  This paper presents Dandelion, a new dish antenna experiment searching for
dark photons (DPs) with masses around the meV that will start acquiring data by
the end of 2023. A spherical mirror acts as a conversion surface between DPs
and standard photons that converge to a matrix of 418 Kinetic Inductance
Detectors cooled down to 150 mK. A tilt of the mirror at 1 Hz moves the
expected signal over the pixels thus enabling a continuous background
measurement. The expected signal has two modulations: a spatial modulation
providing a directional signature for the unambiguous discovery of a DP, and an
intensity modulation allowing the determination of the polarization of the DP.
For masses near the meV, the inflationary production of longitudinal and
transverse DPs are mutually excluded, thus the polarization determination by
Dandelion could shed a new light on the inflation phase of the early universe.
A first Dandelion prototype operating for 30 days would improve by more than
one order of magnitude the current exclusion limits on DPs at the meV mass
scale and would probe this region with an unprecedented discovery potential
based on directional detection.
