Multiple coulomb excitation of γ-vibrational bands in 162Dy, 166Er, 168Er and 170Er

Level structure of170Er observed in the decay of the 2.76 min170Ho

“…The ground band is experimentally known up to spin member 10: Besides the 2 + , 4 + and 6 + states seen in the present study at 78.65, 260.22 and 540.66keV, respectively, the 8 + and 10 + members with energies 913 and 1274keV have been populated by Coulomb excitation [10]. In the model, the first two states were needed to calculate the quadrupole spectrum of 17~…”

“…From Coulomb excitation experiments the 78.65 and 181.57 keV transitions are unquestionably known to be pure electric quadrupole transitions [10]. This is in complete agreement with the intensity balance considerations of our decay scheme, which yield the total conversion coefficients ~tot (78.65)= 7.1 _+ 1.2 and eto,(181.57) = 0.33 _+ 0.17 as compared with the theoretical c~(E2)-values [8] 7.27 and 0.345, respectively.…”

“…The explanation for this contradiction may be the 2.9MeV beta distribution of aSA1 contamination (Tll 2 =2.3min), which is difficult to eliminate without careful coincidence analysis. Considering the states above the well-established ground state band of 17~ the 1010.7 and l l03.6keV states have been assigned previously as the 3 + and 4 + members of the ,/-vibrational band [3, 9, 10] (the uncertain 934.6keV state in our scheme might be the band head observed at 932keV in the Coulomb excitation [10]). The (4 + ) assignment of the l127.2keV state in Figure 2 is based on the assumption that this state is identical with the l124keV 4 + state seen in the reaction investigations of Tjom and Elbek [9] or Domingos, Symons and Douglas [10].…”

“…Considering the states above the well-established ground state band of 17~ the 1010.7 and l l03.6keV states have been assigned previously as the 3 + and 4 + members of the ,/-vibrational band [3, 9, 10] (the uncertain 934.6keV state in our scheme might be the band head observed at 932keV in the Coulomb excitation [10]). The (4 + ) assignment of the l127.2keV state in Figure 2 is based on the assumption that this state is identical with the l124keV 4 + state seen in the reaction investigations of Tjom and Elbek [9] or Domingos, Symons and Douglas [10]. The (6 +) assignment given for the 2.76min aTorz-67"~U103 has a rather firm basis in systematics and theory: All the wellknown odd Z=67 isotopes 16a-~69Ho have the ~-[523~]p Nilsson state as their ground state [11,4,5], while the ground state of the N=103 isotones 171Er, 173yb and 175Hf is ~ [512]'], [11].…”

“…If normalized to the experimental band head energy 932keV [9,10], the projection model calculation Fig. 3.…”