High-spin structures in the 159 Lu nucleus

1. High-spin structuresin the 159Lu nucleus High-spin structuresin the 159Lu nucleus 李聪博 Jilin University , China Institute of Atomic Energy 赤峰 The 13th National Nuclear Structure Conference of China 2010年7月25-27,中国赤峰

2. INTRODUCTION EXPERIMENTAL DETAILS AND ANALYSIS METHODS EXPERIMENTAL RESULTS DISCUSSION SUMMARY Level structures in the 159Lu nucleus

3. Level structures in the 159Lu nucleus Introduction 159Lu There are several properties in the transitional nuclei . Small driving force can produce large changes in transitional region and neighboring region. 64≤Z≤70 and 82≤N≤90 Z=71 N=88 Z=71 N=88 Z=71 N=88

4. Level structures in the 159Lu nucleus Introduction 158Yb 157Tm 160Lu 161Lu 162Lu 163Lu 164Lu 165Lu 166Lu 167Lu 156Er 155HO 154Dy Triaxial strongly deformed (TSD) 159Lu 159Lu Band termination

5. Level structures in the 159Lu nucleus Introduction Ma Yingjun et al., J. Phys. G: Nucl. Part. Phys. 21 937-945 (1995). • 19F+144Sm→159Lu+4n • 14 HPGe-BGO detectors • Collected 107γ-γ events

6. Level structures in the 159Lu nucleus EXPERIMENTAL DETAILS AND ANALYSIS METHODS

7. Level structures in the 159Lu nucleus EXPERIMENTAL DETAILS AND ANALYSIS METHODS • Beam energy: 106MeV • Target: 144Sm 1.2mg/cm2 • 12 HPGe-BGO HPGe detectors and 2 planar-type HPGe detectors • Collected 2×108 γ-γ events

8. Level structures in the 159Lu nucleus EXPERIMENTAL DETAILS AND ANALYSIS METHODS • Beam energy: 106MeV CASCADE计算反应144Sm(19F,4n) 的激发函数曲线

9. Level structures in the 159Lu nucleus EXPERIMENTAL DETAILS AND ANALYSIS METHODS Angular correlation intensity ratio as a function of gamma ray energy for transition in 159Lu

10. Level structures in the 159Lu nucleus EXPERIMENTAL RESULTS The scheme deduced for 159Lu. The transition energies are given in keV and their relative intensities proportional to the widths of the arrows. Dashed lines and parentheses indicate tentative assignments. New transitions are labeled by an asterisk.

11. Level structures in the 159Lu nucleus EXPERIMENTAL RESULTS γ-ray spectrum showing γ rays in coincidence with the 426 KeV transitions in band 1.

12. Level structures in the 159Lu nucleus EXPERIMENTAL RESULTS γ-ray spectrum showing γ rays in coincidence with sum of the 316 and 339 KeV transitions between band 3 and 4. (316 and 339 KeV transitions are uncontaminated.) New transitions are labeled by an asterisk.

13. Level structures in the 159Lu nucleus EXPERIMENTAL RESULTS γ-ray spectrum showing γ rays in coincidence with sum of the 132, 390 and 377 KeV transitions between band 5 and 6. New transitions are labeled by an asterisk.

14. Level structures in the 159Lu nucleus DISCUSSION EF crossing? ApAB, BpAB Discussion on the quasiparticles  described in “C.-H. Yu. et al., Nuclear Physics A489 477-507 (1988)”. i13/2 neutron backbend Ap , Bp The alignment ix as a function of rotational frequency for yrast bands in 159Lu. A reference configuration with J0=12MeV-1 ħ2 and J1=104Mev-1 ħ4 was used.

15. Level structures in the 159Lu nucleus DISCUSSION AB crossing AB crossing AB crossing c=0.29MeV c=0.32MeV c=0.33MeV Experimental routhians eˊ as a function of ħω for the yrast bands in 155Ho, 157Tm, 159Lu. A reference configuration with J0=10, 10, 12 MeV-1 ħ2 and J1=120, 100, 104MeV-1 ħ4 were used.

16. Level structures in the 159Lu nucleus DISCUSSION ApAB, BpAB ApAE, BpAE The alignment ix as a function of rotational frequency for all the bands in 159Lu. A reference configuration with J0=12MeV-1 ħ2 and J1=104Mev-1 ħ4 was used.

17. Level structures in the 159Lu nucleus DISCUSSION To further explore the possible configurations of 159Lu. The experimental B(M1)/B(E2) ratios branching ratios were obtained, using the standard relations: Calculations for B(M1)/B(E2) from the geometric model of Dönau and Frauendorf [21] assuming the quasiparticle configurations Ap, Bp for bands 1 and 2, ApAB, BpAB for bands 3 and 4, and ApAE, BpAE for bands 6 and 7. We use the standard relations:

18. Level structures in the 159Lu nucleus DISCUSSION Here, K=K1+K2+K3, the subscripts 1, 2, 3 refer to the quasiparticles, or aligned pairs of quasiparticles, that couple to form the band, and △e′ is the signature splitting in the energies in the rotating frame. Table I. parameters used in the calculation of B(M1)/B(E2) The calculations show good agreement with the data ,which supports our proposed configuration assignments.

19. Level structures in the 159Lu nucleus DISCUSSION Experimental B(M1)/B(E2) ratios as a function of spin for bands in 159Lu. The thick lines show results of calculations using the geometric model of Dönau and Frauendorf.

20. Level structures in the 159Lu nucleus DISCUSSION 159Lu was only populated up to I～30ħ, therefore it is difficult to conclude whether the band termination phenomenon is observed in this nucleus. Alignment ix as a function of rotational frequency ħω for the (a) 159Lu (b) 157Tm Data are taken from the ref. and the present work

21. The high-spin states of 159Lu were populated through the reaction 144Sm (19F, 4n) at a beam energy of 106 MeV. The level scheme for 159Lu is established up to spin～30 with the addition of about 20 new transitions. The quasiparticle configurations of updated bands are suggested by Routhians, alignments and B(M1)/B(E2) ratios. Level structures in the 159Lu nucleus SUMMARY

22. Level structures in the 159Lu nucleus Thanks for your attention