Electromagnetic moments for isomeric states in nuclei far from stability in nuclei far from...
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Transcript of Electromagnetic moments for isomeric states in nuclei far from stability in nuclei far from...
Electromagnetic moments for isomeric statesElectromagnetic moments for isomeric states
in nuclei far from stabilityin nuclei far from stability
NIPNE Bucharest ↔ INFN LNL Legnaro
10 experiments @XTU - Tandem Legnaro
Detailed studies of isomeric states [ns - µs]Detailed studies of isomeric states [ns - µs]
→ lifetimes and decay schemes
→ g-factors
→ spectroscopic quadrupole moments
• NIPNE – BucharestNIPNE – Bucharest new isomers, g, Qnew isomers, g, Qss nuclei near stabilitynuclei near stability
• INFN INFN LNL XTU – Tandem accelerator XTU – Tandem accelerator
Heavy ions pulsed beams T=2 ns Trep= 200 ns ÷ 6.4 µs
GAMIPE beam line
g factors Hext L = g N Hext /h Cubic crystalline lattice
Qs EElectric FField GGradients Noncubic crystalline lattice
Q = QsVzz / 4I(2I-1)h Vzz EFG EFG (Probe Host) calibrated
Nuclear moment measurementsNuclear moment measurements
Dedicated experiments - Hyperfine interactions Dedicated experiments - Hyperfine interactions
TDPADTDPAD TTime ime DDifferential ifferential PPerturbed erturbed AAngular ngular DDistribution Method istribution Method
• A~130A~130 shape evolutionshape evolution
136Pr 6+ T1/2 g Nucl. Phys. A 603, 50 (1996)
129,131Ce 9/2- g Qs Nucl. Phys. A 633, 459 (1998)
130Ce 7- Qs Phys. Rev. C 60, 024316 (1999)
• A~180 K isomersA~180 K isomers
175W 7/2- g Phys. Lett. B 495, 289 (2000) 176W 14+ T1/2 g Qs Phys. Lett. B 541, 219 (2002)
• Shape coexistence Pb Shape coexistence Pb
191Pb 29/229/2-- 33/2+ T1/2 AIP Conf. Proc. 831, 278 (2006)
193Pb 29/229/2-- 21/2- 33/2+ T1/2 g Qs Eur. Phys. J. A 20, 191 (2004)
Phys. Rev. C 70, 034305 (2004)
192,194Pb 8+ 11- 12+ T1/2 Qs Acta Phys.Pol.B38,1249 (2007)
Phys. Lett. B 2007 in press
188Pb 11- 12+ g LNL Ann. Rep. 2006, p. 33
LNL LNL 164164Dy(Dy(1616O,4n)O,4n)176176W W 83 MeV
T=2 ns Trep=800 ns
176176W 14W 14++ isomer isomer
T 1/2 = 35(10) ns
B. Crowell et al., PRL 72, 1164 (1994)
High K states E transitions
ν = ΔK – λ degree of K-forbiddenness
fν = (T1/2γ /T1/2
W) 1/ν usually fν~100
fν → 2.3 (917 keV) 3.6 (945 keV)
g factor M. Ionescu-Bujor et al., Phys. Lett. B 495, 289 (2000)
Qs M. Ionescu-Bujor et al., Phys. Lett. B 541, 219 (2002)
gR (14+) =
0.269(34)
MI Pb host Hext = 27.5 kG QI Tl host
gexp (14+, 176W) = +0.462 (11)
gcalc (14+) = +0.475 (15)
|Qs | (14+, 176W) = 6.0 (7) eb
Qo = 7.4 (9) eb
14+ 7/2+ [404] 9/2- [514]
5/2- [512] 7/2+ [633]
2 (14+) = 0.29(4)
Shape coexistence in Pb isotopesShape coexistence in Pb isotopes Shape coexistence in Pb isotopesShape coexistence in Pb isotopes
188Pb 190Pb
192Pb 194Pb
D. Karlgren et al., PRC 73, 064304 (2006)
Potential energy surfaces Z=82
0p-0h•
• ••
• •
•
•
Isomers ns - µs
12+12+ (1i13/22)
1111–– (3s1/2-21i13/21h9/2)
88–– (1i13/2 1h9/2
-1)
2p-2h
4p-4h
•
Static moments Qs
M. Ionescu-Bujor et al., Phys. Lett. B (2007) in press
168Er (28Si, 4n) 192Pb 143 MeV pulsed T = 2 ns Trep= 3.2 s
11– (3s1/2-21i13/21h9/2) 9–– (2f5/21i13/2)
8+ (3s1/2-2 1h9/2
2) 6+ admixture intruder
9–– (2f5/21i13/2) 7– (3s1/21i13/2)
192,194Pb TDPAD QI Bi crystalline lattice
|Qs| → 0.32 (4) eb 0.48 (3) eb
Vzz(PbBi)= 1.39(10) 1021 V/m2
|Qs| → 2.9 (3) eb 3.6(4) eb
1111––
1212++
M. Ionescu-Bujor et al., Phys. Lett. B (2007), doi: 10.1016/j.physlettb.2007.05.002
QQoo ( (1111––,, 192192Pb) Pb) shape mixingshape mixing
1111––
12+ (1i13/2
-2) 2 + 0.02
11– (1i13/21h9/2) 2 –0.12
PQPQ Pairing + quadrupole model
PQ TACPQ TAC Magnetic rotation
S. Frauendorf, NPA 677, 115 (2000)
HFBHFB N.Smirnova et al., PLB 569, 151 (2003)
IBMIBM
V. Hellemans , PRC 71, 034308 (2005)
188188Pb Pb triple shape coexistencetriple shape coexistence 188188Pb Pb triple shape coexistencetriple shape coexistence
12+ spherical (1i13/2)2 11– oblate (1i13/2 1h9/2) 8– prolate ( 1i13/2 1h9/2-1)
LNL XTU Tandem LNL XTU Tandem TDPAD experiments in progress TDPAD experiments in progress
g factors 12+ 11-
M. Ionescu-Bujor et al., LNL Ann. Rep. 2006, INFN-LNL-217(2007), p. 33
G.D.Dracoulis et al. , PRC 67, 051301(R) (2003
NIPNE Bucharest:NIPNE Bucharest: M. Ionescu-Bujor, A. Iordachescu, D. Bucurescu,
N. Marginean, C.A. Ur, G. Suliman, C. Rusu
Collaborations:Collaborations: INFN Padova, INFN Legnaro, Bonn, Leuven,
Sao Paolo, Sofia, Surrey