States in 163Dy and 169Er populated in the (t, p) reaction

Angular distributions of protons from the 161Dy(t, p)163Dy and 167Er(t, p)169Er reactions were studied, using 15 MeV and 17 MeV tritons from the McMaster University tandem Van de Graaff accelerator. The reaction products were analyzed with a magnetic spectrograph and detected with nuclear emulsions. Since the 161Dy target ground state is the 52+[642] orbital, a strong L = 0 transition was observed to the 52+[642] bandhead in 163Dy, which was previously assigned at 251 keV. Also transitions to the 72, 92 and 112 band members were observed. Similarly, a strong L = 0 transition was observed to the 72+[633] bandhead at 244 keV in 169Er, with the other band members only weakly populated. The angular distributions to the various members of these two bands can be described when higher-order reaction processes are taken into account. In 163Dy, surprisingly strong L = 0 transitions were observed to levels at 1831 keV, 1937 keV and 2053 keV, with strengths of 23%, 30% and 37% of that for the 52+[642] bandhead. In 169Er, the 905 keV level was populated with an L = 0 transition that had 31% of the strength observed for the strong L = 0 transition to the 244 keV level. The nature of these states is at present not understood.