1. High spin states in 136,137 La, 148 Ce and 105 Mo

2. S. J. Zhu 1, Y. J. Chen 1, M. L. Li 1, H. B. Ding 1., J. H. Hamilton 2, A. V. Ramayya 2, J. K. Hwang 2, X. S. Dong 1, U. Y. Nan 1, L. H. Zhu 3, S. X. Wen 3, X. G. Wu 3 1 Department of Physics, Tsinghua University, Beijing 100084, People’s Republic of China 2 Department of Physics, Vanderbilt University, U.S.A 3 China Institute of Atomic Energy, Beijing, 102413, People’s Republic of China

3. I. INTRODUCTION II. EXPERIMETAL METHODS III. RESULTS AND DISCUSSION IV. SUMMARY

4. I. INTRODUCTION 136,137 La 148 Ce 60 62 64 66 68 105 Mo

5. A. A=135 Region: 136 La (Z=57, N= 79) 137 La (Z=56, N=80) N: near N=82 magic number, stronger single- particle character. At the high spin states, look for collective bands: prolate bands, oblate bands

6. E.S.Paul et al. PRL,58, 984(1987) The shape driving effect :

7. B. A=140 neutron-rich Region: 148 Ce: Searching for octupole deformation.

8. C. A=110 neutron-rich Region: 105 Mo: odd-A nucleus: Searching for two- phonon vibrational- rotation bands.

9. II. EXPERIMETAL METHODS A. 136 La: 130 Te( 11 B, 5n), beam: 60 MeV 137 La: 130 Te( 11 B, 4n), beam: 50 MeV CIAE HI-13 tandem accelerator 50  10 6 coincidence events

10. CIAE In-Beam Gamma-ray detectors

11. B. 148 Ce, 105 Mo : measure the prompt  -rays from spontaneous fission of 252 Cf. Lawrence Berkeley National Laboratory GAMMASPERE Detector Array 105 Compton-Suppressed Ge Detectors 252 Cf Source Total of 5.7×10 11 triple- and higher-fold  -  -  coincidence events (in cube) Radware software package to analyze data

14. III. RESULTS AND DISCUSSION A. 136 La: E.W.Cybulska et al. Acta Phys. Pol.B32, 929 (1999).

15. Old: (8 + )  h 11/2  h 11/2 systematic

17. Band (2) Bands(2) and (3): oblate(  =-60  ). １.stronger △ I=1transitions, ２.no signature splitting, ３. different moments of inertia from plolate. Band (2): Band (3):

19. ↑New! B. 137 La:

20. Band (1): collective backbending

21. Proton routhianNeutron routhian 0.48 MeV 0.40 MeV

22. 带 ( ３ ) ——— 扁椭带 Band (3): oblate band (  ~-60  )

23. C. 148 Ce: Theoretical prediction: When N,Z=34, 56, 88, 132, a pair of single particle orbitals with  N=1,  l=3,  j=3 closes to each other, octupole element Y 30 is very strong, strong octupole correlations occur.

24. Z=56, N=88, around A=144 neutron-rich region, octupole deformation discovered. Using simplex quantum number s to express For even A nuclei, S= +1, I p =0 +, 1 -, 2 +, 3 -, 4 +, 5 -, ….. S= -1, I p =0 -, 1 +, 2 -, 3 +, 4 -, 5 +, ….. For odd A nuclei, S= +i, I p =1/2 +, 3/2 -, 5/2 +, 7/2 -, 9/2 +, 11/2 -, ….. S= -1, I p =1/2 -, 3/2 +, 5/2 -, 7/2 +, 9/2 -, 11/2 +, …..

25. Experimental structure:  Two  I=2 band structures with positive and negative parities respectively.  Strong B(E1) transitions between two opposite parity bands.

26. Z=56: 140 Ba, 141 Xe, 142 Ba, 143 Ba, 144 Ba, 145 Ba, 146 Ba Z=57: 145 La, 147 La Z=58: 144 Ce, 146 Ce Look for the Double octupole bands s=  i in Odd-A nuclei : 143,145 Ba, 145 La (our group)

27. S.J.Zhu et al., Phys. Rev. C60 (1999) 051304.

28. S=+i S=-i S.J.Zhu et al., Phys. Rev. C59 (1999) 1316.

29. s=  1 in even-A nuclei, No identified. S=+1

31. B(E1)/B(E2) s=+1: ~ 0.82  10 -6 fm -2 s=-1: ~ 1.51  10 -6 fm- 2

35. C. 105 Mo: Search for: collective bands:  vibrational- rotational bands one- phonon  vibrational- rotational bands: Mo: 104,106 Mo, 108,110,112 Ru two- phonon  vibrational- rotational bands: 104,106 Mo

36.  -Vibration  -Vibration

37. 1-  2- 

38. In odd-A nuclei, look for 2- two- phonon  vibrational- rotational band is difficult, 105 Mo?

39. 1-  2-  3/2 + [411] 1/2 + [411] 5/2 + [413] 5/2 - [532]

40. 1-  2-  yrast

42. Others: 108,110,112 Ru 1- , 2-  Two-quasiparticle bands Chiral doublet bands?

43. 1-  2- 

44. 1-  2- 

45. 1-  2- 

46. III. SUMMARY We have investigeted: * A=135 region 136,137 La, Yrast band (prolate) and oblate bands. Band crossing and signature inversion. * A=140 region 148 Ce The s=  i double octupole bands. * A=100 region 105 Mo, 108,110,112 Ru One phonon  - band Two phonon  - band