Band structures in 169Tm and the structures of Tm isotopes around N = 98

Md. A. Asgar; G. Mukherjee; T. Roy; S. Nandi; G. H. Bhatt; J. A. Sheikh; R. Palit; S. Bhattacharyya; Soumik Bhattacharya; C. Bhattacharya; A. Dhal; T. K. Ghosh; A. Chaudhuri; K. Banerjee; Samir Kundu; T. K. Rana; Pratap Roy; R. Pandey; S. Manna; J. K. Meena; S. Saha; S. Biswas; J. Sethi; P. Singh; D. Choudhury

doi:10.1140/epja/i2019-12882-3

2021 Impact factor 3.131

Hadrons and Nuclei

Eur. Phys. J. A (2019) 55: 175
https://doi.org/10.1140/epja/i2019-12882-3

Regular Article - Experimental Physics

Band structures in ¹⁶⁹Tm and the structures of Tm isotopes around N = 98

Md. A. Asgar¹^,2^,3, G. Mukherjee¹^,2^*, T. Roy¹^,2, S. Nandi¹^,2, G. H. Bhatt⁴^,5, J. A. Sheikh⁴^,6, R. Palit⁷, S. Bhattacharyya¹^,2, Soumik Bhattacharya¹^,2, C. Bhattacharya¹^,2, A. Dhal¹^,8, T. K. Ghosh¹^,2, A. Chaudhuri¹^,2, K. Banerjee¹^,2, Samir Kundu¹, T. K. Rana¹, Pratap Roy¹, R. Pandey¹^,2, S. Manna¹^,2, J. K. Meena¹, S. Saha⁷, S. Biswas⁷, J. Sethi⁷, P. Singh⁷ and D. Choudhury⁷

¹ Variable Energy Cyclotron Centre, 700064, Kolkata, India
² Homi Bhabha National Institute, Training School Complex, Anushaktinagar, 400094, Mumbai, India
³ Department of Physics, Prabhat Kumar College, 721404, Contai, India
⁴ Department of Physics, University of Kashmir, 190 006, Srinagar, India
⁵ Department of Physics, Govt. Degree College, 192 231, Kulgam, India
⁶ Cluster University Srinagar, 190 001, Srinagar, Jammu and Kashmir, India
⁷ Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, 400005, Mumbai, India
⁸ ELI-NP, Str. Reactorului no.30, P.O.BOX MG-6, Bucharest-Magurele, Romania

^* e-mail: gopal@vecc.gov.in

Received: 9 June 2019
Accepted: 9 September 2019
Published online: 16 October 2019

Abstract

The excited states of ¹⁶⁹Tm have been studied via the ¹⁶⁹Tm(³²S,³²S^′)¹⁶⁹Tm^* reaction at the beam energy of 164MeV. The -rays were detected using the Indian National Gamma Array (INGA) setup, composed of 19 Compton-suppressed clover HPGe detectors. A new level scheme of ¹⁶⁹Tm with 11 newly placed -rays has been proposed. A band crossing in the band and several interband E1 transitions between this and the ground-state band have been observed for the first time in this nucleus. The role of the deformed shell gap has been discussed by comparing the band crossing parameters of the negative parity bands in Tm and other neighboring nuclei. The origin of the interband E1 transitions has been investigated in terms of coupling to octupole degrees of freedom. The shape evolution of the Tm isotopes around have been studied in the projected and cranked shell model approaches, both of which predict a change in shape from an axial prolate to a triaxial one after band crossing in these nuclei. The new data and the calculations help to understand the unusual structural phenomena reported for the nuclei with .