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Synthesis of superheavy nuclei in heavy-ion reactions with transuranium targets

Wang Nan

College of Physics, SZU

Collaborators: S G Zhou, E G Zhao, J Q Li, W. Scheid

Beijing

Jun. 15th 2012

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Outline

Introduction

Formalism

Results and discussions

Summary

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Periodic Table for Chemistry Elements

4

5

Super-heavy elements up to Z=118 have been synthesized

experimentally.

Z=107-113: cold fusion, 208Pb/209Bi based reactions by evaporating 1 or 2 neutrons (Rev.Mod.Phys.72(2000)733, Rep.Prog.Phys.61(1998)639)

Z=112-118: 48Ca induced fusion reactions, 48Ca bombarding actinide targets

by evaporating 3-5 neutrons (J.Phys.G34(2007)R165, NPA787(2007)343c)

GSI: 107-112 Dubna: 112-118 Riken: 113 IMP: 259Db, 265Bh

Question: How heavy element can we produce?

Experimental achievements

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Theoretical models for SHN production

Macroscopic dynamical model

S. Bjornholm and W.J. Swiatecki, NPA 391 (1982) 471

Fusion by diffusion model

Aritomo et al. PRC 59 (1999) 796, Shen Int. J.Mod. E 17(2008)66 , Liu & Bao Phys.Rev.C 80(2009)034601 ,

K. Siwek-Wilczynska, T. Cap, and J. Wilczynski, Int. J. Mod. Phys. E 19, 500 (2010)

Nucleon collectivization model (Zagrebaev et al.PRC65(2001)014607)

Dinuclear system model

Adamian et al. NPA 618(1997) 176

Li, Wang et al. EPL 64 (2003) 750, Eur. Phys. J. A 24, 223 (2005) ， J. Phys. G32 (2006) 1143.

Feng et al., NPA 771 (2006) 50

Huang et al, PRC 84 (2011) 064619

Wang, Zhao, Scheid , Zhou 85(2012) 041601(R)

Other model

Wang et al 84, 061601(R) (2011)

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Evaporation residue cross section:

),(),(),()12(2

)( ........

2

.. JEWJEPJETJE

E mcsurmcCNmcJmc

mcER

Schematic picture of the formation of SHNDinuclear system (used to describe deep inelastic collisions of heavy systems): V.V. Volkov, Phys. Rep. 44(1978)93

TP

EN

CN

CF

capture

fusion

evaporation

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Capture of two colliding nuclei

J

mcmc

mcc JETJE

E ),()12(2

)( ....

2

..

dB

JJJR

BEJ

BfJET

Bmc

mc

)1()(2)(

2exp1

1)(),(

2

2

..

..

Transmission probability calculated from barrier distribution:

mm

mm

BBBB

N

BBBB

NBf

,exp1

,exp1

)(2

2

2

1

2/)(

2/)(

02

0

s

sm

BB

BBB

The value of 1 is 2-4 MeV less than the one of 2

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Formation of compound nucleus - Master equation

),()()],(),'()[(),,(

11'1'11

'1

11111tAPttAPdtAPdtW

dt

tEAdP

A

qfAAAAA

BGA

iiCN APP

0

)(

tVtHtH 0

tatattHKKK

K

0

tVtatatutVKK

KKKK

KK

KKKK

'

''

''

'

,,

Hamiltonian

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Driving potential

Driving potential(Potential Energy Surface)

CNNCPES BrVrVABABV ),,(),,()()( 212121

2

120

222

20111

)(

)(

A

A

C

C

)1( /max

te

2

2,121211int 2

1),,(),,(),( i

iiNC CrVrVAE

Dynamical deformation satisfy

Intrinsic energy

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Driving potential

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Survival probability of excited compound nucleus

iifin

inx

iCNCNsur JEJE

JEJxEPJxEW

),(),(

),(),,(),,(

**

***

The thermal compound nucleus will decay by evaporating -ray, light particles and fission. The survival probabilities can be written as

2222

42

21

1

3

4)(

GG

GE

EA

NZ

c

e

mcf

a

EBE

rotn

rot

dJEBEJE

RmsJE

1

02

2*

,),(

)12(),(

Vfor

VforVRinv

0

/1)(

2

6.1/ RKZZZV

f

rotf aEBE

rotf

rotff

ff EBE

dJEBE

JEJE

1

0 /2exp1

,

),(2

1),(

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Results and discussions

Capture cross sections for 48Ca + 238U, 237Np, 242Pu, 244Pu, 243Am, 248Cm, 249Bk and 249Cf

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Potential energy surface and Pcn for 48Ca+238U

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Fusion probabilities for some hot fusion reactions

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Survival probabilities for some compound nuclei produced in hot fusion reactions

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Exp. Yu.Ts. Oganessian, et al., PRC 70 (2004) 064609

Evaporation residue cross sections for 48Ca+238U, 237Np

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Exp. Yu.Ts. Oganessian et al., PRC 70 (2004) 064609

P. A. Ellison, et al, Phys. Rev. Lett. 105, 182701 (2010)

Evaporation residue cross sections for 48Ca + 242, 244 Pu

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Exp. Yu.Ts. Oganessian et al., PRC 70 (2004) 064609

S. Hofmann, S. Heinz, R. Mann, et al., Euro. Phys. J. A 48, (2012) 1

Evaporation residue cross sections for 48Ca+243Am, 248Cm

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Exp. Yu.Ts. Oganessian et al., PRC 74.044602(2006)

PRC 76, 011601(R) (2007)

Evaporation residue cross sections for 48Ca +249Bk, 249Cf

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Evaporation residue cross sections for the SHN 112-120

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About SHN Z=120

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25

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Evaporation residue cross sections for nuclei Z=120

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Lifetime for some Cf isotopes

28 Evp. Cross sections for some Ti+ Cf isotope reactions

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About SHN 119

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Evp. Cross sections for 50Ti+ 249Bk, 54Cr+ 243Am and 58Fe+237Np reactions leading to nuclei with Z=119

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Lifetime for some Bk isotopes

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Evp. Cross sections for some Ti+ Bk isotope reactions

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Summary

Some evaporation residue cross sections for 112-118 are studied with DNS-DyPES model . The calculated results are in good agreements with the available experimental results.

Several combinations for Z=119, 120 are calculated . Some reactions are suggested.

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Thanks谢谢