1. Mass Measurements on Superallowed β-Emitters Using Ramsey’s Excitation Method at ISOLTRAP
Outline
Sebastian George
Tokyo 2007
High-Precision Mass Spectrometry
Ramsey Method
Weak Interaction Studies

2. Principle of Penning Trap Mass SpectrometryB
PENNING trap
Strong homogeneous
magnetic field
Weak electric 3D
quadrupole field
Cyclotron frequency:
q/m
end cap
Typical frequencies
q = e, m = 100 u,
B = 6 T
 f- ≈ 1 kHz
f+ ≈ 1 MHz
ring
electrode
Brown & Gabrielse, Rev. Mod. Phys. 58, 233 (1986)

3. Triple-Trap Mass Spectrometer ISOLTRAP
10 cm
precision
Penning trap
determination of
cyclotron frequency
(R = 107)
1,2 m
B = 5.9 T
preparation
Penning trap
removal of
contaminant ions
(R = 105)
stable alkali ion
reference source
B = 4.7 T
(dm/m)res = 10-8
cluster ion source
G. Bollen et al., NIM A 368, 675 (1996)
ion beam cooler and buncher
K. Blaum et al., EPJ A 15, 245 (2002)
A. Kellerbauer et al., EPJ D 22, 53 (2003)

4. Time-of-Flight Ion Cyclotron Resonance Detection
(3) TOF measurement 1 2 3 4 5 6 7 8 9
240
270
300
330
360
390 s m
(2) Energy conversion
Mean time of flight /
Centroid: 63 Ga T
= 32.4 s
1/2
Excitation frequency
frf
/ Hz
(1) Excitation of the ion motion
Determine atomic mass from frequency ratio
with a well-known “reference mass”.

5. The Ramsey Excitation Method
S. George et al., Phys. Rev. Lett. 98, (2007)
38Ca (T1/2 = 440 ms)
A precision gain of more than
a factor of 3 is obtained.
S. George et al, Int. J. Mass Spectrom., in press (2007),
doi: /j.ijms

6. First Online Application
Mass measurements on superallowed β-emitters
38Ca (T1/2=440ms) and 26Al (T1/2=6.35s)#
Relative uncertainty at the level of 1*10-8
not limited by the statistical uncertainty
ME(38Ca)= (60) keV and ME(26Ca)= (22) keV
# The superallowed β-emitter is 26Alm
K – Product of fund. constants
GV – Vector coupling constant
MV - Nuclear matrix element
George S. et al, Phys. Rev. Lett. 98 (2007)

7. Experimental Access to FT-Value
Q – Decay energy  mass m
T1/2 – Half-life
b – Branching ratio
PEC – Electron capture fraction
δR – Radiative correction
δC – Isospin symmetry breaking correction
Unitarity of the CKM matrix
Mean Ft value of all decay pairs contributes to Vud via GV
Can check unitarity via sum of squares of elements of the first row
dm/m < 3·10-8
Weak Interaction
symmetry tests,
CVC hypothesis m

8. CVC test
An accuracy of the Q-value by some few 100 eV is reached by mass measurements.
In addition required:
Half-life Branching ratio ● ● ●
ISOLTRAP: Mg-22, Al-26, Ar-34, Ca-38, Rb-74
F. Herfurth et al., Eur. Phys. J. A 15, 17 (2002)
A. Kellerbauer et al., Phys. Rev. Lett.93, (2004)
M. Mukherjee et al., Phys. Rev. Lett. 93, (2004)
S. George et al., Phys. Rev. Lett. 98 (2007)
JVL-TRAP: Al-26m, Sc-42, Ga-62 T. Eronen et al., Phys. Rev. Lett. 97, (2006) T. Eronen et al., Phys. Lett. B 636, 191 (2006) B. Hyland et al., Phys. Rev. Lett. 97, (2006)
CPT: Mg-22, V-46 G. Savard et al., Phys. Rev. Lett. 95, (2005)
J. Clark et al., Phys. Rec. C 70, (R) (2004)
LEBIT: Ca-38 G. Bollen et al., Phys. Rev. Lett. 96 (2006)
Further measurements at the Q3D magnetic
spectrograph (T. Faestermann)

9. Thanks for funding and support:
THE END
Thanks a lot to
K. Blaum, M. Dworschak, C. Guénaut, A. Herlert, F. Herfurth, A. Kellerbauer, J. Ketelaer, H.-J. Kluge, M. Kretzschmar, M. Kowalska, D. Lunney, S. Nagy, D. Neidherr, S.Schwarz, L. Schweikhard, C. Yazidjian, and the ISOLTRAP and MATS collaboration
Thanks for funding and support:
GSI, BMBF, CERN, ISOLDE, HGF
EU networks EUROTRAPS, EXOTRAPS, and NIPNET