Research


My research is primarily focused on building instruments to observe the cosmic microwave background (CMB), a relic radiation from the earliest moments of our universe. In particular, I am interested in making precise measurements of the CMB polarization to understand what happened at the beginning of the universe and pinpoint when the stars in the first galaxies were formed. I work on two CMB projects: the ground-based Cosmology Large Angular Scale Surveyor (CLASS) and the balloon-borne Primordial Inflation Polarization ExploreR (PIPER).  


Recently, I have been working on the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) balloon mission that aims to deepen our understanding of star formation in a cosmological context.  I have added a short description about these telescopes below. If you want to learn more about the telescopes, click on the associated links.


CLASS is an array of microwave telescopes located high up in the Andes mountain in the Atacama Desert of Chile. Mapping 70% of the sky at four frequency bands centered at 40, 90, 150, and 220 GHz, CLASS aims to test the theory of cosmic inflation and determine when galaxies first lit up. CLASS uses superconducting transition-edge sensors, cooled to near absolute zero temperature with helium refrigerators, to make high sensitivity measurements of the CMB polarization.  A key aspect of CLASS is the use of a novel modulation technology  that allows separation of desired CMB signal from atmospheric and instrumental noise. Check out this video to see how CLASS modulation works. The first science results from CLASS are expected soon; stay tuned!

PIPER is a balloon-borne mission designed to measure the CMB polarization on large angular scales in search of gravitational waves produced by inflation. It maps the sky at four frequency bands between 200 to 600 GHz, largely inaccessible from ground. 

PIPER payload consists of twin telescopes inside an open 3500 L liquid helium bucket dewar. The fully cryogenic telescope design allows overnight flights from New Mexico to achieve sensitivity that would otherwise require long-duration Antarctic flights. PIPER completed two engineering flights in 2017 and 2019, and a series of science flights are planned  starting 2024.

EXCLAIM is a cryogenic balloon-borne telescope (like PIPER) that will survey the sky to improve our understanding of the star formation history. EXCLAIM will be a pathfinder to demonstrate an innovative approach known as  intensity mapping. Particularly, EXCLAIM aims to map the redshifted emission of carbon monoxide and singly ionized carbon in cross-correlation with spectroscopic galaxy surveys in windows over the 0 < z < 3.5 redshift range. 

EXCLAIM features six integrated spectrometers, employing kinetic inductance detectors with spectral resolving power R=512 over the 420 – 540 GHz frequency range.  The cryogenic telescope and high sensitivity detectors allow EXCLAIM to access dark windows in the spectrum of emission from the upper atmosphere. EXCLAIM is currently under construction for a planned flight in the fall of 2024.

Selected Publications