1. Addendum to IS 449 Measurement of the isotope shift of 7,9,10,11Be at COLLAPS
The BeTINa Collaboration
W. Nörtershäuser1,2, K. Blaum1,2, J. Ebele4, Ch. Geppert2, M. Kowalska3, J. Krämer1, R. Neugart1, R. Sanchez1, F. Schmidt-Kaler4, D. Tiedemann1, D. Yordanov3, M. Zakova1, C. Zimmermann5
1 Johannes Gutenberg-Universität Mainz, Germany
2 GSI Darmstadt, Germany
3 CERN, CH-1211 Genéve 23, Switzerland
4 Universität Ulm, Germany
5 Eberhard-Karls Universität Tübingen, Germany
Spokespersons: W. Nörtershäuser, C. Geppert
Local Contacts: D. Yordanov, M. Kowalska
Laser Spectroscopy of Highly Charged
Ions and Exotic Radioactive Nuclei
(Helmholtz Young Investigators Group)
Laser
SpHERe

2. Radii of Halo Isotopes Charge radius measurements of
light (Z<18) radioactive isotopes:
2003 : 6,7,8,9Li at GSI G.Ewald et al., PRL 93, (2004)
2004: 6He at Argonne, L.-B. Wang et al. PRL 93, (2004)
2004: 11Li at TRIUMF, R. Sanchez et al., PRL 96, (2006)
2007: 8He at GANIL, P. Müller et al. PRL 99, (2007)

3. DnIS = DnMS + DnFS Isotope Shift D|(0)|2 d r2 2Z 3 0.001 GHz 10 GHz
= Frequency difference in an electronic
transition between two isotopes
Isotop 2
DnIS = DnMS +
DnFS
Field Shift
D|(0)|2 d r2
2Z 3
Mass Effect, nuclear motion
finite size of the nucleus
0.001 GHz
10 GHz
He, Li,
Be :

4. Charge Radii Determination for Light Elements
DnIS =
DnMS +
DnFS
EXPERIMENT
D|(0)|2
2Z 3
THEORY
D|(0)|2
2Z 3
Charge Radius : - = C

5. Level Scheme and Be+ Transitions

6. Simulated Spectra
Gnat  20 MHz
2s½
F=0
2p½
F=1
11Be+ RF

7. Why COLLAPS ?
Standard collinear measurements are limited by the uncertainty of the acceleration voltage
Use “simultaneous” collinear-anticollinear measurement and absolute frequency determination with a frequency comb
Field shift is too small in light isotopes
FS constant in Be+ 2s-2p is considerably larger than in lithium 2s-2p or 2s-3s since the electron is stronger bound
 Charge radii can be measured to a good accuracy with COLLAPS if we apply "new" techniques !

8. Approach
Frequency Comb

9. Laser System for Beryllium Spectroscopy
Wavemeter
Frequency
Comb Dn RF
Comparator
Feedback
l/2
PBC
Dye Laser 1
Nd:Yag Laser
Frequency
Doubler 1
Laser
Beam 1
Collinear
Laser Beam
Dye Laser 2
l/2
Iodine Spectroscopy
Feedback
Frequency
Doubler 2
Laser
Beam 2
Anti-Collinear
Laser Beam

10. Iodine Lines for the 9Be+ 2s1/2  2p1/2 transition (cg)

11. Measurement Procedure
Comb-Laser
Frequency I2
Frequency
Voltage

12. Be Hyperfine Measurements at COLLAPS
1450
2900
4350
Doppler-tuning frequency (MHz)
85 MHz
Previous successful beryllium measurement at COLLAPS
+ Mass shift calculations by G.W.F. Drake and Z.-C. Yan / K. Pachucki:
→ Exakt position of Be Resonances within a few MHz

13. Reachable Accuracy Absolute frequency determination
Line center accuracy 1 MHz
1 mrad Laser – Ion Beam Angle MHz
1 mrad Missalignment of laser beams MHz
Clock-related comb uncertainty < 0.10 MHz
Total Uncertainty < 2 MHz
IS determination (differential effects)
Line center accuracy <1 MHz
1 mrad Missalignment of laser beams MHz
Total Uncertainty ~ 1 MHz

14. Beamtime Request and Schedule
Test Beamtime in April / May ( 8 shifts)
On-line Run in June / July (16 shifts)
Summary :
A nuclear charge radius determination of 7,9,10Be and the 1-Neutron Halo Nucleus 11Be with an accuracy of better than 5% Rc is feasible by frequency-comb based collinear laser spectroscopy at COLLAPS.

15. Be-Isotope properties