Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HK: Physik der Hadronen und Kerne

HK 23: Hauptvortr
äge

HK 23.2: Hauptvortrag

Dienstag, 8. März 2005, 10:45–11:15, TU MA001

Exploring the Driplines: First Observation of ⁶⁰Ge and ⁶⁴Se — •Andreas Stolz — National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA

The discovery of nuclei along the proton dripline is crucial for the understanding of the nuclear forces. The knowledge of lifetimes of these nuclei puts significant constraints on the mass models, which yield important information to nuclear structure and nuclear astrophysics. The closer one approaches the dripline the harder it is to produce new isotopes. It has been over three years that the last new isotope below mass 100 has been observed. This paper will present the first observation of the neutron-deficient nuclei ⁶⁰Ge and ⁶⁴Se.

These isotopes have been produced by fragmentation of a 140-MeV/u ⁷⁸Kr primary beam at the Coupled Cyclotron Facility at Michigan State University. The neutron-deficient fragments were separated by the A1900 fragment separator and identified by a measurement of energy loss, total energy, and time-of-flight.

⁶⁰Ge is the last nucleus along the proton dripline lighter than cadmium which is predicted to be bound by the latest atomic mass evaluation and which has not yet been observed. Theoretical calculations predict ⁶⁰Ge to be bound with respect to two-proton emission, while ⁶⁴Se is predicted not to be bound. No events of ⁵⁹Ga and ⁶³As were observed confirming that these nuclei are unbound with respect to proton emission.

This work was supported by NSF grant No. PHY-01-10253.