1、高自旋中的核結(jié)構(gòu)問題北京大學(xué) 物理學(xué)院 技術(shù)物理系許甫榮I.引言II.Cranking Shell ModelIII. 高自旋運(yùn)動及有關(guān)的核結(jié)構(gòu)問題IV. Summary高自旋中的核結(jié)構(gòu)問題北京大學(xué) 物理學(xué)院 技術(shù)物理系I.引言Chiral RotationTriaxial shape, chiral doubletS. Frauendorf and J. Meng, NPA617, 131(1997)K. Starosta, et al., PRL86, 971 (2001)N=75 isotones130Cs, 132La, 134Pr, 136Pm吉大, 劉運(yùn)祚等清華, 朱勝江等I.引言

2、2. Magnetic rotation Observed strong I=1 transitions 104Ag, 134,136Ce, 82,84Rb, 104Cd, 139Ba, S. Frauendorf and J. Meng, Z. Phys. A357, 263(1996).原子能院: 溫書賢 , 竺禮華等2. Magnetic rotation3. Wobbling motionTriaxial deformationJxJy Jz25年前預(yù)言實(shí)驗(yàn)特性:2個結(jié)構(gòu)相似,有一定的能量shift,帶間躍遷與帶內(nèi)躍遷可以競爭.163Lu, S.W. Odegard, et al.,

3、PRL86, 5866(2001)3. Wobbling motion5. Signature inversion劉運(yùn)祚, 張玉虎 等許甫榮等6. Triaxial superdeformation 楊春祥, 陳永壽等5. Signature inversionII. Cranking Shell ModelII. Cranking Shell Modeli)Total Routhian Surface (TRS) deformationii) Rotational alignmentiii) Rotational band (Eex, J1, J2)iv) Quadruple moment,

4、 transition ratev) Configurationi)Total Routhian Surface (TRS)III. 高自旋中的核結(jié)構(gòu)問題A110區(qū), 非常豐中子, r-process path very soft, oblate rotation, vibration coupling, Tetrahedral symmetry (四面體對稱)形狀共存: NZ, A803) K isomerism Increasing life times of unstable nuclei, 核天體4) Shape evolution for a given nucleus prolat

5、eoblate large deformation (20.35)5) Super alignment Doubly midshell nuclei6) A50 Rotation往往同時有rotation and vibration, 復(fù)雜 III. 高自旋中的核結(jié)構(gòu)問題A110 (neutron-rich, r-process path)F.R. Xu et al., PRC65, 021303(R)(2002)Soft, oblate rotation, vibration A110 (neutron-rich, r-processQ.H. Lu et al., PRC52, 1348(1

6、995)Q.H. Lu et al., PRC52, 1348(19i) S.J. Zhu et al., CPL20, 350 (2003), CPL19, 180 (2002)ii) H. Hua et al., PLB562, 201 (2003)iii) N. Schunk, J. Dudek et al., PRC69, 061305(2004)Tetrahedral symmetry, Double point-group Approximately 320 only i) S.J. Zhu et al., CPL20, 3502) Shape coexistence: A80,

7、ZN2) Shape coexistence: A80, ZExperiments: prolate, oblate coexisting rotationsi)S.M. Fischer et al., PRL87, 132501(2001)72Kr, 76Sr, 80Kr,ii) S.M. Fischer et al., PRL84, 4064(2000) Z=N 68Se, critical point, important for nuclear astrophysics iii)溫淑賢 , 竺禮華等Experiments: prolate, oblate c3) K isomerism

8、Increasing lifetimes of unstable nuclei For example: 140Dy66 drip-line nucleusF.R Xu, et al., PRC59, 731 (1999)3) K isomerismTwo experiments observed our prediction.D.M. Cullen et al., PLB529, 42 (2002)Ex=2164 keV, T1/2=7.21.5 sW. Krolas et al., PRC65, 031303(R) (2002)Ex=2166 keV, T1/2=7.00.5 sNo ob

9、servation for the lifetime of the ground state in 140Dy, very short lifetime?徐樹威, drip-line nucleiTwo experiments observed our p高自旋中的核結(jié)構(gòu)問題課件ii) K isomers increase the production of superheavy nucleiAdiabatic blocking (configuration-constrained)High-K isomers exist systematicallyIncrease barrier heig

10、ht and width of emission due to centrifugal force;Decrease preformation factor of particle; pair density at surface a+b reduce probability for decaysc) Increase barrier height and width of fissionIncrease lifetimes of superheavy nuclei!ii) K isomers increase the proF.R. Xu et al., PRL92, 252501(2004

11、)S. Hofmann et al., EPJ A10, 5(2001)T1/2=6.0 ms (isomers); T1/2=0.1 ms (g.s.)F.R. Xu et al., PRL92, 252501(Spontaneous fissionSpontaneous fission高自旋中的核結(jié)構(gòu)問題課件4) Shape evolution in a given nucleusF.R. Xu et al., PRC62, 014301(2000)Predict: oblate rotation in Hf isotopesA recent calculation for 175HfSh

12、ape: prolate oblatelarge prolate deformation 2 0.25 -0.2 0.35 I 0 40 40 60 60Very recent experiment observed I40 band4) Shape evolution in a given 高自旋中的核結(jié)構(gòu)問題課件高自旋中的核結(jié)構(gòu)問題課件5) 不太重核的譜學(xué)A5060, for example: Cr, Mn, FeExperiment: D.E. Appelbe, F.R. Xu, PRC67, 034309 (2003) 55Cr, 56CrVibration+rotation5) 不太重核的譜學(xué)高自旋中的核結(jié)構(gòu)問題課件55Cr: very configuration dependent55Cr: very configuration depen6) Doubly midshell structureMagic numbers: 8 20 28 50 82 126 Mid: 14 24 39 66 104Even-even midshell nuclei: 28Si14 T1/2=140 ms 48Cr24 T1/2=21.6 hNext: 170Dy66Experiment has not produced the nucleus, but164D