Ausbau und Optimierung des MLLTRAP-Penningfallensystems: Komplettierung des Multi-Passage-Spektrometers als Abschluss der Inbetriebnahme und Charakterisierung sowie Aufbau einer Kohlenstoff-Clusterionenquelle

• Antragsteller: Privatdozent Dr. Peter G. Thirolf
• Fachliche Zuordnung: Kern- und Elementarteilchenphysik, Quantenmechanik, Relativitätstheorie, Felder
• Förderung: Förderung von 2008 bis 2016
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 78251071

A high-accuracy Penning trap mass spectrometer for radioactive nuclides ultimately aiming at a relative mass uncertainty of ( 10-9 is presently being set up at the Maier-Leibnitz-Laboratory in Garching ( MLLTRAP ). This extreme accuracy contributes, among other things, to metrology, and to tests of QED and fundamental CPT symmetry.A possibility for improving the accuracy of the fine structure constant α is given by determining the molar Planck constant NA•һ, combining a mass difference measurement between highly-charged nuclides differing by one neutron in the MLL Penning trap with wavelength measurements of corresponding capture (-rays, which will be performed in close collaboration with the group operating the GAMS facility at the ILL reactor (Grenoble). There the wavelengths of ( rays after neutron capture are measured to extreme accuracy.Highly accurate nuclear mass data on superallowed beta decays grant access to a precise determination of the Vud matrix element of the CKM quark mixing matrix, thus allowing for a stringent test of the unitarity of the CKM matrix. Here the MLLTRAP facility can contribute in a unique way by combining the superb intrinsic energy resolution of the Munich Q3D magnetic spectrograph (~ 2( 10-4) with the high mass accuracies reachable with MLLTRAP. This will allow for improved reaction Q-value measurements especially for the intended extension of the study of superallowed ß decays to heavier nuclei beyond A=54 (Co), where the (then larger) calculated Coulomb correction (C can be tested only at the expense of shorter lifetimes for the corresponding nuclei (thus preventing trap measurements). The determination of the ground state reference masses using the Penning trap combined with precise reaction Q-values from the magnetic spectrograph will allow for progress on probing the CVC hypothesis.A double-Penning-trap mass spectrometer for highly-charged, short-lived nuclides will be developed, combining several novel technologies in order to finally achieve ultimate mass accuracy. The ions will be sympathetically cooled to mK temperatures with a laser-cooled Mg+ plasma, allowing for an improved measurement precision. Consequently, instead of the usual preparation of isobarically purified ions of interest by buffer gas cooling inside a preparation Penning trap, it is planned to achieve the selection using an RF mass filter and a (multi-reflection) Time-of-Flight mass spectrometer after the efficient gas-stopping cell. After charge breeding inside an EBIS, the highly charged ions will be sympathetically cooled down to mK temperatures with laser-cooled Mg+ ions. The sympathetic cooling allows for an exact centering inside the precision traps as well as a considerable efficiency improvement.The setup of the Penningtrap system has already been completed and commissioning of the system is presently in progress and the buffergas stopping cell can be operated successfully with high efficiency. Consequently the scope of this application is the completion of the MLLTRAP facility in order to allow for highly-accurate mass measurements. This requires the setup of a multi-reflection time-of-flight spectrometer for isobaric purification, a multi-passage spectrometer allowing to introduce an EBIS charge breeder (with subsequent q/A selection) as well as the setup of a linear Paul trap for sympathetic laser cooling of the highly-charged ions.While the setup of the time-of-flight spectrometer and the Paul trap will be realized from local funds, within the present application the necessary investment funds for the charge breeder and the corresponding q/A-separator will be requested together with post doctoral positions for the Penning trap and charge breeder systems, respectively.

• DFG-Verfahren: Sachbeihilfen