Search for the Kπ=1+ two-proton band in Er166

The Ho-165 (alpha, t) and (He-3,d) reactions have been measured at beam energies of 40 and 25 MeV to look for the K(pi) = 1+{9/2-[514]-7/2-[523]} two-proton band structure in Er-166. Reaction products were analyzed using a quadrupole-three-dipole spectrometer. Distorted-wave Born approximation predictions were used to extract candidate states with angular momentum transfer l = 5. The measured strengths of all the candidates for l = 5 transitions were compared with the Nilsson fingerprint pattern of the K(pi) = 1+{9/2-[514]-7/2-[523]} band to identify the structure. No strong population of this configuration was found. At best two tentative candidates for the I(pi) = 3+ and 4+ members of this band could be identified, which would represent at most 38% of the expected strength for this configuration. The bandhead for this tentative K(pi) = 1+ excitation does not correspond to any I(pi) = 1+ state observed in the Er-168(gamma, gamma') reaction.