High-K isomers in extreme conditions

1. High-K isomersin extreme conditions 刘红亮 西安交通大学理学院 指导与合作者 许甫荣(北京大学) P.M. Walker (Surrey, 英国) 孙扬(上海交大) C.A. Bertulani (TAMUC，美国) 2012年4月 湖州

2. Outline • Introduction of high-K isomers • Model • Calculations 1. extreme shape 2. extreme mass 3. extreme lifetime • Summary

3. Introduction Nuclear isomers: Long-lived excited states (τ≥10-9 s) P.M. Walker & G.D. Dracoulis, Nature 399, 35 (1999).

4. Introduction A well-known example: 9/2[624] 9/2[514] Fermi Surface 7/2[514] 7/2[404] neutron proton

5. Model Nuclear shape parametrization Configuration-constrained calculations of potential-energy surfaces Standard liquid drop model TRIAXIAL Strutinsky shell correction calculated from Woods-Saxon potential and Lipkin-Nogami pairing traced by F.R. Xu et al.,Phys. Lett. B 435, 257 (1998).

6. Model Potential-energy surfaces of high-K states H.L. Liu et al., Eur. Phys. J. A. 47, 135 (2011). H.L. Liu et al., Phys. Rev. C 83, 011303(R) (2011).

7. extreme shape High-K shape isomer P. Limkilde & G. Sletten Nucl. Phys. A 199(1973)504

8. Calculations • |Ecal. – Eexp.| < 400 keV • Configurations suggested • for the first time High-K shape isomers live longer than the corresponding K=0 shape isomers

9. Calculations long lifetime short lifetime easy to fission hard to fission soft rigid shape isomer high-K shape isomeric state 236Pu T1/2=37ps T1/2=34ns 242Cm T1/2=40ps T1/2=0.18ms H.L. Liu et al., Eur. Phys. J. A. 47, 135 (2011).

10. extreme mass Effects of β6 deformations on heaviest high-K isomers? I. Muntian et al., Phys. Lett. B 500, 241 (2001).

11. 4-qp isomer ANL R.-D. Herzberg et al. Nature 442(2006)896 2-qp isomer S.K. Tandel et al. Phys. Rev. Lett. 97(2006)082502 JYFL LBNL Hessberger et al. Eur. Phys. J. A 43(2010)55 R.M. Clark et al. Phys. Lett. B 690(2010)19 GSI

12. Calculations Increased binding due to β6 deformations Remarkable and stable β6 deformations Solid lines: Cal. with β6 Dashed lines: Cal. without β6

13. Calculations Comparison between exp. and cal. Single-particle levels H.L. Liu et al., Phys. Rev. C 83, 011303(R) (2011).

14. extreme lifetime P.M. Walker & G.D. Dracoulis, Hyperfine Interact. 135, 83 (2001).

16. Softness against triaxial deformation facilitates the tunneling decay through triaxial shapes. P. Chowdhury et al.,Nucl. Phys. A 485, 136 (1988).

17. Calculations Kπ=18+ isomeric state in 188Hf: moderately robust against triaxial distortion H.L. Liu et al., Phys. Rev. C 83, 067303 (2011).

18. Summary • Extension of the model with the inclusion of high-order deformations • Explanation of the long life-time of the high-K shape isomers in actinide nuclei • Significantly improved description of heaviest high-K isomers with β6 deformation • New insight into the occurrence of long-lived isomer in neutron-rich Hf

19. Thank you!