Precision Penning Trap Experiments with Exotic Ions

Transcription

1 EMMI Physics Days 2011, GSI Darmstadt Precision Penning Trap Experiments with Exotic Ions Klaus Blaum November 08, 2011

2 Outline Introduction and motivation Principle of Penning traps Setup and measurement procedure Precision mass and g-factor measurements (see also talk by Sven Sturm yesterday)

3 Part I High-precision mass measurements

4 Why measuring atomic masses? Atomic and nuclear binding energies reflect all forces acting in the atom/nucleus. δm/m General physics & chemistry 10 5 N + Z + Z binding energy 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

5 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

6 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

7 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

8 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)

9 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) Measurements triggered by Prof. Y. Novikov, EMMI Professorship 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 Measurements triggered by Prof. Y. Novikov, EMMI Professorship 2011

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) Gd: Phys. Rev. Lett. 106, (2011) 164 Er: Phys. Rev. Lett. 107, (2011)

12 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)

13 A breakthrough: Octupolar excitation Quadrupolar excitation U cos2ϕ U cos4ϕ Octupolar excitation 164 Er and 164 Dy are not resolved 164 Er and 164 Dy are resolved TOF / μs 70 kev 2.5 kev 23 kev Δf / Hz Δf / Hz At least 20-fold improvement in resolving power!

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 High-precision g-factor measurements 10 cm

16 Single proton sensitivity detection circuit Superconducting helical resonator amplifier C trap R p C p L res B Penning trap Ultra-low noise cryogenic amplifier

17 Status of the g-factor (anti)proton exp. 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)

18 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

19 Summary Breathtaking 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. Z Discovery of a suitable candidate for 0ν2EC search N - Most stringent test of bound-state QED and first direct g-factor measurement on a free proton. - Development of novel and unique storage devices. - and many more!