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g -Factor measurements of high-spin isomers and condensed matter - - PowerPoint PPT Presentation

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g -Factor measurements of high-spin isomers and condensed matter studies using spin-aligned isomeric beams Hiroshi Watanabe Applied Nuclear Physics Laboratory, The Institute of Physical and Chemical Research Outline Introduction g

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SLIDE 1

g-Factor measurements of high-spin isomers and condensed matter studies using spin-aligned isomeric beams

Hiroshi Watanabe Applied Nuclear Physics Laboratory, The Institute of Physical and Chemical Research Outline

  • Introduction
  • g-Factor measurements of the high-spin isomers in N = 83 isotones
  • Condensed matter studies with spin-aligned isomeric beams
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SLIDE 2

Overview of nuclear isomers presented over the chart of nuclei Overview of nuclear isomers presented over the chart of nuclei

Octupole (Fission isomers)

Protons Neutrons He O Ca Ni Sn Pb 2 8 20 28 50 82 126

Prolate (K-isomers) Oblate + Octupole Oblate Spherical 5 f electrons 4 f electrons 4 d electrons 3 d electrons

Nuclear isomerism

Spin selection rules Spin

  • rientation

A large number of isomeric states with various lifetimes and spins have been discovered so far !

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SLIDE 3

Spin-oriented isomers as probes for studies of nuclear moments and solid-state physics

  • 0.6
  • 0.4
  • 0.2

0.2 0.4 0.6 500 1000 1500 2000 2500 3000

R(t) t [ns]

exp (- t /τN) 1 /ωL

Oscillation curve

Larmor frequency

h ) (T B g

ext N N L

β µ ω = T k B J g T

B B J loc

3 ) ( ) 1 ( 1 ) ( µ β χ + = − =

Local susceptibility

  • Local moment

Nuclear relaxation time

J N N N

J B g J τ µ τ

2

} ) ( ){ 1 ( 2

1

h + =

−

T k T J D

B cf F c J 2

)} ( ) ( { 4

1

ε π τ h =

−

4f electron spin fluctuation

  • Exchange

interaction Isomeric g-factor

  • Configuration of the isomer
  • Effect of shell-closure

β known g known

ωL

B e a m

Bext

Nuclear structure Material science

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SLIDE 4

g-Factor measurements of the high-spin isomers in N = 83 isotones

Systematics of the high-spin isomers in N = 83 isotones

Excitation Energy [MeV]

1 2 3 4 5 6 7 8 9

9+ 0.71us 5- 349d

143Nd

13/2+ 6.8ns 7/2-

49/2+ 35ns

144Pm

(27+) >2us

7/2- 340d 13/2+ 12ns

145Sm

49/2+ 0.95us

4- 4.59d 9+ 235us 11- 4.5ns

146Eu

(27+) 10ns

7/2- 38h 13/2+ 22ns 21/2+ 4ns 27/2- 27ns

147Gd

49/2+0.51us

9+ 2m

143Tb

(27+) 1.1us

7/2- 4m 13/2+ 12.5ns 27/2- 510ms

149Dy

49/2+ 28ns

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SLIDE 5

Properties of the high-spin isomer in 147Gd

Isomeric configuration [π（h11/2

2）ν（f7/2h9/2i13/2）]49/2 +

  • 0.22
  • 0.2
  • 0.18
  • 0.16
  • 0.14
  • 0.12
  • 0.1
  • 0.08
  • 0.06
  • 0.04
  • 0.02

5 10 15 20 25 30 35 40

β Spin [ħ]

DIPM calc. exp.

Oblate Sphere g7/2 d5/2 h11/2 d3/2

64

s1/2 d3/2 f7/2 h9/2

82

i13/2 O.Häusser et.al., Nucl. Phys. A379 (1982) 287.

Experimental g -factor Experimental Q -moment Deformation β= -0.19 ※ These properties are well reproduced by the DIPM calculation.

Does the other N = 83 high-spin isomers have the same properties as the 147mGd ?

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SLIDE 6

149Dy Level Structure

146Gd

2 proton + 1 neutron proton proton hole neutron

Eex= 8.52MeV, T1/2 = 28ns High-Spin Isomer

Eex (MeV)

7/2- 13/2+ 1073.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14

4.23 min 12.5 ns 510 ms 1178.8 299.0 110.9 984.9 17/2+ 21/2+ 27/2- 29/2+ 239.8 199.6 1138.2 1337.7 1393.5 254.9 269.8 525.4 430.3 700.3 31/2+ 33/2+ 35/2+ 37/2+ 742.1 491.1 1232.5 39/2+ 41/2+ 43/2+ 168.1 1064.1 580.8 350.3 213.0 479.2 1408.9 253.3 930.5 1143.5 595.4 294.2 829.3 456.5 667.5 962.1* 1354.3 197.7 848.2 704.2 750.4 861.0 802.0 1008.6 543.7 602.8 1137* 303.1 834* 613* 915* 335.1 (11/2-) 1584.0 635* 475* 861* 249* (49/2+)

Z =64 core excitation N =82 core excitation

h 2 49 = I

Oblate shape

β = -0.166

Z =64 core excitation

h 2 47 = I

Spherical shape

β = -0.041

Configuration predicted by the DIPM calc.

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SLIDE 7

143Nd Level Structure

Angular distribution Linear polarization Eex= 8.98MeV, T1/2 = 35ns, Iπ= 49/2+

Configuration predicted by the DIPM calc. Z = 64, N =82 core excitation

h 2 49 = I

Oblate shape

β = -0.176

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SLIDE 8

Experimental details

Injector : RIKEN Heavy-ion Linac (RILAC) Main accelerator : K540 RIKEN Ring Cyclotron (RRC) RIKEN Accelerator Research Facility (RARF) Production of the high-spin isomer in 149Dy

Projectile : 132Xe 7.0 MeV/u, T = 1μs Target : natural Mg of 6.0 mg/cm2 thickness

Production of the high-spin isomer in 143Nd

Projectile : 136Xe 7.6 MeV/u → 6.5 MeV/u, T = 1μs Target : 12C of 1.7 mg/cm2 thickness

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SLIDE 9

Experimental setup for the measurement of g-factors

Dipole Magnet Target Vacuum Ar Gas Ge detector εγ= 0.04% for 1MeV 90° Pb Stopper Beam Ar gas cell Pb Shield

① Inverse reaction & Recoil shadow method Only γ rays emitted through isomeric states can be detected ② Spin relaxation control (Ⅰ) Recoil into Gas Suppress the nuclear spin relaxation during the flight (Ⅱ) Stopper heating system Make the relaxation time long after stopping

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SLIDE 10

Experimental Technique

( )

Factor Correction ic Paramagnet : ) ( ) ( : factor g frequency Larmor : 2 for )] ( 2 cos[ 4 3 ) , 2 / , ( ) , , ( ) , 2 / , ( ) , , ( ) , , ( )] [cos( ) ( ) ( ) , , ( :

  • n

distributi Angular ) , , ( 2 ln exp ) , , ( : ray

  • f

Intensity

int int 22 22 , 2 / 1

T B T B B B B g k t A A B t N B t N B t N B t N B t R t P A I B B t W B t W t T N B t N

ext eff eff N L L L eff eff eff eff eff L k even k k k eff eff eff

β β µ ω ω ω θ π θ θ π θ θ θ ω θ γ θ θ θ γ

γ γ γ γ γ γ γ γ γ γ

= + = ≤ ⋅ − + ≅ + + + − = ⋅ − = ⋅ − =

∑

h ＝ γ-ray Time-Differential Perturbed Angular Distribution (TDPAD) technique

B

T k B J g T

B B J

3 ) ( ) 1 ( 1 ) ( µ β + + =

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SLIDE 11

Calibration of the paramagnetic field

ｇ·β(T) 1/T [K-1]

152Dy I = 21 isomer (g = 0.55±0.06)

β(T) : calculation (5% uncertainty)

0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.001 0.002 0.003 0.004

152Dy I = 21 isomer (present work)

For Dy3+ ion : J = 15/2, gJ = 4/3

calibrated with the known g-factor

  • f the isomeric state in 152Dy

(produced concurrently with the 149mDy)

For Nd3+ ion : J = 9/2, gJ = 8/11

calibrated with B(0) = 3.51(10) MG for Nd3+ ion given by D.Riegel et al.

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SLIDE 12

Result for the high-spin isomer in 149Dy

T [K] ωL [rad/ns] β gexp 328 0.19(2) 6.4(9) 0.41(7) 533 0.11(2) 3.6(5) 0.41(9) Iπ Configuration (DIPM) gcal 47/2- π(h11/2

3g7/2

  • 1)ν(i13/2)

0.82 49/2+ π(h11/2

2)ν(f7/2 h9/2 i13/2)

0.46

＊gℓ(π) = 1.1, gℓ(ν) = -0.03, gs = 0.6gs(free)

gexp = 0.41(6)

  • 0.2
  • 0.15
  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 10 20 30 40 50 60

R(t) t [ns] T = 533 K

  • 0.2
  • 0.15
  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 10 20 30 40 50 60

R(t) t [ns] T = 328 K

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SLIDE 13

Result for the high-spin isomer in 143Nd

0.4

  • 0.4
  • 0.3
  • 0.2
  • 0.1

0.1 0.2

Measured at T = 302 K

0.3

R(t)

10 20 30 40 50 60 70 80 90 100

t [ns]

ωL = 0.082 ± 0.006 rad/ns gexp = 0.56 ± 0.04

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SLIDE 14

0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65

143Nd 144Pm 145Sm 146Eu 147Gd 148Tb 149Dy

Experimental g-factors of the high-spin isomers in N = 83 isotones

g -factor

π(h11/2

2)ν(f7/2 h9/2 i13/2)

Z = 64 shell-gap energies which reproduce the experimental excitation energies of the high-spin isomers in N = 83 isotones

1.9 1.95 2 2.05 2.1 2.15 2.2 2.25 2.3 2.35 2.4

143Nd 144Pm 145Sm 146Eu 147Gd 148Tb 149Dy Z = 64 shell-gap energy [MeV]

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SLIDE 15

Condensed matter studies with spin-aligned isomeric beams 4d atomic-shell 4f atomic-shell

Nucleus Ex [keV] T1/2 I μ[nm] Q[b] 85Y 266 170 ns 5/2- 1.33 88Zr 2889 1.32μs 8+

  • 1.81

0.51 90Zr 3589 134 ns 8+ 10.84

  • 0.51

91Zr 3167 3.6μs 21/2+ 9.82

  • 0.86

97Zr 1264 102 ns 7/2+ 1.37 90Nb 1881 477 ns 11- 8.78 91Nb 2037 3.4 μs 17/2- 10.82 92Nb 2203 167 ns 11- 9.7 90Mo 2875 1.1 μs 8+

  • 1.391

0.58 92Mo 2760 190 ns 8+ 11.3

  • 0.34

94Mo 2956 98 ns 8+ 10.46 0.47 93Tc 2186 10.1 μs 17/2- 10.46 93Ru 2082 2.4 μs 21/2+ 8.97 0.04 100Rh 75 215 ns 2+ 4.324 112+x 140 ns 7+ 4.69 104Rh 215.5+x 47 ns 6- 2 96Pd 2532 2.22 μs 8+ 10.97 Nucleus Ex [keV] T1/2 I μ[nm] Q[b] 134Ce 3209 308 ns 10+

  • 1.87

1.32 136Ce 3096 2.2 μs 10+

  • 1.8

138Ce 3538 82 ns 10+

  • 1.7

139Ce 2632 70 ns 19/2- 3.99 136Pr 548 90 ns 4+ 2.3 138Nd 3172 330 ns 10+

  • 1.74

148Nd 3621 330 ns 10+

  • 1.75

142Sm 2372 170 ns 7- 0.42 1.1 151Sm 92 77 ns 9/2+

  • 0.95

145Eu 716 0.49 μs 11/2- 7.46 147Eu 635 765 ns 11/2- 7.05 148Eu 720 235 ns 9+ 6.12 144Gd 3433 130 ns 10+ 12.76

  • 1.46

147Gd 8587 510 ns 49/2+ 10.9

  • 3.24

158Dy 99 1.66 μs 2+ 0.72 168Er 1094 112.5 ns 4- 0.96 169Tm 316 660 ns 7/2+ 0.156 157Yb 494+x 45 ns 13/2+

  • 0.75
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SLIDE 16

Why Ce beam ?

εF >> Ef εF << Ef The RKKY interaction gives rise to various kinds

  • f magnetic ordering.

Demagnetization is caused by the Kondo effect. localize around the atom itinerate in the crystal Compete εF ≈ Ef

JcfDc(εF) CeIn3 CeAl2 CeB6 CeCu2Si2 CeAl3 CeCu6 CeRu2Si2 CeNi CeSn3 T

Tk TRKKY TN

A.F. Heavy-fermion (Fermi liquid)

kBTRKKY ~ J2

cfDc(εF)

kBTK ~ exp[-1/JcfDc(εF)]

Heavy fermion system Many physical phenomena, such as ferro- and anti-ferromagnetism, Kondo effect, superconductivity, and heavy-fermion behavior can take place in Ce-based compounds and alloys.

Quantum critical point

Properties of Ce-based systems 4f electrons

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SLIDE 17

Anomalous ferromagnetism in CeRh3B2

  • Tc = 115 K

the highest Curie temperature among known Ce-based compounds with nonmagnetic constituents [GdRh3B2 (Tc = 90 K) expected to be Tc ~ 1 K]

  • Hexagonal ternary (CeCo3B2-type) structure

Ce-Ce chain along the c-axis … very close Ce-Ce distance (3.09 Å)

  • Small magnetic moments

μbulk = 0.42 μB /f.u. μCe = 0.38 μB / Ce

  • Magnetic anisotropy

μ(c-plane) /μ(c-axis) = 2.5

de Genne law

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SLIDE 18

Optimal condition for the production of 134mCe48+

  • Projectile : 131Xe, E = 8 MeV/u, I = 5 pnA (T = 3μs)
  • Target : 9Be, 7.5 μm
  • Reaction : 9Be(131Xe, 6n) 134mCe (Isomer ratio = 17 %)

Angular acceptance (± 80 mrad) Momentum acceptance (F1 slit ±10mm) Decay in flight (L = 27.5 m) Cross section (by PACE2) Charge distribution

134mCe intensity @F3 … 6.9×103 /s

Fusion reaction with inverse-kinematics Low energy beam Not-fully-stripped charge state Very large hyperfine fields are produced by the atomic electrons

1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 Incident Energy [MeV/u]

130Xe+9Be

Yields of 134mCe (Q = 48+) @F3

131Xe+9Be 132Xe+9Be

Production of the 134Ce isomeric beam Keep the initial nuclear alignment by transporting only one charge state

  • f Ce ions which have the

Ne-like atomic shell

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SLIDE 19

Summary

Spin-aligned isomers become excellent probes for studies

  • f nuclear moments and condensed matter studies.

g-Factor measurements of high-spin isomers g(149mDy) = 0.41 ± 0.06 g(143mNd) = 0.56 ± 0.04 Main configuration of the high-spin isomers in N = 83 isotones [π（h11/2

2）⊗ν（f7/2h9/2i13/2）]

The g-factors of these isomers gradually increase as the proton numbers decrease. Condensed matter studies with spin-aligned isomeric beams

134Ce isomeric beam will be developed.

CeRh3B2 (Tc = 115 K) will be studied in near future.

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SLIDE 20

Acknowledgements

RIKEN

  • H. Ueno, W. Sato, A. Yoshimi, Y. Kobayashi,
  • T. Haseyama, T. Kishida

Tokyo Institute of Technology

  • K. Asahi, D. Kameda, H. Miyoshi, K. Shimada,
  • S. Emori, G. Kato

Kyushu University

  • Y. Gono

Nishinippon Institute of Technology

  • A. Odahara
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SLIDE 21

Thank you very much for your attention