Darmstadt 2008 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 15: Kernphysik / Spektroskopie

HK 15.4: Vortrag

Montag, 10. März 2008, 17:30–17:45, 2G

Investigation of neutron-deficient ²¹Mg by collinear laser spectroscopy and β-NMR — Klaus Blaum¹, Kieran T. Flanagan³, Christopher Geppert¹, Magdalena Kowalska², •Jörg Krämer¹, Peter Lievens³, Gerda Neyens³, Rainer Neugart¹, Wilfried Nörtershäuser¹, Marieke de Rydt³, Pieter Vingerhoets³, and Deyan T. Yordanov³ — ¹Univ. Mainz, Germany — ²CERN, Switzerland — ³K.U.Leuven, Belgium

We present recent results of collinear laser spectroscopy measurements on ²¹Mg performed at ISOLDE (CERN). The radioactive Mg ions were produced by 1.4 GeV protons impinging on a SiC target and subsequent selective resonant ionization of the reaction products by a laser ion source. The extracted and mass-separated beam is superimposed with an ultra violet cw laser beam in collinear geometry and optical pumping is performed in a weak magnetic guiding field. If the laser is at resonance with the ionic transition, nuclear spin polarization is created by optical pumping of the hyperfine structure Zeeman levels. After implantation into a suitable crystal an asymmetry in the spatial distribution of the positrons from the β⁺ decay can be observed. Detecting this β-asymmetry while Doppler-tuning the laser wavelength yields the hyperfine structure. High-resolution β-NMR measurements were also performed and the nuclear g-factor was determined. After combining the results of β-asymmetry and β-NMR, also the nuclear spin of ²¹Mg could be extracted. The results will be compared to nuclear shell-model predictions, and an outlook to further experiments will be given.