Abstract
The nature of the yrast negative-parity band and its chiral-like partner band in Ag104 is investigated experimentally and theoretically. Lifetimes of states in the negative-parity yrast band and positive-parity band based on the 4424-keV level are measured using Doppler shift attenuation technique. Lifetimes of three more states have been determined along with the upper limit for the lifetime of the highest observed yrast states. Further, lifetimes known from earlier studies are determined with better precision. The level scheme of Ag104 has also been extended with the addition of new enhanced E1 transitions linking the positive-parity band based on the 4424-keV levels and the yrast negative-parity and its partner band. B(E1) and/or B(E1)/B(M1) values for the transitions from the positive-parity band to the yrast and its partner band have been determined for the first time; these suggest strong octupole correlation between the positive-parity and the negative-parity bands. Calculations based on the triaxial projected shell model (TPSM) and covariant density functional theory (CDFT) have been performed to unravel the intrinsic structures of the partner band and the excited positive-parity band. TPSM calculations predict that doublet bands have significant angular momentum contributions along the three principle axes, suggesting that bands could have chiral symmetry breaking origin. The CDFT calculations predict a π(g9/2)-1 - ν(h11/2)(g7/2,d5/2)2 aligned quasiparticle configuration for the negative-parity doublet bands with deformation parameters β≈0.20 and γ≈5∘. The partner band could be interpreted as a chiral vibration mode built on top of the yrast band. The excited positive-parity band is predicted to have aligned four quasiparticle configurations, namely, π(g9/2)-1 - ν(h11/2)2(g7/2,d5/2)1. Further, these calculations predict significant octupole softness in Ag104 which could be the reason for enhanced E1 transitions between the four quasiparticle positive-parity bands and the doublet negative-parity bands.
| Original language | English |
|---|---|
| Article number | 034323 |
| Journal | Physical Review C |
| Volume | 106 |
| Issue number | 3 |
| DOIs | |
| State | Published - Sep 2022 |
Funding
We would like to acknowledge BARC-TIFR pelletron staff for delivering a stable beam of during the experiment. We acknowledge the help of the INGA collaboration. We gratefully acknowledge the Department of Science and Technology (Government of India) for INGA Project No. IR/S2/PF-30/2003-II. This work was supported by the Department of Atomic Energy, Government of India (Project No. RTI 4002). K.K. acknowledges a CSIR research grant (Grant No. 09/760(0032)/2017-EMR-I) for financial support. This work was supported by the U.S. National Science Foundation (Grants No. PHY-1068192 and No. PHY-2011890) and by the APS-IUSSTF Physics Student and Post-Doc Visitation Program. S.J., G.H.B., N.R., and J.A.S. acknowledge the Science and Engineering Research Board, Department of Science and Technology (Government of India) for providing financial assistance under Project No. CRG/2019/004960 to carry out a part of the present research work. We would also like to thank R. Bhattacharjee, S. S. Bhattacharjee, S. Samanta, S. Das, N. Ghosh, A. K. Sinha, S. Mukhopadhyay, L. Dhanu, B. K. Nayak, D. C. Biswas, A. Y. Deo, S. K. Tandel, N. Kaur, Ashok Kumar, J. Sethi, and S. Chattopadhyay for their initial involvement in the project. Fruitful discussions with J. Meng and Z. X. Ren on the theoretical interpretation are also acknowledged. A special thanks goes to Prof. S. C. Pancholi for his unconditional guidance.