Frankfurt 2014 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 46: Poster
HK 46.19: Poster
Thursday, March 20, 2014, 16:00–18:00, HZ Poster
Preparation of an experiment to directly detect the deexcitation of the 229mTh nuclear isomer* — •Benedict Seiferle1, Lars v.d. Wense1, Peter Thirolf1, and Mustapha Laatiaoui2 — 1LMU München — 2GSI Helmholtzzentrum für Schwerionenforschung GmbH
Indirect measurements show that 229Th has a transition energy of 7.6±0.5 eV to its first excited state, which corresponds to an UV transition wavelength of 163±11 nm [1]. The experiment under developement aims to detect and measure this wavelength [2].
For this purpose a 233U source is placed in a buffer gas cell, where a continuous beam is produced out of the recoil ions. By using a quadrupole mass spectrometer the 229Th ions are separated from other short-lived decay products of the 233U decay chain and are then collected on a micro electrode (50µm in diameter). The deexcitation of these 229mTh ions will then be detected by a VUV-optical setup, containing two customized annular parabolic VUV mirrors and a phosphorus screen behind an MCP detector, watched by a CCD camera.
The mirrors, as well as the collection surface, are placed in vacuum and have to be motorized, to allow for an external position control.
The main focus of the poster lies on the UV system with its motorization and alignment.
[1] B.R. Beck et al., (2007), PRL 98, 142501.
[2] L.v.d. Wense et al., (2013), JINST 8 P03005.
* Supported by the DFG Grant number TH956/3-1