rich Pd and Ag isotopes via optical spectroscopy Sarina Geldhof - - PowerPoint PPT Presentation

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Nuclear structure of neutron- rich Pd and Ag isotopes via optical spectroscopy Sarina Geldhof JYU. Since 1863. 7.10.2019 1 Outline Introduction Atomic spectra The IGISOL facility Motivation Neutron-rich Pd isotopes Overview

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SLIDE 1

Nuclear structure of neutron- rich Pd and Ag isotopes via optical spectroscopy

Sarina Geldhof

  • JYU. Since 1863.

1 7.10.2019

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SLIDE 2

Outline

  • Introduction

Atomic spectra The IGISOL facility Motivation

  • Neutron-rich Pd isotopes

Overview Preparation Even-A charge radii

  • Neutron-rich Ag isotopes

Overview Even-A isotopes Odd-A nuclear moments

  • Conclusion

7.10.2019

  • JYU. Since 1863.

2

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SLIDE 3

Atomic spectra

  • Isotope shifts

Changes in RMS charge radii

  • Hyperfine structures

Nuclear spin Magnetic dipole moment Electric quadrupole moment

  • Identification of nuclear

states

I=0 I>1/2 I=0 Isotope 1 Isotope 2 Isotope 3

centroid

πœ‰πΊ = πœ‰0 + 𝐡𝑔 𝐽, 𝐾, 𝐺 + 𝐢𝑕(𝐽, 𝐾, 𝐺) 𝐡 = 𝜈 𝐢𝑓 𝐽𝐾 𝐢 = 𝑓𝑅𝑑 πœ–2π‘Š πœ–π‘¨2

πœ‰0

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  • Some cases quite easy
  • Other cases a bit more tricky

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Atomic spectra

  • In general: higher nuclear spins are harder to tell apart
  • Higher atomic spins make the assignment easier, but

measurement harder Measuring spins

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The IGISOL facility

7.10.2019

from K=130 MeV cyclotron Laser ionisation in-gas cell/ in-jet/in hot cavity Off-line ion sources: (discharge, surface) Mass spectrometry & post-trap spectroscopy Decay spectroscopy line Collinear laser spectroscopy Laser access for optical manipulation Lasers from FURIOS RFQ cooler- buncher Atom trap line

  • Cyclotron beam

hits thin target

  • Recoils stopped

in He buffer gas

  • Supersonic jet

guides into an ion guide

  • Fast and

chemically insensitive β†’ universal

Dipole magnet

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  • JYU. Since 1863.

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The IGISOL facility

7.10.2019

  • Recent additions to the collinear laser spectroscopy

beamline:

Charge-exchange cell* New laser system

* Courtesy of W. NΓΆrtershΓ€user, TU Darmstadt

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  • JYU. Since 1863.

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Motivation

  • Gap in optical spectroscopy

data: Tc, Ru, Rh, Pd and some Ag isotopes β€˜missing’

Refractory elements Complex atomic structure

  • Accessible at IGISOL thanks to

chemical insensitivity and installation of charge-exchange cell

7.10.2019

  • P. Campbell, I. D. Moore and M. R. Pearson,

Progress in Particle Physics 86, 127 (2016)

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  • JYU. Since 1863.

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Motivation

  • Charge radii and nuclear moments needed to clarify various phenomena

in the region

Rapid changes in deformation, shape coexistence,…

  • Ground state and isomer properties important to underpin decay

spectroscopy studies

Firm spin assignments missing: important to understand evolution of shell- model orbits

7.10.2019

  • J. Kurpeta et al., Phys. Rev. C 98, 024318 (2018)
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Neutron-rich Pd isotopes

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Overview

  • Isotopes in the range A = 102-118
  • Even-A: spin zero gs, no isomers β†’ only one resonance
  • Odd-A: high nuclear spins, isomers β†’ complex structure,

analysis ongoing

7.10.2019

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Preparation

4 tested transitions from different metastable states populated in charge exchange

0 cm-1 6564.15 cm-1 J = 0 J = 3 J = 0 J = 2 J = 2 7755.03 cm-1 10093.99 cm-1 11721.81 cm-1 J = 1 34068.98 cm-1 38088.19 cm-1 J = 2 J = 3 35451.44 cm-1 38811.90 cm-1 J = 2 36180.68 cm-1 J = 1

Line 1 363.5726 nm Line 2 357.2173 nm Line 3 361.0577 nm Line 4 369.1386 nm Unfeasible 276.3909 nm

A.R. Vernon et al., Spectrochim. Acta B 153 (2019) 61–83 and private communication

  • JYU. Since 1863.

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Even-A charge radii

King plot technique for calibration of atomic factors

Charge radii from muonic X-rays

7.10.2019

Field shift: -2.89 GHz Mass shift: 142 MHz

πœ€πœ‰π΅,𝐡′ = 𝐺 πœ€ 𝑠2 𝐡,𝐡′ + 𝑁 (𝐡 βˆ’ 𝐡′) 𝐡𝐡′

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  • JYU. Since 1863.

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Even-A charge radii

7.10.2019

  • Comparison of extracted changes in charge radii to nuclear

Density Functional Theory with various Skyrme EDFs

Erler et al., Nature 486, 509 (2012) SkM*: Bartel et al., Nucl. Phys. A 386, 79 (1982). SLy4: Chabanat et al., Nucl. Phys. A 635, 231 (1998). UNEDF0: Kortelainen et al., Phys.

  • Rev. C 82, 024313 (2010).

UNEDF1: Kortelainen et al., Phys.

  • Rev. C 85, 024304 (2012).

SkM* optimised for fission barriers SLy4 optimised for neutron-rich nuclei UNEDF0-1 optimised for deformed nuclei

PRELIMINARY

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  • JYU. Since 1863.

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  • Comparison of total

charge radii β†’ ’offset’ most likely related to different fitted saturation densities in functionals

  • Charge radii influenced by

deformation πœ€ 𝑠2 𝐡,𝐡′ = πœ€ 𝑠2

𝐡,𝐡′ +

𝑠2 0

5 4𝜌 πœ€ 𝛾2 2 𝐡,𝐡′

Even-A charge radii

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SLIDE 15
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Neutron-rich Ag isotopes

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  • JYU. Since 1863.

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Overview

  • First online use of CEC at IGISOL
  • Isotopes in the range A = 113-121
  • Odd-A: 7/2+ and 1/2- states

Spin assignments firm

  • Even-A: more complex, three states in 116, 118 observed

Firm spin assignments will be hard (analysis ongoing)

7.10.2019

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SLIDE 17
  • Combination of laser

spectroscopy and mass spectroscopy with PI-ICR in Penning traps

  • 116Ag:

Three states in literature

  • 118Ag:

Three states found with lasers, two with PI-ICR Third state very short- lived or low-lying?

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  • JYU. Since 1863.

Even-A isotopes

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SLIDE 18
  • G-factors
  • Near constant g-

factor for I = 7/2 (9/2) states with shell effect towards N = 50

  • G-factors of spin 1/2

not constant…

Similar trend observed for indium (Z = 49) I = 1/2 states Mixing? But p1/2 moments are insensitive to first

  • rder config mixing*

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Moments of odd-A isotopes

??

* A. Arima et al., Progress of Theoretical Physics 12, 623–641 (1954)

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Moments of odd-A isotopes

  • Quadrupole moments 𝑅𝑑:

Decrease towards N=50 and N=82 𝑅0 =

3 5𝜌 π‘Žπ‘“π‘†2 𝛾2 (1 + 0.36 𝛾2 ),

𝛾2 static deformation parameter

7.10.2019

T.D. Morris et al., PRL 120 (2018) 152503

  • Similar trends observed in

transition probabilities B(E2) in the region as deformation parameter 𝛾2 β‰ˆ (

4𝜌 3π‘Žπ‘“π‘†0

2) 𝐢(𝐹2)

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  • JYU. Since 1863.

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Conclusion

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SLIDE 21
  • JYU. Since 1863.

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Charge radii in the region

7.10.2019

Sn, In, Ag: P. Campbell, I. D. Moore and M. R. Pearson,

  • Prog. Part. Nucl. Phys. 86,

127 (2016) and refs. therein Sn: C. Gorges et al., Phys.

  • Rev. Lett. 122, 192502 (2019)

Cd: M. Hammen et al., Phys.

  • Rev. Lett. 121, 102501 (2018)

Preliminary results from IGISOL

0.5 fm2

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SLIDE 22

Actinides

  • JYU. Since 1863.

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Outlook

  • Some beamtime remaining to complete datasets on n-rich Ag and

Pd isotopes

  • Push towards n-deficient isotopes using hot-cavity ion source
  • Development of RAPTOR (Low-energy, medium resolution RIS)

which will give higher sensitivity β†’ more exotic nuclei

  • Plans to continue studies in the refractory region and other

β€˜blind spots’

7.10.2019

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SLIDE 23

Thank you!

  • JYU. Since 1863.

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