Two new papers from Heidelberg

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Adriana’s theory group just published two new papers, both of which might have a significant impact on experiments building on the Th-229 isomer.

The first paper is a study on a new optomechanical system, which interfaces optical fields and X-rays via an optical cavity. In short, one mirror of an optical cavity is formed by a micro-cantilever, which bears a layer of Th-229 nuclei. These can be excited by X-rays, which impart momentum to the cantilever and change its quantum state, thereby changing the cavity field: a coupling between the optical and X-ray regime! The paper had already been around on the arXiv and has now been published with Sci. Rep., please find the paper here.

The second paper is of purely theoretical nature and a collaboration with Nikolay Minkov from Sofia, Bulgaria. It discusses a new approach to model the lowest nuclear states in Th-229 and arrives at M1 and E2 transition rates between the isomer and the ground state that are markedly different (substantially smaller) compared to all previous models. Among other explanations (strong IC, isomer energy larger than expected, …), such a small coupling could potentially explain why the optical excitation and de-excitation of the isomer was not observed in past experiments. This work has been accepted for publication with Phys. Rev. Lett. and is already available on the arXiv now.

Congratulations to Adriana and her team!

Theory papers to support experiments

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We have built up a considerable backlog in out presentation of papers related to research on the thorium isomer. Here, we highlight a number of theoretical papers that could support experiments searching for the isomer and trying to measure its energy.

“Magnetic hyperfine structure of the ground-state doublet in highly charged ions 229 Th 89+, 87+ and the Bohr-Weisskopf effect” by E. V. Tkalya and A. V. Nikolaev, published with Phys. Rev. C, link.

“Bound internal conversion versus nuclear excitation by electron transition: Revision of the theory of optical pumping of the Th-229m isomer” by F. F. Karpeshin and M. B. Trzhaskovskaya, published with Phys. Rev. C, link.

“Theoretical analysis of the electron bridge process in 229Th3+” by a theory group at PTB in Germany and performed to support the experimental work at PTB, available on the arXiv, link.

“Impact of the ionization of the atomic shell on the lifetime of the Th-229m isomer” by F. F. Karpeshin et al. in close relation to the LMU Munich experiments, available on the arXiv, link.

LMU grant proposal accepted

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Frontier research builds on solid funding, and the LMU groups just secured financial support for their upcoming research work. Within the framework of a DFG grant, an electron spectrometer to measure the energy of IC electrons will be constructed. The money is sufficient to buy all the required equipment and LMU researcher Benedict Seiferle will be paid for another three years.

 

Congratulations to the LMU team!