Exploring 0.1-10$\,$eV axions with a new helioscope concept

Abstract

We explore the possibility to develop a new axion helioscope type, sensitive to the higher axion mass region favored by axion models. We propose to use a low background large volume TPC immersed in an intense magnetic field. Contrary to traditional tracking helioscopes, this detection technique takes advantage of the capability to directly detect the photons converted on the buffer gas which defines the axion mass sensitivity region, and does not require pointing the magnet to the Sun. The operation flexibility of a TPC to be used with different gas mixtures (He, Ne, Xe, etc) and pressures (from 10 mbar to 10 bar) will allow to enhance sensitivity for axion masses from few meV to several eV. We present different helioscope data taking scenarios, considering detection efficiency and axion absorption probability, and show the sensitivities reachable with this technique to be few $\times$ 10$^{-11}\,$GeV$^{-1}$ for a 5$\,$T$\,$m$^3$ scale TPC. We show that a few years program taking data with such setup would allow to probe the KSVZ axion model for axion masses above 100 meV.