  CCAT-prime will be a 6-meter aperture telescope operating from sub-mm to mm
wavelengths, located at 5600 meters elevation on Cerro Chajnantor in the
Atacama Desert in Chile. Its novel crossed-Dragone optical design will deliver
a high throughput, wide field of view capable of illuminating much larger
arrays of sub-mm and mm detectors than can existing telescopes. We present an
overview of the motivation and design of Prime-Cam, a first-light instrument
for CCAT-prime. Prime-Cam will house seven instrument modules in a 1.8 meter
diameter cryostat, cooled by a dilution refrigerator. The optical elements will
consist of silicon lenses, and the instrument modules can be individually
optimized for particular science goals. The current design enables both
broadband, dual-polarization measurements and narrow-band, Fabry-Perot
spectroscopic imaging using multichroic transition-edge sensor (TES) bolometers
operating between 190 and 450 GHz. It also includes broadband kinetic induction
detectors (KIDs) operating at 860 GHz. This wide range of frequencies will
allow excellent characterization and removal of galactic foregrounds, which
will enable precision measurements of the sub-mm and mm sky. Prime-Cam will be
used to constrain cosmology via the Sunyaev-Zeldovich effects, map the
intensity of [CII] 158 $\mu$m emission from the Epoch of Reionization, measure
Cosmic Microwave Background polarization and foregrounds, and characterize the
star formation history over a wide range of redshifts. More information about
CCAT-prime can be found at www.ccatobservatory.org.
