Structure close to 208Pb

Zsolt Podolyák

The fragment separator

Time from production to spectroscopic analysis: ~ 300 ns

fragmentationor fission

Decay studies:

-internal (isomers)

-beta decay

Very sensitive method

370 implanted 212Pb ions!

M. Pfützner et al., Phys. Lett. B 444 (1998) 32.

Exp. (test) #2: 238U beam

208Hg, 209Tl

Experiment #1

208Pb beam

‘passive stopper’ experiments

Spokesperson: #1,2 Zs. Podolyák, #3 J.J. Valiente-Dobon, G. Benzoni

Analysis by S. Steer (N<=126), N. Al-Dahan (N>126), T.Swan (σ)

Exp. #3: 238U beam

190,192Ta

198,202Ir

203,205,(206)Au

194,196,198Re200Os

Spokespersons: P.H. Regan & J. Benlliure

Analysis by N. Alkhomashi, N. Al-Dahan, G. Farrelly, A.I. Morales et al.,

‘active stopper’ experiments208Pb beam

N=126 nuclei below 208Pb (what was known)

Z=81 Z=80 Z=79 Z=78

206H

g: B

.For

nal e

t al.

Phy

s. R

ev. L

ett.

87(2

001)

212

501.

207T

l: D

. Ecc

lesh

all,

M. J

. L. Y

ates

, Phy

s. L

ett.

19, 3

01 (

1965

).

+

Particle identification

GSI

204Pt 205Au

203Ir

205Au: three proton-hole nucleus

Charged particles

Gammas

Active stopper exp.

Zs. Podolyák et al., Phys. Lett. B 672 (2009) 116.

Shell-model calculations (M.Górska, H.Grawe, H. Maier, A.Brown)

(a)and (d):TBME from L.Rydstrom et al, NPA512(1990)217 (based on Kuo-Brown interaction)

(b) and (c): three TBMEs modified

Δ(d3/2 h11/2; d3/2 h11/2)7- = +135 keV

Δ(s1/2 d5/2; s1/2 d5/2)2+,3+ =+230 keV (monopole only)

Δ(d3/2 h11/2; s1/2 h11/2)6- changed to +0.160 MeV (fit for B(E2)

Good description of energies and B(EL)s

S.Steer et al., Phys. Rev C78 (2008) 061302(R)

πh11/2-2 s1/2

-1

205Au

πh11/2-1 s1/2

-2

πd3/2-1 s1/2

-2

B(E2): 3.1 1.2(2) 1.7 W.u.

Orig. SM Mod. SM

Calc. H. Grawe

203Ir

Orig. SM Mod. SM

Future: further ‘down’ along the N=126 line (acc. exp.)205Au: beta decay from 205Pt => will fix the πs1/2 orbital203Ir: beta decay from 203Os (νg9/2) => will fix the πd3/2,πs1/2,πh11/2 202Os: isomeric decay I=(5),(7),(10)202Os: beta decay of 203Ir (νg9/2)

0+ 0

2+ 1181

4+ 1555

7- 1893

5- 1932

10+ 26738- 2558

8+ 2685

202Os

shel

l mod

el

N>126, Z<82 nuclei (238U beam)

Δq=0

206Hg

208Hg

209Tl

N. Al-Dahan et al.

Shell-model calc. (H. Grawe)TBME: from E.K. Warburton, PRC44, (1991) 233; are based on the Kuo-Herling realistic int.Single particle energies: 207Tl and 209Pb exp.

( νg29/2) states;

2+ mixed with πs-11/2d-1

3/2

B(E2)=1.22 W.u. SM

B(E2)=1.95(39)-1.58(22) W.u. exp.

209Tl: Isomer: 17/2+; ( νg2

9/2) (πs-11/2)

17/2+->13/2+ Δ

13/2+->9/2+ 137 keV

9/2+->7/2+ Δ, allowed M1

7/2+->3/2+ 661 keV

3/2+->1/2+ 324 keV E2(+M1)

B(E2)=0.96 W.u. SM

B(E2)=1.87(22)-1.51(18) W.u. exp.

209Tl: previously from (t,α) and alpha decay.(t,α): C. Ellegaard, P.D. Barnes and E.R. Flynn, Nucl. Phys. A259 (1976) 435.

),2()2,()2,2(),(4

1),( NZBNZBNZBNZBNZVpn

~1/(Δl+Δn)

N>126, Z<82 nuclei

Mass measurement of 208Hg (GSI storage ring)

L. Chen et al., PRL102 (2009) 122503.

proton neutron

i13/2 i11/2

g9/2 g9/2

Z=82 N=126

s1/2 p1/2

d3/2 f5/2

N.

Al-

Dah

an e

t al. s

ubm

itte

d t

o P

RL

T1/2=10(2) sBeta decay:

A.I. Morales, J. Benlliure et al.,

Acta Phys. Pol. B 40, 867 (2009)

Isomer:

S.J. Steer et al.,

Int. J. Mod. Phys.

E18, 1002 (2009)

Shell model: M. Gorska

An example of an N=125 nucleus: 204Au

1-: 186, 336, 437, 686 keV

Seniority isomers in n-rich Pb isotopes

Pb isotopes

S350 experiment – 2.5g/cm2 Be target, 2g/cm2 S1 degrader, 0.7g/cm2 S2 degrader - Setting on 215Pb

214,216Pb isotopes: neutron g29/2 8+ isomers

Partial statistics

Preliminary

J-J. Valiente-Dobon, G. Benzoni,

Sept. 2009

E.Simpson, J.A. Tostevien et al.

Population of isomers by two-proton knockout reaction in 206Hg

Total

10+

5- (with feeding)

Isomeric ratios fig.

Exp. Theory

3.1 4.7 -> 4.3

22 19 -> 18

Summary:

Info through isomeric decays in:

- N=126: 205Au, 204Pt, 203Ir

- N=128: 208Hg, 209Tl

Comparison with shell-model

-New measurements 214,216Pb

-future: higher beam intensity

AIDA

DESPEC

The RISING Collaboration