超重核 ( 新元素 ) 研究进展 任中洲 南京大学 物理系

1. 超重核(新元素)研究进展 任中洲南京大学 物理系 • 寻找重元素的历史回顾 • 实验的新进展 • 理论研究状况 • Z=118新元素的合成(Dubna)

2. 周期表 (1869): 门捷列夫未获 Nobel Prize

3. 周期表(2000s)

4. 1寻找重元素的历史 • 早期物理学家寻找新化学元素 • 物理学+化学: • 光谱线: Fraunhofer, Kirchhoff +Bunsen (Germany): Cs, Rb (37,55); Crookes, Tl(81). • 物理学+天文学: • 日蚀时，观察新光谱线 ，太阳元素：氦 法国物理学家，英国天文学家（1868）. 为什么物理学家介入：物理方法威力大。

5. 1903-1904: Nobel Prize and new elements • 1. Rayleigh(physicist: N) +Ramsy (chemist): Ar; He (Crookes: confirm), Ne ,Kr • 1904 Nobel prize ( Physics+Chemistry) • 2. M.Curie and P. Curie: Radioactivity; • Stronger : new elements, Ra, Po (1898) ? • 1903 Nobel prize (Physics) 1/2+(1/4+1/4) • 1911 Nobel prize (Chemistry)

6. References on arguments • 1. A history of physics, Dover Publications, F. Cajori , 1962, USA. • 2. Une Femme Honorable, Marie Curie; • De Francoise Giroud; • Librairie Artheme Fatard, 1981. • 3. A short history of nearly everything, • Bill Bryson, Jed Mattes Inc. , 2003

7. Lord Kelvin

10. 1 寻找新元素的历史 • 周期表中30多个元素由核方法合成 • 1930—1949 找到“失踪”元素 • 重元素 （U 以后：Z=93,94?)合成 • 核合成的元素被化学家证实 为什么核合成？ 稀有 或 放射性。

11. Year of discovery (1896-1996)

12. 重元素合成的意义 （1） • 扩展元素周期表 • 到底有多少个化学元素 ？ • 新元素的应用？超重岛存在？ • 超重岛存在机制？ 新现象？

13. 元素的命名 Z=101, Md, Mendelevium. (Berkeley). Z=102, No. Nobelium (Berkeley +Nobel) Z=103, Lr, Lawrencium. (Berkeley) Z=104, Rutherfordium. (Berkeley;Dubna) ? Z=105, Db, Dubnium (Dubna;Berkeley) ? Z=106, Seaborgium. (Dubna;Berkeley) ? Z=107, Bohrium (Dubna) Z=108, Hassium (GSI; Dubna) ??? Z=109, Meitnerium. (GSI) Z=110, Darmstadium…. (GSI)

14. New elements Z=114 and Z=116 (Dubna)

15. Z=114, nature

16. 2. Summary of New Results • The elements Z=110,111,112 were produced at GSI, Hofmann, Muenzenberg…. Z. Phys. A, 1995, 1996. • Z=114 was synthesized at Dubna by Oganessian et al. Nature, 1999; Phys. Rev. Lett. 1999;Phys. Rev. C, 2000. • Z=116 , Z=115, Z=118 were produced at Dubna in 2000s. Oganessian et al, Phys. Rev. C, 2001-2006. • Z=113, RIKEN; PSI: 270 108; GSI: 270110 ; Lanzhou: 265107…. 继续争论？？？ 新元素？？？

17. 265Bh 0.94 s 9.24 a 259Db 0. 5 s 9.47 a 超重新核素259Db (Z=105),265Bh (Z=107) 中科院近代物理研究所

18. 国内超重新核素实验265Bh (Z=107) 265Bh的实验结果与理论预言一致

19. 3. theory. • J. A. Wheeler et al, 1950s: Superheavy nuclei • P.R., 1958. • Bethe and his collaborator, PRL, 1967. • 1960s-1980s, macroscopic-microscopic model (MM): Nilsson et al, Z=114 and N=184 ? • Moeller, Nix, Kratz, At. Dat. Nu. Dat. 1997. • Myers and Swiatecki, PRC, 1998.

20. Werner and Wheeler, PR, 1958: superheavy nuclei

21. Siemens and Bethe: nuclei with Z>104 are prolate

22. 3. Theory ( SHF and RMF 1990--) • Zhongzhou REN et al, JPG, 1996; CPL, 1997. • Lalazissis, Ring et al, NPA, 1996. • Cwiok, Nazarewicz, Heenen, PRL, 1999. • Ren and Toki, Nucl. Phys. A689 (2001) 691: Z=110-112,114. Ren, PRC, 2002,May,(R);PRC, Dec.,2002 • Ren et al, PRC 2003, PRC2004, PRC2005...

23. 3. Numerical results and discussion • Z: 94—116; N:150—184. Test the model for even-even nuclei: • Comparison of RMF model and Moeller result for the alpha chain of 277112. * Theoretical decay energy for Z=110-112. Theoretical decay energy for Z=114, 116. Nuclear structure : Shape coexistence in superheavy nuclei

24. Fig. 3 Theoretical and experimental alpha decay energies for GSI Data: Z=110, 111, 112 ( +2, +1, 0 shift).

25. Table 1, RMF results for Cf. (TMA and NLZ2) Experimental deformation Beta2=0.30 for 250,252Cf

26. Table 2, RMF results for No. (TMA and NLZ2) Experimental deformation Beta2=0.27 for 254No

27. Fig. 1 Energy surface of Z=108, A=264

28. Experimental B/A (MeV) is between two sets of RMF results (Z=98-108).

29. Fig. 2 Binding energy of the Z=112, A=277 chain from the RMF and Moller et al.

30. Tab. 4, results for GSI data 269110. (TMA)

31. Fig. 4 Theoretical and experimental alpha decay energy for Z=114, A=289 and Z=118, A=293

32. 创新点及意义 (1) • 提出超重核形状共存----可能是超重核存在新机制: • 改进和发展了数值计算方法和程序 • 完成大规模数值计算 • 提出超重核形状共存, 形变重要, 有低能同质异能态 • 发表了一系列论文(PRC 3篇; NPA 2篇等) • 论文被国外同行引用和肯定: • 论文被国际上著名实验小组引用(Dubna-Livemore-PSI) • 论文被综述文章引用(Nature, PRC, JPG)

33. Oganessian et al, PRC72 2005 Predictions of SHF and RMF compare well with MM results [12,13] 南京大学

34. Oganessian et al, PRC72 2005 SHF [12，49-51] and RMF [13，52-57] compare well with the experimental results 南京大学

35. Sharma,… Stevenson, Gupta, Greiner agree with us:shape coexistence and superdeformation

36. Geng, Toki, Zhao: similar results with us.

37. Geng, Toki, Zhao JPG 32 (2006) 573:shape coexistence and superdeformation.

38. Other RMF calculations agree with ours: superdeformation in superheavy nuclei

39. 配合国内实验, 理论预言: 265107 Qa and Ta Z. Ren et al, PRC 67 (2003) 064302; JNRS 3 (2002) 195. Expt: Gan et al, EPJA 2004, Qa=9.38 , Ta=0.94 s. Good agreement between theory and data.

40. 国内超重新核素实验265Bh (Z=107) 265Bh的实验结果与理论预言一致

41. 3. Density-Dependent Cluster Model • DDCM is a new model of alpha and cluster decay: • 1) effectve potential based on the Reid potential. • 2) low density behavior included. • 3) exchange included • 4) agreement within a factor of three for half-lives • Z Ren, C Xu, Z Wang, PRC 70: 034304 (2004) • C Xu, Z Ren, NPA 753: 174 (2005) • C Xu, Z Ren, NPA 760: 303 (2005) • C. Xu, Z. Ren, PRC 73: 041301(R) (2006)…

42. DDCM for superheavy nuclei (Z=106-118)

43. Density-Dependent Cluster Model • 建立了球形和形变核双折叠势程序 • 推导了球形，形变核alpha衰变寿命公式 • 对已知alpha衰变寿命进行了大规模计算 • 对结团放射性进行了系统研究

45. Deformed DDCM: a spherical alpha-particle interacts with a deformed daughter nucleus with an axially symmetric deformation

46. The distribution of the number of alphaemitters for different factors of agreement (Even-Even).

47. The comparison of experimental alpha-decay half-lives and theoretical ones for even-even nuclei (Z= 52−104)

49. Synthesis of new element Z=118 1. 2002, Dubna: D7-2002-287 2. PRC69, 2004 (May). 3. PRC70, 2004 (Dec.). 4. Phys. Scrt. 2006 (June) 5. PRC 74, 2006 (October).

50. Oganessian PRC69 (2004): Z=118