Abstract
In theories with extra dimensions, the standard QCD axion has excited states with higher mass. These Kaluza-Klein (KK) axions would have a signi cantly shorter decay time and, when produced by the Sun, would remain gravitationally trapped in our Solar System, boosting their local decay rate. A low density detector would be able to distinguish such decays from background, by identifying the separate location of the capture of the two resulting photons. The NEWS-G collaboration uses low-pressure Spherical Proportional Counters, gas- lled metallic spheres with a high voltage electrode in their centre. This work aims to set exclusion limits on the solar KK axion model based on data from NEWS-G detectors.