Beta-decay of very neutron-rich nuclei in N=126 region I.N.Borzov, - - PowerPoint PPT Presentation

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Beta-decay of very neutron-rich nuclei in N=126 region I.N.Borzov, - - PowerPoint PPT Presentation

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Beta-decay of very neutron-rich nuclei in N=126 region I.N.Borzov, K.Langanke, G.Martinez-Pinedo, A.Arcones GSI, D-64291,Darmstadt, Germany Continuum QRPA framework based on the self-consistent g.s. from EDF theory. DF+CQRPA A quest for

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SLIDE 1

Beta-decay of very neutron-rich nuclei in N=126 region

I.N.Borzov, K.Langanke, G.Marti’nez-Pinedo, A.Arcones GSI, D-64291,Darmstadt, Germany

Continuum QRPA framework based

  • n the self-consistent g.s. from EDF theory.

DF+CQRPA A quest for spin-current part of (universal) NDF Nuclear structure at the limit of a high (N-Z). Important applications:

  • RNB experiments on beta-decay of short-lived neutron-rich nuclei.
  • Astrophysical R-process modeling (masses, beta-rates, (n,γ)- rates…).
  • Accelerator Driven Systems (1GeV p + 208Pb and 238U targets).
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SLIDE 2

GSI experiments near N=126

Colour Colour scale: the known half scale: the known half-

  • lives (

lives (NuBase NuBase). ). Circles: T. Circles: T. Kurtukian Kurtukian-

  • Nietto

Nietto , , J.Benlliure J.Benlliure et al. Nucl et al. Nucl-

  • exp.0711.0101v1

exp.0711.0101v1.

.

Empty boxes: identified with no half Empty boxes: identified with no half-

  • life information.

life information. GSI 2007 GSI 2007 8 nuclides: 75 Re, 76 Os, 77 8 nuclides: 75 Re, 76 Os, 77 Ir Ir … …

  • L. Chen et al. Nucl
  • L. Chen et al. Nucl-
  • exp.0110.

exp.0110. Identified with the half Identified with the half-

  • life information

life information GSI 2010 GSI 2010 213Tl , 221,222 Po, 224At, 236Ac 213Tl , 221,222 Po, 224At, 236Ac

Large-scale explorations of the nuclear mass-surface and beta-decay “ landscape”. Gamow-Teller vs first-forbidden decays near closed shell N=126

slide-3
SLIDE 3
  • Energy Density functional

S.A. Fayans, S.V. Tolokonnikov,E.Trykov, D. Zawischa, Nucl.Phys. A676 (2000) 49. I.N. Borzov, S.A. Fayans, E. Kromer, D. Zawischa Z. Phys. A335(1996) 117

  • DF3

Fenomenological (local) energy-density functional by S.A. Fayans et al., δ-function + density dependent (volume+surface) pairing. Fitted to the g.s. properties of very neutron-rich nuclei near “magic cross” Z=50/N=82 at 132Sn.

⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − − − − = h h H μ Δ Δ μ

int , ,

1 [ ] * [ ] 2 " " .

n main Coul sl

E F main volume fin range surface F volume surface

ξ ξ

ε ρ ν ρ ν = + ∝ + ∝ +

∑

ρ ρ δ δ ~ 2

2

E m p h + =

1 1 1 1

Δ ν ρ Δ ν ρ , h , , h , ⇒ ⇒ ⇒

] , [ 2 ] , [

int 2

ν ρ ρ ν ρ E M p Tr E

Sham Kohn

+ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ =

−

δν δ

int

E = Δ

EDF.

Self-Consistent Ground State

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SLIDE 4

2 2

E E F F

ω ξ ττ ττ τ τ τ τ

δ δ δρ δρ δν δν = =

The ground state properties are less sensitive to spin-isospin components of EDF. The spin-isospin (time odd) parts of the effective NN-interaction can be defined independently of the scalar (time-even) parts.

Continuum QRPA based on the self-consistent ground state. Universal effective NN-interaction (A-independent). Universal quenching eq

2=(0.9)2 (A, E-independent).

T=1, ph T=0, pp

'

' pp

r r

F g

ξ ττ

δ − ∝

'

'

r r LM

F g

ω ττ

δ π ρ

−

∝ + +

CQRPA. Effective spin-isospin NN-interaction

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SLIDE 5

Qβ – values: maximal beta-decay energy releases

DFs with m*/M~1 reproduce Qβ–values well enough : For N=82 Typical deviation from the data is 0.5 - 1.5 MeV For N=126 Deviation is 0.5 - 0.6 MeV

(Recent RDFs underestimate the phase-space,

  • vershooting T1/2)

Accurate description of the Qβ-values is crucial for beta-decay studies. Qβ is correlated with the qp-energies, as both are obtained from the same DF framework. Extended mass measurements at N=126 are of high value for impr Extended mass measurements at N=126 are of high value for improving the DF

  • ving the DF
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SLIDE 6

Possible improvements: Spin-orbital part of the Df3

Example: Qbeta-values sensitivity to the velocity dependent interaction (g1np )

208 210 212 214 216 218 220 222 2 4

Qβ,MeV Pb isotopes

A DF3 DF3* Exp.data

204 208 212 216 220 224 2 4 6 8 10

Qβ,MeV Tl isotopes

A

Qβ, DF3 Qβ, DF3* Exp.data Audi est.

Spin-orbital splitting needs re-adjustment in a wide A-region (especially for the nuclei with high spin-orbital density , Z=80-90 region)

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SLIDE 7

The GT and FF strength-functions are calculated within the single DF3+CQRPA framework

2 4

TGT= 0.2255E+06 s GT

202Ir

1 2 3 4 5 2 4 6

Ex, MeV Ex, MeV

TGT+J=1= 22.05 s

202Ir

J=1

1 2 3 4 5 2 4 6

Qb=4.37MeV

Qβ

Ex, MeV log (f0ti) log (f0ti) log (f0ti)

TGT+J=1+J=0=9.8 s

202Ir

J=0

The GT decays are retarded by The GT decays are retarded by

  • the low

the low “ “phase phase-

  • space

space” ” factors factors f(Qb f(Qb-

  • Ex)

Ex)

  • high occupancy factor of the

high occupancy factor of the 1ph11/2 orbital. 1ph11/2 orbital. The high The high-

  • energy FF decays compete with the low transition energy GT de

energy FF decays compete with the low transition energy GT decays cays. . GT GT n1h9/2 n1h9/2 p1h11/2 p1h11/2 FF FF n1i13/2 n1i13/2 p1h11/2 p1h11/2 n3p3/2 n3p3/2 p3d3/2 p3d3/2 n3p1/2 n3p1/2 p3s1/2 p3s1/2

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SLIDE 8

72Hf – 78Pt.

Half-lives approaching N=126

Typical deviation from the exp. data FRDM = 30 DF3 = 1 - 2 ___________________________________ A,Z T1/2 (s) DF3 FRDM 199Os 5 +4-2 6.6 106.8 200Os 6+4-3 6.9 187.1 ___________________________________ New GSI FRS-ESR campaigns TRIAC, KEK Japan, Proposal 09 These Proposals are aimed to pin down the r-process waiting point nuclei 198Hf, 200W, 202Os, 204Pt

184 186 188 190 192 194 196 198 200 0,1 1 10 100 202 204 206 208 210 212 214 216 0,01 0,1 1 10 100 196 198 200 202 204 206 208 0,01 0,1 1 10 194 196 198 200 202 204 206 0,01 0,1 1 10 100 1000

DF3+CQRPA FRDM+Gr.Th. Gr.Th.

A

72Hf

DF3+CQRPA .Expt.GSI_2007 FRDM+Gr.Th.

  • Gr. TH.

78Pt

A A

74W

T1/2, s T1/2, s

76Os

A

DF3+CQRPA FRDM+Gr.Th. Gr.Th.

  • Expt. GSI_ 2007
  • Expt. NuBase
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SLIDE 9

73Ta – 79Au.

190 192 194 196 198 200 202 204 206 208 210 0,01 0,1 1 10 100 1000 10000 198 200 202 204 206 208 210 212 214 0,1 1 10 100 200 202 204 206 208 210 212 214 216 218 220 0,1 1 10 100 1000 10000 188 190 192 194 196 198 200 202 204 206 0,01 0,1 1 10 100

DF3+CQRPA

  • Exp. 2007

FRDM+Gr.Th. Gr.Th. A

75Re

DF3+CQRPA

  • Exp. 2007

FRDM+Gr.Th. Gr.Th. A

77Ir

DF3+CQRPA FRDM+Gr.Th Exp.NuBase. Gr.Th. A

79Au

T1/2, s T1/2, s DF3+CQRPA

  • Exp. NuBase

FRDM+Gr.Th. Gr.Th. A

73Ta

Half-lives of odd-Z nuclides approaching N=126 Typical deviation from the exp. data FRDM = up to 70 DF3 = up to 8 ___________________________________ A,Z T1/2 (s) DF3 FRDM 194Re 1 +- 0.5 2.1 70.8 195Re 6+-1 8.5 3.3 196Re 3+1-2 1.4 3.6 ___________________________________

205Au

  • Exp. 31+/- 2 (s)

FRDM = 221,0 s (7) DF3 = 18.7 s (1.6)

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SLIDE 10

64Gd isotopes near N=126.

186 188 190 192 194 196 198 4 6 8 10 12 14 16 186 188 190 192 194 196 198 1E-3 0,01 186 188 190 192 194 196 198 20 40 60 80 100

Qβn ωGT ω1 ω0 Qβ

A T1/2, s

64Gd

A

DF3+CQRPA FRDM

ω, MeV Pn, % A

“ “saturation saturation-

  • like

like” ”

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SLIDE 11

67Ho,69Tm isotopes near N=126.

188 190 192 194 196 198 200 10 20 30 40 50 60 70 80 90 100 188 190 192 194 196 198 200 0,01 0,1 186 188 190 192 194 196 198 200 202 10 20 30 40 50 60 70 80 90 186 188 190 192 194 196 198 200 202 0,01 0,1

Pn, %

A DF3+CQRPA FRDM

T1/2, s

A

Ho

Pn, % A

Z=67, 69, N ~ 126

Tm

T1/2, s A DF3+CQRPA FRDM

“ “gap gap-

  • like

like” ”

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SLIDE 12

N=126 waiting point nuclei

60 62 64 66 68 70 1E-3 0,01 0,1 70 72 74 76 78 80 82

DF3+CQRPA GT GT+FF SM(2) GT FRDM+gt GT+FF

N=126

A

T1/2, s

1000 100 0.1 1

T1/2, s Z

SM(1) SM(2) DF3+CQRPA GT GT+FF FRDM+gt GT+FF

  • exp. NuBase

10

N=126

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SLIDE 13

Impact of the half-lives

  • n R-process abundances at N=126

(A.Arcones e.a. 2010)

FRDM half FRDM half-

  • lives were replaced by the DF3 ones

lives were replaced by the DF3 ones for the nuclides near N=126 only. for the nuclides near N=126 only. Changes the abundances near the third peak (A~195) Changes the abundances near the third peak (A~195) and for and for fissioning fissioning nuclei nuclei

Hot Hot Cold r Cold r-

  • process

process

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SLIDE 14
  • I. Summary (Beta-decay)
  • Global calculations of the β-decay half-lives.

Systematic studies in a wide (Z=15 – 92) region: Table I. Spherical nuclei. Used for new experiments at GSI, KEK, HRIBF

  • GT decay dominates for Z~ 28, 50 for N<Nmag=50, 82

Competition of GT and high-energy FF decays for heavier Z = 60 - 82 , N approaching Nmag=126.

  • Signatures of the GT/FF competition: “saturation-like” and

“saw-like’ patterns in Pn(A) behavior.

  • The shorter half-lives make evolution faster , break through

the N=126 waiting points faster. The matter flow to heavier (fissioning) nuclei should be also faster in DF3+CQPRA. .

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SLIDE 15

Acknowledgments

Partially supported by DFG Discussions are acknowledged with

  • K. Schmidt GSI, Darmstadt
  • J. Benlluire USC, Santiago de Compostella
  • K. Rykaczewski, HRIBF, Oak Ridge

thanks to

  • Yu. Litvinov (GSI)
  • H. Ishiyama (TRIAC, KEK Japan)
  • N. Costiris, (PYTHAIM Collaboration)

for their interest in DF+CQRPA results

***

I.N.B, K. Langanke, G. Martinez-Pinedo, F. Montes Nucl.Phys. A814,159,2008 J.A.Winger … INB et al., HRIBF Collaboration Phys.ReV.Lett 102 (2009) 142502 T.Kurtukian-Nietto, J.Benlluire, .INB…et al.GSI Collaboration. nucl-ex 0711.0101v1, (Phys.Lett B, 2010)