Dresden 2013 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 31: Struktur und Dynamik von Kernen
HK 31.6: Talk
Tuesday, March 5, 2013, 15:30–15:45, HSZ-301
Preparations for an optical access to the lowest excited nuclear state in 229Th — •L. v.d.Wense1,2, P.G. Thirolf1, D. Kalb1, and M. Laatiaoui3 — 1Ludwig-Maximilians-Universität München — 2Max-Planck-Institut f. Quantenoptik — 3GSI Helmholtzzentrum für Schwerionenforschung GmbH
The isomeric lowest excited nuclear level of 229Th has been indirectly measured to be 7.6±0.5 eV (163±11 nm). In order to improve the accuracy as prerequisite of an all-optical control, 229mTh is populated via a 2% decay branch in the α decay of 233U. The Thorium ions are extracted and cooled with the help of a buffer gas stopping cell and an RFQ-cooler. In order to suppress accompanying α decay chain products other than 229Th, a quadrupole mass spectrometer (QMS) has been constructed. First measurements of extraction and transmission efficiency were made, newest results will be presented. Following the QMS, the Thorium isomers will be collected on a 50 µ m collection surface. The decay of these isomers can then be detected using deep UV optics, presently under construction based on extensive simulation. The sensitivity is predicted to be large enough to lead to a verification of the isomeric transition even in the presence of a significant nonradiative decay branch.[1]
[1] L.v.d.Wense et al., Towards a direct transition energy measurement of the lowest nuclear excitation in 229Th, arXiv:1211.0710 [nucl-ex]