production of new neutron rich heavy and superheavy nuclei...136xe+208pb: productions of heavy...
TRANSCRIPT
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Production of new neutron rich heavy and superheavy nuclei
Valeriy Zagrebaev, Mikhail Itkis, Alexander Karpov
for “SHE-2015”, March 31, 2015, A&M University, USA
JINR (Dubna)
• Fusion reactions • Elements 119 and 120 are on the way. What’s the next? • Radioactive ion beams?
• Multinucleon transfer reactions • Shell effects in damped collisions of heavy ions? • Production of new neutron rich SH nuclei in transfer reactions • Production of new neutron rich Heavy nuclei in transfer reactions • Separation of the products of transfer reaction (GALS setup)
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We are still far from the Island of Stability
2
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What is beyond 118 element?
Ø Heavier projectiles (50Ti, 54Cr, 58Fe, 64Ni) Ø Heavier targets (251Cf, 254Es -???); Ø Symmetric reactions: 136Xe+136Xe, 136Xe+150Nd, 150Nd+150Nd; Ø Multi–Nucleon–Exchange - Reactions with RIB (??, or colliders –
technique – (K4-K10)): Ø Nucleon transfer reactions (136Xe+208Pb, 238U+248Cm).
Sufficient increasing of overall experiment efficiency is needed!
Heaviest target: 249Cf → Zmax= 118 ↓
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New elements 119 and 120 are coming !
4
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Mass-energy distributions of binary reaction fragments
Driving potentials are calculated with the NRV code (nrv.jinr.ru)
150
200
250
300
350
36S+238U→274Hs*
E*=46 MeV
Mass (u)
64Ni+238U→302120*
E*=31 MeV
48Ca+238U→286Cn*
E*=35 MeV
Yie
lds
(arb
.u.)
TK
E (
MeV
)
Z=28
50 100 150 200 250
1
2
3
Z=28
Z=82N=126N=50Z=28
Z=82N=126N=50
M=200 u M=208 u M=215 u
50 100 150 200 250
1
2
3
50 100 150 200 250
1
2
3
4
Z=82N=126N=50
210
220
230
240
250
260poten
tial energ
y (M
eV)
• G.N. Knyazheva, I. Itkis, E.M. Kozulin. The time scale of quasifission process in the reactions with heavy ions. International Symposium Entrance Channel Effect on the Reaction Mechanism in Heavy Ion Collisions, Messina (Italy) - November 6-8, 2013, Journal of Physics: Conference Series 515 (2014) 012009.
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100
150
200
250
300
350
50 100 150 200 250100
150
200
250
300
35064Ni+238U→302120
Mass (u)
58Fe+244Pu→302120
0
1
2
3
4
50 100 150 200 2500123456
Mass (u)
100
150
200
250
300
35048Ca+238U→286Cn
TK
E (
MeV
)
0.0
0.5
1.0
1.5
2.0
2.5
Yie
ld (
arb. u
nit
s)
150 200 250 3000
100200300400500600700800
Co
un
ts
200 250 300 3500
20406080
100120
200 250 300 3500
2
4
6
8
10
TKE (MeV)
Y(ACN/2±20)=12%
Y(ACN/2±20)=8%
Y(ACN/2±20)=4%
1840
2444
2576
Zt Zp
34 u
22 u
11 u
70%
≤2%
≤0.2%
for ACN/2±20
E*CN≈45MeV
E.M. Kozulin et al., Dynamics of the 64Ni+238U reaction as a possible tool for synthesis of element with Z=120. Phys. Lett. B686, (2010), 227-232.
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Influence of entrance channel
Z1Z2=980 1472 2132 2660
• E.M.Kozulin, G.N.Knyazheva, I.M.Itkis, E.M.Gazeeva, N.I.Kozulina, T.A.Loktev, K.V.Novikov, I.Harca. Shell effects in fission, quasi-fission and in multi-nucleon transfer reactions. International Symposium Entrance Channel Effect on the Reaction Mechanism in Heavy Ion Collisions, Messina (Italy) - November 6-8, 2013, Journal of Physics: Conference Series 515 (2014) 012010.
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88Sr+176Yb: shell effects in damped collisions
170 175 180 185 190 195 200 20510-4
10-3
10-2
10-1
100
101
102
Z=82
Yie
ld (
mb
/(sr
u))
Fragment mass (u)
88Sr +176Yb
Z=28
60 80 100 120 140 160 180 2000102030405060708090100
Fragment mass (u)
Exci
tati
on
ener
gy (
MeV
)
40 60 80 100 120 140 160 180 200 220250
260
270
280
290
300
310
208Pb58Fe
N=50
Z=50N=82
N=126Z=82
Z=28
176Yb
Pote
nti
al ener
gy (
MeV
)
Fragment mass (u)
88Sr
140120100806040200-20-40-60
60 80 100 120 140 160 180 200
160180200220240260280300320340360
Fragmet mass (u)
TK
E (
MeV
)
100 3x100 101 3x101 102 3x102 103 3x103 104
TK
EL
(M
eV)
• E.M. Kozulin, G.N. Knyazheva, S.N. Dmitriev, I.M. Itkis, M.G. Itkis, T.A. Loktev, K.V. Novikov, A. Baranov, W.H. Trzaska, E. Vardaci, S. Heinz, O. Beliuskina, S.V.Khlebnikov. Shell effects in damped collisions of 88Sr with 176Yb at the Coulomb barrier energy. Phys. Rev. C89, 014614 (2014).
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Fusion reactions with Radioactive Ion Beams for the production of neutron rich superheavy nuclei ?
No chances today and in the nearest future 9
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Multinucleon transfer reactions for synthesis of heavy and
superheavy nuclei
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Production of superheavies in multi-nucleon transfers (choice of reaction is very important)
11
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Shell effects: Pb valley normal (symmetrizing) quasi-fission
inverse (anti-symmetrizing) quasi-fission
12
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U-like beams give us more chances to produce neutron rich SH nuclei in “inverse quasi-fission” reactions
experiment is scheduled for March at GSI (we want to see Pb+x, then Pb+Ca+Pb) 13
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238U + 248Cm. Primary fragments
14
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Production of transfermium nuclei along the line of stability looks quite possible (only if there are shell effects!?)
Rather wide angular distribution of reaction fragments: a new kind of separators is needed
experiments on Au+Th and U+Th are currently going on in Texas (without separators) 15
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Test (surrogate) reaction aimed on a search for the shell effects
in low-energy multi-nucleon transfer reactions
The experiment was performed (September 2014) at the Flerov Laboratory (Dubna)
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New heavy nuclei in the region of N=126
“blank spot”
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Test experiment on 136Xe + 208Pb collisions (Dubna, 2011)
18 Experiment with Z identification of PLF was performed in Legnaro last summer
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136Xe+208Pb: productions of heavy neutron-rich nuclei in multinucleon transfer reaction
30 0
40 0
50 0
60 0
TK
E (
MeV
)
100 12 0 1 40 160 180 20 0 2 20 24010
-3
10-2
10-1
1 00
1 01
208Pb
Mass (u)
Yie
ld (
mb)
136Xe+208Pb(Ec.m.
=526 MeV)
136Xe 200 205 210 215 220 225 230
10-3
10-2
10-1
100
101
Z=88
Z=84
Z=86
136Xe+208Pb (Ec.m.=514MeV)
cro
ss s
ecti
on (
mb
)
Mass (u)
Cross sec(on for 210Po, 222Rn, 224Ra (Ac(va(on analysis)
• E.M.Kozulin, E.Vardaci, G.N.Knyazheva, A.A.Bogachev, S.N.Dmitriev, I.M.Itkis, M.G.Itkis, A.G.Knyazev, T.A.Loktev, K.V.Novikov, E.A.Razinkov, O.V.Rudakov, S.V.Smirnov, W.Trzaska, V.I.Zagrebaev. Mass distributions of the 136Xe + 208Pb at laboratory energies around the Coulomb barrier: a candidate reactions for production neutron-rich nuclei at N=126. Phys. Rev. C86, 044611 (2012).
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Production of new neutron rich heavy nuclei located along the last “waiting point” of astrophysical nucleosynthesis:
Choice of reaction ?
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How to separate a given nucleus from all the other transfer reaction products ?
Fusion reactions
Transfer reactions
Available separators are not applicable !
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New setup for selective laser ionization and separation of multi-nucleon transfer reaction products stopped in gas
(project GaLS, to be realized in Dubna in 2015)
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New setup for selective laser
ionization (FLNR, Dubna)
two pumping lasers Nd: YAG and three DYE lasers (+ Ti: Sapphire laser)
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Summary
• Elements 119 and 120 can be really synthesized in the Ti and/or Cr fusion reactions with cross sections of about 0.05 - 0.02 pb.
• Multi-nucleon transfer reactions can be really used for synthesis of neutron enriched long-living SH nuclei located along the beta-stability line. U-like beams are needed as well as new kind of separators.
• Shell effects in production of trans-target nuclei (inverse quasi-fission) should be proved experimentally at last.
• Transfer reactions give a unique possibility for synthesis of heavy neutron-rich nuclei with N=126 – the last “waiting point” of astrophysical nucleosynthesis.
• Selective laser-ionization technique (GALS setup being developed at FLNR) is a powerful method of separation of the products of transfer reactions.
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