Enhanced Yield Rate of \textsuperscript{229m}Th via Cascade Decay in Storage Rings and Electron Beam Ion Traps

TL;DR

This paper proposes a scheme to significantly enhance the production of 9m}Th using cascade decay pathways in storage rings and electron beam ion traps, enabling better applications in nuclear clocks and metrology.

Contribution

It introduces an efficient indirect excitation method via NEIES and NEEC to boost 9m}Th yield, with calculations showing up to four orders of magnitude increase.

Findings

NEIES can enhance 9m}Th production by up to four orders of magnitude.

NEEC can contribute an additional tens-fold increase in yield.

Optimized cascade decay pathways significantly improve 9m}Th generation rates.

Abstract

The low-energy nuclear isomeric state of \textsuperscript{229m}Th provides a unique bridge between nuclear and atomic physics, enabling applications such as nuclear clocks and precision metrology. However, efficient and controllable production of \textsuperscript{229m}Th remains a major experimental challenge. We propose an efficient scheme to produce the $^{229\mathrm{m}}$Th in storage rings (SRs) and electron beam ion traps (EBITs), using a cascade decay pathway. Highly charged ions are excited to higher nuclear states via nuclear excitation by inelastic electron scattering (NEIES) and nuclear excitation by electron capture (NEEC), followed by radiative or internal conversion cascades that populate the isomer. Our calculations demonstrate that, under typical SRs and EBITs conditions, optimized indirect excitation pathways significantly enhance \textsuperscript{229m}Th production rate. In particular, NEIES can provide an enhancement of up to four orders of magnitude through cascade de-excitation at high energies, while NEEC can contribute an additional enhancement of up to several tens of times. Such a significant increase in the \textsuperscript{229m}Th yield rate would facilitate its application in various nuclear photonics fields, especially in the development of atomic nuclear clocks.