Optical spectroscopy for nuclear and atomic science at JYFL, Finland

On Wednesday 4th of October, we had the privilege of having Professor Iain D. Moore from the University of Jyväskylä as an invited speaker for one of our AMOPP seminars. The seminar focused mainly on the work they have been doing at the various accelerator facilities at JYFL and had a good mix of nuclear and atomic physics content.

Professor Iain D. Moore kindly agreed to provide a copy of his presentation slides which you can download here.


Optical spectroscopy for nuclear and atomic science at JYFL, Finland

Iain D. Moore, University of Jyväskylä


High-resolution optical measurements of the atomic level structure readily yield fundamental and model-independent data on nuclear ground and isomeric states, namely changes in the size and shape of the nucleus, as well as the nuclear spin and electromagnetic moments [1]. Laser spectroscopy combined with on-line isotope separators and novel ion manipulation techniques provides the only mechanism for such studies in exotic nuclear systems.

Internationally, there are a myriad of tools in use however these are traditionally variants of two main workhorses in the field – collinear laser spectroscopy and resonance ionization spectroscopy. Following a short overview of the Accelerator Laboratory at the University of Jyväskylä, I will briefly present both techniques and their use in accessing the heavy element region of the nuclear landscape which exhibits rather scarce information from optical studies. This reflects a combination of the difficulty in producing such elements (low production cross sections) and a lack of stable isotopes (thus few optical transitions available in literature). Indeed, this past year has seen a number of exciting developments including optical studies of exotic atoms produced at the level of one atom-at-a-time [2], and high-resolution spectroscopy in supersonic gas expansions [3].

Recently, we have initiated a new program on the actinide elements in collaboration with the University of Mainz. I will summarize the current status of the work which includes collinear laser spectroscopy on Pu, the heaviest element attempted with this particular technique [4]. Our focus has recently turned to the study of the lowest-lying isomeric state in the nuclear chart, 229Th.  Almost 40 years of research has been invested into efforts to observe the isomeric transition which, if found, may be directly accessed by lasers. In 2016, the community was given a tremendous boost with the unambiguous identification of the state by a group in Munich, providing a stepping stone towards a future realization of a “nuclear clock” [5].

[1] P. Campbell, I.D. Moore and M.R. Pearson, Progress in Part. and Nucl. Phys. 86 (2016) 127.

[2] M. Laataioui et al., Nature 538 (2016) 495.

[3] R. Ferrer et al., Nature Communications 8 (2017) 14520.

[4] A. Voss et al., Phys. Rev. A 95 (2017) 032506.

[5] L. von der Wense et al., Nature 533 (2016) 47.

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