Date post: | 19-Dec-2015 |
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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
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
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
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
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
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)
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
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-
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