Transcript Document

Физика фундаментальных взаимодействий 2009
Пределы масс и острова стабильности
сверхтяжелых ядер
Ю.Ц.Оганесян
Лаборатория ядерных реакций им. Г.Н. Флерова
Объединенный институт ядерных исследований
Сессия-конференция секции ядерной физики ОФН РАН
23-27 ноября, 2009г., ИТЭФ, Москва
Chart of nuclides
Macroscopic theory (Liquid Drop Model)
about 50 years ago…
proton number
120
TSF = 2·10-7 y
110
TSF < 10-14 s
102No / Tα ≈ 2 s
Spontaneous
fission
100
Th
90
Bi
9
92U / Tα = 4.5·10 y
TSF = 1016 y
80
82Pb / stable
70
110
120
130
140
150
160
170
180
neutron number
190
Spontaneous Fission
Macroscopic theory
(Liquid Drop Model)
Exp.
35
30
neutron capture
208Pb
20
25
10
LogTSF / s
Bf / MeV
30
Fission Barrier Height
20
15
0
LDM
238U
10
255Fm
-10
5
SF-isomers
6.0 MeV
fusion with heavy ions
-20
0
0.60
0.70
0.80
Fissility parameter
0.90
x
0.70
0.75
0.85
0.80
0.90
Fissility parameter x
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
0.95
Nuclear shells
(macro-microscopic approach)
Chart of nuclides
proton number
120
X
114
110
spherical
shells
108
184
100
100
162
deformed
shells
90
82
80
Pb
152
deformed
shells
spherical
shells
126
70
110
120
130
140
150
160
170
180
neutron number
190
Predictions of the microscopic theory
…and Half - Lives
Fission Barriers
15
Bf / MeV
Exp.
Fission Barrier Height
10
255Fm
LogTSF / s
20
Z=112 114
116
10
238U
114 116
0
5
-10
LDM
0
LDM
-20
0.70
0.90
0.80
Fissility Parameter x
0.70
0.75
0.90 0.95
0.80 0.85
Fissility Parameter x
R. Smolańczuk, Phys. Rev. C 56 (1997) 812
New lands
New lands
-5
0
Proton number
120
Microscopic theory
5
10
about 40
1µs
1s years
1h ago…
1y
15
LogT1/2 s
1My
Island of
Stability
Shoal
shoal
110
Peninsula
peninsula
100
90
Continent
continent
Sea of Instability
80
70
100
110
120
130
140
150
160
Neutron number
170
180
190
Reaction of Synthesis
Reactions of synthesis
Cold fusion
Act.+48Ca
proton number
114
island of
stability
of superheavy
nuclei
Light ions
shoal of
deformed
nuclei
108
Th
90
target from
U “peninsula”
Pu
N
WN
NE
W
peninsula
Pb
continent
target
142 146
from
“continent”
126
162
Neutron
capture
SW
neutron number
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
184
Reactions of Synthesis
120
SHE
protons →
-7
110
Cold fusion
Act.+48Ca
-5
-6
-5
100
-6
Hot
fusion
-4
-3
-4
Neutron capture
-3
-2
-4
90
U
Th
-2
Pb
Pb
Bi-14
neutrons →
80
120
130
140
150
160
170
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
180
190
-30
10
22
Projectiles
Ne
Mg
34
S (5n)
Cross sections
σxn ~ (Γn /
Γf)x;
х – number of evaporated
4n-cross section (cm2)
Yu. Oganessian et al. Phys. Rev.
26
No
-32
10
Rf
48Ca
Db
-34
Sg
Bh
10
Hs
-36
Ex=40-50 MeV
10
114
neutrons
(Γn / Γf) ~ exp [(Bf – Bn)]
116
112
Ds
112
-38
10
Bf = BfLD + ΔEShell
0
152
140
150
162
160
184
180
170
Neutron number
190
Calculated Barriers Heights (MeV)
Proton number Z
120
Act +
P. Moller et al., Phys. Rev., C79, 064304 (2009)
spherical
deformed
110
48Ca
298114
deformed
100
Bf (MeV)
1
2
3
4
5 6
7
8
90
spherical
120
130
208Pb
140
150
160
170
180
Neutron number N
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
190
Reactions of Synthesis
Act. + 48Ca
Projectiles
48Ca
Energy:
235-250 MeV
Intensity:
1.0-1.2 pμA
Consumption:
0.5 mg/h
Beam dose:
(0.3-3.0)∙1019
Targets:
thickness
(mg/cm2)
Isotope
enrichment (%)
233U
0.44
99.97
238U
0.35
99.3
237Np
0.35
99.3
242Pu
Chemistry
0.40
1.4
99.98
99.98
244Pu
0.38
98.6
243Am
Chemistry
0.36
1.2
99.9
99.9
245Cm
0.35
98.7
248Cm
0.35
97.4
249Bk
0.35
249Cf
0.34
≥ 90
97.3
Experimental Setup
Measured parameters:
For
recoils:
“veto”
detectors
position sensitive
strip detectors
energy
TOF
positions
For decay
product:
energy
time
positions
side
detectors
SH-recoil
Dubna Gas Filled
TOF-detectors
Recoil Separator
Total detection efficiency:
for α-particles…………..83%
for SF-fragment…….~ 100%
for both fragments……..42%
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
246Cm + 48Ca,
3n
291
+48Ca, 3n3n
238U + 48Ca, 3n
279
4
110
287
2
114
10.01 MeV
283
283
3
112
0.54s
9.52 MeV
5.4s
SF10%
9.70 MeV
108 0.26s
SF>90%
9.30 MeV
0.42 s
116
6
267
104
106
8.54 MeV
48 s
SF 228 MeV
381 s
20
0.65 mm
10
-3
-2
-1
0
1
2
3
Position deviation (mm)
Yu. Oganessian J. Phys. G. 34 (2007) R165
Pixel: 6.5 mm2
252
No
position
271
30
0
275
5
40
Counts / 0.1 mm
242Pu
1
Detector
area ~5000 mm2
strip number
242Pu(48Ca;
Alpha-particle spectra of SH-nuclei
245Cm(48Ca;
238U(48Ca;
2n, 3n)291,290114
3n, 4n)283,282112
249Cf(48Ca;
even-odd
3n, 4n)287,286114
3n),294114
287
even-even
114
283
287
112
114
283
290
112
286
114
275
108
291
279
283
112
110
116
286
116
294
114
118
E
271
106
8.0
9.0
10.0
11.0
12.0
9.0
10.0
11.0
Alpha particle energy (MeV)
12.0
Excitation functions
xn-channel cross sections
from 242,244Pu+48Ca reactions
the maximum cross sections
for evaporation residues are
observed at the excitation
energy ~ 40 MeV
(hot fusion).
Cross sections / 3 MeV (relative units)
50
10
3n
2n
3n
4n
5n
4n
5
1
2n
0.5
5n
0.1
25
30
35 40
55
50
45
Excitation energy (MeV)
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
Synthesis of Element 118
3n
245
Cm +
48
249
Ca
Cf + Ca
2n
3 ev.
1
3n
291
11 ev.
116
10.74 MeV
+32
114 26-9 ms
287
2
10.03 MeV
+1.3
112 1.1 -0.4 s
283
3
9.55 MeV
+8.3
110 7.0 -2.5 s
279
4
48
2
282
112
116
116
1
286
10.84 MeV
+6.4
114 9.7 -2.8 ms
286
10.15 MeV
0.17 +0.09
-0.04 s
1
290
290
1
3 ev.
3
282
112
114
SF
10.16 MeV
0.22 +0.26
-0.08 s
202 MeV
0.9 +-0.1.30 ms
9.70 MeV
108 0.55+0.76
-0.19 s
275
5
271
6
267
104
106
_0.34 MeV
9.56 +
0.42 s
Yu. Oganessian et al., Phys. Rev C 74, (2006) 044602
_0.36
8.84+
91.1 s
SF 240 MeV
21 min
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
118
11.65 MeV
1.3 +1.5
-0.5 ms
10.82 MeV
14 +17
- 5 ms
SF~50%
SF 206 MeV,
1.5+1.0
-0.4 ms
294
Decay
chains
237Np
243Am
293
242Pu, 245Cm
294
117 117
244Pu, 248Cm
89
decay chains
was registered
115/287 115/288
87 ms
32 ms
249Cf

113/282 113/283 113/284
0.1 s
0.48 s
73 ms

111/27 8 111/279
0.17 s
4.2 ms

10.69

109/274 109/275 109/276
0.72 s
0.45 s 9.7 ms

9.76
10.33

107/270 107/271 107/272
9.8 s
1 min

8.93

9.02

270
105/266 105/267 105/268
1.2 d
0.37 h 1.2 h
104/268
Db
104/268
9.71

274
107
10.37

10.63

111/280
3. 6 s
9.75
10.12
10.00

281
282
111 111
10.59
10.46
289
290
115 115

285
286
113 113
249Bk(320d)+48Ca
FLNR-ORNL-LLNL
collaboration
278
109
36 nuclides
June 2009
22 mg of
249Bk
have been produced
at Oak Ridge National Laboratory by
intense neutron irradiation for 250
days in the High Flux Isotope Reactor
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
Confirmation
Darmstadt 2007
GSI SHIP
Reaction:
283
4 events
3
112
9.52+_ 0.02 MeV
6.9+6.9
-2.3 s
279
110
238
U + 48 Ca - 283 112 +3n
TKE 210+32
-11 MeV
+0.32
0.18 -0.07 s
S. Hofmann et al., Eur. Phys. J. A32 (2007) 251
Dubna 2006-2007
CHEMISTRY
Reaction:
242,244Pu
+ 48Ca
FLNR / PSI
2
5 events
283
3
279
110
112
-
287,288114
3
114 events

287
2
10.04
MeV
284
+ 3,4n
288
1
16 evens
114
2
_ 0.1 MeV
9.9+
112
_ 0.12 MeV SF
9.49+
0.1 s
>3s
TKE ~ 220
0.21+0.3
-0.1 s
Dubna 2002-2004
DGFRS
R. Eichler et al., Nature 447 (2007) 72
22 events
3
279
110
283
112
291
292
116
287
114
1
18 evens
2
_ 0.06 MeV 284
10.02 +
0.5+0.2
112
-0.1 s
_ 0.06 MeV
9.54+
3.8+1.2
-0.7 s
_ 7 MeV
SF>90% TKE 225 +
0.2+0.05
-0.04 s
116
288
114
_0.06 MeV
9.94+
0.8+0.3
-0.2 s
SF>90%
_ 7 MeV
TKE 228 +
0.1+0.03
-0.02 s
Decay Properties
12.0
Theory:
118
Alpha decay energy (MeV)
Z-even
11.0
116
10.0
114
108
112
9.0
106
110
Exp:
8.0
7.0
260
Z-even
270
280
290
Atomic mass number
300
18
Th.
Spontaneous fission half-lives
16
14
Actinides
N=152
N=152
N=184
12
Log TSF (s)
10
Z=112
Cf
N=162
8
Superheavy nuclei
Trans-actinides
6
Fm
4
108
2
Exp.
110
0
Cf-No
Rf
Sg
Hs
Ds
112
114
114
No
-2
112
-4
Rf
-6
-8
140
145
150
155
160
165
170
175
Neutron number
180
185
Half-life, T (s)
102
Half lives of
nuclei with Z ≥ 110
111
110
sf
112
113
available for
chemical studies
114
100
sf
N=162
10-2
116
112
115 sf
111
118
112
-4
10-4
10
110
113
112
sf
Act. + 48Ca
10-6
155
160
165
170
Neutron number
175
180
With Z >40% larger than that of Bi, the heaviest stable element,
that is an impressive extension in nuclear survival.
Although the SHN are at the limits of Coulomb stability,
shell stabilization lowers:
the ground-state energy,
creates a fission barrier,
and thereby enables the SHN to exist.
The fundamentals of the modern theory
concerning the mass limits of nuclear matter
have obtained experimental verification
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
protons →
Atomic structure and
chemical properties
of the SHE
Nuclear structure
and decay properties
of the SHN
120
Search for
new shells
SHE
-7
110
-5
-6
Search for
SHE in Nature
-4
-5
100
-3
-4
-3
-2
-4
90
U
Th
-2
Pb Bi-14
neutrons →
80
120
130
140
150
160
170
180
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
190
Chemical properties
Atomic properties
Relativistic Contraction
rmax : principal maximum of the wave function of the outermost orbital
1,05
rel
rmax /rmax
non-rel
1,00
1s 2p 3p
2s 3s
4s
3d
4p
5s
0,95
5p
6p
non-relativistic
-
4d
6s
Hg
Pb
4f
0,90
~ Z2
5d
7s
relativistic
0,85
0,80
5f
J.P. Desclaux, At. Data Nucl..
Data Tables 12, 311 (1973)
112
114
SHE
0,75
0
20
40
60
Z
80
100
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
120
Chemical isolation
Chemical
properties
1
1
H
1
2
2
Li
Be
3
4
3 Na
11
Mg
3
12
6
4
8
7
9
10
11
18
He
13
14
15
16
17
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
14
12
12
Ca
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
19
20
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
Cd
In
Sn
Sn
Sb
Tc
I
Xe
37
38
39
40
42
43
44
45
46
47
48
48
49
50
50
51
52
53
54
Cs
Ba
W
Re
Os
Ir
Pt
Au
Hg
Hg
Ti
Pb
Pb
Bi
Po
At
Rn
Rn
55
56
74
75
76
77
78
79
80
81
82
82
83
84
85
86
86
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Ds
Ds
Rg
87
88
104
105
106
107
108
109
110
110
112
112
113
114
114
relativistic
115
116
117
5
6
7
Hf
Ta
72
Pu
94
Darmstadtium
4 K
111
118
Reaction:
R. Eichler et al., Nature 447 (2007) 72
Compound
Compound Hg(Au)
Hg(Au)
242Pu(48Ca,3n)287114[0.5s]→α→283112[3.6s]
and
and 112(Au)
112(Au)
Au
SiO2
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
-50
Hg
20
Relative yield %
He/Ar + Hg + Rn
Rn
112
1
4
-150
8
12
Gold
30
28
32
-200
Hg
0
Ice
on gold
-50
Rn
20
0
Relative yield %
24
50
40
-100
112
1
4
8
12
50
-150
16
20
Detector number
24
28
32
room temperature
Ice
0
30
Hg
20
0
-200
50
40
on gold
10
gas flow 1.5 l/min
16
20
Detector number
50
10
gas flow 0.89 l/min
-100
-50
on gold
Rn -100
on ice!
-150
112
1
4
8
12
16
20
Detector number
24
28
32
Temperature 0C
0
Ice metal – like Hg
Gold
Element
112 is a noble
30
0
50
Temperature 0C
40
10
gas flow 0.86 l/min
Hg
Rn
-200
Temperature 0C
Relative yield %
on gold
50
Reaction:
Compound
Compound Pb(Au)
and 114(Au)
242Pu(48Ca,3n)287114[0.5s]
1
283
2
112
287
114
10.02 MeV
0.5 s
9.54 MeV
110 3.8 s
281
SF 0.2 s
TKE=225MeV
1
2
283
287
114
10.04 MeV
112
9.53 MeV
110 10.9 s
281
SF 0.24 s
TKE= 220MeV
Ю.Ц. Оганесян «Пределы масс атомных ядер» 27 ноября 2009г. ИТЭФ, Москва
1
1
18
He
H
1
2
Li
Be
3
4
3 Na
11
13
2
14
15
16
17
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
Periodic Table of Elements
Mg
3
12
5
4
6
7
8
9
10
11
12
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Tc
I
Xe
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
6 Cs
Ba
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Ti
Pb
Bi
Po
At
Rn
55
56
73
74
75
76
77
78
79
80
81
82
83
84
85
86
Fr
Ra
Rf
Db
Sg
Bh
Hs
Mt
Ds
Rg
87
88
104
105
106
107
108
109
110
112
113
114
114
115
115
116
117
118
5
7
72
Darmstadtium
Ca
4 K
111
?
more and more inert?
Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept 24-25. 2009, Dubna
Progress
Progress in
in HE-research
HE-research
“relativistic effect”
in SH - atoms
neutron
shells
neutron shells
of
SH-nuclei
of SH-nuclei
162
protons
cold
fusion
evidence of enhanced
stability of SH nuclei
152
184
hot
hot
fusion
fusion
105
chemistry
chemistry of
of
TA-elements
TA-elements
fission
modes
126
search
for SHE
in Nature
SF-isomers
82
neutrons
Спасибо за внимание к моему сообщению
20
Search for SHE
In Nature
Age of the Earth
15
search in the
cosmic rays
Spherical
Shell
108 y
105 y
10
108
α - decay
Log Tα (sec.)
1y
5
1d
Deformed
Shell
β-stable
nuclei
110
114
0
118
-5
108
112
-10
116
140
150
170
180
160
Neutron number
190
search
in nature
120
110
Hs
β-
proton number
105
β-
100
proton
drip line
waiting
point
Pu
U
Th
90
Pb
82
80
β-
A=278
184
waiting
point
70
neutron
drip line
60
A=195
50
50
126
100
120
140
160
180
neutron number
200
Extended Thomas-Fermi plus
Strutinsky integral method
Calculated fission barrier heights
A. Mamdouh et al.,
Nucl. Phys. A679 (2001) 337
Bf < 2.5 MeV
2.5 MeV < Bf < 4.5 MeV
4.5 MeV < Bf < 6.5 MeV
Bf > 6.5 MeV
120
3
110
Z=108
2
Z
1
100
-4
-2
90
-3
α-decay
Cyclamen
1966
-4
4
140
3
160
2
β--decay
EC
1
180
SF
200
N
220
Average number of neutrons per fission
7.0
Exp.
asymm.
fission
Calc.
6.0
282
Sg
286
Hs
symm.
fission
5.0
268
Db
symm.
fission
No
4.0
asymm.
fission Cf
3.0
Bk
Fm
Cm
Pu
2.0
U
1.0
220
230
240
250
270
260
Mass number A
280
290
300
Assuming for the SH-nuclide TSF = 109 years
the counting rate 1 decay / year
from a 1000-g metallic Os sample
corresponds to the ratio Hs/Os:
~ 7·10-16 g/g
or ~ 10-23 g/g
3 He - counters
Os-sample
550 g. (metallic)
Fréjus peak
in the Earth's crust
or in the meteorit’s
matter
in comparison with previous attempts
the sensitivity is increased by a factor ~ 109
Modane
Yu. Oganessian “Heaviest Nuclei” Int. Conf. Nuclear Structure & Dynamics. May 4-8, 2009, Dubrovnik, Croatia
10
9
4.56.10 y
Age of the Earth
search
in nature
LogT1/2 (years)
5

Z = 108
0
SF
SF
-5

-10
-15
140
150
170
180
160
Neutron number
190