ABSTRACT
The gamma decay from Coulomb excitation of 68Ni at 600 MeV/nucleon on a Au target was measured using the RISING setup at the fragment separator of GSI. The 68Ni beam was produced by a fragmentation reaction of 86Kr at 900 MeV/nucleon on a 9Be target and selected by the fragment separator. The gamma rays produced at the Au target were measured with HPGe detectors at forward angles and with BaF2 scintillators at backward angles. The measured spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in terms of an enhanced strength of the dipole response function (pygmy resonance). Such pygmy structure has been predicted in this unstable neutron-rich nucleus by theory.
ABSTRACT
The gamma decay associated with the warm rotation of the superdeformed nuclei 151Tb and 196Pb has been measured with the EUROBALL IV array. Several independent quantities provide a stringent test of the population and decay dynamics in the superdeformed well. A Monte Carlo simulation of the gamma decay based on microscopic calculations gives remarkable agreement with the data only assuming a large enhancement of the B(E1) strength for 1-2 MeV gamma rays, which may be related to the evidence for octupole vibrations in both mass regions.
ABSTRACT
A method for quantitative determination of 90Sr with a germanium gamma-ray spectrometer is presented. The bremsstrahlung energy spectrum produced by high-energy beta particles from the 90Sr source encapsulated in a given absorbing material is measured. The idea was tested on various types of low-background germanium gamma-ray spectrometers. The optimisation of absorber thickness for aluminium, iron, copper, cadmium, tantalum and lead is presented. The lowest achieved detection limit for a 10% efficiency HPGe detector was 0.38 Bq/sample which allows this method to be applied to some environmental studies.
