Application of in-trap $\alpha$ spectroscopy to lifetime measurements with MLLTRAP
Résumé
MLLTRAP is a double Penning-trap designed for high precision mass measurements of exotic nuclei. It was built and commissioned off-line at the Maier-Leibnitz Laboratory (MLL) in Garching and is currently installed at the ALTO facility at IPNO, awaiting online commissioning. A complementary double-trap assembly dedicated to in-trap decay spectroscopy is being studied, in which the central electrode of the second trap has been replaced by an arrangement of four silicon-strip detectors (SSD) set at the trapping potential. By using the well-known buffer-gas cooling technique in the first trap we will be able to deliver a spot-like ion cloud of high purity to the detector trap. The decay products being emitted in-flight and not from an implantation material, we expect to achieve high-resolution decay spectroscopy of the confined ion bunch. In the case of heavy α emitters, α particles can be detected by the in-trap SSD, while conversion electrons are guided very efficiently by the magnetic field to another detector, thus allowing for unperturbed detection of both. In addition, once coupled with a position-sensitive electron detector, this spectroscopic trap will allow for indirect measurements of excited-state lifetimes in the region of heavy and super-heavy nuclei, via a new recoil distance measurement method.