Seminar Details

Shape Coexistence in Gold and Astatine Isotopes Studied by In-Source Laser Spectroscopy at RILIS-ISOLDE

Andrei Andreyev, University of York
Thursday, September 19, 11:00 AM - Research Discussion
NSCL Lecture Hall

The competition between spherical and deformed nuclear shapes at low energy gives rise to shape coexistence in the region of the neutron-deficient lead isotopes with Z~82 and N~104 [1]. In order to determine to which extend the ground and/or isomeric states of those and neighboring nuclides are affected by this phenomenon, an extended campaign of investigation of changes in the mean-square charge radii is on-going at ISOLDE. By combining the high sensitivity of the in-source laser spectroscopy technique, ISOLDE mass separation and Windmill alpha-decay spectroscopy setup [2], it has been possible to study long isotopic chains of lead [3] and polonium [4], down to N=100 and N=107 respectively, and, recently, thallium isotopic chain down to N=98 [5], see Figure. In this contribution, we will first present the basics of the resonance laser spectroscopy as applied in shape coexistence studies. This will be followed by the discussion of the first preliminary results of the 2012 campaign at ISOLDE to study long chains of the astatine and lightest gold isotopes [6]. In the gold and astatine cases, next to Faraday cup and Windmill measurements, also the Multi-Reflection Time-of-Flight (MR-ToF) mass separation technique [7] involving the ISOLTRAP collaboration was used. The first determination of the ionization potential of the element astatine will also be discussed [8]. Figure. Charge radii for Pt-At isotopes. For the sake of clarity the data for different elements are shifted relative to each other by a vertical off-set. Tl data for the light isotopes are from ISOLDE [5] and Gatchina. Preliminary data for gold and astatine chains are from [6]. References [1] K.Heyde and J. Wood. Rev. Mod. Physics 83, 1467 (2011) [2] A.N. Andreyev et al,, Phys. Rev. Lett. 105, 252502 (2010) [3] H. De Witte et al., Phys. Rev. Lett. 98, 112502 (2007) [4] T.E. Cocolios et al., Phys. Rev. Lett. 106, 052503 (2011) [5] A.N. Andreyev, A. Barzakh et al., IS511 experiment at ISOLDE (2012) [6] A.N. Andreyev, V. Fedosseev et al., IS534 experiment at ISOLDE (2012) [7] R. N. Wolf et al., Nucl. Instr. and Meth. A 686, 82-90 (2012) [8] S. Rothe, A. N. Andreyev et al., Nature Communications, 2389 (2013)