In-source laser spectroscopy of Pb, Bi and Po isotopes at ISOLDE

Charge Radii around Z = 82 and N = 104In-source resonant photoionization spectroscopy at ISOLDE182-190Pb: charge radii, magnetic moments…189,191Bi: isotope shifts and magnetic moments Po: photoionization schemes and yield testsDiscussion and outlook

Maxim SELIVERSTOVInstitut für Physik, Johannes Gutenberg Universität, MainzPetersburg Nuclear Physics Institute, Gatchina

Contents:

ISOLDE Workshop and Users meeting 2006/200712-14 February 2007 CERN

Level systematics for the neutron-deficient lead isotopes.R. Julin et al., J. Phys. G: Nucl. Part. Phys. 27 (2001)

100 105 110 115 120 125 130

Pt (Z = 78)

Bi (Z = 83)

Po (Z = 84)

Hg (Z = 80)

N =

10

4

N =

12

6

r 2 ,

fm2

N

Ground state Isomer Droplet model prediction

Pb (Z = 82)

= 0.1 fm2

Charge radii below and above Z = 82

???

???

???

nuclear ground and isomeric state properties : δ r 2

98 100 102 104 106 108 110 112 114 116 118 120 122

N

In-source resonant photoionization spectroscopy at ISOLDE

I , Q S

Isotope shift

r 2

Procedure:• measurement of radioactive Pb isotopes• measurements of stable 206,207,208Pb• reference measurements Advantages:• sensitivity: e.g. 183Pb 10 atoms/s at resonanceLimitation:• large Doppler broadening

Laser Ion Source (LIS)

target

ionizer

Laser beams

Mass separator

Pb: atomic spectroscopy

35285.7 35286.0 35286.3 35286.6 35286.9 35287.2 35287.50

10000

20000190Pb

wavenumber, cm-1

10 GHz

0

2000

4000 188Pb

0

500

1000

1500 187Pb I = 13/2

187Pb I = 3/2

189Pb I = 13/2 189Pb I = 3/2

0

5000

10000 186Pb

co

un

ts

0

500

1000

1500 185Pb I = 13/2

185Pb I = 3/2

0

500

1000

1500

184Pb

0

500

1000

183Pb I = 13/2

183Pb I = 3/2

0

20

40

60

182Pb

0

4000

8000

Isotope shift A,A’:

A,A’= F * A,A’ + (NMS+SMS)

F = 20.26(18) GHz.fm-2

MS =0 .19(25)*NMS(Anselment et al, NPA451 (1986) 471)

Rms charge radius :

A,A’ = r 2 + C2r 4 + … = 0.93 r 2

Relative line position (Hyperfine splitting) hyperfine constants A & B μI & (QS) :A = A (μI , I ), B = B (QS , I )

182Pb: T1/2= 55 msYield: ~1 s-1

189Pb: combination of nuclear and laser spectroscopy

3 -lines belonging to the 189Pb decay have been observed with energies: 5727, 5764 and 5619 keV

40 gamma lines belonging to the β/EC decay of 189Pb have been identified: 386, 480, 700, 399....and 667keV are the main ones.

New isomer identified (I = 3/2)Alpha decay scheme has been established

35286,2 35286,4 35286,6 35286,8 35287,0 35287,20,0

0,2

0,4

0,6

0,8

1,0

1,2

sig

nal,

no

rmaliz

ed

wavenumber, cm-1

High spin isomer (I = 13/2), 480 keV Low spin isomer (I = 3/2), 667 keV

Ground state characteristics of 183–190Pb

Reference value r2190,208 = -0.840(10)

fm2

S.B. Dutta et al., Z. Phys. A 341, 39 (1991)

Isotope I *A,208(GHz) **A (GHz) *r2A,208 (fm2)*** ** (n.m.)

182Pb 0+ -24.56(25) — -1.299(12) —

183m1Pb 3/2– -22.95(15) -5.742(25) -1.2145(75) -1.158(5)

183m2Pb 13/2+ -23.54(15) -1.423(6) -1.2455(75) -1.245(5)

184Pb 0+ -21.74(10) — -1.150(5) —

185m1Pb 3/2– -20.66(15) -5.652(25) -1.0930(75) -1.141(5)

185m2Pb 13/2+ -21.26(15) -1.405(12) -1.1245(75) -1.229(10)

186Pb 0+ -19.81(10) — -1.048(5) —

187m1Pb 3/2– -18.78(12) -5.584(25) -0.993(6) -1.127(5)

187m2Pb 13/2+ -19.37(12) -1.383(6) -1.025(6) -1.210(5)

188Pb 0+ -17.57(12) — -0.930(6) —

189m1Pb 3/2– -16.82(15) -5.36(4) -0.8904(75) -1.081(8)

189m2Pb 13/2+ -17.36(20) -1.374(7) -0.9184(75) -1.202(7)

190Pb 0+ -15.86(10) — -0.839(5) —

* H. de Witte et al., „Nuclear charge radii of neutron deficient lead isotopes beyond N=104 mid shell investigated by in-source laser spectroscopy”, to be published in PRL, 2007 ** Preliminary

*** Errors due to the isotope shifts measurements‘ uncertainties are given only. The total errors are 0,013 fm2

for 183-185Pb and 0.010 fm2 for heavier isotopes.

Nuclear magnetic moments

Magnetic moments for the neutron deficient odd-A lead isotopes. The theoretical curve, labelled "Bauer '73", is taken from Bauer R. et al., Nucl. Phys. A 209 (1973), 535.

100 102 104 106 108 110 112 114 116 118-2,0

-1,9

-1,8

-1,7

-1,6

-1,5

-1,4

-1,3

-1,2

-1,1

-1,0

-0,9

m

ag

neti

c m

om

en

t, n

.m.

N

Dutta'91 (I = 13/2+)

This work (I = 13/2+)

This work (I = 3/2-)

Hg (I = 13/2+)

Schmidt line

Bauer'73

1i13/2

3p3/2

Charge radii for Pb chain

our data

The experimental error bar is smaller than the symbol size. The distance between the different chains is chosen arbitrarily for better display. One minor division on the vertical scale corresponds to 0.1 fm2

.

100 105 110 115 120 125 130

Pt (Z = 78)

Hg (Z = 80)

N =

104

N =

126

r

2 ,

fm2

N

Ground state Isomer Droplet model prediction

Pb (Z = 82)= 0.1 fm2

182-190Pb charge radii: experiment

100 102 104 106 108 110 112

-1.4

-1.2

-1.0

-0.8

-0.6

r2 A

,208

, fm

2

I = 0 low spin I = 3/2 high spin I = 13/2literature dataDroplet Model prediction

|2| = 0.2 |

2| = 0.15

|2| = 0.1

|2| = 0

NH. de Witte et al., „Nuclear charge radii of neutron deficient lead isotopes beyond N=104 mid shell investigated by in-source laser spectroscopy”, to be published in PRL, 2007

182-190Pb charge radii: theoretical models

100 102 104 106 108 110 112

-1.4

-1.2

-1.0

-0.8

-0.6

r2 A

,208

, fm

2

MF MF* IBM

|2| = 0.2 |

2| = 0.15

|2| = 0.1

|2| = 0

N

Beyond Mean Field (MF*)Reduced pairingM. Bender et al., Phys. Rev. C 73, 034322 (2006).

Beyond Mean Field (MF)M. Bender et al., Phys. Rev. C 69, 064303 (2004).

H. de Witte et al., „Nuclear charge radii of neutron deficient lead isotopes beyond N=104 mid shell investigated by in-source laser spectroscopy”, to be published in PRL, 2007

Interacting Boson Model (IBM)J. Pakarinen et al., to be published (2006).V. Hellemans et al., Phys. Rev. C 71, 034308 (2005).R. Fossion et al., Phys. Rev. C 67, 024306 (2003).

Bi: atomic spectroscopy

IP = 58761.65 cm-1

6p3 4So3/2

Ground state

6p27s 4P1/2

32588.22 cm-1

Continuum

= 306.770 nm

= 555.205 nm

= 510.554 nm and = 578.213 nm

(CVL)

209Bi I = 9/2F = 5

F = 4

Hyperfine splitting

24.6 GHz

F3456

6.6 GHz

Bi 32586.9 32587.2 32587.5 32587.8 32588.1 32588.40

2000

4000

6000

wavenumber, cm-1

191Bi (I = 1/2)

10 GHz

0

5000

10000

15000191Bi (I = 9/2)

cou

nts

0

2000

4000

6000 189Bi (I = 9/2)

189,191Bi: isotope shifts

105 110 115 120 125 130

-25

-20

-15

-10

-5

0

5

10

, G

Hz

N

literature data

9/2- (ground state)

1/2+ (isomer)

N =

126

our data

Isotope 209,A , GHz

189Bi (I =9/2-) -21.8(3)191Bi (I =9/2-) -20.4(3)191Bi (I =1/2+) -17.9(3)

preliminary

189,191Bi: charge radii

From the comparison of isotopes shifts of Bi and Pb: F = 27(3) GHz/fm2

P. Campbell et al., Phys. Lett. B 346 (1995) 21

105 110 115 120 125 130

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

r A

,209 ,

fm

2

2= 0.15

2= 0.1

N

literature data

9/2- (ground state)

1/2+ (isomer) droplet model prediction

N =

126

2= 0

our data

No reliable values for electronic factor and specific mass shift constant

preliminary

MCDF calulations are under wayS. Fritsche (Univ. of Kassel)

Bi: magnetic moments

105 110 115 120 125 1303.00

3.25

3.50

3.75

4.00

4.25

,

N

N

N =

126

our dataIsotope A, GHz , N

189Bi (I = 9/2-) -0.405(4) 3.73(4)191Bi (I =

9/2-)-0.403(3) 3.71(3)

191Bi (I = 1/2+) -1.45(2) 1.49(2)Reference:

189Bi (I =9/2-)

-0.44697(4)

4.1106(2)

preliminary

Po: photoionization schemes and yield test

ContinuumIP=67885.3 cm-1

6p4 3P2

6p37s 5S2

6p37p 5P2

6p37s 3S1

6p38p ? 10

6p38p ? 12

255.8 nm245.011 nm

843.38 nm 538.89 nm532.34 nm

510.6 nm 510.6 nm IsotopeHalf life,

sYield,

Atoms/μC

193gPo 0.42 7101

193mPo 0.24 1102

194Po 0.392 2.5103

195gPo 4.64 2104

195mPo 1.92 5104

196Po 5.8 4.7105

197gPo 53.6 2.5105

197mPo 25.8 1.75106

198Po 106.2 7106

a bPo yields (scheme „a“)

Conclusions & future perspectives

Laser spectroscopy and nuclear structure:Extention of laser spectroscopy studies to the very neutron deficient isotopes (and isomers) of Pb and Bi Extention of Pb charge radii systematics beyond mid-shell (e.g. 182Pb, T1/2= 55 ms)Comparison with calculations: Ground states of Pb remains spherical189Pb decay scheme has been established189Pb low spin isomer identifiedPhotoionization scheme for Po was developed

Method:Improved precision & reproducibility of in-source laser spectroscopy techniqueUltra high sensitivity

Future:Extension to other elements e.g. Po isotopes

CERN-ISOLDE project IS407: Study of the neutron deficient Pb and Bi isotopes by simultaneous atomic- and nuclear- spectroscopy

A. Andreyev, N. Barré, M. Bender, J. Billowes, T.E. Cocolios, S. Dean, D. Fedorov, V.N. Fedoseyev, L.M. Fraile, S. Franchoo, J. Genevey, V. Hellemans, P.H. Heenen, K. Heyde, G. Huber, M. Huyse, A. Ionan, H. Jeppesen, K. Johnston, U. Köster, Yu. Kudryavtsev, P. Kunz, S.R. Lesher, B.A. Marsh, I. Mukha, B. Roussière, J. Sauvage, I. Stefanescu, E. Tengborn, K. Van de Vel, J. Van de Walle, P. Van Duppen, Yu.M. Volkov, H. De Witte

CERN-ISOLDE project IS407: Study of the neutron deficient Pb and Bi isotopes by simultaneous atomic- and nuclear- spectroscopy

A. Andreyev, N. Barré, M. Bender, T.E. Cocolios, S. Dean, D. Fedorov, V.N. Fedoseyev, L.M. Fraile, S. Franchoo, J. Genevey, V. Hellemans, P.H. Heenen, K. Heyde, G. Huber, M. Huyse, A. Ionan, H. Jeppesen, K. Johnston, U. Köster, Yu. Kudryavtsev, P. Kunz, S.R. Lesher, B.A. Marsh, I. Mukha, B. Roussière, J. Sauvage, I. Stefanescu, E. Tengborn, K. Van de Vel, J. Van de Walle, P. Van Duppen, Yu.M. Volkov, H. De Witte,

CERN Isolde Institut für Physik, University of Mainz,

Germany Institut de Physique Nucléaire, Orsay , France

Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Belgium

Petersburg Nuclear Physics Institute, Gatchina, Russia

Oliver Lodge Laboratory, University of Liverpool, Liverpool, U.K.

LPSC Grenoble , France