Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer

Seiferle, Benedict; Wense, Lars von der; Amersdorffer, Ines; Arlt, Nicolas; Kotulski, Benjamin und Thirolf, Peter G. (2020): Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer. In: Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, Bd. 463: S. 499-503

Abstract

Th-229 is the only known nucleus with an excited state that offers the possibility for a direct laser excitation using existing laser technology. Its excitation energy has been measured indirectly to be 7.8(5) eV (approximate to 160 nm). The energy and lifetime of the isomeric state make it the presently only suitable candidate for a nuclear optical clock, the uncertainty of the excitation energy is, however, still too large to allow for a direct laser excitation in a Paul trap. Therefore, a major goal during the past years has been an improved energy determination. One possible approach is to measure the kinetic energy of electrons which are emitted in the internal conversion decay of the first isomeric state in Th-229. For this reason an electron spectrometer based on a magnetic bottle combined with electrical retarding fields has been built. Its design, as well as first test measurements are presented, which reveal a relative energy resolution of 3 % and thus enable to measure the electrons' expected kinetic energy to better than 0.1 eV. This is sufficiently precise to specify a laser system able to drive the nuclear clock transition in Th-229.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0168-583X
• Sprache: Englisch