Addendum to IS 449 Measurement of the isotope shift of 7,9,10,11 Be at COLLAPS
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Transcript of Addendum to IS 449 Measurement of the isotope shift of 7,9,10,11 Be at COLLAPS
W. Nörtershäuser 1
Addendum to IS 449
Measurement of the isotope
shift of 7,9,10,11Be at COLLAPS
Laser Spectroscopy of Highly Charged Ions and Exotic Radioactive Nuclei
(Helmholtz Young Investigators Group)
http://www.kernchemie.uni-mainz.de/laser/
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, Germany3 CERN, CH-1211 Genéve 23, Switzerland4 Universität Ulm, Germany5 Eberhard-Karls Universität Tübingen, Germany
Spokespersons: W. Nörtershäuser, C. GeppertLocal Contacts: D. Yordanov, M. Kowalska
W. Nörtershäuser 2
Radii of Halo Isotopes
2004: 11Li at TRIUMF, R. Sanchez et al., PRL 96, 033002 (2006)
2003 : 6,7,8,9Li at GSI G.Ewald et al., PRL 93, 113002 (2004)
2004: 6He at Argonne, L.-B. Wang et al. PRL 93, 142501 (2004)
Charge radius measurements of light (Z<18) radioactive isotopes:
2007: 8He at GANIL, P. Müller et al. PRL 99, 252501 (2007)
W. Nörtershäuser 3
Isotope Shift
IS = MS +Field Shift|(0)|2 r2Z
3
FS
Mass Effect, nuclear motion
21 1
AAA
AA A
'
'MS
3
2
A
ZFS
= Frequency difference in an electronic transition between two isotopes
0.001 GHz10 GHzHe, Li, Be :
Isotop 1
Isotop 2
finite size of the nucleus
W. Nörtershäuser 4
Charge Radii Determination for Light Elements
IS = FS
2δ r
MS +
|(0)|22Z3
THEORYEXPERIMENT
|(0)|22Z3
Charge Radius :',AA
r 2δ',AAνmeasured ',AAν Theory MS,-
=C
I sotope 7 A,MS [Puch06] 7 A,
MS [Drake06] 6Li - 11 452.822 (2) (0) -11 452.83 (2) 8Li 8 634.990 (1) (1) 8 634.98 (2) 9Li 15 331.797 (3)(13) 15332.03 (3) 11Li 25 101.473 (9)(21) 25101.42 (3)
W. Nörtershäuser 5
Level Scheme and Be+ Transitions
0
5
10
15
Ene
rgie
[eV
]
0
20000
40000
60000
80000
100000
120000
140000
Ene
rgie
[cm
-1]
1s2 2s 2S1/2
1s2 2p 2P1/2, 3/2
3s
4s
5s
3p
4p
3d
4d 4f
7,9Be+
2s1/2F=1
F=2
2p1/2F=1
F=2
2p3/2 F=0,1,2,3
313.197 nm
= 8,1 (4) ns, ~ 20 MHz
313.197 nm
= 8,1 (4) ns, ~ 20 MHz
11Be+
2s1/2F=0
F=1
2p1/2F=0
F=1
10Be+
2s1/2
2p1/2
F=1/2
F=1/2
RF
W. Nörtershäuser 6
Simulated Spectra
-1000 -500 0 500 1000
F=
2 -
F=
1
F=
2 -
F=
2
F=
1 -
F=
1
F=
1 -
F=
2
F=
1 -
F=
0 F
=1
- F
=1
9Be
11Be
Am
plitu
de (
arb.
uni
ts)
Frequency (MHz, relative cg)
F=
0 -
F=
1
nat 20 MHz
2s½F=0
2p½F=0
F=1
11Be+
RF
F=1
W. Nörtershäuser 7
Why COLLAPS ?
• Standard collinear measurements are limited by the uncertainty of the acceleration voltageUse “simultaneous” collinear-anticollinear measurement and absolute frequency determination with a frequency comb
• Field shift is too small in light isotopesFS 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 !
W. Nörtershäuser 8
Approach
LASER 1
LASER 2
Ion beam
optic
alde
tect
ion
char
geex
chan
gece
ll
dece
lerat
ion
defle
ction
LASER 1
LASER 2
Ion beam
optic
alde
tect
ion
char
geex
chan
gece
ll
dece
lerat
ion
defle
ction
10p 10a
20
20
22 1 pa
Frequency Comb
W. Nörtershäuser 9
RF Comparator
Feedback
Dye Laser 2/2
Frequency Doubler 1
Laser
Beam 1
Collinear Laser Beam
Frequency Doubler 2
Laser
Beam 2
Anti-CollinearLaser Beam
/2 PBC
Dye Laser 1Nd:Yag Laser
Wavemeter
Frequency Comb
Iodine Spectroscopy
Feedback
Laser System for Beryllium Spectroscopy
W. Nörtershäuser 10
Iodine Lines for the 9Be+ 2s1/2 2p1/2 transition (cg)
46200 46400 46600 46800 47000 47200 47400 47600 478000.0
0.5
1.0
1.5
2.0
2.5
In
ten
sity
[arb
. un
its.]
Voltage [V]
W. Nörtershäuser 11
Measurement Procedure
I2
Voltage
Frequency
Frequency
Comb-Laser
W. Nörtershäuser 12
Be Hyperfine Measurements 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
0 1450 2900 4350
Doppler-tuning frequency (MHz)
85 MHz
Previous successful beryllium measurement at COLLAPS
W. Nörtershäuser 13
Reachable Accuracy
Absolute frequency determinationLine center accuracy 1 MHz1 mrad Laser – Ion Beam Angle 0.005 MHz1 mrad Missalignment of laser beams 0.75 MHzClock-related comb uncertainty < 0.10 MHz
Total Uncertainty < 2 MHz
IS determination (differential effects)Line center accuracy <1 MHz1 mrad Laser – Ion Beam Angle 0.005 MHz1 mrad Missalignment of laser beams 0.075 MHz
Total Uncertainty ~ 1 MHz
W. Nörtershäuser 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.
W. Nörtershäuser 15
Be-Isotope properties