Programme Advisory Committee for Nuclear Physics 33th meeting, January 2011 FLNR Radiochemical Research. Present Status and 7-year Plan S. Dmitriev

2 Identification and Study of Chemical Properties of New Elements of the Mendeleev Periodic Table

3 IVVVI HfTaW  1966 – I.Zvara et al. – Gas-phase Chemistry HfCl 4 TaBr 5 WO 2 Cl 2 HfCl 4 TaBr 5 WO 2 Cl 2 104Cl 4 105Br 5 106O 2 Cl 2 CHEMISTRY OF TRANSACTINIDES (Z>103)

Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 6 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Pt 79 Au 80 Hg Rf 105 Db 106 Sg 107 Bh 108 Hs 109 Mt 110 Ds 111 RgCn RfCl 4 DbCl 5 SgO 2 Cl 2 BhO 3 ClHsO 4  RfBr 4 DbBr Rf(  ) 262,263 Db(  ) 266 Sg( ,SF) 267 Bh(  ) 269 Hs(  ) 268 Mt(  ) 271 Ds(  ) 272 Rg(  ) 277 Cn(  ) 78 s  30 s 21 s17 s9.7 s21 ms1,6 ms3,8 ms0.69 ms

Number of observed decay chains Element Element Element Element Element Element 112 8

Relatively long half-lives of isotopes of elements produced in reactions with 48 Ca and chemical properties of SHE predicted theoretically permit new experiments aimed at:  the chemical identification of SHE,  study of their chemical properties,  determination of masses of the SHE isotopes

~20 s Of-line chemical separation of 268 Db Z=115 Nb / Ta / Db - fraction Dmitriev S N et al., Mendeleev Commun.15 (2005) 1 Schumann D et al., Radiochim. Acta 93 (2005) 727 Stoyer N J et al., Proc.9th Int. Conf. NN Collisions,Brazil, 28 Aug.–1 Sep Oganessian Yu Ts et al., Phys. Rev. C 69 (2004) Transactinides

15 events 48 Ca Am N Sample (data) t irr hr Beam Dose E bot +E top + 1 n (t,c) t detect hr t measurement hr 1 (12.06) 20 2,5 n (5;64) (13.06) 22 3,710 17 ̶ n (57) (14.06) 22 3,4 n (3) n (8;16) (15.06) 22 2,9 n (2) n (151) n (89) (17.06) 38 6,7 n (6,98) n (4,31,43) n n (6,41) (18.06) 23 3,9 n (2,2) (19.06) 22 3,6 (21.06) 45 7,4 n (5;33) n (72,165) n (12,19,29)  3,

9 Spontaneous fission half-life of 268 Db (N=163) T 1/2 = 32 h 15 events 252 Cf 268 Db Q F ~ 280 MeV

Mendeleev periodic table of the elements (2010)

11 GAS PHASE CHEMISTRY WITH ELEMENTS 112 AND 114  Are elements 112 and 114 volatile metals?  How do relativistic effects influence the chemistry of E112 and of E114?

 contraction and stabilization of s and p 1/2 orbitals  expansion and destabilization of d and f orbitals  SO splitting of p, d, f orbitals j = l  s j = l  s  R e (7s) = 20% scale as ~ Z 2 Relativistic effects

13 How to determine experimentally a metallic character of a volatile element at a single atom level? → Determine interaction energy (adsorption enthalpy) with noble metals (e.g. Au) → If metallic: strong interaction (adsorption enthalpy) if non-metallic (noble gas like): weak interaction

Reaction: 242 Pu (48 Ca,3n) [0.5s ]→α→ [3.6s ] Compound Hg(Au) and 112(Au)

Observed in Chemistry: s 9.54 MeV s MeV 279 Ds 0.18 s SF(>90%) 205 MeV Reported at FLNR: Oganessian et al ms 10.7 MeV The Observation Dubna 2006/2007 Eichler, R. et al. Nature (2007) Experiments with element °C -5°C -26°C -44°C on gold -126°C on ice 242 Pu ( 48 Ca, 3n) weeks: 6*10 18 of 48 Ca

17 48 Ca Pu 48 Ca Pu s 9.53 MeV MeV 279 Ds 0.24 s SF s 9.54 MeV s MeV 279 Ds 0.18 s SF DGFRSDGFRS ChemistryChemistry Т ads = -88 °C

18 48 Ca Pu 48 Ca Pu MeV  :109 ms SF ms SF s 9.95 MeV Т ads = -84 °C DGFRSDGFRS ChemistryChemistry

19 Result from the chemistry experiment with element 114 → Element 114 exhibits a very weak interaction with Au - pointing to a physisorptive interaction (similar to a noble gas). → A quantitative description of this behaviour is lacking so far.

The results obtained up to 2010 (synthesis of new elements with atomic numbers 113, 114, 115, 116 and 118, investigation of their nuclear and chemical properties, first experimental observation of the influence of relativistic effects on the chemical behavior of SHE) served as a starting for the new 7-year program for 2010 – 2016.

FLNR main directions of studies according to the JINR 7-year plan ( ) 1. Synthesis of superheavy elements and study of their properties; 2. Chemistry of SHE; 3. Investigation of spontaneous and induced fission; 4. Mass-spectrometry and nuclear spectroscopy of isotopes of heavy and transfermium elements; 5. Study of mechanisms of reactions with stable and radioactive nuclei; Accelerator operation time in the 2010: U hours U400M4570 hours

22 Synthesis of a new element with atomic number Z=117 Yu. Ts. Oganessian, 1) F. Sh. Abdullin, 1) P. D. Bailey, 2) D. E. Benker, 2) M. E. Bennett, 3) S N. Dmitriev, 1) J. G. Ezold, 2) J. H. Hamilton, 4) R. A. Henderson, 5) M. G. Itkis, 1) Yu. V. Lobanov, 1) A. N. Mezentsev, 1) K. J. Moody, 5) S. L. Nelson, 5) A.N. Polyakov, 1) C. E. Porter, 2) A. V. Ramayya, 4) F. D. Riley, 2) J. B. Roberto, 2) M. A. Ryabinin, 6) K. P. Rykaczewski, 2) R. N. Sagaidak, 1) D. A. Shaughnessy, 5) I.V. Shirokovsky, 1) M. A. Stoyer, 5) V. G. Subbotin, 1) R. Sudowe, 3) A. M. Sukhov, 1) Yu. S. Tsyganov, 1) V. K. Utyonkov, 1) A. A. Voinov, 1) G. K. Vostokin, 1) and P. A. Wilk 5) 1 Joint Institute for Nuclear Research, RU Dubna, RF 2 Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 3 University of Nevada Las Vegas, Las Vegas, NV 89154, USA 4 Vanderbilt University, Nashville, TN 37235, USA 5 Lawrence Livemore National Laboratory, Livermore, CA 94551, USA 6 Research Institute of Atomic Reactors, RU Dimitrovgrad, RF (Dated: April 1, 2010) The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes and were produced in fusion reactions between 48 Ca and 249 Bk. Decay chains involving eleven new nuclei were identified by means of the Dubna Gas Filled Recoil Separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z≥111, validating the concept of the long sought island of enhanced stability for super-heavy nuclei

23 DGFRS Chemistry of the Element MeV 3.6 s Mt 276 Rg MeV 0.72 s Bh 272 SF TKE = 205(5) MeV 16 h 9.02 MeV 9.8 s Db Am + 48 Ca 3n MeV 0.48 s α2α2α2α2 α4α4α4α4 α3α3α3α3 α5α5α5α5 α1α1α1α MeV 87 ms (9) MeV MeV α2α2α2α α3α3α3α3 SF TKE = 218(5) MeV 38 s Rg (8) MeV 9.48(11) MeV 9.96 MeV (8) MeV MeV α1α1α1α1 7.9 s 1.2 s 0.32 s 0.22 s 21 ms 10 ms (40) MeV MeV α2α2α2α (10) MeV 9.43 MeV Mt 278 α4α4α4α4 Rg 282 α3α3α3α3 9.55(19) MeV 9.14 MeV Bh 274 α5α5α5α5 SF TKE = 219(5) MeV 33.4 h α6α6α6α6 8.80(10) MeV 8.43 MeV Db (10) MeV 9.56 MeV (10) MeV MeV α1α1α1α1 1.3 min 7.4 min 11.0 s 13 s 0.74 s 8.1 s 28.3 s 16 s s 1.0 s 112 ms 45 ms Bk + 48 Ca

24 Target ( 249 Bk ;  0,5 mg/cm 2 ) SiO 2 - Ta 800°C (4  ) (4  ) He/Ar (70/30) CHEMISTRY OF THE 113 ELEMENT Au pairs 2.5m 1 L/min

25 16 pairs of gold covered detectors

26 Target 249 Bk (0.5 mg∙cm -2 ) nat Nd (30 μg∙cm -2 ) 48 Ca E mid. target = 252 MeV I ~ 9 eμA Irradiation: – ; target I - 3.5∙10 18 ; target II - 5.6∙ ∙ Ca Bk

27 Alpha and SF spectra

DGFRS 04 May :05:4616 May :29:54 Bk-target I Bk-target II α2α2α2α MeV s Mt 278 α4α4α4α4 Rg 282 α3α3α3α MeV 6.49 s Bh 274 α5α5α5α5 SF MeV h α6α6α6α MeV min Db Bk + 48 Ca 3n 9.62 MeV α1α1α1α1 Bot (40) MeV MeV α2α2α2α (10) MeV 9.43 MeV Mt 278 α4α4α4α4 Rg 282 α3α3α3α3 9.55(19) MeV 9.14 MeV Bh 274 α5α5α5α5 SF TKE = 219(5) MeV 33.4 h α6α6α6α6 8.80(10) MeV 8.43 MeV Db (10) MeV 9.56 MeV (10) MeV MeV α1α1α1α1 1.3 min 7.4 min 11.0 s 13 s 0.74 s 8.1 s 28.3 s 16 s s 1.0 s 112 ms 45 ms E* = 35 MeV 1 event α2α2α2α MeV 1.85min Mt 278 α4α4α4α4 Rg 282 α3α3α3α3 Bh 274 α5α5α5α5 SF MeV h α6α6α6α MeV <1.42 min Db Bk + 48 Ca 3n α1α1α1α1 Bot. 4 Top 4 28 preliminary

29 Hg-185 DISTRIBUTION

Experimental program of Chemistry of 113 element ( 243 Am + 48 Ca) Chemistry of 112 and 114 elements ( 242 Pu + 48 Ca) Chemistry of 105 element ( 243 Am + 48 Ca)(off-line)

New Set-ups for Radiochemistry according to the 7-year plan ( ) 1. Pre-separator (background, short lived isotopes); 2. New detector systems (max. information from single event); 3. New high beam current targets; 4. New radiochemical laboratory, II class (targets preparation, chemistry of long-lived SHE).

244 Pu ( 48 Ca, 3-4n) Experiments with element 114 DGFRS COLD D Q1 Q2 10°C -160°C 400  g/cm Pu t trans ~1.4 s Gas flow: Ar 2.1 l/min Recoil ranges tested with: 206 Rn, 185 Hg, 254 No  Reliable design: 3  m Mylar, 1.5 cm Ar (1 bar)

Preliminary Results Dubna 2007/2008 Factor ~2-3 loss in overall efficiency: thin targets (2-3) transmission of a separator (3) No preseparation DGFRS preseparation 

New FLNR gas-filled separators “physical” “chemical” ReactionTransmission 244 Pu( 48 Ca,3n) % 244 Pu( 58 Fe,4n) %

Detectors for chemical studies cryo-on-line-detectorcombined α-, γ-, SF- detector carrier gas Si (α,SF) - detectors Clover γ - detectors

NEW EXPERIMENTAL HALL

New Set-ups for Radiochemistry according to the 7-year plan ( ) 1. Pre-separator (background, short lived isotopes); 2. New detector systems (max. information from single event); 3. New high beam current targets; 4. New radiochemical laboratory, II class (targets preparation, chemistry of long-lived SHE). Creation of set-ups will be synchronized with the construction of the new experimental hall and accelerator.

THANKS FOR YOUR ATTENTION!

39 48 Ca Enrichment up to 68-70% (Lesnoy) isotope production high flux reactors (Oak Ridge, Dimitrovgrad) isotope enrichment 98-99% S-2 separator (Sarov) New ECR-ion source (GANIL, JINR) New separator & detectors (Dubna, Livermore) New target matter technology of the target preparation – 0.3 mg/cm 2 Separation and detection of superheavy nuclei Efforts focused on the synthesis of SHE REACTORREGIMEACCELERATORS ISOTOPE ISOTOPEENRICHMENT TARGET TECHNOLOGY NEWRECOILSEPARATOR

40 SHE fusion survival Cold & hot fusion cross sections

Aqueous-phase Chemistry 1980 г. –E.Hulet et al.; D.Hoffman et al. 261 Rf (78 s ) - extraction RfClx (amine, TBP, TIOA) - Sorbtion (cation-exchange resin) - Sorbtion (cation-exchange resin) Rf  Hf  Zr (of- line) ARCA (Automated Rapid Chemistry Apparatus) 263 Db – 27 s Db  Ta  Nb SISAK (Short-lived Isotopes Studied by the AKufve technique) ( 257 Rf – 4 s) 104

243 Am + 48 Ca   268 Db 3n 5555 “Physical” experiment“Chemical” experiment Separation methodKinematic separatorRadiochemical separation Separation efficiency≈ 40%≈ 80% Registration Decay chains of nuclei with Z=115 SF nuclei with Z=105 Energy of 48 Ca-ion beam at the middle of target layer 246 MeV247 MeV Total ion beam dose (ions)4.5· ·10 18 Thickness of 243 Am target 0.3 mg/cm mg/cm 2 The number of events of the decay observed at experiment 315 Cross section of producing the mother nucleus of element 115 ~ 2,7 +4,8 -1,6 pb4,2 +1,6 -1,2 pb Half-life of 105 element hours hours Total kinetic energy of fission fragments ( TKE ) ~ 225 MeV~ 230 MeV The average neutron multiplicity per fission-4.2