Conceptual Design of BabyIAXO, the intermediate stage towards the International Axion Observatory

TL;DR

BabyIAXO is a prototype helioscope designed to test key subsystems for the larger IAXO project, while also independently exploring solar axions and axion-like particles with significant sensitivity.

Contribution

It introduces BabyIAXO, a scaled prototype that simultaneously serves as a fully operational helioscope and a testbed for IAXO's subsystems and physics capabilities.

Findings

Detects or rejects solar axions with couplings down to 1.5e-11 GeV^-1

Probes axion masses up to 0.25 eV

Develops advanced x-ray detectors for axion spectral features

Abstract

This article describes BabyIAXO, an intermediate experimental stage of the International Axion Observatory (IAXO), proposed to be sited at DESY. IAXO is a large-scale axion helioscope that will look for axions and axion-like particles (ALPs), produced in the Sun, with unprecedented sensitivity. BabyIAXO is conceived to test all IAXO subsystems (magnet, optics and detectors) at a relevant scale for the final system and thus serve as prototype for IAXO, but at the same time as a fully-fledged helioscope with relevant physics reach itself, and with potential for discovery. The BabyIAXO magnet will feature two 10 m long, 70 cm diameter bores, and will host two detection lines (optics and detector) of dimensions similar to the final ones foreseen for IAXO. BabyIAXO will detect or reject solar axions or ALPs with axion-photon couplings down to $g_{a\gamma} \sim 1.5 \times 10^{-11}$ GeV$^{-1}$, and masses up to $m_a\sim 0.25$ eV. BabyIAXO will offer additional opportunities for axion research in view of IAXO, like the development of precision x-ray detectors to identify particular spectral features in the solar axion spectrum, and the implementation of radiofrequency-cavity-based axion dark matter setups.