  The CERN Axion Solar Telescope (CAST) searches for $a\to\gamma$ conversion in
the 9 T magnetic field of a refurbished LHC test magnet that can be directed
toward the Sun. Two parallel magnet bores can be filled with helium of
adjustable pressure to match the X-ray refractive mass $m_\gamma$ to the axion
search mass $m_a$. After the vacuum phase (2003--2004), which is optimal for
$m_a\lesssim0.02$ eV, we used $^4$He in 2005--2007 to cover the mass range of
0.02--0.39 eV and $^3$He in 2009--2011 to scan from 0.39--1.17 eV. After
improving the detectors and shielding, we returned to $^4$He in 2012 to
investigate a narrow $m_a$ range around 0.2 eV ("candidate setting" of our
earlier search) and 0.39--0.42 eV, the upper axion mass range reachable with
$^4$He, to "cross the axion line" for the KSVZ model. We have improved the
limit on the axion-photon coupling to $g_{a\gamma}< 1.47\times10^{-10} {\rm
  GeV}^{-1}$ (95% C.L.), depending on the pressure settings. Since 2013, we
have returned to vacuum and aim for a significant increase in sensitivity.
