Precision Penning Trap Experiments with Exotic Ions

Transcription

1 Hirschegg 2012 Precision Penning Trap Experiments with Exotic Ions Klaus Blaum January 16, 2012

2 Outline Introduction and motivation Principle of Penning traps Setup and measurement procedure Precision mass and g-factor measurements

3 Part I High-precision mass measurements

4 Applications of precision masses High-accuracy mass measurements allow one to determine the atomic and nuclear binding energies reflecting all forces in the atom/nucleus. = N + Z + Z binding energy M Atom = N m neutron + Z m proton + Z m electron -(B atom + B nucleus )/c 2

5 Why measuring atomic masses? Atomic and nuclear binding energies reflect all forces acting in the atom/nucleus. δm/m General physics & chemistry 10 5 Nuclear structure physics 10 6 Astrophysics separation of isobars separation of isomers 10 7 Weak interaction studies 10 8 Metrology fundamental constants 10 9 Neutrino physics CPT tests QED in highly charged ions separation of atomic states 10 11

6 Principle of Penning trap mass spectrometry B q/m Cyclotron frequency: 1 q f c = B 2π m PENNING trap Strong homogen. magnetic field Weak electric 3D quadrupole field B ν z ν + ν - Typical freq. q = e m = 100 u B = 6 T - f 1kHz + f 1MHz

7 TOF cyclotron resonance detection (3) TOF measurement MCP Detector 390 (2) Energy conversion (1) Excitation of the ion motion Mean time of flight / μs Centroid: f = 1 q B 2 π m Determine atomic mass from frequency ratio with a well-known reference mass. c f 63 Ga T 1/2 = 32.4 s Excitation frequency ν RF / Hz f rf c,ref f c = m - m e m - m ref e

8 TRIGA-SPEC: TRIGA-LASER + TRIGA-TRAP project TRIGA: 01/08 start data taking: 05/09 ECR ion source TRIGA Mainz G. Hampel K. Eberhardt N. Trautmann TRIGA-LASER W. Nörtershäuser Mass separator RFQ steady 100 kw, pulsed 250 MW, neutron flux 1.8x10 11 / cm 2 s Nucl. Instrum. Meth. A 594, 162 (2008) TRIGA-TRAP

9 Making gold in nature r-process nucleosynthesis Most nuclear data experimentally unknown Theoretical predictions needed Astrophysical site uncertain Observational data to be matched Conditions for an A=80 abundance peak with new 81 Zn mass with new 80 Zn mass situation 2007 D. Rodríguez et al., Phys. Rev. Lett. 93, (2004) X.L. Tu et al., Phys. Rev. Lett. 106, (2011) S. Baruah et al., Phys. Rev. Lett. 101, (2008) E. Haettner et al., Phys. Rev. Lett. 106, (2011)

10 Neutrino-less double EC (0ν2EC) Is the neutrino a Majorana or Dirac particle? 2ν2EC (T 1/2 >10 24 y) 0ν2EC (T 1/2 >10 30 y) 0ν2EC might be resonantly enhanced (T 1/2 ~10 25 y) Contribution of Penning traps: Search for nuclides with Δ=(Q εε B 2h -E γ ) < 1 kev by measurements of Q εε values at ~100 ev accuracy level

11 Resonance enhancement factors 2EC - transition Δ (old), kev Δ (new), kev T 1/2 m 2, yr 152 Gd 152 Sm -0.2(3.5) 0.9(0.2) Er 164 Dy 5.2(3.9) 6.81(0.12) W 180 Hf 13.7(4.5) 12.4(0.2) If m ββ = 1 ev If m ββ = 0.1 ev 30 kg for 1 capture event a year 3 tons for 1 capture event a year Gd can be used for a seach search for for 0ν2EC 152 Gd: Phys. Rev. Lett. 106, (2011) 164 Er: Phys. Rev. Lett. 107, (2011)

12 Non-destructive ion detection ion signal mass/frequency spectrum Amplitude very small signal ~fa FT-ICR Fourier-Transform- Ion Cyclotron Resonance Induced current: Signal / Noise I eff = 1/ 2 r ion / D ω q (Schottky et al....) S/N ~ 1 / T 1/2 Operation of traps and electronics at cryogenic (4 K) temperature.

13 Single ion sensitivity Superconducting helical resonator detection circuit amplifier Ctrap Rp Cp B Penning trap Ultra-low noise cryogenic amplifier Lres

14 THe-TRAP for KATRIN A high-precision Q( 3 T- 3 He)-value measurement 3 1 H 3 He 2 + e +ν Q lit = (1.2) ev We aim for: δq( 3 T 3 He) = 20 mev ΔT < 0.05 K/d at 24 C δm/m = ΔB/B < 10 ppt / h Δx 0.1 μm First 12 C 4+ / 16 O 6+ mass ratio measurement at δm/m stat = performed.

15 Part II The g factor of a free proton

16 The g-factor (anti)proton experiment electron gun analysis trap transport electrodes precision trap target The analysis trap The cryostat hω L ω L = 2μ B h = g e 2m p B g ωl = 2 ω c ω c = e mp B COMSOL simulation S. Ulmer et al., Rev. Sci. Instrum. 80, (2009)

17 Continuous Stern-Gerlach effect Larmor-frequency cannot be directly measured Microwaves are irradiated to induce a spin flip Spin direction has to be detectable Magnetic inhomogeneity produces an effective spin-dependent potential Axial frequency depends on spin-direction Small frequency difference between and : hω L g μb B2 Δν z = 240mHz 2 π m ν 4 ion z ,5 spin up COMSOL simulation axial frequency [Hz] , ,5 spin down Ferromagnetic ring produces a magnetic bottle , Time [min]

18 High-precision g factor measurement hω L ω L = 2μ B h = g e 2m p B One measurement cycle i.detection of spin-orientation in analysis trap 10min B q/m g ω c = ωl = 2 ω e mp c B ii.transport to precision trap iii.measurement of eigenfrequencies and simultaneous irradiation with microwaves 0.5min 5min iv.transport to analysis trap v.detection of spin orientation in analysis trap Spin flip in the precision trap? 0.5min 10min

19 g-factor resonance of a single proton spin flip probability (%) Compare g-factors of p and p: Test of matter-antimatter symmetry. Highly challenging experiment since one million times harder compared to e khz drive frequency (MHz) PDG: mass difference g-factor (g-2) mass planned HFS-spectroscopy (planned) 1E-21 1E-18 1E-15 1E-12 1E-9 1E-6 1E-3 relative precision g-factor charge/mass g-factor achieved Larmor resonance based on first spin flip ever observed with a nuclear magnetic moment. We aim for δg/g = S. Ulmer et al., Phys. Rev. Lett. 106, (2011) K 0 K 0 e + e - p p μ + μ e + e - p p H H

20 Summary Exciting results in high-precision experiments with stored and cooled exotic ions have been achieved! - Accurate masses have been obtained for reliable nucleosynthesis calculations. - High-precision mass measurements with strong impact on neutrino physics research. - Discovery of a suitable candidate for 0ν2EC search. - First direct observation of a spin-flip of a single proton - Development of novel and unique storage devices. - and many more!

21 Thanks Thanks a lot for the invitation and your attention! klaus.blaum@mpi-hd.mpg.de WWW: ERC Advanced Grant Agreement No