Coulomb excitation of 184,186,188Hgegp-workshop.in2p3.fr/docs/Talks-Vendredi/Bree N....
28
Coulomb excitation of 184,186,188 Hg Nick Bree & Andrew Petts Katholieke Universiteit Leuven & University of Liverpool P.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
Transcript of Coulomb excitation of 184,186,188Hgegp-workshop.in2p3.fr/docs/Talks-Vendredi/Bree N....
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
Content
• Motivation: shape coexistence• Experimental set-up• Shape measurements by Coulomb
excitation• Preliminary experimental results• Conclusion and outlook
Coulex of 184,186,188Hg: Content
Z = 82
Coulex of 184,186,188Hg: Motivation
π
82
2d5/21h11/2
2d3/23s1/2
1g7/2
1h9/2
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
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
Coulex of 184,186,188Hg: Experimental set-up
θP
θD
184Hg projectile
120Sn target
bϑ P
ϑ D
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.
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
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
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+
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+
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
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
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
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
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
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)
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)
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).
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
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
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
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
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
Q>0
Q=0
Q<0
Coulex of 184,186,188Hg: Preliminary experimental results
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)
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)
0+
2+
4+
0
367
1089
375
534653
0+
2+
4+
<18E0+E2
100
100 100
