Presentation on theme: "Systematic study of fusion reactions leading to super-heavy nuclei"— Presentation transcript:
1 Systematic study of fusion reactions leading to super-heavy nuclei 1. Introduction2. capture cross sections3. Survival probablity Wsur4. Fusion probabilty PCN5. ConclusionNing WangGuangxi Normal UniversityBLTP/JINR-KLFTP/CAS Joint Workshop on Nuclear Physics, Aug. 2-6, 2012, Dubna
3 I. Capture cross sections with the Skyrme energy-density functional Density distributions of the reaction partnersSkyrme energy-density functionalEntrance-channel fusion barrierBarrier penetration & empirical fusion barrier distribution D(B)Fusion cross sectionsM. Liu, N. Wang, Z. Li, X. Wu and E. Zhao, Nucl. Phys. A 768 (2006) 80Ning Wang, et al., Phys. Rev. C 74 (2006)
4 1. Determination of density distributions according to Hohenberg-Kohn theoremWoods-Saxon form for densitiesSearch for the minimum of energy by varying densities (R0p, R0n, ap, an)
5 2. Entrance-channel fusion barrier Sudden approximation for densityV.Yu. Denisov and W. Noerenberg,Eur. Phys. J. A15, 375 (2002).
6 3. Fusion (capture) cross section withD(B) considers the coupling between the relative motion and other degrees of freedom such as dyn. deform. etc.16O+208Pb, E=80MeV, ImQMD
7 for reactions with nuclei near the beta-stability line but the neutron-shell is not closed
8 The fusion excitation functions for a series of reactions with 16O bombarding on medium mass targets.Wang et al. Sci China G 52, 1554 (2009)
12 Deviations from exp. data for 120 reactions N. Wang et al., J. Phys. G: 34 (2007) 1935rms deviation for (E>B)About 70% systems are less than 0.005, which gives the system error 18%.
13 II. Survival probability Wsur with HIVAP The sensitive parameters:1. fission barriers (Liquid-drop barriers, Sierk’s barriers…)2. level density parameters (Fermi gas model, angular-momentum and shape-dependent)3. masses shell corrections and particle separation energiesIn the standard HIVAP code: ra=1.153fm
16 Deviations of calculated evaporation (and fission) cross sections from exp. data for 51 fusion-fission reactionsFor 68% reactions, the deviations are smaller than ,Estimated systematic errors of the HIVAP code: 1.85Wsur and Wsur /1.85
17 WS*3). Masses of super-heavy nucleiA reliable nuclear mass formula is crucial for a description of the properties and production cross sections of super-heavy nucleiWS : PRC 81 (2010)WS*: PRC 82 (2010)WS3: PRC 84 (2011)
18 Alpha decay energies of super-heavy nuclei have been predicted rms ~ 248 keV to 46 Qa of SHN
19 N=178WS*N=162N=178N=178WS*WS*Zhang, et al., Phys. Rev. C 85, (2012)
20 III. Fusion probability 1) quasi-fission barrierYu. OganessianWang, Tian, Scheid, PRC84, (R) (2011)
25 Conclusion and discussion Methods for calculations of capture cross sections, survival probability of compound nucleus and the fusion probability in fusion reactions leading to super-heavy nuclei have been established and checked step by step.Coulomb barrier, fission barrier and quasi-fission barrier play important roles for the calculations of three parts.More precise calculations for masses, fission barriers, fission fragment yields and the study of fusion dynamics are still required.
26 Zhu-Xia Li、Xi-Zhen Wu、Kai Zhao （李祝霞） （吴锡真） （赵凯） China Institute of Atomic energy：Zhu-Xia Li、Xi-Zhen Wu、Kai Zhao（李祝霞） （吴锡真） （赵凯）Institute of Theoretical Physics (CAS)：En-Guang Zhao （赵恩广）Justus-Liebig-Univ. Giessen：Werner ScheidGuangxi Normal Univ.Min Liu （刘敏）Anyang Normal Univ.Jun-Long Tian （田俊龙）
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