Seminar Details

Beta-Delayed Fission: from Neutron-Deficient to Neutron-Rich Nuclei

Andrei Andreyev, University of York
Wednesday, September 18, 4:10 PM - Nuclear Science Seminar
NSCL Lecture Hall

In the last decade, through technological, experimental and theoretical advances, the situation in experimental low-energy fission studies has changed dramatically. With the use of advanced production and detection techniques, much more detailed fission information can be obtained for traditional regions of fission research and, very importantly, new regions of nuclei have become accessible for fission studies. The talk will, first of all, give a review of recent low-energy fission experiments in very proton-rich nuclei in the lead region. Results of experiments at ISOLDE (CERN) on the very exotic process of beta-delayed fission (βDF) of the neutron-deficient isotopes 178,180Tl [1], 194,196At and 200,202Fr will be presented. The studies of Tl and At isotopes were facilitated by the use of the highly-selective Resonance Ionization Laser Ion Source of ISOLDE [2]. As a result of these experiments, a new type and a region of asymmetric fission was established, which includes isotopes 178,180Hg (N/Z=1.22-1.25), in addition to the previously known broad area of asymmetric fission in the heavy actinides with N/Z~1.55-1.6. The much more intense beams of the future ISOL-based facilities will allow in-depth studies of these and neighbouring βDF isotopes. Some examples of complementary experiments to study beta-delayed fission at the velocity filter SHIP (GSI, Darmstadt) will be given. The talk will also address the prospects of detailed βDF studies in the neutron-rich isotopes, which will become possible with the new generation of ISOL-based facilities and approaches using the multi-nucleon transfer reactions. As some examples, possible βDF studies of very neutron-rich isotopes of Fr, Ac and Pa will be presented. The recent complementary fusion-fission experiments in the lead region, performed by our collaboration at the tandem of Japan Atomic Energy Agency (JAEA) will also be reviewed. 1. A. Andreyev et al., “New type of asymmetric fission in proton-rich nuclei”, Phys. Rev. Lett. 105, 252502 (2010) 2. S. Rothe et al., “Measurement of the first ionization potential of astatine by laser ionization Spectroscopy”, Nature Communications (2013). *On behalf of York – Leuven - Los-Alamos – Bratislava – Darmstadt – Geneva – Grenoble –Liverpool – Manchester – Tokai collaboration