High spin states in 136,137La,

148Ce and 105Mo

High spin states in 136,137La,

148Ce and 105Mo

S. J. Zhu1, Y. J. Chen1, M. L. Li1, H. B. Ding1., J. H.

Hamilton2, A. V. Ramayya2, J. K. Hwang2, X. S. Dong1,

U. Y. Nan1, L. H. Zhu3, S. X. Wen3, X. G. Wu3

1 Department of Physics, Tsinghua University, Beijing 100084,

People’s Republic of China2 Department of Physics, Vanderbilt University, U.S.A3 China Institute of Atomic Energy, Beijing, 102413, People’s

Republic of China

• I. INTRODUCTION• II. EXPERIMETAL METHODS• III. RESULTS AND

DISCUSSION• IV. SUMMARY

I. INTRODUCTION136,137La

148Ce

60 62 64 66 68

105Mo

A. A=135 Region: 136La (Z=57, N= 79) 137La (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

E.S.Paul et al. PRL,58, 984(1987)

The shape driving effect :

B. A=140 neutron-rich Region:

148Ce: Searching for octupole deformation.

C. A=110 neutron-rich Region:

105Mo: odd-A nucleus: Searching for two- ph

onon vibrational- rotation bands.

II. EXPERIMETAL METHODSA. 136La: 130Te(11B, 5n), beam: 60 MeV 137La: 130Te(11B, 4n) , beam: 50 MeV

CIAE

HI-13 tandem accelerator

50106 coincidence events

CIAE In-Beam Gamma-ray detectors

B. 148Ce, 105Mo : measure the prompt -rays from spontaneous fission of 252Cf.

Lawrence Berkeley National Laboratory GAMMASPERE Detector Array

105 Compton-Suppressed Ge Detectors 252Cf Source Total of 5.7×1011 triple- and higher-fold --

coincidence events (in cube) Radware software package to analyze data

III. RESULTS AND DISCUSSION

A. 136La:

E.W.Cybulska et al. Acta Phys. Pol.B32, 929 (1999).

Old: (8+)h11/2h11/2 systematic

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):

22/112/72/11 )()()( hgh

12/11

32/11 )()( hh

↑New!

B. 137La:

MeVc 48.0

Band (1): collective backbending

Proton routhianNeutron routhian

0.48 MeV0.40 MeV

带 ( ３ )——— 扁椭带Band (3): oblate band (~-60)

C. 148Ce:Theoretical prediction:

When N,Z=34, 56, 88, 132, a pair of single particle or

bitals with N=1, l=3, j=3 closes to each other, octu

pole element Y30 is very strong, strong octupole correl

ations occur.

Z=56, N=88, around A=144 neutron-rich region,

octupole deformation discovered.

Using simplex quantum number s to expressFor even A nuclei,S= +1, Ip=0+, 1-, 2+, 3-, 4+, 5-, …..S= -1, Ip=0-, 1+, 2-, 3+, 4-, 5+, …..For odd A nuclei, S= +i, Ip=1/2+, 3/2-, 5/2+, 7/2-, 9/2+, 11/2-, …..S= -1, Ip=1/2-, 3/2+, 5/2-, 7/2+, 9/2-, 11/2 +, …..

Experimental structure:

Two I=2 band structures with

positive and negative parities

respectively.

Strong B(E1) transitions between two opposite parity bands.

Z=56: 140Ba, 141Xe, 142Ba, 143Ba, 144Ba, 145Ba, 146Ba

Z=57: 145La, 147La

Z=58: 144Ce, 146Ce

Look for the Double octupole bands

s= i in Odd-A nuclei :143,145Ba, 145La (our

group)

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

S=+i S=-i

S.J.Zhu et al., Phys. Rev. C59 (1999) 1316.

s= 1 in even-A nuclei, No identified.

S=+1

S=+1

S=+1

B(E1)/B(E2) s=+1: ~ 0.8210-6 fm-2

s=-1: ~ 1.5110-6 fm-2

C. 105Mo:

Search for: collective bands:

vibrational- rotational bands

one- phonon vibrational- rotational bands:

Mo: 104,106Mo, 108,110,112Ru

two- phonon vibrational- rotational bands:

104,106Mo

-Vibration -Vibration

8 6 0 . 4

1 4 +

3 6 8 .6

5 1 9 .4

7 9 9 . 5

6 4 1 . 5

7 3 4 .0

0

1 9 2 .4

5 6 1 .0

1 0 8 0 .4

1 7 2 1 .9

2 4 5 5 . 9

3 2 5 5 . 4

4 1 1 5 .8

0 +

2 +

4 +

6 +

8 +

1 0 +

1 2 +

2 5 9 .7

2 8 9 .56 0 1 .8

6 7 8 .8

4 0 2 .7

5 1 0 . 2

7 6 0 .4

7 8 7 .1

8 1 2 .1

1 0 2 7 .9

1 2 1 4 .8

1 4 7 4 .7

1 7 2 5 .0

2 0 3 6 .7

2 3 2 6 .8

2 6 8 2 .8

3 0 0 5 . 6

3 3 9 6 .5

3 7 6 6 .0

4 1 8 3 . 6

2 +

3 +

4 +

5 +

6 +

7 +

( 8 + )

( 9 + )

( 1 0 + )

( 1 1 + )

( 1 2 + )

( 1 3 + )

1 5 8 3 .4

1 8 2 4 .1

2 0 8 3 .8

2 3 7 3 .3

2 6 8 5 .4

4 +

5 +

6 +

( 7 + )

(8 + )

( 2 )

( 3 )7 1 3 . 7

2 1 5 . 8

2 5 0 . 3

2 5 9 . 9 4 4 6 .8

5 6 2 .05 0 0 .4

6 0 1 .6

5 4 9 .2

2 4 0 .7

M o1 044 2 62

1 8 6 .9

5 0 6 0 .9 ( 1 6 + )

(1 )

9 4 5 . 1

1 9 2 .4

4 6 2 7 .7

8 6 1 .7

(1 4 + )

6 3 7 .7

3 0 1 1 . 0 ( 9 + )

6 4 6 . 1

2 2 3 .0

2 5 2 .6

2 8 9 .3

1 4 3 4 .9

1 6 5 7 .9

1 9 1 0 .5

2 1 9 9 .8

5 4 1 .9

4 7 5 .6

2 5 2 1 .1

2 8 7 7 .5

3 2 6 4 .1

3 6 8 2 .2

4 1 3 2 .7

6 1 0 .6

7 4 3 .0

8 6 8 .6

8 0 4 .7

6 7 7 .7

( 1 1 + )

(3)

3 2 1 .3

4 +

5 +

6 +

7 +

8 +

9 +

1 0 +

( 1 2 + )

7 1 0 .5

8 8 5 .4

1 0 6 8 .0

1 3 0 7 .0

1 5 6 3 .4

1 8 6 8 .4

2 9 5 1 .0

3 3 7 0 .8

3 8 1 2 .0

8 6 1 .0

7 5 6 .5

4 9 5 .4

3 5 7 .5

8 1 1 .4

6 9 1 .0

5 6 1 .4

4 2 1 .6

( 1 1 + )

2 5 6 .4

2 3 9 .0

1 8 2 .6

1 7 4 .9

(2 )

4 2 9 2 .4

4 7 5 7 .9

9 4 5 .9

9 2 1 .6

1 0 3 3 .5

3 3 6 9 .1 1 2 +

1 6 8 8 .4

4 3 6 0 .8

5 2 2 .6

1 7 1 .8

5 1 0 .9

6 5 4 .9

8 9 6 .6

(1 )

5 4 2 5 .0

1 0 6 4 .2

M o1 0 64 2 6 4

0 +

2 +

4 +

3 5 0 .8

6 +

8 +

7 8 4 .1

1 0 +

1 4 +

9 9 1 .7

1 6 +

2 +

3 +

4 +

5 +

6 +

7 +6 3 1 .1

9 +2 5 5 9 .4

1 0 +

( 1 2 + )

( 1 3 + )

(1 4 + )

2 1 9 4 .5

2 4 7 2 .5

8 +

1-1-

2-

2-

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

1-

2- 3/2+[411]

1/2+[411]

5/2+[413] 5/2-[532]

1-1-

1-

2- 2-

2-yrast yrast yrast

Others: 108,110,112Ru

1-, 2-Two-quasiparticle bandsChiral doublet bands?

1-

2-

1-

2-

1-

2-

III. SUMMARY

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