Alpha decay half-lives of even-even superheavy elements

1. Alpha decay half-lives of even-even superheavy elements 报告人：王永佳 指导老师：张鸿飞 兰州大学核科学与技术学院 Email：zhanghongfei@lzu.edu.cn wangyjia05@lzu.cn 2010-07-25 第13届核结构讨论会 内蒙古赤峰学院

2. Outline • Introduction • Generalized Liquid Drop Model (GLDM) • Numericalresults and discussions • Summary

3. Introduction In 1911, Geiger -Nuttall law: In 1928, G. Gamow created the QM theory of alpha decay. 1928 In 1928, W. Gurney and U. Condon obtained a general idea of the mysterious instability of the nucleus. Difference: Gurney and Condon argued that the same QM tunneling analysis should also be applicable to beta decay, whereas Gamow already knew that beta decay posed a much deeper theoreticalchallenge.

4. Various models Viola–Seaborg–Sobiczewski: • Semi-empirical formula: G. Royer and H.F. Zhang : • Theoretical models: Cluster model, DDCM , GDDCM GLDM, DDM3Y, unified fission model [Ref.] J. Phys. G: Nucl. Part. Phys. 35 (2008) 085102

5. Introduction • Superheavy elements • Decay modes: alpha decay and spontaneous fission • Identification Dubna: 48Ca+249Bk-----293,294117 GSI : 48Ca+244Pu-----288,289114 [Ref.] Phys. Rev. Lett. 104(2010) 252701 [Ref.] Phys. Rev. Lett. 104(2010) 142502

6. Our method • Generalized liquid drop model (GLDM) Preformation factor Assault frequency [For heavy even-even nuclei Z>82 and N>126] The standard deviation between the extracted data and the values obtained from this Eq. is only 0.1622, implying that the average deviation between the theoretical estimates and the experimental data for alpha decay half-lives of heavy even-even nuclei will be 100.1622 = 1.45. [Ref.] wang yong-jia and zhang hong-fei at el. CHIN. Phys. Lett. 27(6) 062103

7. Alpha decay energy [Ref.] T. Dong and Z. Ren, Phys. Rev. C 77, 064310 (2008). [Ref.] B. Buck, A. C. Merchant and S. M. Perez, Phys. Rev. C45(1992), 2247. [Ref.] E.L. Medeiros et al. , J. Phys. G 32(2006) B23.

8. Alpha decay energy The previously mentioned formula can be simplified: Royer formula: [Ref.] G. Royer and H. F. Zhang Phys. Rev. C77 037602 [Ref.] Jianmin Dong at el. Phys. Rev. C81(2010)064309

9. Compared with experimental data

10. Compared with experimental data Experimental Data come from: Yu. Ts. Oganessian et al., Phys. Rev. C 69, 021601(R) (2004);70, 064609 (2004); 72, 034611 (2005); 74, 044602 (2006); 76, 011601(R) (2007) and G. Audi et al. Nucl. Phys. A 729 (2003) 3.

11. Superheavy elements • Cold fusion：Z<113 • Hot fusion：48Ca， 56Fe ： Dubna: Ca+Pu，Am，Cm，Bk，Cf 114---118 GSI: Ca+Pu---114 281 Ds---277Hs+alpha Future: Ca + Md ---121 Fe + Md ---127 Nuclei which Z<127 would be synthesized in the near future.

12. Alpha decay and spontaneous fission Phys. Rev. C78(2008) 044329 For 45 nuclei Region from 232Th to 286114

13. Very long SF half-life, why? Z. Ren, et al. NPA 759 (2005) 64. Chang Xu, et al. PRC78 (2008) 044329. K.P. Santhosh et al. NPA832(2010)220

14. Summary • We improved the assault frequency in the GLDM. • The improved model agrees with the experimental data of heavy nuclei within a factor of 2. • General predictions

15. Thanks for your attention! Thanks for the organizer of this conference!