SYNTHESIS AND STUDY OF PROPERTIES

of SUPERHEAVY ELEMENTS AT FLNR.PRESENT STATUS AND FUTURE

S. DMITRIEV

Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research,

Dubna, 141980, Russia

e-mail: dmitriev@jinr.ru

Dual year Russia-Spain, Barcelona, Nov.8-11, 2011Particle Physics, Nuclear Physics

and Astroparticle Physics

United Nations Educational, Scientific and Cultural OrganizationInternational Union of Pure and Applied Chemistry

“Chemistry – our life, our future”

,

The 100th anniversary of the Nobel Prize in Chemistry awarded to

Marie Skłodowska-Curie

3

Synthesis of SHE via hot fusion of heavy target nuclei with light projectiles1960 1980

Synthesis of SHE via hot fusion of heavy target nuclei with light projectiles

Rutherfordium (Z=104)

Nobelium (Z=102)Lawrencium (Z=103) Seaborgium (Z=106)

Dubnium (Z=105)

-By irradiation of actinides with light ions inBerkeley (USA) and Dubna (Russia)the elements up to Z=106 could be synthesized Mendelevium (Z=101)

Synthesis of SHE via cold fusion (Pb and Bi as target nuclei)1980 2006

Synthesis of SHE via cold fusion (Pb and Bi as target nuclei)

Element 112

Hassium (Z=108)Meitnerium (Z=109)

Bohrium (Z=107)Darmstadtium (Z=110)Roentgenium (Z=111)

The linear acceleratorUNILAC and thevelocity filter SHIP at GSI allowed for the synthesis of elements with Z=107-112. -

Element 113

Neutron periodNeutron period

Astatin (Z=85)Neptunium (Z=93)

Americium (Z=95)Curium (Z=96)

Plutonium (Z=94) Californium (Z=98)

Berkelium (Z=97)

1940 1960

Ensteinium (Z=9 )9Fermium (Z=100)

1934Enrico Fermi proposed toirradiate Uranium withneutrons in order to synthesize heavier elements

1938Otto Hahn andFritz Strassmanndiscover theneutron inducednuclear fission

1896Discoveryof radioactivityby A.H. Becquerel

Radioactivity periodRadioactivity period

1899Actinium (Z=89) 1908

Radon (Z=86) 1918Protactinium (Z=91)

1896 1940

1898Polonium (Z=84)Radium (Z=88) 1940

G. Flerov andK. Petrzhakdiscover thespontaneousnuclear fission

5

10-30

10-32

10-34

10-36

10-38

102 104 106

1n

4n

108 110 112 114 116 118 120Atomic number

Cro

ss s

ectio

ns (

cm)2

Cold fusion

Hot fusion

208 209 48 50 70Pb, Bi + Ca, Ti,... Zn

Actinides + Ne, Mg,... S 22 26 34

SHE

Cold & hot fusion cross sections

fusion

survival

6

Isotopes: +U , Pu , Am , Cm[233, 238] [242, 244] [245, 248], [249][243] Cf Z = 112 - 118 48Ca

beam time - 4000 h/y

beam intensity - 4 - 8.10 /s 12

48Ca

Enrichment up to 68-70%

(Lesnoy)

isotope productionhigh 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/cm2

Separation and detection of superheavy nuclei

Efforts focused on the synthesis of SHE

REACTORREGIME

ACCELERATORSISOTOPEENRICHMENT

TARGET TECHNOLOGY

NEWRECOILSEPARATOR

FLNR U400 cyclotron

Number of observed decay chainsElement 118 3Element 116 26Element 115 4Element 114 43Element 113 2Element 112 8

9

10-30

10-32

10-34

10-36

10-38

102 104 106

1n

4n

108 110 112 114 116 118 120Atomic number

Cro

ss s

ectio

ns (

cm)2

Cold fusion

Hot fusion

208 209 48 50 70Pb, Bi + Ca, Ti,... Zn

Actinides + Ne, Mg,... S 22 26 34

4n-3nActinides + Ca 48

SHE

fusion

survival

Cold & hot fusion cross sections

The Bk-249 was produced at ORNL (USA) by irradiation: of Cm and Am targets for approximately 250 daysby thermal-neutron flux of 2.5 × 1015 neutrons/cm²·sin the HFIR (High Flux Isotope Reactor).

Irradiation ends December 2008

11

249Bk was produced at High Flux Reactor in Oak-Ridge………...March 09, 2009

22 mg of pure 249Bk was shipped to Moscow……………................June 20, 2009Arrived at Dimitrovgrad (Russia) for target preparation……………..July 01, 2009Experiment have started at Dubna…………….....................................July 27, 2009

Dubna Gas Filled Recoil Separator

v (A=48) = 0.11 cq = 16.5+

v (A=288) = 0.017 cq = 6.2+

Experimental Setup

6 cm2

310 μg/cm2 BkO2on 1.5 μm-Ti foilω = 1700 rpm

Target

target-makingJune 2009

0 5 10 15 20 25 30 35 40 45 500

5

10

15

20

25

30

27 1 10 20 30 40 50

10

20

30

0

Bea

m c

urre

nt (e

mA

)

Beam dose 1.5*1019

1 p A

~50 days3*10 per day17

0 5 10 15 20 25 30 35 40 45 50268269270271272273274275276277278

27 1 10 20 30 50

+_0.

75 M

eV

AugustJuly September

Ener

gy (M

eV)

273

269

277

Time (d)

E*=39.2 MeV

40

First run: from July 27 to October 23, 2009 Beam dose: 2.4·1019

0.3

%

15

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. Wilk5)

1 Joint Institute for Nuclear Research, RU-141980 Dubna, RF2 Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA3 University of Nevada Las Vegas, Las Vegas, NV 89154, USA4 Vanderbilt University, Nashville, TN 37235, USA5 Lawrence Livemore National Laboratory, Livermore, CA 94551, USA6 Research Institute of Atomic Reactors, RU-433510 Dimitrovgrad, RF

(Dated: April 1, 2010)

The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. 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

Number of observed decay chainsElement 118 3Element 116 26Element 115 4Element 114 43Element 113 2Element 112 8

Pure Appl. Chem., Vol. 83, No. 7, pp. 1485–1498, 2011

Discovery of the elements with atomic numbers greater than or equal to 113

(IUPAC Technical Report)

The IUPAC/IUPAP Joint Working Party (JWP) on the priority of claims to the discovery of new elements 113–116 and 118 has reviewed the relevant literature pertaining to several claims.

It was determined that the Dubna-Livermore collaborations share in the fulfillment of those criteria both for elements Z = 114 and 116.

17

Recognition of discovery of the elements 114 and 116

Confirmation of the synthesis of the 117th element

Relatively long half-lives of isotopes of elements 104-116produced in the reactions with 48Caand 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 268Db

rotatingentrance window

catcher ofrecoiling atoms

rotatingAm-target243

He box (1 tor)

beam

12.50

Nb / Ta / Db - fraction4 - fissionfragment detectors

π

78-3He - neutrondetector

Dmitriev S N et al., Mendeleev Commun.15 (2005) 1Schumann D et al., Radiochim. Acta 93 (2005) 727Stoyer N J et al., Proc.9th Int. Conf. NN Collisions,Brazil, 28 Aug.–1 Sep. 2006.

Oganessian Yu Ts et al.,Phys. Rev. C 69 (2004) 021601

10.46 MeV

9.75 MeV

9.71 MeV

125 ms

0.69 s

5.2 s

14.14 s

1.03 s

115

R

113

111

Mt

Bh

288

284

280

276

272

5

4

3

2

1α

α

α

α

α9.02 MeV

0.

23.1 h

SF

Db268

205 MeV

10. MeV00

EXPERIMENT SCHEME

Dubna Gas Filled Recoil Separator

v (A=48) = 0.11 cq = 16.5+

v (A=288) = 0.017 cq = 6.2+

Experimental Setup

Chemical Separation of 268Db- 2011

48Ca + 243Am

2005 2011243Am (mg cm-2) 1.2 0.5εtransm. 0.9 0.4

______________________________ K(Db/Ac)sep. --- 104-105

K(Db/Ac)chem. 104 104

Lanthanum fluoride radiochemical separation flow chart (4 h) Copper foil (~400 mg)

Dissolution7.5 ml 8 M HNO3175Hf, 92mNb, 177Ta (1 kBq)

Co-precipitationof group 4 and 5 elements

(2 times)Remove copper

Dissolve La(OH)3

Co-precipitationof group 4 elements

0.5 ml 1 M HF

0.5 ml 1 M HCl

3 M HFRemove Traces of La, Cu

La(NO3)3 (0.7 mg La)

Group 4 FractionDissolve LaF3

Group 5 Fraction0.5 M HCl / 0.5 M HF

AdsorptionAnion Exchange Column

DOWEX1×8, 6×12 mm

1 M HF Elute Group 4 elements

Sat. Boric acid 2 M HNO3

NH4OH

solutionprecipitate

AdsorptionCation Exchange Column

DOWEX50×8, 8×40 mm

Evaporation (1.5 ml)

Group 4 sample65-70 % Hf

Evaporation (0.5 ml)

Group 5 sample70 -80 % Nb, 65-75% Ta

1.5% H2O2 / 1.5 M HNO3Elute Group 5 elements

Mendeleev periodic table of the elements (2011)

29

GAS PHASE CHEMISTRY WITH ELEMENTS 112, 113 AND 114

Are elements 112, 113 and 114 volatile metals?

How do relativistic effects influence the chemistry of E112, 113 and of E114?

Relativistic Effects

contraction and stabilization of s1/2 and p1/2 orbitals

expansion and destabilization of p3/2 and d3/2

d5/2 orbitals

SO splitting of p, d, f orbitals: j = l± s

20 )/(1(/ cvmm −=

2200 /4 mea πε=

∆Re(7s) = 20%

scale as ~ Z2-23

-19

-15

-11

-7

-3

1

E, e

V

7s

6d

nr rel

7s1/2

6d5/2

6d3/2

112

112

31

How to experimentally determine a metallic character of a volatile element at a single

atom level?

→ Determine interaction energy (adsorptionenthalpy) with noble metals (e.g. Au)

→ If metallic: strong interaction (adsorptionenthalpy) if non-metallic (noble gas like):weak interaction

Reaction:242Pu(48Ca,3n)287114[0.5s]→α→283112[3.6s]

Compound Hg(Au)

and 112(Au)

2831126.1 s

9.54 MeV

2871141.1 s

10.04 MeV

279Ds0.29 s

SF(>90%)205 MeV

283112>3 s

9.45 MeV

287114

279Dslt: 0.592 s

SF108+123 MeV

283112>3 s

9.53 MeV

287114

279Dslt: 0.536 s

SF127+105 MeV

Reported at DGFRS:Oganessian et al. 2004 Observed in Chemistry:

11.05.20062:40 (Moscow time)Det. 2 (T ~ -24°C)

25.05.20068:37 (Moscow time)Det. 7 (T ~ -5°C)

34

283112

9.35 MeV

287114

279Dsτ: 0.773 s

SF85+12 MeV

Result from additional 48Ca + 242Pu experiments in 2007

Bombardement 21.3.- 17.4. 2007 with 3.1x1018 48Ca ions at 237± 3 MeV

283112

9.52 MeV

287114

279Dsτ: 0.072 s

SF112 + n.d MeV

283112

9.52 MeV

287114

279Dsτ: 0.088 s

SF94+51 MeV

4 81

50

50

-50

-50

0

0

-100

-100

-150

-150

-200

-20012

Rn

RnHg

Hg

RnHg

Detector number

Tem

pera

ture

C0

Tem

pera

ture

C0

16 20 24 28 32

4 81 12Detector number16 20 24 28 32

0

10

20

30

40

50

Rel

ativ

e yi

eld

%

0

10

20

30

40

50

Rel

ativ

e yi

eld

%

Gold Ice

Gold Ice

4 81

50

-50

0

-100

-150

-20012

RnHg

Detector number

Tem

pera

ture

C0

16 20 24 28 320

10

20

30

40

50

Rel

ativ

e yi

eld

%

Ice

He/Ar + + Hg Rngas flow 0.86 l/min

gas flow 0.89 l/min

gas flow 1.5 l/min

>140 MeV

α9.52 MeV

0.09 s

110279

112283

SF

on ice!

9.38+_0.12 MeV >3 s

0.53 s

110279

112283

231 MeV SF

α

on goldon gold

α>3 s

0.59 s

9.47+_0.12 MeV 110

279

112283

232 MeV SF on goldon gold

α9.52 MeV

0.07 s

110279

112283

112+F2 MeV SF

on goldon goldα

9.35 MeV

0.77 s

112283

85+12 MeV SF 110

279on goldon gold

112

112

112

Element 112 is a noble metal – like Hg

room temperature

36

48Ca + 244Pu

288114

9.95 MeV

284112τ:109 ms

SF

284112101 ms

SF

2881140.8 s

9.95 MeVТads= -84 °C

DGFRS Chemistry

37

Result from the chemistry experiment with element 114

→ Element 114 exhibits a very weak interactionwith Au - pointing to a physisorptiveinteraction (similar to a noble gas).

→ A quantitative description of this behaviour is lacking so far.

CHEMISTRY of ELEMENT 113

113 – 7s2 7p1/2 – less reactive and more volatile than TL

-∆Hads (Au): Tl = 240 kJ/mol (S.König)113 = 158.6 (V. Pershina)

- ∆Hads (inert surf) = 14 kJ/mol

39DGFRS

Chemistry of the Element 113

115288

113284

9.75 MeV3.6 s

Mt276

Rg280

9.71 MeV0.72 s

Bh272

SFTKE = 205(5) MeV

16 h

9.02 MeV9.8 s

Db268

243Am + 48Ca 3n

10.00 MeV0.48 s

α2

α4

α3

α5

α110.46 MeV

87 ms

115289

10.31(9) MeV10.48 MeV

α2

113285

α3

SF

TKE = 218(5) MeV38 s

Rg281

9.74(8) MeV9.48(11) MeV

9.96 MeV

117293

11.03(8) MeV11.26 MeV

α1

7.9 s1.2 s

0.32 s0.22 s

21 ms10 ms 117

297

115290

9.95(40) MeV10.23 MeV

α2

113286

9.00(10) MeV9.43 MeV

Mt278

α4Rg

282

α3

9.55(19) MeV9.14 MeV

Bh274

α5

SF

TKE = 219(5) MeV33.4 h

α68.80(10) MeV

8.43 MeVDb

270

9.63(10) MeV9.56 MeV

117294

10.81(10) MeV11.00 MeV

α1

1.3 min7.4 min

11.0 s13 s

0.74 s8.1 s

28.3 s16 s

0.023 s1.0 s

112 ms45 ms 117

297249Bk + 48Ca

40

Target 249Bk (0.5 mg·cm-2)natNd (30 μg·cm-2)

48Ca Emid. target = 249 MeVI ~ 9 eμA

Irradiation: - 18.04.2010 – 31.05.2010;

target I - 3.5 1018 ; target II - 5.6 1018

9.1·1018

48Ca + 249Bk

41

Target (249 Bk; ≅0,5 mg/cm2)

SiO2-

800°C

(4π)

He/Ar (70/30)

CHEMISTRY OF THE 113 ELEMENT

Au - 11316 pairs

2.5m

1 L/min

4000 6000 8000 10000 12000

100

101

102

103

104

105

106

107

Coun

ts /

5 ke

V

7450

8785

5300

5650

5867

66206805

211Po211At

210Po

185Hg

212Po

219Rn + 216Po

211Bi

20 40 60 80 100 120 140 160 180 200

100

101

102

103

Coun

ts / 0

.05

MeV

2 FF coincidedAlphas

4000 6000 8000 10000 12000

100

101

102

103

104

105

Coun

ts /

5 ke

V

Energy (keV)

7450

8785

5300 56505867 211Po211At210Po

185Hg

212Po

66206805

211Bi219Rn + 216Po

20 40 60 80 100 120 140 160 180 200

100

101

102

103

Coun

ts / 0

.05

MeV

Energy (MeV)

2 FF coincidedAlphas

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

a) b)

c) d)

9.61 MeV

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

10

20

30

40

50 Exp Hg-185 Sim Hg Exp At-209 Sim At

Yiel

d, %

Det #

Bk-target II

286113

The deposition of 185Hg compared to the deposition of 209At in the isothermal detector array at 0°C together with Monte-Carlo simulation of the depositions.

45DGFRS

Chemistry of the Element 113

115288

113284

9.75 MeV3.6 s

Mt276

Rg280

9.71 MeV0.72 s

Bh272

SFTKE = 205(5) MeV

16 h

9.02 MeV9.8 s

Db268

243Am + 48Ca 3n

10.00 MeV0.48 s

α2

α4

α3

α5

α110.46 MeV

87 ms

115289

10.31(9) MeV10.48 MeV

α2

113285

α3

SF

TKE = 218(5) MeV38 s

Rg281

9.74(8) MeV9.48(11) MeV

9.96 MeV

117293

11.03(8) MeV11.26 MeV

α1

7.9 s1.2 s

0.32 s0.22 s

21 ms10 ms 117

297

115290

9.95(40) MeV10.23 MeV

α2

113286

9.00(10) MeV9.43 MeV

Mt278

α4Rg

282

α3

9.55(19) MeV9.14 MeV

Bh274

α5

SF

TKE = 219(5) MeV33.4 h

α68.80(10) MeV

8.43 MeVDb

270

9.63(10) MeV9.56 MeV

117294

10.81(10) MeV11.00 MeV

α1

1.3 min7.4 min

11.0 s13 s

0.74 s8.1 s

28.3 s16 s

0.023 s1.0 s

112 ms45 ms 117

297249Bk + 48Ca

Experimental program of 2011-2012

Synthesis of 115 element (243Am + 48Ca)

Synthesis of 117 (119) element (249 Bk + 48Ca (50Ti)

Mass number measurement of 112 - 114 elements

242Pu(48Ca,3n)287114(0.5s,α) –> 283112(4 s)243Am(48Ca,3n) –> 288115 (0.1 s, α) –> 284113(0.5 s)

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

STATUS of the MASS-SPECTROMETER

Material of the catcher – flexible graphiteOperating temperature of hot catcher – 1500-1800оС Delivery time of atoms from hot catcher to the ECR ion source ~ 1 s

ECRion source

Hot catcher Target Beam line

Recoil transport

Heavy ionbeam

Target

Hot catcher(graphite)

1TO12, 114

ECR

Heater

Separating foil

Hot catcher scheme

Mass-spectrometer “MASHA” status

DRIBs-III

Creation of the new experimental hall (≈ 2600 м2) Creation of high current heavy ion accelerator Development and creation of next generation set-ups

2010 -2016

Gas-Filled Separator

Ready time must be synchronized with the construction of the new experimental hall & accelerator

ADVANTAGES: presence of a gas – H2, He; high energy and charge

acceptances; additional target cooling

through convection; low number of elements; no high voltage.

General ion-optical parameters of “MASHA” with gas catcher

Parameters ECR ion source

Gas catcher

Range of energy variation, kV 15-40 15-40Range of Bρ variation, Tm 0.08-0.5 0.08-0.5Mass acceptance, % 2.8 2.8Angular spread, mrad 14 5Diameter the ion source exit hole, mm 5.0 1.0Horizontal magnification at F1/F2 0.39/0.68 0.24/0.90Vertical magnification at F1/F2 2.4/3.13 1.5/1.25Linear mass resolution at F1 75 420Mass resolution at F2 1150 5700

UPGRADE OF THE MASS SPECTROMETER “MASHA”

Target box

Quadrupole

DeflectorGas catcher

Main parameters• Operating gas – He purity ~1 ppb. • Pressure into gas cell – 100-200 mbar.• Gas flow from the nozzle – 90-120 mbar·l/s• Extraction time ~ 10 ms.• Efficiency 10-40%.• Beam emittance ~3.0 π.mm.mrad

FROM ISOL TECHNIQUE TO GAS CATCHER

Gas catcher for heaviest nuclei research

Geometry• Entrance foil – Ti (d=2 mm,∅=100 mm)

• Diameter of the gas cell – 160 mm• Length of the gas cell – 210 mm• Exit nozzle diameter – 1,2 mm

NEW EXPERIMENTAL HALL

DRIBs-III: New experimental building

FLNR, JINR (Dubna)

ORNL (Oak-Ridge, USA)

LLNL (Livermore, USA)

RIAR (Dimitrovgrad, Russia)

Vanderbilt University (Nashville, USA)

CollaborationThank you