In the near future BabyIAXO will be the most powerful axion helioscope,
relying on a custom-made magnet of two bores of 70 cm diameter and 10 m
long, with a total available magnetic volume of more than 7 m3. In this
document, it proposes and describe the implementation of low-frequency
axion haloscope setups suitable for operation inside the BabyIAXO magnet.
The RADES proposal has a potential sensitivity to the axion-photon coupling
ga𝜸 down to values corresponding to the KSVZ model, in the (currently
unexplored) mass range between 1 and 2 𝛍 eV, after a total effective exposure
of 440 days. This mass range is covered by the use of four differently
dimensioned 5-meter-long cavities, equipped with a tuning mechanism based
on inner turning plates. A setup like the one proposed will also allow an
exploration of the same mass range for hidden photons coupled to photons.
An additional complementary apparatus is proposed using LC circuits and
exploring the low energy range (≈ 10−4 − 10−1 𝛍 eV). The setup includes a
cryostat and cooling system to cool down the BabyIAXO bore down to about 5
K, as well as an appropriate low-noise signal amplification and
detection chain.