First spatial separation of a heavy ion isomeric beam with a multiple-reflection time-of-flight mass spectrometer
Dickel, T., Plaß, W., Andres, S., Ebert, J., Geissel, H., Haettner, E., . . . Xu, X. (2015). First spatial separation of a heavy ion isomeric beam with a multiple-reflection time-of-flight mass spectrometer. Physics Letters B, 744, 137-141. doi:10.1016/j.physletb.2015.03.047
Published in
Physics Letters BAuthors
Date
2015Discipline
FysiikkaCopyright
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license. Funded by SCOAP3.
211Po ions in the ground and isomeric states were produced via 238U projectile fragmentation at
1000 MeV/u. The 211Po ions were spatially separated in flight from the primary beam and other reaction
products by the fragment separator FRS. The ions were energy-bunched, slowed-down and thermalized in
a gas-filled cryogenic stopping cell (CSC). They were then extracted from the CSC and injected into a highresolution
multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). The excitation energy of
the isomer and, for the first time, the isomeric-to-ground state ratio were determined from the measured
mass spectrum. In the subsequent experimental step, the isomers were spatially separated from the ions
in the ground state by an ion deflector and finally collected with a silicon detector for decay spectroscopy.
This pioneering experimental result opens up unique perspectives for isomer-resolved studies. With
this versatile experimental method new isomers with half-lives longer than a few milliseconds can be
discovered and their decay properties can be measured with highest sensitivity and selectivity. These
experiments can be extended to studies with isomeric beams in nuclear reactions.
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