14th international conference on nuclear reaction mechanisms formation, separation and detection of...

14th INTERNATIONAL CONFERENCE ON NUCLEAR REACTION MECHANISMS

Formation, separation and detection of evaporation residues produced in complete fusion reactions

R.N. SagaidakFlerov Laboratory of Nuclear Reactions, JINR, Dubna, Russian Federation

1.Fusion probability and survivability as main values that determine the heavy ER production cross section in HI reactions

2.Fusion probability in reactions with a different entrance-channel mass asymmetry

3.Survivability and macroscopic fission barriers derived with the statistical model analysis of ER cross section data obtained in very asymmetric projectile-target reactions

4.Experimental approaches to the separation and detection of ERs produced in HI reactions

1



The ER production cross section in the framework of different models

2 * */ (2 1) ( , ) ( , )srvxn L fus CN xn CNk L T P E L W E L

Capture (barrier passing) CS

FusionProbability

SurvivalProbability

Measured Calculated with SSM

Pfus=1 for very asymmetric projectile-target combinations (SSM, no fusion suppression)

Pfus<1 for nearly symmetric massive projectile-target combinations (fusion suppression)

Can we estimate Pfus for nearly symmetric massive projectile-target combinations empirically?

2

14th INTERNATIONAL CONFERENCE ON NUCLEAR REACTION MECHANISMS Extraction of CN-fission events from fission data with the decomposition of FF angular distributions integrated over masses and energies (B.B. Back’s approach): PCN=σCN/σcap

3R. S. Naik et al., PRC 76, 054604 (2007)

Pfus from experiment (reasons)?


Pfus experimentally obtained in reactions leading to the less fissile 202Pb* CNG.N. Knyazheva et al., PRC 76, 054604 (2007); A.M. Stefanini et al., EPJA 23, 473 (2005); R.N. Sagaidak, EPJWC 21, 06001 (2012)

The decomposition of fission fragment mass-angular and TKE distributions

The comparison of ER cross sections with those obtained in a very asymmetric reaction implying no fusion suppression

4


Comparison of the ER production in the 16O+186W and 48Ca+154Sm

reactions leading to the 202Pb* CN

5


Why Pfus < 1 in nearly symmetric combinations of fusioning nuclei?

R. N. Sagaidak et al., PRC 68, 014603 (2003)

GLDM of G.Royer & B.Remaud, NPA 444, 477 (1985)

Potential energy surface calculated in the (Z,N)-plane for contact configurations with the expression for the proximity energy: R. Moustabchir & G. Royer, NPA 683, 266 (2001).

R.N. Sagaidak, EPJWC 21, 06001 (2012) 6


The description of experimental ER cross sections for very asymmetric combinations of fusioning nuclei in the framework of barrier passing and statistical models (HIVAP)Barrier passing model (Pfus ≡ 1)●Coupling to various entrance channels – via the radius (barrier) fluctuations σ(r0)/r0

generated using a Gaussian distribution with the mean value r0 and width σ(r0)

●The exponential nuclear potential with varied V0 and σ(r0)/r0 , fixed r0=1.12 fm and d=0.75

fm●The WKB approximation for transmission coefficients of partial waves penetrating the

barrier

Statistical model approximations●Intrinsic level density only with the shell damping energy ED = 18.5 MeV

●The expression of W. Reisdorf for the macroscopic level density parameters in the fission and evaporation channels of the CN decay

●ER and fission cross section calculations adjusted with the LD barrier scaling using a scaling parameter kf as a main fitted parameter:

●Calculations of ground-state shell correction ΔWgs (a difference between empirical and LD

masses), excitation and separation energies with empirical masses

( / 1)fa a

( ) ( )LDf f f gsB L k B L W

7

14th INTERNATIONAL CONFERENCE ON NUCLEAR REACTION MECHANISMS Macroscopic fission barriers derived with the SM analysis of ER cross section data obtained in very asymmetric combinations leading to Rn, Ra, Fr and Th

nuclei

R.N. Sagaidak, EPJWC 21, 06001 (2012) 8


Production of At nuclei in the 12C + 197Au fusion-evaporation reaction

9


Production and fission of Po and At nuclei in the 3,4He + Pb,Bi fusion-evaporation and fusion-fission reactions

R.N. Sagaidak, JPCS 580, 012039 (2015)

10


Macroscopic fission barriers and shell corrections for Po and At nuclei

11

R.N. Sagaidak & A.N. Andreyev, PRC 79, 054613 (2009) R.N. Sagaidak, JPCS 580, 012039 (2015)


Experimental approaches to the separation and detection of ERs

12

THE LNL ELECTROSTATIC DEFLECTOR (ED)S. Beghini et al., NIMA 239, 585 (1985)

SLIDING SEALED TARGET CHAMBER

TWO PAIRS OF

CONDENSOR PLATES

TOF-E (MCP + SSBD)

Energy - TOF matrix obtained for the reaction 48Ca+154Sm, at Elab=208 MeV and θlab=0◦

A.M. Stefanini et al., EPJA 23, 473 (2005)

Nearly symmetric combinations

Very asymmetric combinationsleading to α-radioactive nuclei– detection of α-particles of ERs implanted into SSBD



13

Peculiarities of the experiments with LNL ED

R.N. Sagaidak et al., LNL Annual Report 2014R.N. Sagaidak & A.V Yeremin, NIMB 93, 103 (1994)

R.N. Sagaidak et al., LNL Annual Report 2014R.N. Sagaidak & A.V Yeremin, NIMB 93, 103 (1994)

R.N. Sagaidak et al., LNL Annual Report 2014

R.N. Sagaidak et al., NIMA 700, 111 (2013)


14

The updated results of the 12C+Pb experiments carried out with LNL ED


15


Dubna experiments on synthesis of SHE with DGFRS


16

Experimental approaches to the separation and detection of ERs Results of Dubna DGFRS experiments on synthesis SHE with Z=113, 115,and

117Yu.Ts. Oganessian et al., PRC 87, 014302 (2013); PRC 87, 054621 (2013)


17

Dubna DGFRS experiments on synthesis SHE

19 nucleisynthesized

53 nuclei identified in their decays


18

Acknowledgements

Dubna DGFRS experiments on synthesis SHEYu.Ts. Oganessian1, F.Sh. Abdullin1, C. Alexander2, J. Binder2, R. A. Boll2, S.N. Dmitriev1,

J. Ezold2, K. Felker2, J.M. Gostic3, R.K. Grzywacz2,4, J.H. Hamilton5, R.A. Henderson3, M.G. Itkis1, K.Miernik2, D. Miller4, K.J. Moody3, A.N. Polyakov1, A.V. Ramayya5,

J.B. Roberto2, M.A. Ryabinin6, K.P. Rykaczewski2, D.A. Shaughnessy3, I.V. Shirokovsky1, M.V. Shumeiko1, M.A. Stoyer3, N.J. Stoyer3, V.G. Subbotin1, A.M. Sukhov1, Yu.S. Tsyganov1,

V.K. Utyonkov1, A.A. Voinov1, and G.K. Vostokin1

1Flerov Laboratory of Nuclear Reactions JINR, RU-141980 Dubna, Russian Federation2Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

3Lawrence Livermore National Laboratory, Livermore, California 94551, USA4Dep. of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA

5Dep. of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA6Research Institute of Atomic Reactors, RU-433510 Dimitrovgrad, Russian Federation

LNL experiments on study of ER production in various reactionsN.A. Kondratiev1, L. Corradi2, E. Fioretto2, T. Mijatović2, R. Silvestri2, A.M. Stefanini2,

P. Mason3, G. Montagnoli3, and F. Scarlassara3, 1Flerov Laboratory of Nuclear Reactions JINR, RU-141980 Dubna, Russian Federation

2 INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Padova), Italy3INFN and Dipartimento di Fisica, Università di Padova, I-35131 Padova, Italy


19

Thank you for your attention

14th international conference on nuclear reaction mechanisms formation, separation and detection of...

Documents

fusion suppressionpfus

hi reactionsfusion probability

complete fusion reactionsr

detection of ers

ssm pfus

framework of different

macroscopic fission

main values