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HK: Physik der Hadronen und Kerne
HK 33: Kernphysik/Spektroskopie
HK 33.5: Talk
Tuesday, March 8, 2005, 18:00–18:15, TU MA041
Mass and Half-life Measurements at FRS-ESR Facilities at GSI — •Yu.A. Litvinov — GSI Darmstadt — JLU Giessen
Progress and perspectives of mass and lifetime measurements of stored exotic nuclei at GSI are presented.
Exotic nuclei were produced via projectile fragmentation and fission and separated in flight with the fragment separator FRS. The spatially separated fragments were injected into the storage-cooler ring ESR. The energies, up to 900 MeV/u, were high enough to produce bare and few-electron projectile fragments for all elements. This allows to investigate nuclear decay properties under conditions which prevail in hot stellar plasmas. Dramatic prolongations of nuclear lifetimes and the open branch of bound-state beta decay for bare ions have been observed.
Masses have been measured with Schottky (SMS) and Isochronous (IMS) Mass Spectrometry for stored fragments. SMS requiring electron cooling has a lower limit for lifetimes of the order of a few seconds. 114 new masses of neutron-deficient isotopes in the lead region have been measured with time-resolved SMS with an improved accuracy of typically 1.5× 10−7 (30 µu). Neutron-rich uranium projectile fragments were measured in the element range from neodymium to uranium. New long-lived K-isomers are expected in the A=180 mass region. New masses of short-lived neutron-rich fission fragments have been obtained with IMS which yields access to nuclei with lifetimes down to the sub-millisecond range. The experimental results will be compared with theoretical predictions.