Dr. Sumit Dahal Profile

Dr. Sumit Dahal

Postdoctoral Fellow at NASA Goddard Space Flight Ctr

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Author

Publications (10)

Proceedings Article | 31 August 2022 Poster + Paper

Design and characterization of new 90 GHz detectors for the Cosmology Large Angular Scale Surveyor (CLASS)

Carolina Nunez, John Appel, Sarah Marie Bruno, Rahul Datta, Aamir Ali, Charles Bennett, Sumit Dahal, Jullianna Denes Couto, Kevin Denis, Joseph Eimer, Francisco Espinoza, Tom Essinger-Hileman, Kyle Helson, Jeffrey Iuliano, Tobias Marriage, Carolina Morales Peréz, Deniz Augusto Nunes Valle, Matthew Petroff, Karwan Rostem, Rui Shi, Duncan Watts, Edward Wollack, Zhilei Xu

Proceedings Volume 12190, 121901J (2022) https://doi.org/10.1117/12.2630081

KEYWORDS: Sensors, Bolometers, Telescopes, Staring arrays, Silicon, Polarization, Microwave radiation, Wafer-level optics, Detector arrays, Astronomical instrumentation, Detector development, Superconducting detectors, Astronomical telescopes

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Proceedings Article | 31 August 2022 Poster + Paper

Cosmology Large Angular Scale Surveyor (CLASS): pointing stability and beam measurements at 90, 150, and 220 GHz

Rahul Datta, Michael Brewer, Jullianna Couto, Joseph Eimer, Yunyang Li, Zhilei Xu, John Appel, Ricardo Bustos, David Chuss, Joseph Cleary, Sumit Dahal, Thomas Essinger-Hileman, Jeffrey Iuliano, Tobias Marriage, Carolina Nunez, Matthew Petroff, Karwan Rostem, Duncan Watts, Edward Wollack

Proceedings Volume 12190, 121902S (2022) https://doi.org/10.1117/12.2630649

KEYWORDS: Telescopes, Polarization, Receivers, Calibration, Optical testing, Physics

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Proceedings Article | 31 August 2022 Poster + Paper

Long-timescale stability in CMB observations at multiple frequencies using front-end polarization modulation

Joseph Cleary, Rahul Datta, John Appel, Charles Bennet, David Chuss, Jullianna Denes Couto, Sumit Dahal, Francisco Espinoza, Thomas Essinger-Hileman, Kathleen Harrington, Jeffery Iuliano, Yunyang Li, Tobias Marriage, Carolina Núñez, Matthew Petroff, Rodrigo Reeves, Rui Shi, Duncan Watts, Edward Wollack, Zhilei Xu

Proceedings Volume 12190, 121902Q (2022) https://doi.org/10.1117/12.2629723

KEYWORDS: Polarization, Modulation, Sensors, Telescopes, Data modeling, Interference (communication), Demodulation, Astronomy, Theoretical astronomy, Physics

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Proceedings Article | 31 August 2022 Poster + Paper

Construction of a large diameter reflective half-wave plate modulator for millimeter wave applications

Joseph Eimer, Michael Brewer, David Chuss, John Karakla, Rui Shi, John Appel, Charles Bennett, Joseph Cleary, Sumit Dahal, Rahul Datta, Thomas Essinger-Hileman, Tobias Marriage, Carolina Núñez, Matthew Petroff, Duncan Watts, Edward Wollack, Zhilei Xu

Proceedings Volume 12190, 121901N (2022) https://doi.org/10.1117/12.2630637

KEYWORDS: Polarization, Modulators, Wave plates, Modulation, Servomechanisms, Telescopes

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Proceedings Article | 15 December 2020 Poster + Paper

Control and systems software for the Cosmology Large Angular Scale Surveyor (CLASS)

Matthew Petroff, John Appel, Charles Bennett, Michael Brewer, Manwei Chan, David Chuss, Joseph Cleary, Jullianna Denes Couto, Sumit Dahal, Joseph Eimer, Thomas Essinger-Hileman, Pedro Fluxá Rojas, Kathleen Harrington, Jeffrey Iuliano, Tobias Marriage, Nathan Miller, Deniz Augusto Nunes Valle, Duncan Watts, Zhilei Xu

Proceedings Volume 11452, 114521O (2020) https://doi.org/10.1117/12.2561609

KEYWORDS: Control systems, Telescopes, Packaging, Optical instrument design, Polarization, Microwave radiation, Human-machine interfaces, Data compression, Internet

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Proceedings Article | 10 July 2018 Paper

The Cosmology Large Angular Scale Surveyor receiver design

Jeffrey Iuliano, Joseph Eimer , Lucas Parker, Gary Rhoades, Aamir Ali, John Appel, Charles Bennett , Michael Brewer , Ricardo Bustos , David Chuss , Joseph Cleary , Jullianna Couto, Sumit Dahal, Kevin Denis, Rolando Dünner , Thomas Essinger-Hileman, Pedro Fluxa , Mark Halpern , Kathleen Harrington , Kyle Helson, Gene Hilton , Gary Hinshaw , Johannes Hubmayr , John Karakla , Tobias Marriage , Nathan Miller , Jeffrey John McMahon, Carolina Nuñez, Ivan Padilla , Gonzalo Palma , Matthew Petroff , Bastian Pradenas Márquez, Rodrigo Reeves , Carl Reintsema , Karwan Rostem , Deniz Augusto Nunes Valle, Trevor Van Engelhoven, Bingjie Wang , Qinan Wang , Duncan Watts , Janet Weiland , Edward Wollack , Zhilei Xu, Ziang Yan , Lingzhen Zeng

Proceedings Volume 10708, 1070828 (2018) https://doi.org/10.1117/12.2312954

KEYWORDS: Receivers, Sensors, Tolerancing, Lenses, Magnetism, Optical alignment, Polarization, Absorption filters

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Proceedings Article | 9 July 2018 Paper

SiAl alloy feedhorn arrays: material properties, feedhorn design, and astrophysical applications

Aamir Ali, Thomas Essinger-Hileman, Tobias Marriage, John Appel, Charles Bennett, Matthew Berkeley, Berhanu Bulcha, Sumit Dahal, Kevin Denis, Karwan Rostem, Kongpop U-Yen, Edward Wollack, Lingzhen Zeng

Proceedings Volume 10708, 107082P (2018) https://doi.org/10.1117/12.2312817

KEYWORDS: Silicon, Sensors, Aluminum, Copper, Cryogenics, Temperature metrology, Interfaces, Waveguides, Gold, Packaging

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Proceedings Article | 9 July 2018 Paper

Variable-delay polarization modulators for the CLASS telescopes

Kathleen Harrington, Joseph Eimer, David Chuss, Matthew Petroff, Joseph Cleary, Martin DeGeorge, Theodore Grunberg, Aamir Ali, John Appel, Charles Bennett, Michael Brewer, Ricardo Bustos, Manwei Chan, Jullianna Couto, Sumit Dahal, Kevin Denis, Rolando Dünner, Thomas Essinger-Hileman, Pedro Fluxa, Mark Halpern, Gene Hilton, Gary Hinshaw, Johannes Hubmayr, Jeffrey Iuliano, John Karakla, Tobias Marriage, Jeffrey McMahon, Nathan Miller, Carolina Nuñez, Ivan Padilla, Gonzalo Palma, Lucas Parker, Bastian Pradenas Marquez, Rodrigo Reeves, Carl Reintsema, Karwan Rostem, Deniz Augusto Nunes Valle, Trevor Van Engelhoven, Bingjie Wang, Qinan Wang, Duncan Watts, Janet Weiland, Edward Wollack, Zhilei Xu, Ziang Yan, Lingzhen Zeng

Proceedings Volume 10708, 107082M (2018) https://doi.org/10.1117/12.2313614

KEYWORDS: Polarization, Telescopes, Modulation, Sensors, Computer programming, Control systems, Microscopes, Modulators, Microwave radiation, Physical cosmology

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The search for inflationary primordial gravitational waves and the measurement of the optical depth to reionization, both through their imprint on the large angular scale correlations in the polarization of the cosmic microwave background (CMB), has created the need for high sensitivity measurements of polarization across large fractions of the sky at millimeter wavelengths. These measurements are subject to instrumental and atmospheric 1=f noise, which has motivated the development of polarization modulators to facilitate the rejection of these large systematic effects.

Variable-delay polarization modulators (VPMs) are used in the Cosmology Large Angular Scale Surveyor (CLASS) telescopes as the first element in the optical chain to rapidly modulate the incoming polarization. VPMs consist of a linearly polarizing wire grid in front of a movable flat mirror. Varying the distance between the grid and the mirror produces a changing phase shift between polarization states parallel and perpendicular to the grid which modulates Stokes U (linear polarization at 45°) and Stokes V (circular polarization). The CLASS telescopes have VPMs as the first optical element from the sky; this simultaneously allows a lock-in style polarization measurement and the separation of sky polarization from any instrumental polarization further along in the optical path.

The CLASS VPM wire grids use 50 μm copper-plated tungsten wire with a 160μm spacing across a 60 cm clear aperture. The mirror is mounted on a flexure system with one degree of translational freedom, enabling the required mirror motion while maintaining excellent parallelism with respect to the wire grid. The wire grids and mirrors are held parallel to each other to better than 80 μm, and the wire grids have RMS flatness errors below 50 μm across the 60 cm aperture. The Q-band CLASS VPM was the first VPM to begin observing the CMB full time, starting in the Spring of 2016. The first W-band CLASS VPM was installed in the Spring of 2018.

Proceedings Article | 9 July 2018 Paper

Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane

Sumit Dahal, Aamir Ali, John Appel, Thomas Essinger-Hileman, Charles Bennett, Michael Brewer, Ricardo Bustos, Manwei Chan, David Chuss, Joseph Cleary, Felipe Colazo, Jullianna Couto, Kevin Denis, Rolando Dünner, Joseph Eimer, Trevor Engelhoven, Pedro Fluxa, Mark Halpern, Kathleen Harrington, Kyle Helson, Gene Hilton, Gary Hinshaw, Johannes Hubmayr, Jeffery Iuliano, John Karakla, Tobias Marriage, Jeffrey McMahon, Nathan Miller, Carolina Nuñez, Ivan Padilla, Gonzalo Palma, Lucas Parker, Matthew Petroff, Bastian Pradenas, Rodrigo Reeves, Carl Reintsema, Karwan Rostem, Marco Sagliocca, Kongpop U-Yen, Deniz Valle, Bingjie Wang, Qinan Wang, Duncan Watts, Janet Weiland, Edward Wollack, Zhilei Xu, Ziang Yan, Lingzhen Zeng

Proceedings Volume 10708, 107081Y (2018) https://doi.org/10.1117/12.2311812

KEYWORDS: Sensors, Polarization, Signal detection, Detector arrays, Telescopes, Silicon, Receivers, Bolometers, Superconducting detectors

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Proceedings Article | 19 July 2016 Paper

The Cosmology Large Angular Scale Surveyor

Kathleen Harrington, Tobias Marriage, Aamir Ali, John Appel, Charles Bennett, Fletcher Boone, Michael Brewer, Manwei Chan, David Chuss, Felipe Colazo, Sumit Dahal, Kevin Denis, Rolando Dünner, Joseph Eimer, Thomas Essinger-Hileman, Pedro Fluxa, Mark Halpern, Gene Hilton, Gary Hinshaw, Johannes Hubmayr, Jeffrey Iuliano, John Karakla, Jeff McMahon, Nathan Miller, Samuel Moseley, Gonzalo Palma, Lucas Parker, Matthew Petroff, Bastián Pradenas, Karwan Rostem, Marco Sagliocca, Deniz Valle, Duncan Watts, Edward Wollack, Zhilei Xu, Lingzhen Zeng

Proceedings Volume 9914, 99141K (2016) https://doi.org/10.1117/12.2233125

KEYWORDS: Polarization, Telescopes, Sensors, Space telescopes, Mirrors, Receivers, Modulation, Lenses, Optical filters, Physics

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