Identification of rotating and vibrating tetrahedrons in the heavy nucleus 208Pb

Abstract

Ten known states in the heavy nucleus 208Pb at $2.6 < E_{x} < 7.9$ MeV are described by rotating and vibrating tetrahedrons. The $ 3^{-}$ and $ 4^{+}$ yrast states are the first members of the rotational band. A $ 2^{\pm}$ doublet state with the $ 2^{+}$ yrast state as one member and the newly recognized $ 2^{-}$ yrast state as the other member, the $ 1^{-}$ yrast state, and the third $ 0^{+}$ state are the heads of the three elementary tetrahedral rotating and vibrating bands. The newly recognized state at $ E_{x} = 4142$ keV was assigned spin 2 in 1975 and is suggested to have negative parity by the absent 208Pb $(\alpha, \alpha')$ excitation. Four more states at $5.7< E_{x}< 7.9$ MeV are identified as the next members of the three elementary tetrahedral rotating and vibrating bands. The ambiguous spin assignment to the state at $E_{x}= 7020$ keV is settled with $ 3^{-}$ , the state at $ E_{x} = 7137$ keV is assigned $ 4^{-}$ .