  The EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) is a
cryogenic balloon-borne instrument that will survey galaxy and star formation
history over cosmological time scales. Rather than identifying individual
objects, EXCLAIM will be a pathfinder to demonstrate an intensity mapping
approach, which measures the cumulative redshifted line emission. EXCLAIM will
operate at 420-540 GHz with a spectral resolution R=512 to measure the
integrated CO and [CII] in redshift windows spanning 0 < z < 3.5. CO and [CII]
line emissions are key tracers of the gas phases in the interstellar medium
involved in star-formation processes. EXCLAIM will shed light on questions such
as why the star formation rate declines at z < 2, despite continued clustering
of the dark matter. The instrument will employ an array of six superconducting
integrated grating-analog spectrometers (micro-spec) coupled to microwave
kinetic inductance detectors (MKIDs). Here we present an overview of the
EXCLAIM instrument design and status.

Instrumentation and Methods for Astrophysics;Cosmology and Nongalactic Astrophysics