Investigating Shape Coexistence With Coulomb Excitation Above And Below Z=82

Nele Kesteloot1,2

On behalf of the IS452/IS479 collaboration

1KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, B-3001, Belgium2SCK CEN (Studiecentrum voor Kernenergie, Mol, B-2400, Belgium

Shape coexistence• Different types of deformation at low excitation energy

• Interplay between two opposing tendencieso Stabilizing effect of closed shellso Residual proton-neutron interactionHeyde and Wood, Review of Modern Physics (2011)

Andreyev et al Nature 405:430 (2000)

• Evidence across the light lead region

• Lack of experimental informationo Nature of deformationo Degree of mixing

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

2nd of June 2014 2ARIS 2014, Tokyo

T.E. Cocolios et al, Phys. Rev. Lett. (2011)

Miniball @ REX-ISOLDE

θP

2.9 MeV/A Projectile eg: 200Po

Target eg: 104Pd

EP

ET

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Z = 82

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

I182Hg = 4x10³ pps

I196Po = 2x104 ppsPurity = 54(1)%

I188Hg = 2x105 pps

I202Po = 7x104 ppsPurity = 98(2)%

Z = 84: 196-202Po: Quality of the data

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• Data analysiso pγ coincidenceso Population of 2+

1 state in all isotopes

o Multi-step coulex observed in 196,198Po

• Extraction of matrix elementso Gosia o χ² fit of experimental data

196Po on 104Pd

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

T. Czosnyka et al, Am. Phys. Soc. (1982)

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196Po196Tl104Pd

Comparison with Beyond Mean Field

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Lifetime experiments194Po: T. Grahn et al PRL 97, 062501 (2006)

196Po: T. Grahn et al PRC 80, 014323 (2009)

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

J.M. Yao, M. Bender, P.-H. Heenen PRC 87, 034322 (2013)

Comparison with Beyond Mean Field:198Po

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Experiment BMF

39(9)

180(50)

1.8(6)

300(300)

230(130)70(90)

25

90 53

1

37

63B(E2) down [Wu]

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

J.M. Yao, M. Bender, P.-H. Heenen PRC 87, 034322 (2013)

Z = 80: 182-188Hg

0

N.Bree et al, PRL 112, 162701 (2014)

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Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

Interpretation with two-level mixing modelα0+

2 α2+2 α4+

2

182Hg 92% 29% 3%184Hg 95% 51% 4%186Hg 98% 90% 7%188Hg 99% 98% 20%

“concealed” configuration mixing of the 2+

1 states of 182-188Hg

un-mixed ME2’s:

1.2 eb

3.3 eb 1.8 eb

-4.0 eb

0+I

2+I

0+II

2+II

182Hg184Hg186Hg188Hg

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Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

N.Bree et al, PRL 112, 162701 (2014)

L.P. Gaffney et al, PRC 89, 024307 (2014)

Comparison to theory – IBM and BMF

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Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

BMF: J.M. Yao, M. Bender, P.-H. Heenen PRC 87, 034322 (2013)IBM: J.E. Garcia-Ramos, K. Heyde PRC 89, 014306 (2014)

unmixed 2+1

unmixed 2+2

Courtesy of K. Wrzosek-Lipska

Outlook• Coulex of Po isotopes

o Finish analysiso Compare matrix elements with BMF and IBM

• HIE-ISOLDEo Radioactive ion beams @ 5MeV/A

• Continuation of shape-coexistence studies in the light lead region• Coulex of 182,184Hg: proposal accepted

• Establish deformation of 0+2 state

• B(E2)’s between non-yrast states up to 8+

o Extend studies towards odd-A

• SPEDE (Spectrometer for Electron Detection)o Detection of conversion electronso Constructed jointly by universities of Jyväskylä and Liverpool

2nd of June 2014 10ARIS 2014, Tokyo

Shape coexistence Miniball @ REX-ISOLDE OutlookZ = 84:196-202Po Z = 80: 182-188Hg

Thank you for your attention!

B. BastinE. ClémentN. Lecesne

N. BreeH. De WitteJ. DirikenL.P. GaffneyM. HuyseN. KestelootO. IvanovR. OrlandiN. PatronisI. StefanescuP. Van DuppenK. Wrzosek-Lipska

J. CederkällV. FedosseevL.M. FraileB. MarshE. PiselliE. RapisardaM. SeliverstovT. StoraD. VoulotJ. Van de WalleF. Wenander

T. GrahnR. JulinJ. KonkiJ. PakarinenP.J. PeuraP. Rahkila

A. BlazhevB. BruyneelCh. FransenK. GeibelH. HessP. ReiterB. SiebeckN. WarrA. Wiens

P.-H. Heenen, Université Libre de BruxellesK. Heyde, Ghent UniversityJ.L. Wood, Georgia Institute of TechnologyT. Kröll, Technische Universität DarmstadtM. Zielinska, CEA SaclayM. Bender, Université BordeauxM. Carpenter, Argonne National LaboratoryA. Ekström, University of LundJ.E. Garcia-Ramos, Universidad de Huelva

A. PettsP.A. ButlerR.-D. HerzbergR.D. Page

A. AndreyevJ. ButterworthD.G. JenkinsP. Marley

T.E. CocoliosA. DeaconC. FitzpatrickS.J. FreemanA.P. Robinson

B. HadiniaM. ScheckJ.F. Smith

K. Hadynska-KlekP.J. NapiorkowskiJ. Srebrny

R. GernhäuserR. Krücken

M. GuttormsenA.C. LarsenS. SiemG.M. Tveten

2nd of June 2014 11ARIS 2014, Tokyo