The Magnetic Moment of the Proton. A. Mooser for the BASE collaboration

Transcription

1 The Magnetic Moment of the Proton A. Mooser for the BASE collaboration

2 Motivation CPT-Symmetry fundamental cornerstone of Standard Model Strategy: Compare properties of matter and antimatter conjugates with high precision. S. Ulmer et al., Nature (015) A. Mooser et al., Nature 509, 596 (014) Measured proton magnetic moment with ppb precision plan to improve Plan to apply methods to magnetic moment of antiproton Plan to improve on our recent charge-to-mass ratio comparison

3 How to measure these? Determination of Larmor frequency in a given magnetic field e L g m p B Monitoring magnetic field via simultaneous measurement of the free cyclotron frequency e c B m p B L g L L c c ω c, p = q p/m p ω c,p q p /m p

4 The Penning Trap Superposition of homogeneous magnetic field and electrostatic quadrupole potential B B Be z radial confinement ( z, ) U 0 c z axial confinement V V V k 0 k axial magnetron modified cyclotron () z axial modified cyclotron magnetron z 700 khz 9 MHz 10 khz Invariance Theorem: c z [L. S. Brown and G. Gabrielse, Phys. Rev. A, 5:43, 198.]

5 Detection of the spin state The continuous Stern-Gerlach effect Introduce magnetic inhomogeneity, the magnetic bottle B z B 0 B z Coupling of spin moment to axial oscillation z B p z Spin flip results in shift of the axial frequency p z m B spin down Time spin up

6 Axial Frequency (arb units) Magnetic Field (T) Detection of the spin state Challenge I Applied with great success for electron g -factors Bohr magneton z z m B spin momentum Additional factor of 4 for 3 He Axial Position (mm) Dealing with nuclear magneton requires magnetic bottle of B 30 T/cm

7 Frequency Fluctuations (Hz) z Detection of the spin state Challenge II In addition strong coupling of radial modes to axial mode 1 B E, m p z,0 B0 3 cyclotron quantum (10neV) jumps shift axial frequency by same amount as spin flip Axial frequency (Hz) # Measurement Cyclotron Energy (mev) Consistent with external power spectral density of: S( ) 1.6*10 1 V²/m² Sub-thermal energies needed for spin state detection hours of preparation

8 Observation of Single Spin Flips Series of axial frequency measurements in AT 10 cyclotron quantum jumps in 1 hour Statistical Bayes rule conditional probability of particle being in spin state Bayes method allows for spin state detection fidelity of 88% A. Mooser and K. Franke et al., Phys. Rev. Lett. 110, (013). A. Mooser and S. Ulmer et al., Phys. Lett. B 73, (013).

9 Double Penning-trap method High Precision measurement demands homogeneous magnetic field Introduce two traps double Penning trap setup (H. Häffner, Phys. Rev. Lett.85, 5308 (000)) I. Determination of Spin State (AT) V. Determination of Spin State (AT) Analysis Trap: Detection of spin state # Measurement # Measurement 44 mm B Precision Trap: Measurement of frequencies II. Transport to PT Frequency offset (Hz) III. Driving Spin Transition and measure B-field(PT) g-factor measurement IV. Transport to AT 7 mm

10 Milestones In 014 we performed the most precise and first direct high-precision measurement of the proton g-factor g p = (14) stat (1) syst Can be applied to the antiproton to obtain thousand fold improved CPTtest

11 Limitations of recent measurement Main limitations in the previous measurement B in precision trap constraints on line width Saturation broadening of the Larmor resonance old new B 4T/m 0.5 T/m Line-witdh 00 mhz 40 mhz Magnetic field relative prec Old setup 1 cm New setup Analysis trap Precision trap

12 Improvement of appartus Implementation of self-shielding coil Reduction of external magnetic field fluctuations by a factor of 50 G.Gabrielse and J. Tan, J. Appl. Phys. 63, 10 (1988).

13 Frequencyfluctuations (Hz) Fraction of total counts (%) P(E<E p ) (%) Limitation on statistics Cyclotron frequency measurement heats cyclotron mode to 30 mev Low energies required in analysis trap for high fidelity spin state detection In analysis trap Fidelity >75% Cyclotronenergy E + (mev) Cyclotronenergy E + (mev) Coupling to thermal bath in precision trap Preparation of subthermal E + 3 hours for one spin flip trail in precision trap with fidelity of 75%

14 Improvement of Measurement Time Old setup t cool =10s at T=5K New superconducting cyclotron detector t cool =40s at T=K Reduces measurement time for one g-factor datapoint from 3h to 1h C. Smorra, Hyperfine Interactions 8, 31 (014).

15 Optimization of Precision Trap Cyclotron frequency stability in precision trap Improvement by one order magnitude reduced magnetic field inhomogeneity, improved detection system and self-shielding coil

16 First Results Started double trap method Saturation broadening further optimization going on

17 Next Laser Cooling Heating rates and stability scale with cyclotron energy Limits spin state detection fidelity Fidelity deterministic temperature by sympathetic cooling Current Status resistive cooling Probability Cyclotron Temperature Cool cyclotron mode by sympathetically coupling the proton/antiproton to an lasercooled ion we use Beryllium Faster measurement cycles at higher spin state detection fidelity Lower phase uncertainty - higher precision for phase methods

18 Coupling I Direct coulomb coupling with ions at close proximity p Ω exc = 1 4πε 0 r 3 ω q m p m Be Be Coupling strengths up 100 Hz Demands construction of miniature Penning trap, e.g. inner diameter 400µm Sensitive to offset and patch potentials Potential wall for protons in the order of mv only Potentials configurations for both ions coupled

19 Coupling II Coupling via common end cap (D. Wineland, Phys. Rev. A 4, 977 (1990) ) C T = 1pF C T = 3pF C T = 10pF C T Ω exc = 1 1 q 4 ω D eff C T m p m Be N Lower coupling strengths compared to direct coupling still 100mHz sufficient / expected heating rates of 100µHz Allows for easy adjustment of laser position with ion position less optics Allows for easy matching of ion frequencies resonance condition Insensitive to offset and patch potentials We pursue this option

20 313nm Linewidth 100kHz 313nm

21 Energy/h (GHz) Nuclear Magnetic Moment of 3 He So far no direct measurement of µ He Application polarized 3 He magnetometers e.g. Muon g- 60ppt Meyers 0.76ppt Gabrielse a μ = g e ω a ω s μ s μ e m μ m e μ h μ e = Penning trap μ h eħ m 3 m u m h m e 1 (1 σ m u g He ) e 30ppt Sturm ppb Neronov Indirect measurement via HFS of single charged 3 He in magentic field Direct measurement by application of laser cooling New methods beyond standard g-factor techniques Magnetic field (T) m J m I

22 Summary Sub parts per billion measurement in reach measurements on going Started on implementation of laser cooling Started work on 3 He measurement BASE Collaboration: Stefan Ulmer, Christian Smorra, Hiroki Nagahama, Takashi Higuchi, Andreas Mooser, Mustafa Besirli, Mathias Borchert, James Harrington, Nathan Leefer, Stefan Sellner, Georg Schneider, Toya Tanaka, Klaus Blaum, Yasuyuki Matsuda, Christian Ospelkaus, Wolfgang Quint, Jochen Walz, Yasunori Yamazaki

23 Thank you for your attention VH-NG-037 Adv. Grant MEFUCO (#90870)

24 Different CPT tests CPT invariance is the most fundamental symmetry in the Standard Model Strategy: Compare properties of matter and antimatter conjugates with high precision. Red: Recent tests Purple: Past tests Green: Planned antideuteron m/q antihelium m/q kaon m ALICE Nature Physics ( /nphys343) positron g S. Ulmer et al., Nature (015) muon g antiproton q/m Planned by others ASACUSA / ALPHA / ATRAP A. Mooser et al., Nature 509, 596 (014) J. disciacca et al., PRL (013) antiproton g antihydrogen 1S/S antihydrogen GS HFS CERN AD relative precision CPT test with fractional precision of available why continue measuring?

25 Concept of CPT violation Basic idea: Add CPT violating extension to Hamiltonian of Standard Model Treat CPT violating terms perturbative H = H SM + V < ψ V ψ >= E System based on SM CPT violating term Contributions at absolute energy scale - Absolute energy resolution might be more appropriate measure of sensitivity with respect to CPT violation High sensitivity - precise measurement at small intrinsic energy Single particles in Penning traps - precise measurement of frequencies at uev-energy scales Relative precision Energy resolution Kaon m ~10 18 ~10 9 ev p- p g-factor ~10 6 ~10 1 ev BASE aims to improve with 10 9 relative precision

26 Detection of particle motion Particle acts as a perfect short Amplitude (dbm) Frequency (Hz).5 Hz Linewidth: z N p Line Width (Hz) 10 8 Single Proton Number of Particles Enables cyclotron frequency measurement at 1ppb

27 Setup