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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