Probing Solar Axions with X-ray Optics for BabyIAXO

The nature of dark matter is a driving question of 21st century physics. Axions are among the best motivated candidates for dark matter, as they could solve underlying problems in our understanding of fundamental particle interactions, and other axion-like particles are a generic prediction of many new physics theories, in particular string theory. Axions would alter the processes taking place within the extreme environments of stellar interiors, such as within our own Sun. The International Axion Observatory (IAXO) will search for axions from our Sun, opening novel sensitivity to axions and axion-like particles across a broad range of masses. The goal of this proposal is to construct a focusing X-ray telescope and take leadership in analysis for BabyIAXO, the pathfinder to IAXO. This work will also expand instructor training in methods to promote “belonging” in undergraduate courses, in line with recommendations from the American Institute of Physics and the National Academies, as well as provide undergraduate and graduate students with hands-on expertise in instrumentation, facilitating broader applications of this X-ray telescope technology.The IAXO instrument is a next-generation axion helioscope, designed to search for axions from the Sun that are reconverted into X-ray photons via a strong laboratory magnetic field. BabyIAXO will advance technology for all IAXO subsystems at relevant scale while also offering novel physics reach and discovery potential. BabyIAXO and IAXO are the only experiments beyond the R&D phase sensitive to QCD axions in the meV to eV mass range, which is motivated by many dark matter scenarios, as well as a broad range of ALPs that could constitute all of dark matter. The goals of this proposal are to construct the inner core X-ray optic for BabyIAXO; lead implementation of the optics response into the simulation and analysis chain; and contribute to commissioning and initial analysis of BabyIAXO data. Cost-effective, large-area X-ray optics are key to reducing detector size and background while still exploiting large magnet areas, allowing a leap forward in axion helioscope sensitivity. This work will leverage the expertise and facilities from construction of the NuSTAR X-ray optics, on which the BabyIAXO and IAXO optics are based. Thus, a modest investment in student training and materials can establish the US as a leader of the IAXO X-ray optics system and the next generation of solar axion searches. The broader impacts of this work include (i.) educating a new generation of instrumentalists, helping ensure the US builds a globally competitive STEM workforce, (ii.) expanding the PI’s established collaborations with educational researchers on methods that foster “belonging” in undergraduate STEM classrooms, helping ensure that this workforce better reflects the diversity of the nation, and (iii.) enabling broader applications of segmented glass X-ray optics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.