Springer Online Journal Archives 1860-2000
Abstract Theγ ray continuum structures of the transitional Er isotopes withA∼154 are studied using the reaction74Ge(84Kr,xn)158−xEr atE lab=340 MeV. The measurements include energy spectra, total energies, multiplicities, angular distributions and lifetimes using the DSAM method. The analysis of data confirms the previously observed two-bump structure of the continuum radiation. A meticulous subtraction of discrete contributions proves the persistence of the low-energy bump even at high spins, i.e.I〉40ħ. The angular-distribution measurements assign predominant dipole structure to the bump atE γ=0.65 MeV, whereas the bump atE γ=1.3 MeV is of almost pure quadrupole character at high spins. The lifetime measurements give evidence for a strong enhancement of theB(E2) values of the upper bump,B(E2)/B sp〉130. Spin-selection studies reveal, in the spin rangeI=30−50ħ an almost constant energy for the 1.3 MeV bump,ΔE〈60 keV.
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