Recoil Distance Lifetime Measurement of 38 Si and Implementation of - - PowerPoint PPT Presentation

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Recoil Distance Lifetime Measurement of 38 Si and Implementation of - - PowerPoint PPT Presentation

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Recoil Distance Lifetime Measurement of 38 Si and Implementation of Active Target Technique Mara Grinder Acknowledgements: This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award

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SLIDE 1

Acknowledgements: This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003180

Mara Grinder

Recoil Distance Lifetime Measurement of 38Si and Implementation of Active Target Technique

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SLIDE 2
  • Physics Background and Motivation for 38Si
  • Experimental set up and Method
  • Preliminary 38Si Lifetime Data
  • Discussion of 38Si Results
  • Active Target Implementation

Outline

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data, Slide 2

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SLIDE 3
  • Neutron rich nuclei
  • Magic Numbers 20 and 28 [1],[2]
  • Persistent in 40,48Ca, 34Si
  • Absent in 32,40Mg, 42Si
  • Island of inversion [3],[4]
  • Magicity disappears

Shell Evolution from Mg→Ca

, Slide 3

[1] T. Otsuka et al. Phys. Rev. Lett. 87, 082502 [2] O. Sorlin and M-G Porquet 2014 Phys. Scr. 2013 014003 [3] E. K. Warburton et al. Phys. Rev. C. 41, 1147 (1990) [4] B.A. Brown Physics 3,104 (2010)

Stable Nuclei

1d3/2 1f7/2 1s1/2 2s1/2 1d5/2 1p1/2 1p3/2 2p3/2

2 8 20 28

48Ca 42Si

Proton Neutron

2 8 20 28 1d3/2 1f7/2 1s1/2 2s1/2 1d5/2 1p1/2 1p3/2 2p3/2 2 8 20 28 2 8 20

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 4
  • Si isotopes N=20-28
  • Shell evolution
  • 34Si is closed shell
  • No N=28 shell at 42Si [1]
  • Triaxial deformation [2]
  • Cross shell excitations [3]
  • Between 1f7/2 and 2p3/2
  • Bubble Structure in 34Si
  • Persists in neutron rich Si?

Shape Evolution Near 38Si

, Slide 4

[1] B. Bastin et al, PRL 99, 022503 (2007) [2] Y. Utsuka et al. Phys. Rev. C 051301(R)(2012) [3] S. R. Stroberg et al. Phys. Rev. C 91, 041302 (R) (2015) [4] T. Otsuka et al. Phys. Rev. Lett. 87, 082502

Potential Energy Surface

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

[5] A. Mutschler et al. Nature Physics 13, 152-156 (2017)

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SLIDE 5

Vibrational Limit Rotational Limit Vibrational Limit Rotational Limit

  • 38Si
  • Collective nature
  • Turning point
  • Vibrational → Deformed
  • B(E2) transition strength

measurement

»Hint at shell configuration »Intruder p3/2 »Information on (4+

2) state

Collectivity in 38Si

, Slide 5

[1] R. W. Ibbotson et al, Phys. Rev. Lett. 80, 2081 (1998) [2] F. Nowacki and A. Poves, Phys. Rev. C. 79, 014310 (2009) [3] S. Takeuchi et al. PRL 109, 182501 (2012) [4] W. T. Chou et al. Phys. Rev. C 47,157 (1993)

Vibrational Triaxial (γ=30°)[4] Deformed E(4+)/E(2+) 2 2.67 3.3 B(E2;4+→2+) B(E2;2+→0+) 2 1.39 1.43

collectivity

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 6

Experimental Setup

, Slide 6

  • Two Reactions
  • 44Cl+9Be→38Si
  • 45Cl+9Be→38Si

http://nscl.msu.edu/public/science/isotope.html

48Ca 44,45Cl 38Si

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

Target Degrader 2nd Degrader

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SLIDE 7

S800 Particle Identification

, Slide 7

38Si

44Cl Beam Particle Identification Time of Flight (arb. units)

44Cl+17

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 8

Recoil Distance Method

, Slide 8

  • Doppler-shift correction
  • Each β → peak
  • Peak height → # decays
  • Relative height give lifetime information
  • Advantages
  • Model independent B(E2) measurement
  • 1 ns to 10 ps lifetime range
  • Disadvantages
  • Multiple distance measurements
  • Reactions in degrader foils

Target component First degrader component Second degrader component

Energy (keV) at forward angles Counts

2mm Be 0.57mm Ta 0.26mm Ta Target Degrader Degrader

1mm≈10ps

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 9

Target Only Data

, Slide 9

(4+) 1074 2239 2382 4+ 2+ 0+ Energy (keV)

38Si

1159 (2) 1074 (2)

1074 1159 1308

1308 (15) Population 10 (2) 59 (12) 31 (6) CM Frame

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

[1] K. Steiger et al. Euro Phys J.A (2015) 51:117

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SLIDE 10

Three Foil Data

, Slide 10

1074 1159 1308

(4+) 1074 2239 4+ 2+ 0+ Energy (keV)

38Si

1159 (2) 1074 (2) Lifetime (ps) 1 (4) 11 (3) 12 (3) 2382 1308 (15)

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

[1] K. Steiger et al. Euro Phys J.A (2015) 51:117

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SLIDE 11

B(E2) from Preliminary Lifetimes

, Slide 11

Transition Energy (keV) Lifetime (ps) B(E2↓) (e2fm4) Previous B(E2↓) (e2fm4)

Energy Ratio B(E2) Ratio 2+→0+ 1074(2) 12 (3) 50 (10) 39 (14)[1]

  • 4+→2+

1159(2) 11 (3) 36 (7)

  • 2.08

0.72 (4+)→2+ (2+)→2+ 1308(15) 1 (4) >44 B(M1):>5.2x10-3

  • 2.20

[1] R. W. Ibbotson et al, Phys. Rev. Lett. 80, 2081 (1998) [2] W. T. Chou et al, Phys. Rev. C 47,157 (1993)

* Assuming pure M1 transition

Vibrational Triaxial (γ=30°)[2] Deformed E(4+)/E(2+) 2 2.67 3.3 B(E2;4+→2+) B(E2;2+→0+) 2 1.39 1.43

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 12

Isotopes with B(E2) Ratio less than 1

, Slide 12

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

Jun Chen, Private Communication

Extracted from NuDat 2.7

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SLIDE 13
  • Track reaction point in target
  • Better Doppler-shift corrections
  • Reduce degrader background
  • Increased sensitivity

»Short lifetimes, < a few ps

Active Target

, Slide 13

44Cl (Beam)

38Si (Product)

DE

Z (beam axis)

[1] P. Voss et al. Phys. Rev. C 90, 014301 (2014)

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 14
  • Diamond detector
  • Radiation hard
  • 1% energy resolution
  • 500 μm thick
  • 4.5 mm x 4.5 mm
  • Use in place of target foil
  • Next Steps
  • Diamond Detector

»Beam test with heavy ions »Characterize

Diamond Active Target

, Slide 14

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 15
  • For the nuclei in the region around N=20 to 28, there is an evolution of

shape and structure due to the change in nuclear shell structure far from stability.

  • The Si isotopic chain is expected to show a variety of collectivity as

predicted by most recent shell model calculations.

  • The change in collectivity can be seen in B(E2) ratios resulting from

deformations due to cross shell excitations.

  • 38Si is of particular importance as the turning point between vibrational

and rotational collective pictures.

  • Preliminary lifetimes for the first three transitions in 38Si have been

determined.

  • A diamond active target will be implemented to improve sensitivity of

future lifetime measurements.

Summary

, Slide 15

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 16
  • Lifetime Group: Hiro Iwasaki, John Ash, Rob Elder, Tea Mijatovic
  • Collaborators: Nobuyuki Kobayashi, Hye Young Lee, Kenneth

Whitmore, Charles Loelius, Jun Chen, Daniel Bazin, Alfred Dewald, Alexandra Gade, Dirk Weisshaar, Peter Bender, Joe Belarge, Eric Lunderberg, Brandon Elman, Brenden Longfellow, Thoryn Haylett, Michael Mathy, Sebastian Heil

  • NSSC
  • Questions?

Thanks and Questions

, Slide 16

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

Acknowledgements: This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003180

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SLIDE 17

, Slide 17

[1] T. Otsuka et al. Phys. Rev. Lett. 87, 082502 (2001)

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 18
  • Coulomb excitation (1998) [1]
  • E(2+)=1084 (20) keV,
  • B(E2↑) of 193 (71) e2fm4
  • Inelastic proton scattering (2007) [2]
  • Three gamma peaks in spectrum
  • Two candidates for the 4+ state
  • Multinucleon removal (2012) [3]
  • E(2+)= 1071 (12), E((4+))= 2239 (22),

E((4+))= 2355 (26) keV

  • Beta decay (2015) [4]
  • E(2+)=1074 (2), E(4+)=2233 (2) keV
  • Suggested the lower state as 4+
  • No lifetimes measured previously
  • Jπ at 2355 keV not confirmed

Previous Measurements

, Slide 18

[1] R. W. Ibbotson et al, Phys. Rev. Lett. 80, 2081 (1998) [5] Y. Utsuno et al Prog.Theor.Phys.(Kyoto),Suppl. 196, 304 (2012) [2] C. M. Campbell et al, Phys. Rev. B 4, 652 (2007) [3] S. Takeuchi et al. Phys. Rev. Lett. 109, 182501 (2012) [4] K. Steiger et al, Eur. Phys. J. A (2015) 51:117

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 19

Target Only Data

, Slide 19

Lab Frame

74Ge(n,n’) 72Ge(n,n’) 72Ge(n,n’), 27Al(n,n’) 27Al(n,α)

e+e-

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data

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SLIDE 20

Three Foil Data

, Slide 20

1074 1159 1308

(4+) 1074 2239 4+ 2+ 0+ Energy (keV)

38Si

1159 (2) 1074 (2) Ratio Tgt/deg = 1.5 2382 1308 (15)

  • M. Grinder, October 19, 2018 Joint ICTP-IAEA

Workshop on Nuclear Structure and Decay Data