Outline

1
Brighton, University of Sussex, 16.02.2005
A Penning trap as a precision mass balance
Mass measurements for fundamental studies
Klaus Blaum University of Mainz and GSI Darmstadt
Outline
Introduction and motivation
Mass measurements of radionuclides
Mass measurements of stable ions
Future experiments
Conclusions
2
Mass and Energy

• EnergyMass equivalence
• ? High-precision mass measurements convey
  information on
• nuclear and atomic binding energies

3
The Importance of Atomic Masses
atomic masses
Weighing
4
Principle of Penning Traps
Cyclotron frequency
q/m
5
Ion Motion in a Penning Trap

• Motion of an ion is the superposition of three
  characteristic
• harmonic motions
• axial motion (frequency fz)
• magnetron motion (frequency f)
• modified cyclotron motion (frequency f)
• The frequencies of the radial motions obey the
  relation

Typical frequencies q e, m 100 u, B 6
T ? f- 1 kHz f 1 MHz
6
Excitation of Radial Ion Motions
Dipolar azimuthal excitation Either of the ion's
radial motions can be excitedby use of an
electric dipole field in resonancewith the
motion (RF excitation) ? amplitude of motion
increases without bounds Quadrupol
ar azimuthal excitation If the two radial motions
are excited at theirsum frequency, they are
coupled ? they are continuously converted
into each other
Conversion of radial motions
Magnetron excitation r?
Cyclotron excitation r
7
TOF Resonance Mass Spectrometry
Time-of-flight resonance technique
Scan of excitation frequency
Dipolar radial excitation at f- ? increase of r-
Quadrupolar radial excitation near fc ? coupling
of radial motions, conv.
1.2 m
Ejection along the magnetic field lines ? radial
energy converted to axial energy
Time-of-flight (TOF) measurement
Resolving power
8
TOF Cyclotron Resonance Curve (Stable Nuclide)
TOF as a function of the excitation frequency
Centroid
Determine atomic mass from frequency ratio with
a well-known reference mass.
9
Mass measurement programs for radionuclides
worldwide
See Lunney, Pearson Thibault, Rev. Mod.
Phys. 75 (2003)
10
Comparison of Direct Mass Measurement Techniques
-4
10
SPEG
TOFI
m
-5
10
/
m


d



Y
C
-6
10
A
R
U
C
C
-7
A
10
-8
10
3
-4
-3
-2
-1
0
1
2
10
10
10
10
10
10
10
10
HALF-LIFE RANGE s
11
Triple-Trap Mass Spectrometer ISOLTRAP
precision Penning trap
1.2 m
10 cm
determination of cyclotron frequency (R 107)
B 5.9 T
preparation Penning trap
stable alkali ion reference source
B 4.7 T
removal of contaminant ions (R 105)
532 nm
NdYAG
cluster ion source
ion beam cooler and buncher
F. Herfurth, et al., NIM A 469, 264 (2001) K.
Blaum et al., NIM B 204, 478 (2003)
K. Blaum et al., EPJ A 15, 245 (2002)
12
ISOLTRAP Setup at ISOLDE/CERN
1 m
13
Problem of Reference Masses
14
Carbon Clusters as Reference Masses
K. Blaum et al., EPJ A 15, 245 (2002)
15
Benefits of Carbon Clusters as Reference Masses

• References throughout the chart of the nuclides
• Reference mass at most 6 u from the measured mass
• Absolute mass measurements can be performed
• 12C is microscopic mass standard u 1/12
  m(12C)
• elimination of the uncertainty of the reference
  mass by definition
• Cross-reference measurements allow determination
  of various
• uncertainties of setup and procedure and
  determination of the
• present mass accuracy limit

Residual mass uncertainty (dm/m)res
810-9
K. Blaum et al., EPJ A 15, 245 (2002)
A. Kellerbauer et al., EPJ D 22, 53 (2003)
16
Isobaric Multiplet Mass Equation
A 33, T 3/2 quartet
Mass formula for multiplets of nuclear states
with same mass and isospin
17
Recently Most Stringent Test of IMME (with
32,33Ar)
d / keV
K. Blaum et al., Phys. Rev. Lett. 91, 260801
(2003).
18
Superallowed b Decay and the Standard Model

• Conserved-vector-current hypothesis
• Vector part of weak interaction not influenced by
  strong interaction
• Intensity of ß decays (ft value) only a
  function of the vector
• coupling constant and the matrix element
• Corrections
• to the statistical rate function f
• dC isospin symmetry breaking correction
• (Coulomb force, strong force)
• to the nuclear matrix element ?MV?
• dR radiative correction
• (bremsstrahlung etc.)

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Experimental Access to Ft Value

• Q Decay energy ? mass m
• T1/2 Half-life
• b Branching ratio
• PEC Electron capture fraction
• dR Radiative correction
• dC 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

20
Results FT Value

ISOLTRAP mass measurements 22Mg ? 22Na dQ0.28
keV, 34Ar ? 34Cl dQ0.41 keV, 74Rb ? 74Kr
dQ4.5 keV
I.S. Towner J.C. Hardy, submitted to Phys.
Rev. C (2005)
74Rb
34Ar
22Mg
F. Herfurth et al., Eur. Phys. J. A 15, 17
(2002) A. Kellerbauer et al., Phys. Rev. Lett.93,
072502 (2004) M. Mukherjee et al., Phys. Rev.
Lett. 93, 150801 (2004)
21
Status CKM Matrix

• Check unitarity via elements of the first row
• Vus and Vub from particle physics data (K and B
  meson decays)
• From nuclear ß decay (world average 2005)
• Vud obtained from avg. Ft and GA from muon decay
• From neutron decay
• Vud obtained from neutron ß decay asymmetry A
  and lifetime t

D -0.0034(14)
I.S. Towner J.C. Hardy, submitted to Phys.
Rev. C (2005)
(RPP world average 2002)
H. Abele et al., PRL 88 (2002) 211801
22
Solution to the Non-Unitarity Problem
Contribution to the unitarity
Present status
0.00001
Vub
0.05
Vus
Vud (nuclear b-decay) 0.9738(4) Vus
(kaon-decay) 0.2200(26) Vub (B meson decay)
0.0037(5)
Hardy2005
PDG2004
99.95
Vud
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Non-Destructive Single Ion FT-ICR Detection
Pickup-Elektrode
mass spectrum
ion current signal
I
I
f
t
FT-ICR fourier-transform-i
on cyclotron resonance
very small 0.2pAeff
Pickup-Elektrode
Applications

• Mass measurements on superheavy rare elements
  (SHIPTRAP)
• Ultra high-precision mass measurements on
  stable ions

C. Weber et al., PhD Thesis, Heidelberg (2004).
24
SMILETRAP High-Precision Mass Measurements
Principle Using highly-charged stable ions
Cyclotron frequency
I. Bergström et al., Eur. Phys. J. D 22, 41
(2003).
25
The Kilogram Problem
Present
Future
Single crystalline silicon ball
Prerequisite dm/m 1?10-9
Kilogram prototype Bureau International des Poids
et Mesures
26
An Atomic Definition of the Kilogram
The Avogadro Project The kilogram is the mass
of Nkg 12C-atoms.
Recipe ? Produce a perfect Si crystal ?
Make a ball out of it ? Measure the diameter ?
Determine the lattice parameter ? Measure the
contaminations ? Calculate the number of Si
atoms ? Measure the isotopic abundance
? Measure the 28Si/12C mass ratio
? Measure the 28Si/12C mass ratio ? DONE with
SMILETRAP
? and do all steps with an uncertainty of 10-9
or better!
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High-Precision Mass Spectrometers Worldwide
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Gaining Precision From Past to Present
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to Future
Design and installation of a ...

• Novel Penning trap setup for ultra high-precision
  mass spectrometry with dm/m ? 110-11
• Help to place limits on the electron neutrino
  rest
• mass, e.g. Q(3T(b)3He) for the KATRIN
  experiment
• QED tests, Determination of e-binding energies
• Measurement of fundamental constants (a, NA/h)
• Metrology, e.g. new kilogram definition ...
• CPT (p-pbar mass comparison)

M.P. Bradley et al., PRL 83, 4510 (1999) G.
Gabrielse et al., PRL 82, 3198 (1999)
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Novel High-Precision Penning Trap Mass
Spectrometer
Proposed setup
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First Application of the Planned Penning Trap
System
Determination of the of 3T - 3He mass
difference with a precision of 20 meV for the
KATRIN experiment (present absolute precision is
1.7 eV)
in discussion with C. Weinheimer et al.
E0
KATRIN LOI If a 1ppm precision (?20 meV) in the
3He-T mass difference DM (3He,T) and the absolute
calibration of KATRIN could be achieved the
sensitivity on mn could be improved further by
using an external DM (3He,T) value in the
analysis.
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Conclusions and Outlook
Ion traps are an ideal tool to perform atomic and
nuclear physics precision experiments!

• The development of a carbon cluster-comb was a
  breakthrough in mass spectrometry of
  radionuclides.
• ISOLTRAP can perform high-precision mass
  measurements
• (lt 10-8) on very short-lived nuclides (lt 100 ms)
  that are
• produced with very low yields (lt 100 ions/s),
  SMILETRAP
• (lt 10-9) on stable highly-charged ions
• Such high-precision mass measurements can provide
  valuable input to nuclear structure and
  fundamental studies
• Future trap experiments aim for dm/m ? 10-11 for
  stable ions and can thus help to discover
  exciting new physics

33
Final Conclusion
Heinz Maier-Leibnitz (1911-2000)
Whenever you invent a method ten or a hundred
times better than the existing ones, you can be
sure that this will lead to new science!
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Not to Forget
Thanks to my colleagues G. Audi, G. Bollen, D.
Beck, P. Delahaye, T. Fritioff, S. George, C.
Guénaut, A. Herlert, F. Herfurth, A. Kellerbauer,
H.-J. Kluge, D. Lunney, S. Schwarz, R. Schuch,
L. Schweikhard, C. Weber, C. Yazidjian, and the
ISOLTRAP and ISOLDE collaboration Thanks for the
funding and support GSI, BMBF, CERN, ISOLDE, EU
networks EUROTRAPS, EXOTRAPS, and NIPNET
Thanks a lot for your attention.
www.physik.uni-mainz.de/quantum/mats/