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Coulomb excitation of 184,186,188HgNick Bree & Andrew Petts
Katholieke Universiteit Leuven & University of LiverpoolP.A. Butler, J. Cederkäll, E. Clement, T.E. Cocolios, L. Fraile, T. Grahn, M. Guttormsen, K. Hadynska, R.-D.
Herzberg, M. Huyse, D.G. Jenkins, R. Julin, S. Knapen, Th. Kroell, R. Krücken, A.C. Larsen, P. Marley, P.J.
Napiorkowski, J. Pakarinen, N. Patronis, P.J. Peura, E. Piselli, M. Scheck, S. Siem, I. Stefanescu, J. Van de
Walle, P. Van Duppen, D. Voulot, F. Wenander and M. Zielinska
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Content
• Motivation: shape coexistence• Experimental set-up• Shape measurements by Coulomb
excitation• Preliminary experimental results• Conclusion and outlook
Coulex of 184,186,188Hg: Content
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Z = 82
Coulex of 184,186,188Hg: Motivation
π
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
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Coulex of 184,186,188Hg: Motivation
184HgN=104
0+
2+
4+
0+
2+4+
0
367
1089
375
534653
0+
2+
4+
0
405
1080
523621808
0+2+4+
0+
2+
4+
0+2+
4+
0
413
1005
824881
1208
186HgN=106
188HgN=108
MID SHELL
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Coulex of 184,186,188Hg: Motivation
π=80
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν=104
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
E*intruder(4p-6h)=4(εjπ-εj’π) - ΔEππpair + ΔEπνM – ΔEπνQ
K. Heyde et al, Nucl. Phys. A 466, 189 (1987)
4(εjπ-εj’π)
ΔEπνQ~NπNν
2(εjπ-εj’π)
ΔEπνQ~NπNν
ΔEpairing
ΔEpairing
g.s. g.s.
Hg,Pb Pt,Po,Rn,Ra
184Hg
Slightly oblate ground state bandProlate band SHAPE COEXISTENCE
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Coulex of 184,186,188Hg: Experimental set-up
θP
θD
184Hg projectile
120Sn target
bϑ P
ϑ D
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Coulex of 184,186,188Hg: Experimental set-up
Isotope Charge state
Intensity@Miniball
184Hg 43+ 1000 pps
186Hg 43+ 2.0 x 105 pps
188Hg 44+ 2.5 x 105 pps
All 3 isotopes were post-accelerated by REX to 2.85 MeV/u.
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Miniball
• Doppler shift in the gamma energy!
Coulex of 184,186,188Hg: Experimental set-up
θP
EP
ED
CD-detector
184Hg 2,85 MeV/u target 120Sn
2.3 mg/cm2
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Coulex of 184,186,188Hg: Shape measurements
0+
2+
+ + σ⎛ ⎞→ ⎜ ⎟Ω⎝ ⎠CEdB(E2 : 0 2 )
d
The cross section for exciting 184Hg to its 2+ state does not only depend on its reduced transition probability B(E2: 0+ -> 2+), but also on the diagonal matrix element <2+||M(E2)||2+>.
B(E2) = 19500±4500 e2fm4
N. Rud et al, PRL 31, 1421, 1973+ life time measurements
Since the B(E2) value is known, the sign and magnitude of the quadrupole moment of the 2+ state can be measured by calculating the excitation cross section out of the intensity ofthe detected γ photo peak of the 2+->0+ transition.
184Hg120Sn
184Hg
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Coulex of 184,186,188Hg: Preliminary experimental results
In August 2007 a Coulomb excitation experiment was performed on the neutron deficient 184,186,188Hg isotopes.
non Doppler corrected γ spectrumDoppler corrected γ spectrum
0+
2+
4+
0
367
1089
375
534653
0+
2+4+
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Coulex of 184,186,188Hg: Preliminary experimental results
In August 2007 a Coulomb excitation experiment was performed on the neutron deficient 184,186,188Hg isotopes.
non Doppler corrected γ spectrumDoppler corrected γ spectrum
0+
2+
4+
0
367
1089
375
534653
0+
2+4+
![Page 12: Coulomb excitation of 184,186,188Hgegp-workshop.in2p3.fr/docs/Talks-Vendredi/Bree N. Gammapool.pdf · Hg,Pb Pt,Po,Rn,Ra 184Hg Slightly oblate ground state band Prolate band SHAPE](https://reader034.vdocuments.net/reader034/viewer/2022042317/5f06bb6b7e708231d41974c9/html5/thumbnails/12.jpg)
Coulex of 184,186,188Hg: Preliminary experimental results
In August 2007 a Coulomb excitation experiment was performed on the neutron deficient 184,186,188Hg isotopes.
Doppler corrected γ spectrum
0+
2+
4+
0
405
1080
523621808
0+2+
4+
403
![Page 13: Coulomb excitation of 184,186,188Hgegp-workshop.in2p3.fr/docs/Talks-Vendredi/Bree N. Gammapool.pdf · Hg,Pb Pt,Po,Rn,Ra 184Hg Slightly oblate ground state band Prolate band SHAPE](https://reader034.vdocuments.net/reader034/viewer/2022042317/5f06bb6b7e708231d41974c9/html5/thumbnails/13.jpg)
Coulex of 184,186,188Hg: Preliminary experimental results
In August 2007 a Coulomb excitation experiment was performed on the neutron deficient 184,186,188Hg isotopes.
Doppler corrected γ spectrum
0+
2+
4+
0+2+
4+
0
413
1005
824881
1208
![Page 14: Coulomb excitation of 184,186,188Hgegp-workshop.in2p3.fr/docs/Talks-Vendredi/Bree N. Gammapool.pdf · Hg,Pb Pt,Po,Rn,Ra 184Hg Slightly oblate ground state band Prolate band SHAPE](https://reader034.vdocuments.net/reader034/viewer/2022042317/5f06bb6b7e708231d41974c9/html5/thumbnails/14.jpg)
Coulex of 184,186,188Hg: Preliminary experimental results
Example: determination of the <2+||M(E2)||2+> matrix element in 186Hg.
0,8
1
1,2
1,4
1,6
1,8
2
-2 -1 0 1 2 3
<2+1||E2||2+
1> [eb]
<0+ g.
s.||E
2||2+ 1>
[eb]
PRELIMINARY186Hg on 107Ag1σ confidence levelno multiple Coulex
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Coulex of 184,186,188Hg: Preliminary experimental results
Example: determination of the <2+||M(E2)||2+> matrix element in 186Hg.
0,8
1
1,2
1,4
1,6
1,8
2
-2 -1 0 1 2 3
<2+1||E2||2+
1> [eb]
<0+ g.
s.||E
2||2+ 1>
[eb]
PRELIMINARY186Hg on 107Ag1σ confidence levelno multiple Coulex
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Coulex of 184,186,188Hg: Preliminary experimental results
Example: determination of the <2+||M(E2)||2+> matrix element in 186Hg.
0,8
1
1,2
1,4
1,6
1,8
2
-2 -1 0 1 2 3
<2+1||E2||2+
1> [eb]
<0+ g.
s.||E
2||2+ 1>
[eb]
PRELIMINARY186Hg on 107Ag1σ confidence levelno multiple Coulex
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Coulex of 184,186,188Hg: Preliminary experimental results
Example: determination of the <2+||M(E2)||2+> matrix element in 186Hg.
0,8
1
1,2
1,4
1,6
1,8
2
-2 -1 0 1 2 3
<2+1||E2||2+
1> [eb]
<0+ g.
s.||E
2||2+ 1>
[eb]
Lifetime measurementD. Proetel et al., Phys. Lett. 48B, 102 (1974)
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Coulex of 184,186,188Hg: Conclusion and outlook
Conclusions:
The heavy 184,186,188Hg were successfully produced and post-accelerated by REX-ISOLDE.
Apart from the first 2+ state, also other states have been populated.
The detected γ yields of the photo peaks can be used to extract:
• transitional matrix elements (B(E2) values)• diagonal matrix elements (quadrupole moments)
This is done by the program GOSIA by fitting the matrix elements to produce the obtained γ yields by a χ2
minimization. (T. Czosnyka et al, GOSIA2)
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Coulex of 184,186,188Hg: Conclusion and outlook
Outlook:
A proposal for a Coulomb excitation experiment on 180,182Hg at REX-ISOLDE has been accepted.
A proposal for lifetime measurements in 184,186,188Hg at Argonne National Laboratory has been submitted.
Other experiments aiming at studying this heavy mass region have been proposed (Ra and Rn).
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Coulex of 68Ni: Challenges and analysis improvements
π
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
π
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
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Me a
n S
quar
e C
harg
e ra
dii <
r2 >
• Influence of intruder states on the <r2> values in Pt and Hg isotopes• Evidence for a deviation of the <r2> values from the DM in Pb’s around 190-194Pb
0
500
1000
1500
2000
2500
3000
0+
2+
4+
6+
174 178 182 186 190 194Mass Number
E*[keV]
Hg (Z=80)
0p-2h
2p-4h
100 105 110 115 120 125 130
=0.1 fm2
Pb
Hg
Pt
N=104 N=126
Neutron Number
Pb 0+ & l.s.Pb 13/2+
Hg 0+ & l.s.Hg h.s.Pt g.s.Pt isomer
DM
0p-4h2p-6h
Mass Number
0+2+
4+
6+
8+
176 180 184 188 192 196
E*[keV] Pt (Z=78)
N=104
190Pb
oexistence and <r2> in the Lea
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Coulex of 184,186,188Hg: Motivation
π=80
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν=106
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
0+2+
4+186Hg
0+
2+
4+
0
405
1080
523621808
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Coulex of 184,186,188Hg: Motivation
π=80
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν=108
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
188Hg
0+
2+
4+
0+2+
4+
0
413
1005
824881
1208
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Coulex of 184,186,188Hg: Preliminary experimental results
In August 2007 a Coulomb excitation experiment was performed on the neutron deficient 184,186,188Hg isotopes.
Doppler corrected γ spectrum
0+
2+
4+
0+2+
4+
0
413
1005
824881
1208Q>0
Q=0
Q<0
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Q>0
Q=0
Q<0
Coulex of 184,186,188Hg: Preliminary experimental results
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Coulex of 184,186,188Hg: Motivation
π=80
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν=104
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
184Hg
0+0
2+
4+
367
1089
6+1549
8+2057
shell model: π0p2h states
mean-field approximation:
slightly oblateJ.L.Wood et al, Phys, Rep., 215, 3&4 (1992)
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Coulex of 184,186,188Hg: Motivation
π=80
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
ν=104
126
2f7/21i13/2
3p3/22f5/2
1h9/2
3p1/2
2g9/2
184Hg
0+0
2+
4+
367
1089
6+1549
8+2057
shell model: π4p6h states
mean-field approximation:
stronger prolatedeformation
0+375
2+4+
534653
6+994
8+1412
10+1901
J.L.Wood et al, Phys, Rep., 215, 3&4 (1992)
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0+
2+
4+
0
367
1089
375
534653
0+
2+
4+
<18E0+E2
100
100 100