Speaker
Description
This contribution presents the latest experimental results from the QUARTET collaboration on high-resolution muonic lithium spectroscopy, aiming for the precise determination of nuclear charge radii for lithium isotopes. Precise measurements of absolute nuclear charge radii are a crucial ingredient for precision QED tests and serve as ideal benchmarks for modern nuclear structure theory [1]. Muonic atom spectroscopy is a well-established method to accurately determine the root-mean-square (RMS) radii of nuclear charge density distributions and has already delivered the most accurate results for very light (Z < 3) as well as heavier nuclei (Z > 10) [2]. However, a gap remains for muonic atoms from lithium to neon due to technological limitations in the relevant energy range (~20–200 keV) based on the lack of resolving power of conventional solid-state detectors.
To address this gap, the QUARTET collaboration employs cryogenic metallic magnetic calorimeters (MMCs) that combine broadband spectral coverage with record resolving power. In October 2024, the first experimental campaign at the Paul Scherrer Institute demonstrated the feasibility of this approach and showed the first high-resolution spectra of muonic lithium, beryllium, and boron, resolving the 2p-1s transitions of the individual stable isotopes. These results mark a significant step forward in bridging the low-Z charge radius gap and offer promising prospects for future precision measurements [3]. This talk will shed light on the ongoing analysis and showcase the preliminary results of the muonic lithium measurements.
References:
[1] Karshenboim, S. G. (2005). Precision physics of simple atoms: QED tests, nuclear structure, and fundamental constants. Physics Reports, 422(1–2), 1–63.
[2] Fricke, G., Heilig, K., & Schopper, H. F. (2004). Nuclear charge radii (Vol. 454). Berlin: Springer.
[3] Ohayon, B.; Abeln, A.; Bara, S.; Cocolios, T.; Eizenberg, O.; Fleischmann, A.; Gastaldo, L.; Godinho, C.; Heines, M.; Hengstler, D.; Hupin, G.; Indelicato, P.; Kirch, K.; Knecht, A.; Kreuzberger, D.; Machado, J.; Navratil, P.; Paul, N.; Pohl, R.; Unger, D.; Vogiatzi, S.; Schoeler, K.; Wauters, F. Towards Precision Muonic X-ray Measurements of Charge Radii of Light Nuclei. Physics 2024, 6(1), 206–215.
