Synthesis of superheavyelements

Dr. Andrey G. Popeko

Flerov Laboratory of Nuclear Reactions,Joint Institute for Nuclear Research

2

Heavy Ion Physics

Staff : 310 people (including 100 younger than 35 years old) Budget: ~ 7.0 M$ Out budget staff: 110 people

The scientific activity of the FLNR in the field of heavy-ion physics develops in three main directions. They are:

Physics and chemistry investigations of the superheavynuclei with Z 112; structure and properties of the neutron reach light exotic nuclei;

accelerator technology;

heavy ion interaction with matter and applied research.

3

Periodic table of the elementsDmitri Mendeleev (1869)

4

1934: search for transurane238U + n 239U* 239Nn + e + 92 92 93

Otto Hahn und Lise Meitner

+ + +

5

1938: discovery of nuclear fission235U + 1n 236U* 90Kr + 144Ba + 1n + 1n 92 0 92 36 56 0 0

Liquid drop model

+ + + +

6

Spontaneous fission half-lives of actinides

-20

UPu

CmCf

Fm

20

10

-10

0.80 0.85Fissility

Log

T /

sSF

0.90 0.95

0LD

102

SF-isomers

HI-fusion

mfU

mfPu

mfCm

104

7

Chart of the Nuclides

SphericalShell

SphericalShell

208Pb

132Sn

298114

100Sn

40Ca

4He

48Ca

Transuranium Elements

StableElements

8

Prehistory 1966: A. Sobiczewski, F.A. Gareev, B.N. Kalinkin:

next magic numbers are Z=114, N=184; 1966: W.D. Myers, W.J. Swiatecki: next magic

numbers are Z=126, N=184 1966: V.M. Strutinsky; shell correction method 1967: H.B. Meldner: next magic numbers are

Z=114, N=184

Accuracy of predictions: Spontaneous fission half-life: T1/2 1010 !! -decay: T1/2 1010 !!

9

Synthesis of SHE at accelerators

1971; Orsay, France; 232Th + 82Kr 310126 + 4n; 4n < 0.5 mb !!!

1971-1975; Dubna, SU; deep inelastic or fission reactions of 76Ge, 136Xe + 238U

1975; Dubna, SU; 48Ca + actinides

10

Complete Fusion

11

The energy is to low

12

The energy is to high

13

The energy is correct

14

FLNR accelerators

U400M - 4m heavy ion cyclotron E = 6 100 MeV/nU400 - 4m heavy ion cyclotron E = 0.5 20 MeV/nU200 - 2m heavy ion cyclotron E = 3 15 MeV/nIC-100 - 1m heavy ion cyclotron E = 0.5 1.2 MeV/nMicrotron MT-25 - electron accelerator E = 25 MeV

15

FLNR accelerators

16

Experimental conditions

Isotopes:

+233,238 242,244 243 245,247 249 U, Pu, Am, Cm, Cf Z = 112 - 118 48Ca

beam time - 2000 h/y

beam intensity - 5.10 /s12

And detection their radioactive decay

Consumption of the mg/h 48 (68%) - 0.5

technology of the target preparation - 0.3 mg/cm2

isotope enrichment - 98-99% S2-separator

(Sarov)

Separation of super heavy nucleiDGFRS

VASSILISSAChemistry

17

On-line separation

Beam

Target

Separator

Focal plane detector

Beam stop

18

FLNR U400 cyclotron

19

UNILAC (GSI)

20

ECR - ion source

21

ECR ion source

22

Design of the superconducting (liquid He free) 18 GHz ECR ion source

Running at IC-100

23

SHIP-target

31 cm

24

Target Cooling Infra-red Snapshots

vaccum 0.6 mbar He

25

249Cf - target

26

Molten Beam Stop

27

The Velocity Filter SHIP

28

Electrostatic separator VASSILISSA

29

Dubna Gas Filled Recoil Separator

0

1

2

3

4

Targetwheel

Quadrupolelenses

Time of flight

Beam

Focal planedetector

Magneticdipole 22.5o

Dista

nce i

n metr

es

30

Research groups at DGFRS and VASSILISSA

31

Berkeley Gas-filled Separator

32

Position-Time Correlation

33

Focal plane detectors

Time-of-flight

Maindetector

Additionaldetectors, x, -, n,

34

Time-of-flight detector VASSILISSA

BEAM

MCP

1

2

foca

l pla

ne d

etec

tor

TOF 1 TOF 2

1

2

Time resolution: 300 ps (FWHM)

35

Focal plane detectors

60 mm 120 mm

36GABRIELA - Gamma Alpha Beta Recoil Investigation with the Electromagnetic Analyser

Focal plane detector GABRIELA

37

On-line neutron detector

74 3He-counters = 25 %

T (252No) = 4.43

38

SHIP-trap

39

SHIP data taking system

40

Total beam dose: 2.3.1019

248Cm + 48Ca 296 *116

Total beam dose: 1.5.1019

244Pu + 48Ca 292 *114

Strip # 5 Strip #1

4n

2

3

1

296116*

288114

292116

284112

9.81 MeV

10.56 MeV

197 MeV (195+2)

2.42 s

46.9 ms

July 19, 2000 01:21

Strip # 4

Strip # 8Strip # 2

SF

280110

9.09+0.46 MeV53.9 s

6.9 s

4n

2

3

1

296116*

288114

292116

284112

9.81 MeV

10.49 MeV

221.5 MeV

0.31 s

125.5 ms

May 02, 2001 06:21

SF

280110

9.15 MeV88.54 s

23 s

4n

2

3

1

296116*

288114

292116

284112

9.80 MeV

10.54 MeV

177 MeV

10.97 s

55 ms

May 08, 2001 16:54

SF

280110

3.15 s

9.11 MeV152.62 s

SF

2

1

288114

284112

280110

9.80 MeV

9.13 MeV

213 MeV (171+42)

4.58 s

18.0 s

7.4 s

SF

4n

2 2

1

292114*

288114

284112

280110

9.87 MeV

9.21 MeV

221 MeV (156+65)

0.77 s

10.3 s

14.3 s

June 25, 1999 05:39 Oct. 28, 1999 22:24

4n

292114*27.8 mm

28.3 mm

27.9 mm

28.5 mm

19.2 mm

19.5 mm

19.2 mm

19.8 mm

19.6 mm

20.7 mm

20.8 mm

20.3 mm

20.4 mm

20.6 mm

11.8 mm

11.4 mm

11.5 mm

30.5 mm

30.6 mm

30.1 mm

30.6 mm

11.7 mm

The beam was switched off

41

Charts of transactinide nuclides

1984 1996

42

Chart of transactinide nuclides 2006

43

Methods of identification:

generic decay links; cross-bombardments; on-line post separator; quasi-on-line mass analyzer; calorimetric detectors; Ge-- detectors; ion traps.

We need higher production rates!

44

Chemistry and masspectrometry

25

20

030 35 40

40

60

80

100

120

45 50

xn

(ar

b. u

nit

s)

E* (MeV)

2n

3n4n

1.5 mg/cm20.3 mg/cm2

45

Ar +CH4mixture

48Ca

Heinlet

Heoutlet

He

Gasoutlet

Chemical isolation of the element 112

Target:U3O8- 2mg/cm2 + Nd2O3 - 50 g/cm2

Beam:48Ca (262 MeV)0.6 pA

115288

R

10.46 MeV125 ms

1

113284

9.75 MeV5.2 s

Mt276

3

9.71 MeV1.03 s

Bh272

4

0.69 s111

280

210. MeV00

23.1 hr

SF205 MeV

Decay chain of 268 Db observed with Dubna Gas-filled Recoil Separator in 243Am + 48Ca reaction

Decay chain of 268 Db observed with Dubna Gas-filled Recoil Separator in 243Am + 48Ca reaction

14.14 s

5 9.02 MeV

Db268

47

Irradiation of 243Am-target with 48Ca-ions

48

Taking off thin layer of Cu-catcher(100150 mg of Cu)

49

Detection system

50

Fission fragment Total Kinetic Energy300

250

200

150

100

50

00 500 1000 1500 2000

Tran

slat

iona

l Kin

etic

Ene

rgy

(MeV

)

Z /A2 1/3

Yukawa + Exponential Nuclear EnergyTwo - body viscosity

(TP) = 0,0000.010

0.020

Z=88

94

102

106

112

118A.J. Sierk and J.R. Nix, Phys.Rev. C 21 (1980) 982

51

Total Kinetic Energy distributions of252Cf and 268Db

0 20 40 60 80 100 120 140 160 180 200 220 240 2600

20

40

60

80

100

120C

ount

s

TKE / MeV

52

Average numbers of prompt neutrons emitted in spontaneous fission

90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 122

2

3

4

5

6

7

8

9

10

11

12

Z

Target (238U, 242Pu; 1 mg/cm2)

Beam (48Ca; 233-239 MeV)

Beamstop

SiO2-FilterTa metal850C

Quartzcolumn

CryoCryo OnOn--lineline DetectorDetector (4(4 COLD)COLD)

Carrier gas He/Ar (70/30)

Capillary with 2 s transport time

(32 pairs PIN diodes, one side gold covered)

HgHg LoopTemperature gradient: 35C to 184 C

T

l

RnRn

ChemistryChemistry of of thethe elementselements 112 & 114112 & 114

112112Recoilchamber

Quartzinlay

54

Periodic table of the elements (2006)

55

Mass Analyzer of Super Heavy Atomsm/m=1000

Ion source

Ion beam

Target

V = 40 0 V

Magnetic mass-analyser

Hot catcher 2000=

Detectors

56

Mass Analyzer of Super Heavy Atoms(MASHA)

57

MASHA test with Xe and Hg isotopes

mass, a.m.u.128 129 130 131

54XeM =3071/ M

0.04 a.m.u.

21.2%

3.9%2%

I,nA

26 %.4

mass, a.m.u.195 196 197 198 199 200 201 202 203 204 205

0.01

0.1

1

10

10080Hg

M/M= 7127

0.0 a.m.u.7

29.7%

6.8%

23.1%16.9%

10.1%

0.15%

13.2%

I,nA

58

Search for SHE in Nature

Search for SHE in terrestrial matter Search for SHE in meteorites Search for SHE in cosmic rays Investigation of isotopic anomalies

20 years Void result,

but many new high sensitive detection methods were developed

59

Search for SF of natural Eka Os by detection of fission neutrons

150 160 170 180 190140

15

20

10

5

0

-5

-10

116

116

118

112

112

114

114

110

110

108

108

Neutron number

- decay

DeformedShell

SphericalShell

Log

T (s

econ

ds)

Age of the Earth

stablenuclei

60

Detector installed in Modana(France)

FrFrjus peakjus peak

ModaneModane

Entrance to Entrance to thethe roadroad tunneltunnel

France

61

RIB Accelerator Complex of the FLNR

+ + + +

+

+

,

-400

V 50 f = 2000

Kr, Xe0,5 6 /

Principle of Track Membrane Production

++

Scanning Ion BeamsScanning Ion Beams

Polymer FilmPolymer Film

Vacuum Ion Beam LineVacuum Ion Beam LineFrom From

acceleratoraccelerator

63

TRACK MEMBRANES

PARALLELPARALLELCYLINDRICALCYLINDRICAL

PORESPORES

NONNON--PARALLELPARALLELCYLINDRICALCYLINDRICAL

PORESPORES

CIGARCIGAR--LIKE PORESLIKE PORES BOWBOW--TIE PORESTIE PORES

MICROWELL: TOP VIEW

CROSS-SECTION OF MICROWELL:- 12 m IN DIAMETER- 35 m IN DEPTH

65

Nano-structures

66

Thank you for your attention!

Synthesis of superheavy elementsHeavy Ion PhysicsPeriodic table of the elementsDmitri Mendeleev (1869) 1934: search for transurane1938: discovery of nuclear fissionSpontaneous fission half-lives of actinidesChart of the NuclidesPrehistorySynthesis of SHE at acceleratorsComplete Fusion The energy is to low The energy is to high The energy is correctFLNR acceleratorsFLNR acceleratorsExperimental conditionsOn-line separationFLNR U400 cyclotronUNILAC (GSI)ECR - ion sourceECR ion sourceDesign of the superconducting (liquid He free) 18 GHz ECR ion sourceSHIP-targetTarget Cooling Infra-red Snapshots249Cf - targetMolten Beam StopThe Velocity Filter SHIPElectrostatic separator VASSILISSA Dubna Gas Filled Recoil Separator Research groups at DGFRS and VASSILISSABerkeley Gas-filled SeparatorPosition-Time CorrelationFocal plane detectorsTime-of-flight detector VASSILISSAFocal plane detectorsOn-line neutron detectorSHIP-trapSHIP data taking systemCharts of transactinide nuclides 19841996Chart of transactinide nuclides 2006Methods of identification:Chemistry and masspectrometryIrradiation of 243Am-target with 48Ca-ionsTaking off thin layer of Cu-catcher(100150 mg of Cu)Detection systemFission fragment Total Kinetic EnergyTotal Kinetic Energy distributions of252Cf and 268Db Average numbers of prompt neutrons emitted in spontaneous fissionMass Analyzer of Super Heavy AtomsDm/m=1000Mass Analyzer of Super Heavy Atoms(MASHA)MASHA test with Xe and Hg isotopesSearch for SHE in NatureSearch for SF of natural Eka Os by detection of fission neutronsDetector installed in Modana(France)RIB Accelerator Complex of the FLNRNano-structuresThank you for your attention!