High Spin Studies of 130Ce

1
High Spin Studies of 130Ce

• Introduction
• Experimental details
• Results
• Discussion

• Masood Akmali

UNIVERSITY OF LIVERPOOL
IoP Nuclear Physics Conference- April 09
2
Introduction

• Light rare earth nuclei A130 normally deformed
  (ß2 0.25 ).
• 130Ce may lay in a ? soft potential. 1
• Multi quasiparticle states may imprint the
  geometry of their orbits onto the nucleus i.e.
  polarising the core.2
• Existence of Superdeformed bands.3

132
131
130
129
Pr
Pr
Pr
Pr
132
131
130
129
Ce
Ce
Ce
Ce
132
131
130
129
La
La
La
La
132
131
130
129
Ba
Ba
Ba
Ba
1Y.S. Chen, et al. Phys. Rev.C 28(1983)
2437. 2 S. Frauendorf and F. R. May, phys.
lett. B (1983) 245. 3 E.S.Paul et al, APH N.S,
Heavy Ion Phys. 6 (1997)281-284
3
Experiment

• 100Mo( 34S,4n) fusion-evaporation reaction,
• A 155-MeV 34S beam and the EUROGAM II
  spectrometer at Strasbourg,
• 30 single 24 Clover detectors total solid angle
  of 40, calculated total peak efficiency of 8.1.
• Total of 8 108 high-fold coincidences
  (?n, n5),

4
Resultsnew parts in red
MN
130Ce
GSB
New bands
FJ
?
1a1b
2a2b
SD1
P
Q

• E.S.Paul et al, APH N.S, Heavy Ion Phys. 6
  (1997)281-284
• D.M.Todd et al. J. Phys. G Phys.10(1984)
  1470-1433

SD1
5
1
2
Spectrums of Gamma-rays in coincidence with 1)
204 and 232, 2) 328 and 255 kev transitions to
illustrate the newly found coupled bands.
6
Results
Experimental Alignment Plots
New bands Alignments 8 - 10 h
Harris parameters I032 MeV-1h2 I134 MeV-3h4
7
Results Continued....
Experimental Single-Particle Routhian Plots
New bands No crossings, Very little signature
splitting
8
Interpretation
GSB Alignment ( 8.8 h), crossing at h? 0.3
MeV. h11/2 protons
FJ Initial alignment 5 h, 2 qp states
excited h11/2 protons crossing at h? 0.45
MeV, alignment 5 h 4 qp states
NM Initial alignment 3 h, 2 qp states
h11/2 neutrons crossing at h? 0.318 MeV
alignment 8 h. 4 qp states
12 Initial alignment 8 h, no crossings 4qp
states i.e the sum of F,J,N,M ( 3NM 5FJ 8
) h11/2 protons and neutrons
9
Cranked Shell Model Calculation
Deformation ß 0.25
Neutrons
Protons
A
B
a
b
f
F
e
E
Lowest levels (E,F) h11/2 5413/2 ve
parity (A,B) g7/24135/2 ve parity
Lowest levels (e,f) h11/2 5237/2 ve
parity (a,b) g7/24047/2 ve parity
New bands protons EA coupled to neutrons ea and
eb protons EB coupled to neutrons ea and eb
10
Summary

• Through quadruples analysis (?4) of the data
  several bands have been identi?ed for the ?rst
  time and the previously reported structures have
• been extended to high spin.
• After preliminary analysis of the data possible
  candidate band con?guration assignments for such
  new structures have been made including 4
  quasiparticle con?gurations.
• The band structures observed in 130Ce can be
  interpreted through comparison with Woods-Saxon
  CSM calculations.
• Further work is needed on the remaining data

11
Collaborators

• M.Akmali1, E.S.Paul1, P.J. Nolan1, A.T. Semple1,
  A.J. Boston1, D.T. Joss1, S.L. Shepherd1, I.M.
  Hibbert2, N.J. OBrien2, C.M. Parry2 and R.
  Wadsworth2
• 1Oliver Lodge Laboratory, University of
  Liverpool, Liverpool L69 7ZE
• 2 University of York, Heslington, York Y01 5DD

Thank You