Overview 

Our research focuses on developing new instrumentation to study the formation and evolution of the universe through precision measurements of microwave radiation. Past measurements of the cosmic microwave background (CMB) provided an exquisite picture of the early universe, which combined with astronomical observations at other wavelengths led to strong evidence that we live in a dark energy and dark matter dominated universe; however, we still do not fully understand fundamental aspects of the universe. What are dark energy and dark matter? Did inflation occur in the early universe, and can we understand it? How did the primordial fluctuations evolve into galaxies, stars, and planets? What physical models best describe the past, present, and future of the cosmos?

The instruments we develop help address aspects of these questions through more sensitive observations at millimeter and sub-millimeter wavelengths. We survey the CMB temperature and polarization in unprecedented detail, enabling a wide range of science objectives, including: new constraints on the physics of inflation, new probes of dark energy and modified gravity, characterization of the dark matter distribution, measurements of the neutrino mass sum, and the discovery of both galaxy clusters and high-redshift galaxies.

In 2008 observations began with the six-meter Atacama Cosmology Telescope (ACT, photo above), located at 5190 meters elevation in the Chilean desert. The ACT data has led to a variety of results, including first detections of the power spectrum of CMB gravitational lensing as well as the kinematic Sunyaev-Zel'dovich effect (see publications and people for details). We are now working on ACTPol – the first polarization sensitive receiver for ACT. ACTPol includes the largest CMB polarimeter arrays yet deployed. We are working on characterizing the instrument, running observations, developing detectors and instrumentation for the Advanced ACTPol upgrade, and analyzing ACTPol data, including cross-correlating the data with measurements from other observatories that span the electromagnetic spectrum.

Another exciting aspect of our research is that advances in millimeter and sub-millimeter radiation measurements are largely being driven by the development of new superconducting and optical techniques. We have helped to design, build, and deploy some of the largest arrays of superconducting detectors yet, with thousands of transition-edge sensor (TES) detectors cooled to sub-Kelvin temperatures. TES detectors are becoming a widely used technology spanning eight orders of magnitude in detection energy (from CMB bolometers to gamma ray microcalorimeters). Arrays of TESes are generally measured using multiplexed superconducting quantum interference devices (SQUIDs). We are working on new detector and SQUID measurement technologies to enable readout of even larger superconducting detector arrays, and are developing new optics and instrument designs to couple to these arrays in next generation observatories. We also work in the Cornell Nanoscale Facility developing new optics and detector microfabrication techniques that can be tested and integrated in our laboratory.

The people, research, news, and publications pages provide more information about us and the science, observatories, and technologies we are working on to improve our understanding of the universe.

Research opportunities:  

Prospective postdoctoral researchers and graduate students may apply for various fellowships to do research with us. Please send a copy of your curriculum vitae along with a brief description of your research interests to Professor Niemack if you are interested in applying for fellowships.

Cornell undergraduates may apply to do research during the academic year or during the summer. Students who start during the academic year are often asked to commit to continuing research with us for at least one summer. If you are interested, please send a copy of your resume or curriculum vitae including: a description of technical skills, relevant physics, engineering, computer science, or astronomy courses, and GPA to Professor Niemack. No prior research experience is required, though it may help secure a position.

Undergraduates from other institutions may apply for summer research opportunities through the Louis Stokes Alliance for Minority Participation (LSAMP) Program or the Summer Research for Community College Students (SRCCS) Program. There are also several programs offering research opportunities at institutions we collaborate with on the Atacama Cosmology Telescope.