Synthesis of superheavy elements at FLNR S. DMITRIEV Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, , Russia PASIFICHEM 2010, PASIFICHEM 2010, 18 December 2010, Honolulu, Hawaii, USA

2 Cn

3 SHE Cold & hot fusion cross sections fusion survival

4 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

FLNR U400 cyclotron

v ( A=48 ) = 0.11 c q = v ( A=288 ) = c q = 6.2+ Experimental Setup

7 Total detection efficiency: for α-particles…………..83% for SF-fragment…….~ 100% for both fragments……..42% Focal plane detector

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

9 SHE fusion survival Cold & hot fusion cross sections

Relatively long half-lives of isotopes of elements produced in the reactions with 48 Ca and chemical properties of SHE predicted theoretically permit new experiments aimed at:  the chemical identification of SHE ( 268 Db)  study of their chemical properties (112,114),  determination of masses of the SHE isotopes

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

The Bk-249 was produced at ORNL (USA) by irradiation: of Cm and Am targets for approximately 250 days by thermal-neutron flux of 2.5  neutrons/cm²·s in the HFIR (High Flux Isotope Reactor). Irradiation ends December 2008

13 249Bk was produced at High Flux Reactor in Oak-Ridge………...March 09, mg of pure 249Bk was shipped to Moscow…………… June 20, 2009 Arrived at Dimitrovgrad (Russia) for target preparation……………..July 01, 2009 Experiment have started at Dubna…………… July 27, 2009

cm μg/cm 2 BkO 2 on 1.5 μm-Ti foil 120 mm ω = 1700 rpm Target target-making June 2009 Yu. Oganessian 2010

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% beam 48 Ca Experimental technique target 249 Bk Experiment was started July Yu. Oganessian 2010

First run: from July 27 to October 23, 2009 Beam dose: 2.4· %

17 2  1  3  Rg MeV 7.89 ms mm MeV str.#10, 12:28 Sep.10, mm 9.52 MeV ( ) MeV ( ) 2.22 s mm 4.25 s missing  N=N= ran N= ran  1  3  Rg ms mm mm MeV str.#10, 04:50 Sep.18, mm s MeV MeV ( ) 1.16 s mm s SF MeV ( ) MeV ( ) N= ran MeV 2  1  3  Rg ms mm mm mm 9.96 MeV str.#8, 04:23 Oct.17, mm 0.51 s MeV ( ) 0.24 s mm s SF MeV MeV SF MeV str.#10, 09:40 Aug.20,  1  3  Rg MeV ms mm mm missing  MeV 9.72 MeV s mm mm N= ran s SF N= ran MeV ( ) 2  1  3  Rg ms mm mm mm 9.36 MeV str.#10, 01:37 Oct.23, mm 0.42 s MeV s mm s SF MeV MeV E x =39 MeV Beam dose: 2.4·10 19

n E x =39 MeV E x =35 MeV Beam dose: 2.0·10 19

19 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

20 Decay properties of the nuclei in the decay chains of Z=117 isotopes Yu. Oganessian 2010

21 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

22 Capillary length from target chamber to detector system is 2.5 m

23 16 pairs of gold covered detectors

24 48 Ca Bk 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 ; target II ∙10 18

25 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 26 preliminary

DGFRS 04 May :05:4616 May :29:54 Bk-target I Bk-target II α2α2α2α MeV s Mt 27 8 α4α4α4α4 Rg 282 α3α3α3α MeV 6.49 s Bh 27 4 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 1.85m in Mt 27 8 α4α4α4α4 Rg 282 α3α3α3α3 Bh 27 4 α5α5α5α5 SF MeV h α6α6α6α MeV <1.42 min Db Bk + 48 Ca 3n α1α1α1α1 Bot. 4 Top 4 27 preliminary

29 Hg-185 DISTRIBUTION

30 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

Experimental program of Chemistry of 113 element (243Am + 48Ca) Chemistry of 114 element (244Pu + 48Ca) Mass number measurement of elements 242 Pu( 48 Ca,3n) (0.5s,α) –> (4 s) 243Am(48Ca,3n) –> (0.1 s, α) –> (0.5 s)

Introduction MA ss S eparator of H eavy A toms The proposed setup is a combination of the so-called ISOL method of synthesis and separation of radioactive nuclei with the classical method of mass analysis, allowing mass identification of the synthesized nuclides in the wide mass range. General ion-optical parameters: Range of energy variation, kV15-40 Range of Br variation, Tm Mass acceptance, %+/-2.8 Angular acceptance, mrad+/-14 Diameter the ion source exit hole, mm 5.0 Horizontal magnification at F1/F20.39/0.68 Mass dispersion at F1/F2, mm/%1.5/39.0 Linear mass resolution at F175 Mass resolution at F2 1150

Mass-spectrometer MASHA at the beam line of the cyclotron U-400M STATUS of the MASS-SPECTROMETER

FIRST EXPERIMENTS Mass identification of 112 и 114 elements synthesized at the reactions Mass identification of 112 и 114 elements synthesized at the reactions 242 Pu( 48 Ca,3n) (0.5 s) –> (4 s) Mass identification of 113 elements synthesized at the reaction Mass identification of 113 elements synthesized at the reaction 243 Am( 48 Ca,3n) (0.1 s) → (0.5 s) FIRST EXPERIMENTS Mass identification of 112 и 114 elements synthesized at the reactions Mass identification of 112 и 114 elements synthesized at the reactions 242 Pu( 48 Ca,3n) (0.5 s) –> (4 s) Mass identification of 113 elements synthesized at the reaction Mass identification of 113 elements synthesized at the reaction 243 Am( 48 Ca,3n) (0.1 s) → (0.5 s)

DRIBs-IIIDRIBs-III  Creation of the new experimental hall (≈ 2600 м 2 )  Creation of high current heavy ion accelerator  Development and creation of next generation set-ups

Gas-Filled Separator Ready time must be synchronized with the construction of the new experimental hall & accelerator ADVANTAGES:  presence of a gas – H 2, He; high energy and charge acceptances; additional target cooling through convection;  low number of elements;  no high voltage.

NEW EXPERIMENTAL HALL

a)b) c)d) a). Cumulative alpha spectrum from 16 pairs of detectors b). Cumulative spectrum of fission fragments from 16 pairs of detectors c). Cumulative alpha spectrum from 8 th pair of detectors d). Cumulative spectrum of fission fragments from 8 th pair of detectors

a). Cumulative alpha spectrum from 16 pairs of detectors b). Cumulative spectrum of fission fragments from 16 pairs of detectors c). Cumulative alpha spectrum from 4 th pair of detectors d). Cumulative spectrum of fission fragments from 4 th pair of detectors a)b) c)d)

Chromatographic deposition of 209 At and 185 Hg in the detector array at 0°C together with a standard Monte-Carlo simulation of the 209 At deposition.

The deposition of 185 Hg compared to the deposition of 209 At in the isothermal detector array at 0°C together with Monte-Carlo simulation of the depositions. The Hg deposition points to an efficient chromatographic gold surface the second part of the experiment.

THANK YOU FOR YOUR TIME!