1. Muon Spectroscopy WS, Villigen Nuclear charge radii measurements by collinear laser spectroscopy and Penning trap g-factor experiments: The need for absolute charge radii
Collinear laser spectroscopy studies
g-factors of bound electrons in HCI
Klaus Blaum
Oct 21th, 2016

2. Laser spectroscopy studies
Charge radii
Laser spectroscopy studies
CERN, Darmstadt, Leuven, Liverpool, Manchester, MPIK

3. Principle of collinear laser spectroscopy
electrostatic
deflection
charge exchange cell (Na)
ion beam
Ekin<60 keV
electrostatic lenses for retardation
excitation & observation reg. +
laser beam
fixed frequency + +
fine
250 25 Mg
HFS of
A(S1/2) = 596.5(5) MHz
300
350
fine Doppler tuning voltage (V)
400
photons D
6.5 o o
photo multiplier

4. HFS and Isotope shift Experimental spectrum Isotope 1
Isotope Shift := Frequency difference in an electronic transition between two isotopes
Isotope 2
J=3/2
J=1/2
Experimental spectrum

5. HFS and Isotope shift Isotope 1
Isotope Shift := Frequency difference in an electronic transition between two isotopes
Isotope 2

6. Isotope shift Mass Shift Field Shift Isotope 1 Isotope 2 IS E r p s
(center-of-mass motion)
Field Shift
(finite size) r E s p
|IS|, GHz Z

7. Laser spectroscopy of radionuclides
Pulsed Resonance
Ionization (RIS)
Collinear
Spectroscopy
(+ cw RIS)
Low-Medium
Resolution,
High Efficiency
Medium-High
Resolution,
Lower Efficiency
Specialized
Techniques
High Resolution
+ High Efficiency
Courtesy:
W. Nörtershäuser
H.-J. Kluge and W. Nörtershäuser, Spectrochim. Acta B, 58 (2003).

8. Isotope shifts in Cu and Ga
COLLAPS (ISOLDE)
5/2
3/2
1/2
Spin 1/2 col.
Spin 3/2, 5/2
inversion
π p3/2(f5/2)2
π (p3/2)3
Emptying of p3/2
Sudden nuclear structure changes between N=40 and N=50
71,73,75Cu: PRL 103, (2009); Ga: PRL 104, (2010); Cd: PRL 110, (2013)

9. Charge radii in Cu and Ga
Changes in mean-square charge radii for the Cu isotopes
and neighboring isotopic chains. The other isotopic chains are offset
by the nominal differences in absolute mean-square charge radii
from [42] without further consideration of the associated large and
model-dependent uncertainties. Cu results based only on theMCDHF
calculations, without alteration of Mk to reproduce the muonic atom
data are shown as the black dashed line. Systematic uncertainties for
Cu and Ga [43] are represented by the shaded lines above and below
the respective trends.
Courtesy:
M. Missell
Cu: PRC 93, (2016) Ga: PRC 86, (2012)

10. The Ca radii puzzle Rch(40Ca) = 3.478(2) fm
RFQ
Rch(40Ca) = 3.478(2) fm
R. Garcia-Ruiz et al., Nature Physics (2016)

11. g-factors and fundamental tests
The need of absolute charge radii for g-factor measurements
* In collaboration with Ch. H. Keitel (MPIK), W. Quint (GSI), G. Werth (Mz)

12. Quantum-ElectroDynamics (QED)
QED describes the quantum interaction of
light (photons) and matter (charged particles)
through a series of simple fundamental interaction processes depicted by Feynman diagrams
Calculated values are in impressive
agreement with experimental results
QED is our best tested theory
in weak fields
Richard P. Feynman
Highly charged ions
However: Lack of tests in extreme situations

13. The g-factor g(12C5+) g(28Si13+) [J. Zatorski et al., 2011]
K. Pachucki et al.,
Phys. Rev. A 72, (2005)
[J. Zatorski et al., 2011]

14. Measurement principle
Measurement of the free cyclotron frequency to determine the
magnetic field: B
Measurement of the Larmor frequency in a well-known magnetic field: B
Measured by independent precision experiments
has to be
determined
Experimental
conditions:
Cryogenic temperatures (4.2K)
Non-destructive ion detection
Vacuum better than mbar
less than 20 gas atoms
in the trap volume !

15. g-factor resonance of a single 28Si13+ ion
Uncertainty on electron mass got reduced by a factor of 13 using 12C5+.
Most stringent test of BS-QED in strong fields.
Theory colleagues: Harman, Keitel, Zatorski
S. Sturm et al., Phys. Rev. Lett. 107, (2011)
A. Wagner et al., Phys. Rev. Lett. 110, (2013)
Experiment limited by uncertainty
of electron mass
Theory limited by nuclear structure effects
gexp = (5)(3)(8)
gtheo= (17)

16. g factor results
The current measurement is testing QED theory at the level of 1.4∙10-7
Higher order contributions to two-loop theory are relevant for the first time
Nuclear size effect tested
for the first time, nuclear
charge radius extracted:
<r2>1/2 = 3.12 (15) fm
Vacuum polarization tested
Measurements of other
g factors will allow further
tests
Theory will provide more
accurate results in the future
Rrms(238U) = (23) fm
T. Beier, Phys. Rep. 339, 79 (2000)
our measurement

17. What comes next? a
ALPHATRAP: A high-precision Penning- trap setup at MPIK for HITRAP
Production of HCI 208Pb77+,81+
Larmor-to-cyclotron frequency ratio measurement in a double Penning trap yields dg/g ≈ 10-12
Experiment and theory provide stringent test of BS-QED and FSC a

18. Thanks a lot for the invitation
Conclusion
There is a strong need for absolute charge radii measurements by muon spectroscopy!
Thanks a lot for the invitation
and your attention!
WWW:
Max Planck Society
Adv. Grant MEFUCO
Helmholtz Alliance
IMPRS-PTFS