Production of new neutron rich heavy and superheavy nuclei

Production of new neutron rich heavy and superheavy nuclei 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) Valeriy Zagrebaev, Mikhail Itkis, Alexander Karpov for SHE-2015, March 31, 2015, A&M University, USA JINR (Dubna)

We are still far from the Island of Stability 2

What is beyond 118 element? Heaviest target: 249 Cf Z max = 118 Ø Heavier projectiles ( 50 Ti, 54 Cr, 58 Fe, 64 Ni) Ø Heavier targets ( 251 Cf, 254 Es -???); Ø Symmetric reactions: 136 Xe+ 136 Xe, 136 Xe+ 150 Nd, 150 Nd+ 150 Nd; Ø Multi Nucleon Exchange - Reactions with RIB (??, or colliders technique (K4-K10)): Ø Nucleon transfer reactions ( 136 Xe+ 208 Pb, 238 U+ 248 Cm). Sufficient increasing of overall experiment efficiency is needed!

New elements 119 and 120 are coming! 4

Yields (arb.u.) TKE (MeV) 350 300 250 200 150 3 2 1 Mass-energy distributions of binary reaction fragments 36 S+ 238 U 274 Hs * Z=28 N=50 E*=46 MeV Z=82 N=126 50 100 150 200 250 48 Ca+ 238 U 286 Cn * E*=35 MeV Z=28 N=50 Mass (u) Z=82 N=126 Z=28 64 Ni+ 238 U 302 120 * E*=31 MeV 3 M=200 u M=208 u M=215 u 4 2 3 1 50 100 150 200 250 2 1 N=50 Z=82 N=126 50 100 150 200 250 260 250 240 230 220 210 Driving potentials are calculated with the NRV code (nrv.jinr.ru) potential energy (MeV) 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.

48 Ca+ 238 U 286 Cn Z t Z p 1840 2444 2576 TKE (MeV) 350 300 250 200 150 100 350 300 250 200 150 100 350 300 250 200 150 100 50 100 150 200 250 Mass (u) Yield (arb. units) 2.5 2.0 1.5 1.0 0.5 0.0 4 3 2 1 0 6 5 4 3 2 1 0 Y(A CN /2±20)=12% 58 Fe+ 244 Pu 302 120 Y(A CN /2±20)=8% 22 u 34 u 64 Ni+ 238 U 302 120 Y(ACN/2±20)=4% 11 u 50 100 150 200 250 Mass (u) Counts 800 700 600 500 400 300 200 100 0 120 100 80 60 40 20 0 10 8 6 4 2 0 70% 150 200 250 300 2% 200 250 300 350 0.2% 200 250 300 350 TKE (MeV) E * CN 45MeV for A CN /2±20 E.M. Kozulin et al., Dynamics of the 64 Ni+ 238 U reaction as a possible tool for synthesis of element with Z=120. Phys. Lett. B686, (2010), 227-232.

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.

88 Sr+ 176 Yb: shell effects in damped collisions TKE (MeV) Excitation energy (MeV) 360 340 320 300 280 260 240 220 200 180 160 100 10 0 3x10 0 10 1 3x10 1 10 2 3x10 2 10 3 3x10 3 10 4 60 80 100 120 140 160 180 200 90 80 70 60 50 40 30 20 10 Fragmet mass (u) 0 60 80 100 120 140 160 180 200 Fragment mass (u) -60-40 -20 0 20 40 60 80 100 120 140 TKEL (MeV) Potential energy (MeV) Yield (mb/(sr u)) 310 300 290 280 270 260 250 10 2 10 1 10 0 10-1 10-2 10-3 Z=28 N=50 58 Fe 88 Sr Z=50 N=82 176 Yb 40 60 80 100 120 140 160 180 200 220 Fragment mass (u) 88 Sr + 176 Yb Z=28 Z=82 10-4 170 175 180 185 190 195 200 205 Fragment mass (u) N=126 Z=82 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 88 Sr with 176 Yb at the Coulomb barrier energy. Phys. Rev. C89, 014614 (2014). 208 Pb

Fusion reactions with Radioactive Ion Beams for the production of neutron rich superheavy nuclei? No chances today and in the nearest future 9

Multinucleon transfer reactions for synthesis of heavy and superheavy nuclei

Production of superheavies in multi-nucleon transfers (choice of reaction is very important) 11

Shell effects: Pb valley normal (symmetrizing) quasi-fission inverse (anti-symmetrizing) quasi-fission 12

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

238 U + 248 Cm. Primary fragments 14

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

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)

New heavy nuclei in the region of N=126 blank spot

Test experiment on 136 Xe + 208 Pb collisions (Dubna, 2011) Experiment with Z identification of PLF was performed in Legnaro last summer 18

136 Xe+ 208 Pb: productions of heavy neutron-rich nuclei in multinucleon transfer reaction TKE (MeV) Yield (mb) 60 0 50 0 40 0 30 0 10 1 10 0 10-1 10-2 136 Xe+ 208 Pb(E c.m. =526 MeV) 136 Xe 208 Pb 10-3 100 12 0 1 40 160 180 20 0 2 20 240 Mass (u) cross section (mb) Cross sec(on for 210 Po, 222 Rn, 224 Ra (Ac(va(on analysis) 10 1 10 0 10-1 10-2 10-3 136 Xe+ 208 Pb (Ec.m.=514MeV) Z=84 Z=86 Z=88 200 205 210 215 220 225 230 Mass (u) 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 136 Xe + 208 Pb at laboratory energies around the Coulomb barrier: a candidate reactions for production neutron-rich nuclei at N=126. Phys. Rev. C86, 044611 (2012).

Production of new neutron rich heavy nuclei located along the last waiting point of astrophysical nucleosynthesis: Choice of reaction?

Fusion reactions How to separate a given nucleus from all the other transfer reaction products? Transfer reactions Available separators are not applicable!

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)

two pumping lasers Nd: YAG and three DYE lasers (+ Ti: Sapphire laser) New setup for selective laser ionization (FLNR, Dubna)

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 neutronrich 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. 24