Indication of γ -vibration in ^123,125,127I

Abstract

High spin states in 127I were populated via 124Sn(7Li, 4nγ) fusion-evaporation reaction at Ebeam = 33 MeV. Level scheme of 127I has been updated by placing new γ-rays and also by confirming the spin/parity of several energy levels. Two new levels at Ex = 2628 and 3199 keV have been identified which are found to decay into the negative parity πh11/2 band. These two states and two earlier reported states at 3502 and 3989 keV have been interpreted as the γ-vibrational states on the basis of their decay pattern. Two positive parity three-quasiparticle bands above Iπ = 23/2+ states at 2901 and 3060 keV have been identified to be a possible candidate of chiral band. A comparison in the isotopic and isotonic chains reveals the possible existence of γ-vibration and chiral rotation in 123–127I.

Three-quasineutron γ-band in 127Xe

“…At higher angular momentum, a few more even-A nuclei including 166−172 Er, 156 Dy, 136,138 Nd, 134 Ce, 126 Ba, 124 Te, 102 Ru and 70 Ge are found to exhibit the γ-vibrational motion coupled to a rotation-aligned multi-quasiparticle configuration [12][13][14][16][17][18][19][20][21]. On the other hand, γ-band coupled to an odd-quasiparticle is also reported in several nuclei [7][8][9]. In the case of 131 Cs, γ-bands built on both positive (πg 7/2 ) and negative (πh 11/2 ) parity onequasiparticle configurations were observed [9].…”

“…The relative excitation energy of the constituent states of the γ-band depends on both the magnitude and nature of the γ-deformation and hence can be used as a probe to study the axial asymmetry in nuclear shapes [4][5][6]. These structures are expected to be built on each quasiparticle configuration [7][8][9][10][11][12][13][14]. For instance, γ-band built on the ground-state configuration is observed in most of the deformed even-even nuclei [15].…”