Speaker
Description
Muonic atom spectroscopy is a technique that studies the atomic transitions between levels that are occupied by muons orbiting a nucleus. Due to the heavier mass of muons with respect to that of electrons, its atomic orbitals will be substantially closer to the nucleus. Consequently, the sensitivity to nuclear effects is enhanced. In particular, muonic atoms have an increased sensitivity to the finite size correction (~$10^7$ compared to electronic atoms). As a result, absolute nuclear charge radii can be extracted, providing invaluable input for laser spectroscopy experiments in the form of benchmarks [1].
By employing a high-pressure hydrogen cell, with a small deuterium admixture, it became possible to reduce the required target quantity from 10 mg to about 5 µg. This opens the door to measurements on long-lived radioactive isotopes and materials not available in large quantities [2]. In 2022, we performed an experiment that showed implanted targets could be used for the spectroscopy [3]. As a result, samples that have been prepared by employing mass separation and subsequent implantation, can be measured with our technique. Following this success, we did another experimental campaign in October 2023 with the goal of measuring the absolute charge radius of potassium and chlorine isotopes.
In this contribution, we shall report on the experimental method and recent results obtained for muonic x-ray measurements on $^{39, 40, 41}$K and $^{35, 37}$Cl, as well as their implication for future research.
[1] Fricke, Gerhard, K. Heilig, and Herwig F. Schopper. Nuclear charge radii. Vol. 454. Berlin: Springer, 2004.
[2] Adamczak, Andrzej, et al. "Muonic atom spectroscopy with microgram target material." The European Physical Journal A 59.2 (2023): 15.
[3] Heines, Michael, et al. "Muonic x-ray spectroscopy on implanted targets." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 541 (2023): 173-175.
