  Kaluza-Klein (KK) axions appear in theories with extra dimensions as higher
mass, significantly shorter lifetime, excitations of the Peccei-Quinn axion.
When produced in the Sun, they would remain gravitationally trapped in the
solar system, and their decay to a pair of photons could provide an explanation
of the solar corona heating problem. A low-density detector would discriminate
such a signal from the background, by identifying the separation of the
interaction point of the two photons. The NEWS-G collaboration uses large
volume Spherical Proportional Counters, gas-filled metallic spheres with a
spherical anode in their centre. After observation of a single axionlike event
in a 42 day long run with the SEDINE detector, a $90\%$ C.L. upper limit of
$g_{a\gamma\gamma}<8.99\cdot10^{-13}\,GeV^{-1}$ is set on the axion-photon
coupling for a KK axion density on Earth of $n_{a}=4.07\cdot10^{13}\,m^{-3}$
and two extra dimensions of size $R = 1\,eV^{-1}$.
