2025/05/09 by Altenmüller, K., Anastassopoulos, V., Arguedas-Cuendis, S. +61 · 1 citation
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)
paper · doi:10.48550/arxiv.2505.05909
We present a search for solar axions produced through the axion-electron coupling (gae) using data from a novel 7-GridPix detector installed at the CERN Axion Solar Telescope (CAST). The detector, featuring ultra-thin silicon nitride windows and multiple veto systems, collected approximately 160 hours of solar tracking data between 2017-2018. Using machine learning techniques and the veto systems, we achieved a background rate of 1.06× 10-5 keV-1cm-2s-1 at a signal efficiency of about 80 % in the 0.2-8 keV range. Analysis of the data yielded no significant excess above background, allowing us to set a new upper limit on the product of the axion-electron and axion-photon couplings of gae⋅ gaγ < 7.35× 10-23 GeV-1 at 95 % confidence level. This result improves upon the previous best helioscope limit and demonstrates the potential of GridPix technology for rare event searches. Additionally, we derived a limit on the axion-photon coupling of gaγ < 9.0× 10-11 GeV-1 at 95 % CL, which, while not surpassing CAST's best limit, provides complementary constraints on axion models.