Nuclear Excitation by Muon Capture

TL;DR

This paper introduces a novel nuclear excitation mechanism via muon capture, showing significantly higher cross sections than existing methods, with potential applications in nuclear physics and technology.

Contribution

The study presents the first theoretical evaluation of nuclear excitation by muon capture (NEμC), demonstrating its advantages over photo-excitation and electron capture methods.

Findings

Cross section of NEμC is up to ten orders of magnitude higher than known processes.

NEμC is effective for MeV excitations due to strong muon binding.

Detectable probability of NEμC in modern muon facilities.

Abstract

Efficient excitation of nuclei via exchange of a real or virtual photon has a fundamental importance for nuclear science and technology development. Here, we present a new mechanism of nuclear excitation based on the capture of a free muon into the atomic orbits (NE$\mu$C). The cross section of such a new process is evaluated using the Feshbach projection operator formalism and compared to other known excitation phenomena, i.e. photo-excitation and nuclear excitation by electron capture (NEEC), showing up to ten orders of magnitude increase in cross section. NE$\mu$C is particularly interesting for MeV excitations that become accessible thanks to the stronger binding of muons to the nucleus. The binding energies of muonic atoms have been calculated introducing a state of the art modification to the Flexible Atomic Code (FAC). An analysis of an experimental scenarios in the context of modern muon production facilities shows that the effect can be detectable for selected isotopes. The total probability of NE$\mu$C is predicted to be $ P \approx 10^{-6}$ per incident muon in a beam-based scenario. Given the high transition energy provided by muons, NE$\mu$C can have important consequences for isomer feeding and particle-induced fission.