HEAVY ELEMENT RESEARCH AT THE FLNR (DUBNA) Yuri Oganessian Flerov Laboratory of Nuclear Reaction Joint institute for Nuclear Research The Fifth International Conference on Exotic Nuclei and Atomic Masses ENAM′08 September 7-13, 2008, Ryn, Poland

Macroscopic theory (Liquid Drop Model) Chart of nuclides Macroscopic theory (Liquid Drop Model) about 50 years ago… Spontaneous fission TSF = 2·10-7 y TSF = 1016 y TSF < 10-14 s 102No / Tα ≈ 2 s Th Bi 92U / Tα = 4.5·109 y 82Pb / stable

X Pb Chart of nuclides Nuclear shells (Shell model) 114 184 114 spherical shells Pb X spontaneous fission 162 108 deformed shells 152 100 deformed shells spherical 126 82 spontaneous fission

New lands Microscopic theory New lands about 40 years ago… -5 5 10 15 Neutron number P r o t n u m b e 100 110 120 130 140 150 160 170 180 190 90 80 70 New lands Microscopic theory New lands -5 5 10 15 LogT1/2 s 1µs 1s 1h 1y 1My about 40 years ago… Island of Stability Shoal Island of Stability shoal Peninsula Continent Sea of Instability peninsula continent

Reactions of Synthesis SHE actinides deformed nuclei spherical Pb Fusion of massive Ions with Pb-target nuclei Cold fusion Since 1975 protons → Light ion fusion with Act.-nuclei Hot fusion Neutron capture neutrons → Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Cold fusion cross sections and fusion probability Act.+48Ca Z=112-118 Ex=40-45 MeV Hot fusion Ex=12-15 MeV Cold fusion 1 event / year SHE

Cross sections σxn ~ (Γn / Γf)x; х – number of neutrons (Γn / Γf) ~ exp (Bf – Bn) Bf = BfLD + ΔEShell

Reactions of Synthesis SHE Cold fusion protons → Act.+48Ca Neutron capture Hot fusion actinides Pb neutrons → Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Reactions of Synthesis Targets: thickness (mg/cm2) Isotope enrichment (%) 233U 0.44 99.97 238U 0.35 99.3 237Np 0.35 99.3 242Pu 0.40 99.98 Chemistry 1.4 244Pu 0.38 98.6 243Am 0.36 99.9 Chemistry 1.2 99.9 245Cm 0.35 98.7 248Cm 0.35 97.4 249Cf 0.34 97.3 Act. + 48Ca Projectiles 48Ca Energy: 235-250 MeV Intensity: 1.0-1.2 pμA Consumption: 0.5 mg/h Beam dose: (0.35-2.5)∙1019

Experimental Setup Measured parameters: For recoils: energy TOF Total detection efficiency: for α-particles…………..83% for SF-fragment…….~ 100% for both fragments……..42% Experimental Setup Measured parameters: For recoils: energy TOF positions For decay product: time Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

242Pu +48Ca, 3n Recoils R-α-α-..SF correlations Fission fragments Yu. Oganessian J. Phys. G. 34 (2007) R165 Recoils R-α-α-..SF correlations Fission fragments 242Pu +48Ca, 3n

Z=114

Alpha-particle spectra of SH-nuclei 242Pu(48Ca; 3n, 4n)287,286114 Alpha-particle spectra of SH-nuclei 245Cm(48Ca; 2n, 3n)291,290114 238U(48Ca; 3n, 4n)283,282112 249Cf(48Ca; 3n),294114 even-odd even-even Alpha particle energy (MeV)

Synthesis of Element 118 Yu. Oganessian et al., Phys. Rev C 74, (2006) 044602 Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

The identification of the atomic and mass numbers of the nuclides was performed in several independent ways based on: the mechanism of fusion reactions excitation functions and cross bombardments ensuring variation of the proton and neutron numbers in the compound nucleus; production the same nuclei in different ways: as evaporation residues and as -decay products of heavier nuclei; the decay properties of the nuclei in the decay sequences: half-lives Tα and -decay energies Qα of even-even (and for many even-odd) isotopes; the radiochemical identification of the nuclides: 268Db 283112 and 287114 in correlated -decay chains.

Confirmation Confirmation CHEMISTRY 4 evens Confirmation Confirmation 5 evens 3 evens Dubna 2006-2007 Reaction: 242,244Pu + 48Ca - 287,288114 + 3,4n CHEMISTRY 16 evens 18 evens 22 evens

226Ra 237Np 243Am 242Pu, 245Cm 244Pu, 248Cm 249Cf Decay chains 89 Sg/266 0.2 s Hs/270 10 s 9.06 a Decay chains 237Np 249Cf 243Am + 48Ca 118 242Pu, 245Cm 36 nuclides 89 decay chains was registered 244Pu, 248Cm 116 114 112

Spontaneous fission half lives Actinides Superheavy nuclei Trans-actinides break of α-decay chains of SH-nuclei SF hole!

Alpha-decay energies Theory: I. Muntian, Z. Patyk, A. Sobiczewski, Acta Phys. Pol. B 34 (2003) 2073. Experiment: black – light ion induced reactions blue – cold fusion red – Act. + 48Ca reaction Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Theory and Experiment 48Ca-induced reactions cold fusion deformed shells spherical shells

available for chemical studies Act.+48Ca Pb+50Ti,…64Ni Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

It is my pleasure to convey my gratitude to my colleagues For these investigations we used intense 48Ca beams, produced at the heavy-ion cyclotron U-400 of the Flerov Laboratory of Nuclear Reactions (FLNR, JINR, Dubna). The experiments at the Recoil Separator were carried out in collaboration with the Analytical and Radiochemical Division of the Lawrence Livermore National Laboratory (LLNL, Livermore); the experiments on the chemical identification of 268Db and 283112 within the collaboration: Paul Scherrer Institute (PSI, Villigen), University of Bern, FLNR (Dubna), LLNL (Livermore), Institute of Electronic Technology (IET,Warsaw) and Dr. M. Hussonois from Institute of Nuclear Physics (IPN, Orsay). It is my pleasure to convey my gratitude to my colleagues and co-authors Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Thanks for your attention More information in topical review published in: the Journal of Physics G 34 (2007) R165-R242 Thanks for your attention

Atomic properties Atomic properties Zn Ge Cd Sn Hg Pb

Chemical properties relativistic 12 14 Ca 20 Rn 86 Pu 94 Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Compound Hg(Au) and 112(Au) Compound Hg(Au) and 112(Au) Reaction: R. Eichler et al., Nature 447 (2007) 72 Reaction: 242Pu(48Ca,3n)287114[0.5s]→α→283112[3.6s] Au SiO2 Yu. Oganessian. HE-research at FLNR. ENAM’08, Sept.7-13, 2008, Ryn, Poland

Element 112 is a noble metal – like Hg room temperature

Search for Element 120 The sensitivity of experiment MMM HFB RMF Search for Element 120 The sensitivity of experiment corresponds to σ=0.4 pb for detection of one event.

292120 294118 Nuclear density of the SHE α Z=120, A=298-300 60 α-particles + 60 neutrons 292120 294118 was produced in 249Cf+48Ca reaction

Search for SHE In Nature 108 y 105 y 1 y 1 d

β- Hs Pu U Th Pb β- waiting point

Calculated fission barrier heights Extended Thomas-Fermi plus Strutinsky integral method A. Mamdouh et al., Nucl. Phys. A679 (2001) 337 Z=108 Cyclamen 1966 α-decay β--decay EC SF

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 in the Earth's crust or in the meteorit’s matter Assuming for the SH-nuclide TSF = 109 years Fréjus peak in comparison with previous attempts the sensitivity is increased by a factor ~ 109 Modane

R-process simulation Courtesy: Gabriel Martinez-Pinedo

Th-U SHE

Theory and Experiment 48Ca-induced reactions cold fusion deformed nuclei spherical

Search for Element 120 In symmetric fusion in symmetric fusion 1event 136Xe+136Xe → 269-271Hs+1n-3n Testing in reaction: 176Yb+132Sn→306120+2n

xn-channel cross sections 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). Yu. Oganessian, Synthesis of the heaviest nuclei. Sept. 1-7, 2008, Zakopane, Poland