106 th Session of the JINR Scientific Council September 24-25, 2009, Dubna Perspectives of JINR – ORNL Collaboration in the Studies of Superheavy Elements For JINR: Yu.Oganessian

1.Short Introduction 2.The “Island of Stability” of SHE 3.Test of nuclear models 4.Beyond the Periodic Table 5.Setting of the Z=117-experiment 6.Our efforts CONTENT

cold fusion about 25 years Act+ 48 Ca from 2000 Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Gas-Filled Recoil Separator Transmission for: EVR 35-40% target-like projectile-like Registration efficiency: for α-particles 87% for SF single fragment 100% two fragments ≈ 40% Targets: Isotopes of U, Pu, Am, Cm and Cf (now Bk) Beam: 48 Ca Experimental technique

Act Ca Target materials producer Isotope enrichment (%) 233 U IAR U — Np IAR Pu IAR Pu ORNL Am IAR / ORNL Cm IAR Cm ORNL / IAR Bk ORNL ≥ Cf ORNL / IAR 97.3 Projectiles 48 Ca produced by Heavy Ion Accelerator U Energy: MeV Intensity: pμA Consumption: mg/h Beam dose: ( )∙10 19 Reactions of Synthesis

243 Am 242 Pu, 245 Cm 226 Ra Sg/ s Hs/ s 9.06  σ 4n ≈ 10pb 237 Np 244 Pu, 248 Cm 249 Cf Decay chains Decay chains 34 nuclides 48 Ca + T 1/2 = 320d / / / / / / / / / / / / / / / / / / Bk + 48 Ca Collaboration: FLNR (Dubna) ORNL (Oak-Ridge) LLNL (Livermore) IAR (Dmitrovgrad) Vanderbilt University (Nashville)

Decay Properties of SH- nuclei

Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Spontaneous fission half-lives Actinides Trans-actinides Superheavy nuclei

Half lives of nuclei with Z ≥ 110 N=162 Half lives Act Ca

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 been verified experimentally for the first time Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Element 120 Test of nuclear models

MMM HFB RMF Microscopic theory and the properties of heaviest nuclei Microscopic theory and the properties of heaviest nuclei

116(exp) 298, EVR 3μs3μs 0.03s Z=116 Z=120 Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

3n 251 Cf ( α /898y) 238 U + 64 Ni GSI Pu + 58 Fe FLNR Cm + 54 Cr GSI Cf + 50 Ti ( α,SF/2.6y)

Cold fusion cross sections and fusion probability 1 event / year SHE E x =12-15 MeV Cold fusion Act.+ 48 Ca Z= Bk+ 48 Ca 251 Cf+ 50 Ti 248 Cm+ 54 Cr 244 Pu+ 58 Fe 238 U+ 64 Ni ~ pb Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Beyond the Periodic Table

Chemical properties Chemical properties Ca 20 Pu 94 Rn relativistic C h e m i c a l i s o l a t i o n 80 Hg 48 Cd 86

Reaction: 242 Pu (48 Ca,3n) [0.5s ]→α→ [3.6s ] R. Eichler et al., Nature 447 (2007) 72 Compound Hg(Au) and 112(Au) Compound Hg(Au) and 112(Au) Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Atomic properties Hg Pb critical SHE

more and more inert? Periodic Table of Elements 249 Bk( 320d ) + 48 Ca 243 Am( 7370y ) + 48 Ca Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

Isotopes of Element Bi + 70 Zn RIKEN (Tokyo) 0.24ms σ =0.03pb 243 Am + 48 Ca 237 Np + 48 Ca 243 Am + 48 Ca half-life JINR (Dubna) - - LLNL (Livermore) - - ORNL (Oak-Ridge) collaboration 0.07s0.5s10s σ =4.2pb Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

rotating target entrance window beam RECOILS q=q eq pumping acceleration RF RF+E RF q=1+ He H 2 +B stopping volume E separating window GAS CATCHER Guy Savard from Argonne National Laboratory beam of high quality Δt = ms transmission ≈ 50%

Mass Analyzer of Super Heavy Atoms (MASHA) Transmission for Hg-atoms ≈ 75% Mass measurements gas catcher intermediate focus Position of the detector array magnetic deflection electrostatic deflection M / M 3500 

Periodic Table of Elements 251 Cf + 48 Ca 3ms Es + 48 Ca 1ms 119

Setting an Experiment on the Synthesis of Setting an Experiment on the Synthesis of Element 117

Reaction: 249 Bk + 48 Ca → * → n T 1/2 =320d high intensity of 48 Ca beam (~1.5 pμA) U- 400 FLNR, JINR Separation, Detection & Identification 1 SH-atom / reaction products DGFRS Dubna Gas-filled Recoil Separator high neutron flux HIFR, ORNL chemical separation from 252 Cf (factor ) target preparation 36cm μm BkO μmTi IAR, Dimitrovgrad Yu.Oganessian. Perspectives of JINR – ORNL Collaboration in the studies of SHE. JINR Scientific Council, Sept , Dubna

22 mg of 249 Bk have been produced with neutrons of HIFR ORNL

Expected decay chain of the isotopes of element 117 A. Sobiczewski 10/ MeV 8.42 MeV 7.94 MeV 6.55 MeV 6.41 MeV 4.8h 5.1min 0.7h SF 5.9y27y

Cross sections Bk + 48 Ca

Gain factors for production of Super-heavy nuclei

In theory:from macroscopic (liquid drop) to microscopic (microscopic models) Checking models In accelerators from light ions 12 C- 16 O to massive one 48 Ca- 136 Xe new cyclotrons, ECR sources, etc to higher intensity new acceleratorors In method:from slow techniques wheels, He-jet to fast in-flight separators recoil separators to on-line separator gas catcher In the sensitivity: from the cross sections ≥ 10,000pb to the cross sections ≥ 0,5pb to the cross sections ≥ 0,05pb In the chemistry: from Actinidesto Trans-Actinidesto Superhavy Elements All these tasks took us about 40 years Now we would like to have it in 6 years! In order to understand the limits in the existence of the elements we had to move:

Thanks for your attention

Cross sections 117

T ads  C Hg 112 rel 112 nr Rn Localized adsorption (gold): Mobile adsorption (quartz): T ads of Hg and Element 112 on Quartz and Gold T ads  C V. Pershina 2006 Predictions Exp.2007 Quartz Gold