  The discovery of cosmic acceleration has inspired ambitious experimental and
observational efforts to understand its origin. Many of these take the form of
large astronomical surveys, sometimes using new, special-purpose
instrumentation, and in some cases entirely new facilities. This Report
summarizes some of the major ongoing and planned dark energy experiments,
focusing on those in which the U.S. community has a leading or significant
supporting role. It provides background information for other Reports from the
"Dark Energy and CMB" working group of the APS Division of Particles and Fields
long-term planning exercise. We provide 1-2 page summaries of the SDSS-III
Baryon Oscillation Spectroscopic Survey (BOSS) and its SDSS-IV successor eBOSS,
the Dark Energy Survey (DES), the Subaru Hyper-Suprime Camera (HSC) and Prime
Focus Spectrograph (PFS), the Hobby-Eberley Telescope Dark Energy Experiment
(HEDTEX), the Dark Energy Spectroscopic Instrument (DESI), the Large Synpotic
Survey Telescope (LSST), and the Euclid and AFTA-WFIRST (Wide Field Infrared
Survey Telescope) space missions. Over the next one to two decades, these
experiments seek to improve the precision of measurements of the cosmic
expansion history and cosmic structure growth by factors of 10-100, while
simultaneously increasing their redshift range and tightening control and
cross-checks of sytematic effects. These measurements will dramatically improve
the empirical constraints on theoretical explanations of cosmic acceleration
and could lead to breakthroughs in our understanding of the nature of gravity
and spacetime or the forms of energy present in the universe.
