-1)Mpc(-1). These measurements agree well with Lambda CDM-model extrapolations from the CMB anisotropies measured by Planck. To compare these constraints to those from the KiDS, DES, and HSC galaxy surveys, we revisit those data sets with a uniform set of assumptions, and find S-8 from all three surveys are lower than that from ACT+Planck lensing by varying levels ranging from 1.7-2.1 sigma. These results motivate further measurements and comparison, not just between the CMB anisotropies and galaxy lensing, but also between CMB lensing probing z similar to 0.5-5 on mostly-linear scales and galaxy lensing at z similar to 0.5 on smaller scales. We combine our CMB lensing measurements with CMB anisotropies to constrain extensions of Lambda CDM, limiting the sum of the neutrino masses to & sum;m(nu)<0.12 eV (95% c.l.), for example. Our results provide independent confirmation that the universe is spatially flat, conforms with general relativity, and is described remarkably well by the Lambda CDM model, while paving a promising path for neutrino physics with gravitational lensing from upcoming ground-based CMB surveys
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    The Atacama Cosmology Telescope: Systematic Transient Search of 3 Day Maps
    (2023) Li, Yaqiong; Biermann, Emily; Naess, Sigurd; Aiola, Simone; An, Rui; Battaglia, Nicholas; Bhandarkar, Tanay; Calabrese, Erminia; Choi, Steve K.; Crowley, Kevin T.; Devlin, Mark; Duell, Cody J.; Duff, Shannon M.; Dunkley, Jo; Dunner, Rolando; Gallardo, Patricio A.; Guan, Yilun; Hervias-Caimapo, Carlos; Hincks, Adam D.; Hubmayr, Johannes; Huffenberger, Kevin M.; Hughes, John P.; Kosowsky, Arthur; Louis, Thibaut; Mallaby-Kay, Maya; Mcmahon, Jeff; Nati, Federico; Niemack, Michael D.; Orlowski-Scherer, John; Page, Lyman; Salatino, Maria; Sifon, Cristobal; Staggs, Suzanne T.; Vargas, Cristian; Vavagiakis, Eve M.; Wang, Yuhan; Wollack, Edward J.
    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.