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