A ground-based 21cm Baryon acoustic oscillation survey
  Baryon acoustic oscillations (BAO) provide a robust standard ruler with which
to measure the acceleration of the Universe. The BAO feature has so far been
detected in optical galaxy surveys. Intensity mapping of neutral hydrogen
emission with a ground-based radio telescope provides another promising window
for measuring BAO at redshifts of order unity for relatively low cost. While
the cylindrical radio telescope (CRT) proposed for these measurements will have
excellent redshift resolution, it will suffer from poor angular resolution (a
few arcminutes at best). We investigate the effect of angular resolution on the
standard ruler test with BAO, using the Dark Energy Task Force Figure of Merit
as a benchmark. We then extend the analysis to include variations in the
parameters characterizing the telescope and the underlying physics. Finally, we
optimize the survey parameters (holding total cost fixed) and present an
example of a CRT BAO survey that is competitive with Stage III dark energy
experiments. The tools developed here form the backbone of a publicly available
code that can be used to obtain estimates of cost and Figure of Merit for any
set of parameters.
