83m Kr, a potentially powerful PAC probe
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83m Kr,
a potentially powerful PAC probe
M. Arenz · R. Vianden
Published online: 28 November 2012 © Springer Science+Business Media Dordrecht 2012
Abstract In the decay of 83 Rb to 83m Kr and the subsequent decay to the 83 Kr ground state a 553 –9.4 keV γ -γ and a 17.85 –9.4 keV e− -γ cascade are populated. The intermediate 9.4 keV 7/2+ state with a half-life of 154 ns is a perfect candidate for the application of the perturbed angular correlation (PAC) technique. Thus, it is possible to investigate the lattice environment of the implanted probes via the electric quadrupole interaction of the 9.4 keV 7/2+ state with the electric field gradient produced by the host lattices. Details of the production of this new PAC probe and planned measurements will be discussed. Keywords PAC · Perturbed angular correlation · 83 Rb · 83m Kr · KATRIN
1 Introduction The 17.85 keV conversion electron line emitted in the decay of 83m Kr has been shown to be a perfect calibration source for The Karlsruhe Tritium Neutrino (KATRIN) experiment [1]. Therefore, the production and implantation of the parent activity 83 Rb has been studied in Bonn [2]. Recently, however, precision measurements of the 17.85 keV conversion electron line emitted from 83 Rb implanted Pt and Au foils showed an unexpected double line structure [3]. A possible cause could be different lattice environments of the electron emitting nuclei.
Work partially funded by the BMBF Germany under contract number 05A11PD1. M. Arenz (B) · R. Vianden Helmholtz-Institut für Strahlen- und Kernphysik, Nussallee 14-16, Universität Bonn, 53115 Bonn, Germany e-mail: [email protected]
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M. Arenz, R. Vianden
Fig. 1 Simplified decay scheme of 83 Rb/83m Kr with possible PAC cascades
2 Properties of the probe 83
Rb mainly decays through two channels in which two cascades, a 553 –9.4 keV γ -γ and a 17.85 –9.4 keV e− -γ cascade are populated (all data on 83 Rb, 83 Kr and 83m Kr taken from [4] unless stated otherwise). These have the same intermediate state, the 9.4 keV 7/2+ 83 Kr state with a half-life of 154 ns. This is a perfect situation for the application of the perturbed angular correlation technique (PAC) observing the electric quadrupole interaction of this intermediate state with the electric field gradient (EFG) produced by host lattices. The specific properties of these two cascades provide the possibility to examine two different lattice environments using the same probe nucleus. The half-life of 83m Kr (t1/2 = 1.83 h), the parent activity of the 17.85 –9.4 keV e− γ cascade in 83 Kr, is quite short as compared to typical times it takes to prepare samples, for instance, by implantation and subsequent annealing steps. However, in the decay of 83 Rb the isomeric state 83m Kr is populated with 75 % (Fig. 1) and can thus serve as a generator for 83m Kr. During the rather long half-life of 1.83 h of the cascades initial level there is considerable time for the 83m Kr probe nucleus to interact with its environment e.g. undergo diffusion processes. The 17.85 keV K-conversi
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