Excited states of 133 La have been investigated to search for the wobbling excitation mode in the low-spin regime. Wobbling bands with nω = 0 and 1 are identified along with the interconnecting ∆I = 1, E2 transitions, which are regarded as one of the characteristic features of the wobbling motion. An increase in wobbling frequency with spin implies longitudinal wobbling for 133 La, in contrast with the case of transverse wobbling observed in 135 Pr. This is the first observation of a longitudinal wobbling band in nuclei. The experimental observations are accounted for by calculations using the quasiparticle-triaxial-rotor (QTR) model, which attribute the appearance of longitudinal wobbling to the early alignment of a π = + proton pair.

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Excited states in the 101 Pd nucleus were investigated through the 75 As( 31 P, 2p3n) fusion-evaporation reaction at E lab = 125 MeV using the Indian National Gamma Array (INGA) spectrometer equipped with 21 clover Ge detectors. The level scheme is considerably extended for medium spin values. New positive-parity band structures in 101 Pd have been studied within the framework of the projected shell model (PSM) and are found to undergo transition from single quasiparticle to high-K three quasiparticle configuration after bandcrossing, i.e., from principal-axis rotation to tilted-axis rotation. The negative-parity band structures are discussed in the framework of the hybrid version of tilted-axis cranking (TAC) shell model calculations. The observed alignment gain in the lowest excited νh 11/2 negative-parity band results from successive (νg 7/2 ) 2 and (πg 9/2 ) 2 pair alignments. The higher excited negative-parity bands are reproduced for the ν[h 11/2 (g 7/2 /d 5/2 ) 2 ] and (πg 9/2 ) −2 ⊗ νh 11/2 configurations.

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