Towards Precision Muonic X-Ray Measurements of Charge Radii of Light Nuclei

TL;DR

This paper proposes a new experiment using cryogenic microcalorimeters to measure the charge radii of light nuclei with significantly higher precision, enhancing nuclear physics understanding and testing fundamental theories.

Contribution

It introduces a novel experimental approach employing quantum-sensing microcalorimeters for high-precision muonic X-ray measurements of light nuclei.

Findings

Potential to increase measurement accuracy by up to 20 times

Improved understanding of nuclear structure and quantum electrodynamics

Enhanced capability for testing physics beyond the Standard Model

Abstract

We propose an experiment to measure the nuclear charge radii of light elements with up to 20~times higher accuracy. These are essential both for understanding nuclear physics at low energies, and for experimental and theoretical applications in simple atomic systems. Such comparisons advance the understanding of bound-state quantum electrodynamics and are useful for searching for new physics beyond the Standard Model. The energy levels of muonic atoms are highly susceptible to nuclear structure, especially to the mean square charge radius. The radii of the lightest nuclei (with the atomic number, $Z=1,2$) have been determined with high accuracy using laser spectroscopy in muonic atoms, while those of medium mass and above were determined using X-ray spectroscopy with semiconductor detectors. In this communication, we present a new experiment, aiming to obtain precision measurements of the radii of light nuclei $3 \leq Z \leq 10$ using single-photon energy measurements with cryogenic microcalorimeters; a quantum-sensing technology capable of high efficiency with outstanding resolution for low-energy X-rays.