A Penning trap as a precision

1
Workshop on NDBD, Durham, 23.05.2005
A Penning trap as a precision mass balance
Q-Value determinations with ISOLTRAP and SMILETRAP
Klaus Blaum University of Mainz and GSI Darmstadt
Outline
Introduction and motivation
Q-value measurements of radionuclides
Q-value measurements of stable ions
Conclusions and outlook
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
A Brief History of Mass Spectrometry
5
Principle of Penning Traps
B
Cyclotron frequency
q/m
6
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
7
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
8
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
9
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.
10
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)
11
ISOLTRAP Setup at ISOLDE/CERN
1 m
12
Problem of Reference Masses
13
Carbon Clusters as Reference Masses
K. Blaum et al., EPJ A 15, 245 (2002)
14
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)
15
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.)

16
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

17
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
Tz -1
34Ar
22Mg
Tz 0
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)
18
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
19
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
20
SMILETRAP High-Precision Mass Measurements
Stockholm Mainz Ion LEvitation TRAP
Principle Using highly-charged stable ions
Cyclotron frequency
21
SMILETRAP High-Precision Mass Measurements

• PreTrap
• After magnet 106 ions
• 1/250 beam captured 4000
• pretrap length/beam length
• 2 V deep trap / 7 V energy spread

• Precision Trap
• After injection aperture 150 ions
• Captured 50 ions
• After energy selection 1-4 ions
• 50 mV / 2 V

I. Bergström et al., Eur. Phys. J. D 22, 41
(2003).
22
Determination of the 3T? 3He Q-Value

• Q-value of Tritium beta decay
• Q18 588(1.7) eV

SMILETRAP
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.
23
n-less double b-decay
76Ge 1Kg
24
76Ge-76Se for constraints on neutrino-less double
beta decay
Energy for 2e- by Q-value for
76Ge
SMILETRAP
76Se
17-times improvement in both masses 7-times
improvement in the Q-value 2 039.006(50)
keV
G. Douysset et. al. PRL 86, 2001
25
Some Neutrino-Less Double Beta Decay Candidates
2bDecay Q-value
Precision 40Ca 40Ar 193.6(0.2) 5.7E-09 64Zn
64Ni 1095.7(0.9) 1.5E-08 74Se
74Ge 1209.7(2.3) 3.4E-08 78Kr
78Se 2856.4(2.0) 2.8E-08 106Cd
106Ag 2770.0(7.2) 7.3E-08 2b- 48Ca
48Ti 4273.7(4.1) 9.1E-08 76Ge
76Se 2039.006(50) 7.1E-10 82Se
82Kr 2995.7(2.6) 3.4E-08 96Zr
96Mo 3349.5(3.6) 4.0E-08 116Cd
116Sn 2809.1(4.2) 3.9E-08
Almost all Q-values can be improved by a factor
of 10 (dQ lt 200 eV), but we need your input
concerning the importance.
26
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 and JYFLTRAP 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.
• New developments (e.g. Ramsey) will allow even
  higher precision and can thus help to discover
  exciting new physics.
• We need your wishes for Q-value measurements on
  0n2b.

27
Not to Forget
Thanks to my colleagues J. Äystö, G. Audi, G.
Bollen, D. Beck, I. Bergström, P. Delahaye, T.
Fritioff, S. George, C. Guénaut, A. Herlert, F.
Herfurth, A. Jokinen, A. Kellerbauer, H.-J.
Kluge, D. Lunney, Sz. Nargy, S. Schwarz, R.
Schuch, L. Schweikhard, C. Yazidjian Thanks for
the funding and support GSI, BMBF, CERN, ISOLDE,
HGF EU networks EUROTRAPS, EXOTRAPS, and NIPNET
Thanks a lot for your attention.
www.isoltrap.cern.ch/ www.physik.uni-mainz.de/quan
tum/mats/