Post on 14-Jun-2020
Physics background Update on the analysis method Proposed experiment
Measurements of competing structures inneutron-deficient Pb isotopes by employing
Coulomb excitation
Spokespersons:Tuomas Grahn
Janne Pakarinen
University of Liverpool, UK&
Collaborators
INTC meetingFebryary 16, 2009
T. Grahn (University of Liverpool) Pb CoulEx INTC 1 / 18
Physics background Update on the analysis method Proposed experiment
Outline
1 Physics background
2 Update on the analysis method
3 Proposed experiment
T. Grahn (University of Liverpool) Pb CoulEx INTC 2 / 18
Physics background Update on the analysis method Proposed experiment
Chart of nuclides in the vicinity of light Pb nuclei
Hg 184
104
83
84
82
81
80
Bi 187 Bi 188 Bi 189 Bi 190 Bi 191
Pb 189Pb 188Pb 187Pb 186Pb 185Pb 184
Bi 185
Pb 183Pb 182Pb 181Pb 180
Tl 179 Tl 180 Tl 181 Tl 182 Tl 183 Tl 184 Tl 185 Tl 186
Hg 185Hg 183Hg 182Hg 181Hg 180Hg 179Hg 178Hg 177Hg 176Hg 175Hg 174
Bi 186
Po 190 Po 191 Po 192
decay decay
Alpha
decay
Beta + Proton
Tl 178Tl 177
Pb 178 Pb 179
Tl 176
Hg 173Hg 172Hg 171
Bi 184
Po 189Po 188
Pb 190
Po 193 Po 194
Pb 192 Pb 193 Pb 194Pb 191
Bi 192 Bi 193 Bi 194 Bi 195 Bi 196
Tl 188 Tl 189 Tl 190 Tl 191 Tl 192
Po 195 Po 196 Po 197 Po 198
Hg 186 Hg 187 Hg 188 Hg 189 Hg 190
Tl 187
Nucleus
interestof
Unique laboratory to study shape-coexistence phenomena
Many spectroscopic techniques to investigate these isotopes(β and α decay, in-beam γ-ray, isomer, trap-assisted spectroscopy etc.)
T. Grahn (University of Liverpool) Pb CoulEx INTC 3 / 18
Physics background Update on the analysis method Proposed experiment
Level energy systematics for Pb isotopes
T. Grahn (University of Liverpool) Pb CoulEx INTC 4 / 18
Physics background Update on the analysis method Proposed experiment
Triple shape coexistence in neutron-deficient Pb isotopes
See e.g. J.L. Wood et al., Phys. Rep. 215, 101 (1992).
T. Grahn (University of Liverpool) Pb CoulEx INTC 5 / 18
Physics background Update on the analysis method Proposed experiment
Triple-shape coexistence in 186Pb (in-beam and decayspectroscopy)
A.N. Andreyev et al., Nature 405, 430 (2000).
J. Pakarinen et al., Phys. Rev. C 75, 014302 (2007).T. Grahn (University of Liverpool) Pb CoulEx INTC 6 / 18
Physics background Update on the analysis method Proposed experiment
Mean square charge radii of neutron-deficient Pb isotopes
H. De Witte et al., Phys. Rev. Lett. 98, 112502 (2007).
T. Grahn (University of Liverpool) Pb CoulEx INTC 7 / 18
Physics background Update on the analysis method Proposed experiment
Transition quadrupole moments for yrast states in 186,188Pb
T. Grahn et al., Phys. Rev. Lett. 97, 062501 (2006).
T. Grahn (University of Liverpool) Pb CoulEx INTC 8 / 18
Physics background Update on the analysis method Proposed experiment
Theoretical studies of neutron-deficient Pb nuclei
Recent studies using IBM and self-consistent mean-field approaches. B(E2)values for the 2+ → 0+ transition in 188Pb.
V. Hellemans et al.,Phys. Rev. C 77,064324 (2008).
M. Bender et al.,Phys. Rev. C, 69,064303 (2004)
R.R.Rodríguez-Guzmánet al., Phys. Rev. C,69, 054319 (2004)
T. Grahn (University of Liverpool) Pb CoulEx INTC 9 / 18
Physics background Update on the analysis method Proposed experiment
Open questions related to neutron-deficient Pb isotopes
Confirmation of three different shapes in the same nucleus
Systematic behaviour of mixing between different shape coexistingstructures
Is the collectivity of the prolate yrast bands in Pb nuclei higher than thatof the identical prolate bands in Hg and Pt nuclei?
What is the validity of different models?
T. Grahn (University of Liverpool) Pb CoulEx INTC 10 / 18
Physics background Update on the analysis method Proposed experiment
Open questions related to neutron-deficient Pb isotopes
Confirmation of three different shapes in the same nucleus
Systematic behaviour of mixing between different shape coexistingstructures
Is the collectivity of the prolate yrast bands in Pb nuclei higher than thatof the identical prolate bands in Hg and Pt nuclei?
What is the validity of different models?
T. Grahn (University of Liverpool) Pb CoulEx INTC 10 / 18
Physics background Update on the analysis method Proposed experiment
Open questions related to neutron-deficient Pb isotopes
Confirmation of three different shapes in the same nucleus
Systematic behaviour of mixing between different shape coexistingstructures
Is the collectivity of the prolate yrast bands in Pb nuclei higher than thatof the identical prolate bands in Hg and Pt nuclei?
What is the validity of different models?
T. Grahn (University of Liverpool) Pb CoulEx INTC 10 / 18
Physics background Update on the analysis method Proposed experiment
Open questions related to neutron-deficient Pb isotopes
Confirmation of three different shapes in the same nucleus
Systematic behaviour of mixing between different shape coexistingstructures
Is the collectivity of the prolate yrast bands in Pb nuclei higher than thatof the identical prolate bands in Hg and Pt nuclei?
What is the validity of different models?
T. Grahn (University of Liverpool) Pb CoulEx INTC 10 / 18
Physics background Update on the analysis method Proposed experiment
Outline
1 Physics background
2 Update on the analysis method
3 Proposed experiment
T. Grahn (University of Liverpool) Pb CoulEx INTC 11 / 18
Physics background Update on the analysis method Proposed experiment
Analysis - what is learnt from the Hg experiments IS452
Energy (keV)0
2 0
4 2
2 0 2
0
Cd
Hg
X−
rays
200 400 600 800 1000
Co
un
ts
0
100
200
300
400
500
600
700+
+ 1g
.s.
++ 1
1
++ 2
g.s
.
++ 1
g.s
.
11
2
Doppler-corrected γ-ray spectrum of 182Hg (IS452).
−3 −2.5 −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3
<2+||E2||2
+> [eb]
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
<0+
||E2
||2+>
[eb
]
Low COM Angular Range
Med COM Angular Range
High COM Angular Range
186Hg on
107Ag
0.0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
(0+
2+1)
[b]
0 20 40 60 80 100 120 140 160 180
COM [o]
< 2+
1 |E2 | 2+
1 > = 1 eb< 2
+1 |E2 | 2
+1 > = 0 eb
< 2+
1 |E2 | 2+
1 > = -1 eb
Extraction of the matrix elements
from the measured σCE .
Nuclear reorientation effect:σCE(Ji → Jf ) ∝ |〈Jf | ˆO(E2)|Ji〉|2 · [1 − 〈Jf | ˆO(E2)|Jf 〉 · f (ζ)]
T. Grahn (University of Liverpool) Pb CoulEx INTC 12 / 18
Physics background Update on the analysis method Proposed experiment
Analysis - what is learnt from the Hg experiments IS452
T. Grahn (University of Liverpool) Pb CoulEx INTC 13 / 18
Physics background Update on the analysis method Proposed experiment
Outline
1 Physics background
2 Update on the analysis method
3 Proposed experiment
T. Grahn (University of Liverpool) Pb CoulEx INTC 14 / 18
Physics background Update on the analysis method Proposed experiment
Experimental details
Proposed measurement can only be carried out at REX-ISOLDE
RILIS + REX-EBIS + REX-ISOLDE + MINIBALL
Recent purity test of Pb beams reported the the purity of at least 80% for190,192Pb. Contaminants in 188Pb beam do not pose a problem (seeproposal)
Counts obtained in requested beam time for the 2+1 → 0+
g.s. transition
Nucleus ISOLDE Beam intensity on 〈0|| ˆO(E2)||2〉 (eb) γ-ray yieldyield (µC−1) MINIBALL target (pps)
188Pb 1.7 × 106 1.7 × 104 0.475 2200190Pb 2.3 × 107 2.3 × 105 0.475 7400192Pb 4.0 × 107 4.0 × 105 0.475 10700
T. Grahn (University of Liverpool) Pb CoulEx INTC 15 / 18
Physics background Update on the analysis method Proposed experiment
Experimental details
Proposed measurement can only be carried out at REX-ISOLDE
RILIS + REX-EBIS + REX-ISOLDE + MINIBALL
Recent purity test of Pb beams reported the the purity of at least 80% for190,192Pb. Contaminants in 188Pb beam do not pose a problem (seeproposal)
Counts obtained in requested beam time for the 2+1 → 0+
g.s. transition
Nucleus ISOLDE Beam intensity on 〈0|| ˆO(E2)||2〉 (eb) γ-ray yieldyield (µC−1) MINIBALL target (pps)
188Pb 1.7 × 106 1.7 × 104 0.475 2200190Pb 2.3 × 107 2.3 × 105 0.475 7400192Pb 4.0 × 107 4.0 × 105 0.475 10700
T. Grahn (University of Liverpool) Pb CoulEx INTC 15 / 18
Physics background Update on the analysis method Proposed experiment
Experimental details
Proposed measurement can only be carried out at REX-ISOLDE
RILIS + REX-EBIS + REX-ISOLDE + MINIBALL
Recent purity test of Pb beams reported the the purity of at least 80% for190,192Pb. Contaminants in 188Pb beam do not pose a problem (seeproposal)
Counts obtained in requested beam time for the 2+1 → 0+
g.s. transition
Nucleus ISOLDE Beam intensity on 〈0|| ˆO(E2)||2〉 (eb) γ-ray yieldyield (µC−1) MINIBALL target (pps)
188Pb 1.7 × 106 1.7 × 104 0.475 2200190Pb 2.3 × 107 2.3 × 105 0.475 7400192Pb 4.0 × 107 4.0 × 105 0.475 10700
T. Grahn (University of Liverpool) Pb CoulEx INTC 15 / 18
Physics background Update on the analysis method Proposed experiment
Experimental details
Proposed measurement can only be carried out at REX-ISOLDE
RILIS + REX-EBIS + REX-ISOLDE + MINIBALL
Recent purity test of Pb beams reported the the purity of at least 80% for190,192Pb. Contaminants in 188Pb beam do not pose a problem (seeproposal)
Counts obtained in requested beam time for the 2+1 → 0+
g.s. transition
Nucleus ISOLDE Beam intensity on 〈0|| ˆO(E2)||2〉 (eb) γ-ray yieldyield (µC−1) MINIBALL target (pps)
188Pb 1.7 × 106 1.7 × 104 0.475 2200190Pb 2.3 × 107 2.3 × 105 0.475 7400192Pb 4.0 × 107 4.0 × 105 0.475 10700
T. Grahn (University of Liverpool) Pb CoulEx INTC 15 / 18
Physics background Update on the analysis method Proposed experiment
Aims of the proposed experiment
Determine the sign of thespectroscopic quadrupolemoment of the 2+
1 states in188,190,192Pb
Probe the collectivity oflow-lying states in188,190,192Pb isotopes(spherical/oblate)
Study the mixing of the 2+
states as a function of N
0 0
2 724
4 10642 953
4 1315
0 588
724
340
953
362592
251
5−12 ps
15.9(10) ps
188Pb
T. Grahn (University of Liverpool) Pb CoulEx INTC 16 / 18
Physics background Update on the analysis method Proposed experiment
Aims of the proposed experiment
Determine the sign of thespectroscopic quadrupolemoment of the 2+
1 states in188,190,192Pb
Probe the collectivity oflow-lying states in188,190,192Pb isotopes(spherical/oblate)
Study the mixing of the 2+
states as a function of N
2 774
0 0
4 1229
0 658
2 1163
0 0
2 854
4 1356
0 768
2 1238
455
774
389
1163
854
502
1238
384 469
190 192Pb Pb
T. Grahn (University of Liverpool) Pb CoulEx INTC 16 / 18
Physics background Update on the analysis method Proposed experiment
Aims of the proposed experiment
Determine the sign of thespectroscopic quadrupolemoment of the 2+
1 states in188,190,192Pb
Probe the collectivity oflow-lying states in188,190,192Pb isotopes(spherical/oblate)
Study the mixing of the 2+
states as a function of N
T. Grahn (University of Liverpool) Pb CoulEx INTC 16 / 18
Physics background Update on the analysis method Proposed experiment
Requested beamtime
3 shifts are requested for setting up the REX facility
12 shifts for the γ-ray yield measurement of 188Pb (9 laser on + 3 laseroff)
For the measurements of 190,192Pb, 3 shifts for each nucleus are required
21 shifts are requested in TOTAL
T. Grahn (University of Liverpool) Pb CoulEx INTC 17 / 18
Physics background Update on the analysis method Proposed experiment
Collaboration
CERN-ISOLDE (J. Cederkäll, P. Delahaye, J. Van de Walle, F. Wenander)STFC Daresbury Laboratory (D. O’Donnell, J. Simpson)University of Edinburgh (T. Davinson, P. Woods)GANIL (E. Clément)University of Göttingen (K.-P. Lieb)University of Jyväskylä (P.T. Greenlees, R. Julin, S. Juutinen, P. Peura, P. Rahkila)KU Leuven (A.N. Andreyev, B. Bastin, N. Bree, J. Diriken, M. Huyse, P. Van Duppen)University of Liverpool (P.A. Butler, T. Grahn, L.P. Gaffney, T. Grahn,R.-D. Herzberg, J. Pakarinen, R.D.Page, A. Petts, M. Scheck)University of Lund (A. Ekström, C. Fahlander)LMU München (L, Csige, D. Habs, P.G. Thirolf)TU München (V. Bildstein, R. Gernhäuser, Th. Kröll, R. Krücken, K. Wimmer)University of Oslo (A. B’urger, M. Guttormsen, A.C. Larsen, H.T. Nyhus, S. Siem, N.U.H. Syed, H. Toft)CEA-Saclay (A. Görgen, W. Korten, J. Ljungvall, A. Obertelli, B. Sulignano, Ch. Theisen)University of Sofia (G. Rainovski)HIL University of Warsaw (K. Hadynska, J. Iwanicki, P. Napiorkowski, J. Srebrny, K. Wrzosek-Lipska,M. Zielinska)University of York (C. Barton, M. Bentley, D.G. Jenkins, B.S. Nara Singh, A.P. Robinson, R. Wadsworth)
T. Grahn (University of Liverpool) Pb CoulEx INTC 18 / 18