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

Outline Summary Introduction Generalized Liquid Drop Model (GLDM) Numerical  results and discussions Summary

Introduction In 1911, Geiger -Nuttall law: Difference: 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 theoretical challenge.

Various models Theoretical models: Semi-empirical formula: Viola–Seaborg–Sobiczewski: 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

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

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

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.

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

Compared with experimental data AZ Qexp(MeV) QDong(MeV) T(exp.) T(cal.) 294118 11.81±0.06 11.718 0.89(+1.07/-0.31)ms 0.94ms 292116 10.80±0.07 10.810 18(+16/-6)ms 48.4ms 290116 11.00±0.0.08 11.087 7.1(+3.2/-1.7)ms 16.1ms 288114 10.09±0.07 10.164 0.69 (+0.17/-0.11)s 0.827s 286114 10.33±0.06 10.447 0.26s 0.18s 284112 SF 9.510 99(+24/-16)ms 29.34s 282112 9.799 0.82(+0.30/-0.18)ms 1.56s 270110 11.24±0.05 11.092 100(+140/-40)s 0.93s 266108 10.38±0.02 10.481 2.3(+1.3/-0.6)ms 2.32ms

Compared with experimental data AZ Qexp(MeV) QDong(MeV) T(exp.) T(cal.) 264108 10.848 10.766 81s 20.5s 260106 9.92±0.03 10.155 9.5(+2/-2)ms 8.1ms 260104 8.947 8.935 1s 0.846s 258104 9.296 9.238 92ms 82.5ms 256104 8.966 9.109 0.304s 0.596s 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.

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.

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

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

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

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