GSI Experiments on Synthesis and GSI Experiments on Synthesis and Nuclear Structure Investigations of Nuclear Structure Investigations of

Heaviest NucleiHeaviest Nuclei

F. P. HeßbergerF. P. Heßberger

Gesellschaft für Schwerionenforschung Gesellschaft für Schwerionenforschung mbH, D-64291 Darmstadt, GermanymbH, D-64291 Darmstadt, Germany

XII Nuclear Physics WorkshopXII Nuclear Physics Workshop

Maria and Pierre CurieMaria and Pierre Curie

Nuclear Structure Physics and Low Energy ReactionsNuclear Structure Physics and Low Energy Reactions

21.-25. September 2005, Kazimierz Dolny, Poland21.-25. September 2005, Kazimierz Dolny, Poland

Outline of the talkOutline of the talk

Physical MotivationPhysical Motivation Experimental Set-up at GSIExperimental Set-up at GSI GSI Experiments on Search for SHEGSI Experiments on Search for SHE GSI Experiments on Nuclear Structure GSI Experiments on Nuclear Structure

Investigations of Transfermium Isotopes Investigations of Transfermium Isotopes

-- Decay Studies of odd-mass odd-Z nuclei-- Decay Studies of odd-mass odd-Z nuclei -- Decay Studies of odd-mass even-Z nuclei-- Decay Studies of odd-mass even-Z nuclei -- -- Systematic Trends in Single Particle LevelsSystematic Trends in Single Particle Levels

-- -- K-Isomers in even-even nucleiK-Isomers in even-even nuclei

• • ConclusionsConclusions• • CollaborationsCollaborations

Predictions of Superheavy ElementsPredictions of Superheavy Elements

H. Meldner Arkiv fys. 36,593 (1967)

82

126 126

82

126

(164)

126

(164)

184 184

114114

140 150 160 170 180 190

100

102

104

106

108

110

112

114

116

118

120Möller et al.

F.P.Heßberger /konferenzen/Kazimiersz/ 12.9.2005

Pro

ton

nu

mb

er

- 4

- 9

- 8-7

- 7

- 6

- 6- 4

- 5

- 3- 2-1

- 2- 3

- 3- 2- 1

Pro

ton

nu

mb

er

Neutron number

140 145 150 155 160 165 170 175 180 185 190

100

102

104

106

108

110

112

114

116

118

120 Sobiczewski & Smolanczuk

Neutron number

-7

- 6

- 3

- 4

- 3

- 4- 5

-7

- 6- 3- 5- 4

- 2

g9/2

7/2+[624]

j15/2

9/2-[734]

d5/2

1/2+[631]

114

f7/2

i13/2

h9/2

f5/2

1/2-[521]

7/2-[514]

3/2-[521]

7/2+[633]

184

152

142

126134

Nilsson – Diagrams for Neutron (left) and proton (right) single particle levels

82

114

100

96

Excerpt from Chart of Nuclei

Mastertitelformat bearbeiten

Velocity separator SHIP

SHIP Separation time: 1 – 2 μs

Transmission: 20 – 50 %

Background: 10 – 50 Hz

Det. E. resolution: 18 – 25 keV

Det. Pos. resolution: 150 μm

Dead time: 25 μs

Synthesis of SHE

104 106 108 110 112 114 116 118

0,1

1

10

100

1000

10000

konferenzen/kazimiersz/quersschn 13.9.2005

48Ca + actinide targets (4n)

48Ca + actinide targets (3n)

34S + actinide targets

'cold' fusion (Pb,Bi-targets)

/ p

bar

n

ZER

Basic Rule in Physics:Basic Rule in Physics: Experimental results have to be reproduced independently before Experimental results have to be reproduced independently before

being generally acceptedbeing generally acceptedReaction Reaction 238238U(U(4848Ca,xn) Ca,xn) 276-x276-x112 are technically ‚easy‘ to perform 112 are technically ‚easy‘ to perform a ‚key‘ to a ‚key‘ to

SHE SHE

E* / MeVE* / MeV Dose/10Dose/10-19-19 eventsevents TT1/2 1/2 /s/s σσ/pb/pb

VassilissaVassilissa 3333 0.350.35 2 (ER-sf)2 (ER-sf) 8181 5.05.0

(Oganessian et al.)(Oganessian et al.) 3939 0.220.22 00 <7.3<7.3

3333 0.590.59 00 <2.2<2.2

35.535.5 0.470.47 2 (ER-sf)2 (ER-sf) 568568 3.03.0DGFRSDGFRS 31.431.4 0.580.58 1 (ER-[1 (ER-[αα]-sf)]-sf) 3.43.4 0.5 0.5 +1.2/-0.4+1.2/-0.4 (3n)(3n)((Oganessian et al.)Oganessian et al.) 35.035.0 0.710.71 2 (ER-[2 (ER-[αα]-sf]-sf

3 (ER- 3 (ER- αα-sf)-sf)1 (ER- 41 (ER- 4αα-sf)-sf)

1.41.42.72.76.16.1

2.5 2.5 +1.8/-1.1+1.8/-1.1 (3n)(3n)

39.839.8 0.520.52 1 (ER-sf)1 (ER-sf) 0.14 0.14 (ms(ms)) 0.6 0.6 +1.6/-0.6+1.6/-0.6 (4n)(4n)

Chemistry Chemistry (Yakushev et al.)(Yakushev et al.)

34.234.2 0.280.28 7 sf7 sf >60>60 ≈≈22

BGS BGS (Loveland,(Loveland, 31.931.9 0.2260.226 00 -- <0.8<0.8Gregorich et al.)Gregorich et al.) 36.936.9 0.1850.185 00 -- <0.96<0.96

SHIPSHIP 32.032.0 0.70.7 00 -- <0.8<0.8

(Hofmann et al.)(Hofmann et al.) 34.534.5 1.01.0 1 (ER-sf)1 (ER-sf) 5.25.2 0.7 0.7 +1.6/-0.6+1.6/-0.6

37.037.0 1.21.2 00 -- <0.6<0.6

Nuclear Structure Investigations of Transfermium Nuclear Structure Investigations of Transfermium Isotopes Isotopes

What can be (presently) achieved by decay studies ?What can be (presently) achieved by decay studies ?

Production rates:Production rates: 207207Pb(Pb(4848Ca,2n)Ca,2n)253253No : No : σσ ≈ 900 nb, i( ≈ 900 nb, i(4848Ca) Ca) ≈≈ 1p1pμμA A z z αα ≈ 7000 /h ≈ 7000 /h 206206Pb(Pb(4848Ca,3n)Ca,3n)251251No : No : σσ ≈ 25 nb, i( ≈ 25 nb, i(4848Ca) Ca) ≈≈ 1p1pμμA A z zαα ≈ 200 /h ≈ 200 /h 207207Pb(Pb(5050Ti,2n)Ti,2n)255255Rf : Rf : σσ ≈ 10 nb (50% sf), i( ≈ 10 nb (50% sf), i(5050Ti) Ti) ≈≈ 0.4p0.4pμμA A z zαα ≈ ≈

20/h20/h 209209Bi(Bi(4040Ar,2n)Ar,2n)247247Md : Md : σσ ≈ 7 nb, i( ≈ 7 nb, i(4040Ar) Ar) ≈≈ 1.5 1.5ppμμA A z zαα ≈ 40 /h ≈ 40 /h

Collection of several (ten) thousand decays within several daysCollection of several (ten) thousand decays within several days Fine structure measurements possible, but not sufficient for detailed levelFine structure measurements possible, but not sufficient for detailed level schemes (like for nuclei where weighable amounts are available)schemes (like for nuclei where weighable amounts are available) Establishing global trends in nuclear structure (for some Nilsson levels)Establishing global trends in nuclear structure (for some Nilsson levels) Similarities in Nuclear Structure along the ‚Isotope Line‘ in odd-Z nucleiSimilarities in Nuclear Structure along the ‚Isotope Line‘ in odd-Z nuclei Similarities in Nuclear Structure along the ‚Isotone Line‘ in even-Z nuclei Similarities in Nuclear Structure along the ‚Isotone Line‘ in even-Z nuclei

Nuclear Structure Investigation of odd-A odd-Z nuclei

8700 8800 8900 9000 9100 9200 9300 94007600

7800

8000

8200

8400

8600

8800

9000

9200

- - correlations observed for 50Ti + 209Bi --> 259Db* at E = 4.85 AMeV

F.P.Heßberger 12.9.2005

253mLr253gLr

249Md

(258Db

--> 254Lr)

253mLr

253gLr

257mDb257gDb

E

(dau

gh

ter)

/ ke

V

E (mother) / keV

100 150 200 250 300 350 400 4500

50

100

150

200

250

300 350 400

4

8

Spectrum of -events in prompt

coincidence with -decays of 251Md

376.

9

354.

8

303.

2

F.P.Heßberger 12.9.2005

293.

7

242.

7

cou

nts

E / keV

even

ts

E / keV

9/2+9/2+

200

Present status of nuclear structureinvestigations of odd A odd Z elementsin the region Z=99-105

Level assignments are partly tentive

243

9/2+(?)

207Pb(48Ca,2n)253No -EC-> 253Md

209Bi(48Ca,2n)255Lr209Bi(50Ti,2n)257Db

209Bi(40Ar,2n)247Md

FPH 12.9.2005

9/2+[624] ?9/2+[624] ?

261Db259Db8930

257Lr259Lr

7/2-[514] 7/2-[514]

87968861

9/2-?

7/2-[514] 7/2-[514]

7100

253Md251Md

353(E1 ?)

249Es247Es

3/2-[521] ?3/2-[521] ?

7/2+[633]

7/2-[514] 7/2-[514]

no

3/2-[521] ? 3/2-[521] ? 3/2-[521]

253 (E1)

9/2-

7/2-[514]

9/2+

7/2+[633] 7/2+[633]

405(E1)

453(E1)

7/2-[514]

7/2-[514]

7752

7714

73277274

8450

8470(8385)

251Es

255Md

255Lr

8785

1/2-[521]

157

7/2+[633]

90749474

257Db8967

9163

253Lr

9/2+[624]

1/2-[521]

1/2-[521]

1/2-[521]

9/2- ?

7/2-[514]

?

8385(8470)

no

87948722

1/2-[521]

8030 7540

1/2-[521] 1/2-[521]

sf

7/2-[514]

7/2-[514]

7/2-[514]

7/2-[514]

294(E1)

7/2+[633]

8421

249Md247Md

245Es243Es

210 (E1)

Comparison of theoretical and experimental Nilsson levels of odd mass Es - isotopes

a) Calculations of Cwiok et al. (black) and Parkhomenko and Sobiczewski (red)

b) experimental values

Trend of increasing energy with increasing N satisfactoily reproduced by Cwiok et al. but maximum at Es-249

Opposite trend predicted by Parkhomenko and Sobiczewski

Ground state predicted as 7/2+[633]; situation not fully clear from experimental side

Energies of the 7/2-[514] – levels differ by several hundreds of keV

0

100

200

300

400

500

600

700

800

900

0

100

200

300

400

500

a)

Es-255Es-253

7/2-[514]

7/2-[514]

1/2-[521]

1/2-[521]

3/2-[521]3/2-[521]

1/2-[521]

3/2-[521]

Es-243

3/2-[521]

7/2+[633]

Es-251

E* /

keV

7/2-[514]

Es-249Es-247Es-245

b)

E* /

keV

Es-253Es-251Es-249Es-247Es-245Es-243

7/2+[633]

352+x

295+x253+x

210+x

0+x0+x0+x0+x

Deformation of odd-mass Es-isotopes as function of mass number

Evidently: Relation between energy of 7/2- [514] level and deformation

2 3 8 2 4 0 2 4 2 2 4 4 2 4 6 2 4 8 2 5 0 2 5 2 2 5 4 2 5 6 2 5 80 , 2 2 0

0 , 2 2 4

0 , 2 2 8

0 , 2 3 2

0 , 2 3 6

0 , 2 4 0

0 , 2 4 4

0 , 2 4 8

0 , 2 5 2

R e f . M o N i9 5

R e f . C w i9 5

R e f . P a S 0 4

F ig . 51 . 6 . 2 0 0 5

2

M a s s N u m b e r 242 244 246 248 250 252 254

30

40

50

60

70

200

250

300

350

400

450

500

E((9/2+)-(7/2+))

E((7/2-[514])-(7/2+[633]))

E /

keV

Mass Number

Nuclear Structure Investigation of odd-A even-Z nuclei Example: Alpha-gamma decay measurements of 251No and its daughter products

0

500

1000

1500

2000

2500

7000 7500 8000 8500 90000

50

100

150

200

250

243 C

f24

4 Cf 24

7 Fm

247m

Fm

252 N

o25

1 No

251m

No

cou

nts

E / keV

E /

keV

80 100 120 140 1601

10

100

F.P.Heßberger 28.4.2005

15

2.1

105.5

82.2

166.

6K

(

Cf)

121.

8

141.

8

K

(

Cf)

Ere

ign

iss

e

E / keV

Alpha – gamma – gamma coincidence measurements of 247Fm

coincidences between K-x-rays two transitions E > 136 keV coincidences of K-x-rays with 121.9 keV and 166.3 keV

121.9 keV coincident with x-rays, 141.8 keV but not with 166.3 keV, which has a higher intensity than the 141.8 keV line

0

4

8

12

0

2

4

0

2

4

80 100 120 140 160 180 2000

2

4

coinc. K - xrays

E / keV

co

un

ts

coinc. 121.9 keV

coinc. 141.8 keV

coinc. 166.3 keV

Attempt to assign ‚gamma‘ – pairs to transitions:

40

44

48

52

56

60

0,20 0,21 0,22 0,23 0,24 0,25 0,26

40

44

48

52

56

60

(166.6-121.8)

(141.8-82.2)Möller-Nix

E(7

/2+

-->

5/2

+[6

22

]) /

ke

V

F.P.Heßberger 27.4.2005

(166.6-121.8)

(141.8-82.2)Sobiczewski et al.

(gs)

35

40

45

50

55

60

0,20 0,21 0,22 0,23 0,24 0,25 0,26

35

40

45

50

55

60

(166.6-121.8)

(141.8-82.2)

CmPu

Th

Möller-Nix

U

E(5

/2+

-->

3/2

+)1

/2+

[63

1] /

ke

V

(166.6-121.8)

(141.8-82.2)

F.P.Heßberger 27.4.2005

CmPuUTh

Sobczewski et al.

2 (gs)

Preliminary Decay schemes of 251No and 247Fm

F.P.Heßberger 2.5.2005

~196

~15282.2

(7/2+)

(5/2+)

(3/2+)~70

141.8(M1+E2)

~10(1/2+[631])

5.1 s

31 s

E = 8171 keVHF = 1.3

E = 8668 keV, HF = 2.0

121.8 166.6(M1+E2)

~318

(1/2+[631])

(1/2+[631])

E = 8608 keV, HF = 1.1

~901.04 s

(7/2+[624])

(7/2+[624])

0.85 s

~30

gs

gs

gs

(5/2+[622])

(7/2+[624])

E ~7840 keVHF ~0.8

243Cf

247Fm

251No

209.

7 (3

.5)

228.

2 (1

1.3)

277.

6 (1

5.0)

285.

5 (0

.8)

181.

7 (1

.1)

226.

4 (3

.3)

7/2+

7/2+

5/2+

3/2+

1/2+[631]

5/2+[622]

7/2+[624]

239Pu

0

100

200

300

400

500

600

700

800

5/2+[622]3/2+[622] ?

23s23s

45s

25s

1/2+[620]

9/2-[734]

1/2+[631]

5/2+[622]

7/2+[624]

E* /

keV

Calculation Sobiczewski et al. Priv. Comm. 2005

3/2+[622]

3/2+[622]

1/2+[620]

1/2+[620]

5/2+[622]

7/2+[624]

7/2+[624]

9/2-[734]

9/2-[734]

Calculation Cwiok et al. Nucl. Phys. A573 (1995)Experiment

253No251Fm255Rf253No

251Fm249Cf249Cf247Cm247Cm

Nilsson-Level systematics of N=151 isotones (even Z)

Nilsson - Level systematics of N=149 Isotones (even Z)

0

100

200

300

400

500

0

100

200

300

400

500

253Rf 255Sg243Pu 245Cm247Cf 249Fm 251No

1/2-[631]

7/2-[624]

5/2+[622]

9/2-[734]

7/2+[624]

251No

251No

249Fm

249Fm

247Cf

247Cf

245Cm

245Cm

243Pu

243Pu

E* /

keV

E* /

keV

Calculations Sobiczewski et al. priv. comm. 2005

5/2+[622]

1/2+[631]

experiment

9/2-[734]

Nilsson-Level systematics of N = 147 Isotones (even Z)

0

50

100

150

200

250

300

350

400

450

0

50

100

150

200

250

300

350

400

450

7/2-[743]

1/2+[631]

243Cm241Pu239U 239U

5/2+[622]253Sg

247Fm 249No 251Rf245Cf

9/2-[734]

7/2+[624]

5/2+[622]

247Fm245Cf243Cm

241Pu

243Cm

239U

241Pu

E* /

keV

E* /

keV

F.P.Heßberger 5.9.2005

calculations Sobiczewski et al., priv. comm 2005experiment

7/2-[743]

1/2+[631]

247Fm245Cf

5/2+[622]

7/2+[624]

Identifikation of a K-Isomer in Identifikation of a K-Isomer in 254254No No (R.Herzberg et al., Exp. at RITU, Jyväskylä)(R.Herzberg et al., Exp. at RITU, Jyväskylä)

0

5

1 0

1 5

2 0

1 0 0 2 0 0 6 0 0 7 0 0 8 0 0 9 0 00

1 0 0

2 0 0

3 0 0

c o r r . E R w i t h i n 0 . 5 m s606

F m - X - r a y s

E / k e V

even

ts

c o r r . E R w i t h i n 5 0 0 m s53

844

887

943

Spectra from confirmation experiment at SHIP 06/05

9 4 2

8 4 48 8 7

d e c a y i n c l u d e sC E a n d 6 0 6 k e V

2 . 5 M e V ?

=

1 2 9 3 k e V

9 8 8 k e V

K = 8K = 3

5 3 ( E 1 )

8 26 95 74 5

3 1 8

2 6 7

2 1 4

1 5 9

1 0 24 4

7 + 8 -

5 +6 +

0 +

1 2 +

1 0 +

8 +

6 +

4 +2 +

3 +4 + 266 ms

184 μs

Identification of an isomeric state in Identification of an isomeric state in 252252NoNo

1 3 4 ?

7 / 2 + [ 6 3 3 ] x 7 / 2 - [ 5 1 4 ]a t 1 . 4 M e V ( C h u e t a l . )

7 5 5 , 8 2 8 , 8 6 2 ,8 8 5 , 9 1 1 , 9 2 0

9 0 + - 2 5 m sc a . 1 . 3 M e V

S k e t c h o f t h e d e c a y o f 2 5 2 m N o

c a . 1 M e V3 2 8

2 7 7

2 2 4

1 6 7

1 0 7

4 6

7 - ?

0 +

1 2 +

1 0 +

8 +

6 +

4 +

2 +

0 4 0 8 0 1 2 0 1 6 0 2 0 0 2 4 0 7 2 0 7 6 0 8 0 0 8 4 0 8 8 0 9 2 0 9 6 0 1 0 0 00

1 0

2 0

3 0

0

2 0

4 0

6 0

8 0

F . P . H e ß b e r g e r 2 0 . 9 . 2 0 0 5

224

(8+

-->

6+)

208

(238 N

p)

134

107

(4+

-->

2+?

)

920

911

885

862

828

755

C o r r . E R - e _ - , s f t < 1 0 s

cou

nts

E / k e V

Pu

-x-

rays

59.5

(23

7 Np

)

167

(6+

-->

4+)

C o r r . E R - e _ , t < 5 0 0 m s

R e a c t i o n : 4 8 C a + 2 0 6 P b , E = 4 . 6 A M e VS p e c t r u m - r a y s c o i n c . w i t h e l e c t r o n s ( E < 2 5 0 k e V , t < 5 0 0 m s )

gamma energies in keV

ConclusionsConclusions ☺☺ ‘‘Cold’ fusion reactions have been a successful method to produce isotopes of elementsCold’ fusion reactions have been a successful method to produce isotopes of elements up to Z = 113; however, cross sections decrease drastically with increasing atomic num- up to Z = 113; however, cross sections decrease drastically with increasing atomic num- ber;for element 113 only 0.055 pb were measured (but probably not the maximum) ber;for element 113 only 0.055 pb were measured (but probably not the maximum)

☺☺ ‘ ‘Hot’ fusion reactions may be a suited method to produce SHE; interesting results haveHot’ fusion reactions may be a suited method to produce SHE; interesting results have been obtained from DGFRS, but could not be confirmed in other laboratories so far; been obtained from DGFRS, but could not be confirmed in other laboratories so far; more effort is needed more effort is needed

☺☺ To better understand the properties of heaviest known nuclei and to get a firm base for To better understand the properties of heaviest known nuclei and to get a firm base for

reliable predictions of nuclear properties in the expected region of (spherical) reliable predictions of nuclear properties in the expected region of (spherical) superheavy nuclei detailed investigations of nuclear structure are indispensable;superheavy nuclei detailed investigations of nuclear structure are indispensable; experimental tools are experimental tools are αα --γγ- (- (αα –CE)- –CE)-decay spectroscopy or in-beam spectroscopy decay spectroscopy or in-beam spectroscopy

☺☺ Experimental results presently available Experimental results presently available allow to follow systematics in the energy of single particle levels in N = 145, 147, allow to follow systematics in the energy of single particle levels in N = 145, 147, 149 and 151 isotones with even atomic numbers up to Z = 102149 and 151 isotones with even atomic numbers up to Z = 102 indicated close similarities in the nuclear structure of neutron deficient isotopes with indicated close similarities in the nuclear structure of neutron deficient isotopes with even neutron numbers of odd Z elements in the region einsteinium to dubnium even neutron numbers of odd Z elements in the region einsteinium to dubnium

☺☺ Production rates indicate, that detailed nuclear structure investigations by means of Production rates indicate, that detailed nuclear structure investigations by means of -- - coincidence measurements are possible with present techniques down to cross - coincidence measurements are possible with present techniques down to cross sections of sections of 100pb (265Hs)100pb (265Hs)

‘‘On and on but the road is never ending, at least we know, we’re on our way’ On and on but the road is never ending, at least we know, we’re on our way’ (from ‘On and on’ by Fiddler’s Green)(from ‘On and on’ by Fiddler’s Green)

CollaborationCollaborationGSI, DarmstadtGSI, DarmstadtS. Hofmann, D. Ackermann, S. Hofmann, D. Ackermann, B. Kindler, I.Kojouharov, B. Kindler, I.Kojouharov, P. Kuusiniemi, B. Lommel, P. Kuusiniemi, B. Lommel, R. Mann, K. Nishio, R. Mann, K. Nishio, B. Sulignano, F.P.HB. Sulignano, F.P.H

University Bratislava, SlovakiaUniversity Bratislava, SlovakiaS. Antalic, S. Saro, B. Streicher, S. Antalic, S. Saro, B. Streicher, M. Venhart, M. Venhart, P. Cagarda (until 2003P. Cagarda (until 2003))

University Jyväskylä, FinlandUniversity Jyväskylä, FinlandM. Leino, J. UusitaloM. Leino, J. Uusitalo

FLNR-JINR Dubna, RussiaFLNR-JINR Dubna, RussiaA.G. Popeko, A.N. EreminA.G. Popeko, A.N. Eremin

University Liverpool, UKUniversity Liverpool, UKR.-D. HerzbergR.-D. Herzberg

University Warsaw, PolandUniversity Warsaw, PolandA. Sobiczewski, A. ParkhomenkoA. Sobiczewski, A. Parkhomenko