FFK Conference 2019, Tihany, Hungary

Precision measurements of the (anti) and magnetic moment

Wolfgang Quint GSI Darmstadt and University of Heidelberg on behalf of the BASE collaboration spokesperson: Stefan Ulmer 2019 / 06 / 12 BASE – Collaboration • Mainz: Measurement of the magnetic moment of the proton, implementation of new technologies.

• CERN Decelerator: Measurement of the magnetic moment of the antiproton and proton/antiproton q/m ratio

• Hannover/PTB: Laser cooling project, new technologies

Institutes: RIKEN, MPI-K, CERN, University of Mainz, Tokyo University, GSI Darmstadt, University of Hannover, PTB Braunschweig

C. Smorra et al., EPJ-Special Topics, The BASE Experiment, (2015) WE HAVE A PROBLEM

mechanism which created the obvious /antibaryon asymmetry in the is not understood

One strategy: Compare the fundamental properties of / conjugates with ultra-high precision CPT tests based on /antiparticle comparisons

R.S. Van Dyck et al., Phys. Rev. Lett. 59 , 26 (1987). Recent B. Schwingenheuer, et al., Phys. Rev. Lett. 74, 4376 (1995). Past CERN H. Dehmelt et al., Phys. Rev. Lett. 83 , 4694 (1999). G. W. Bennett et al., Phys. Rev. D 73 , 072003 (2006). Planned M. Hori et al., Nature 475 , 485 (2011). ALICE G. Gabriesle et al., PRL 82 , 3199(1999). J. DiSciacca et al., PRL 110 , 130801 (2013). S. Ulmer et al., Nature 524 , 196-200 (2015). ALICE Collaboration, Nature Physics 11 , 811–814 (2015). M. Hori et al., Science 354 , 610 (2016). H. Nagahama et al., Nat. Comm. 8, 14084 (2017). M. Ahmadi et al., Nature 541 , 506 (2017). M. Ahmadi et al., Nature 586 , doi:10.1038/s41586-018-0017 (2018).

CERN AD 1S/2S antihydrogen 1S-2S

antihydrogen GSHFS Limits on Exotic Physics

• Experiments test the for exotic interactions

0

Dirac equation CPT-odd modifications | |

V. A. Kostelecky, N. Russell, → + + 0801.0287v10 (2017). • exclusively coupling to antimatter Δ , Single in Penning traps test the SM at an energy resolution of 10 -24 to 10 -26 GeV

sensitive: comparisons of particle/antiparticle magnetic moments in traps – CERN

5.3 MeV antiprotons 25 GeV/c 3.5 GeV/c antiprotons

-> Degrader -> 1keV Within a production/deceleration -> cooling -> 0.1 eV cycle of 120s + 300s of preparation -> Resistive cooling -> 0.000 3 eV time we bridge 14 orders of -> Feedback cooling -> 0.000 09 eV magnitude The BASE Apparatus at CERN

RT: Reservoir trap RT PT CT AT PT: Precision trap CT: Cooling trap AT: Analysis trap

HV Electrodes 7 Degrader Spin flip coil Electron gun Pinbase Main Tool: r B r radial confinement: = ˆ B B0 z Invariance-Relation ρ2  Φρ =2 − axial confinement: ( ,z ) Vc0 2  z  2  2 2 2 νν =+ + − + r c z B

Vk V Modified Cyclotron Motion Axial Motion 0 Cyclotron Frequency V ν k z 1 q ν ν = ion B + c π 2 m ion Magnetron Motion

ν − Φ(z )

ν = Axial z 680 kHz

Magnetron ν − = 8 kHz

Modified Cyclotron ν + = 28,9 MHz Proton/Antiproton -to-Mass Comparison

S. Ulmer et al., Nature 524 , 196 (2015) Measurements in Penning traps

Cyclotron Motion Larmor Precession r g: magnetic moment in units of B nuclear magneton

ω = e e c B ω = g B hω m L 2m L simple p p difficult

,̅ ̅/̅ S. Ulmer, A. Mooser et al. PRL 106, S. Ulmer, A. Mooser et al. PRL 107, 253001 (2011) 103002 (2011) , /

Determinations of the q/m ratio and g-factor reduce to measurements of frequency ratios -> in principle very simple experiments –> full control, (almost) no theoretical corrections required. Frequency Measurements

• Measurement of tiny image currents induced in trap electrodes

-95 Low Noise Axially excited, trapped antiprotons Amp -100

-105

C R L -110 p p p Amp Amp FFT

-115

-120 Signal Signal (dBm) Resonator FFT -125 -130 645300 645400 645500 645600 645700 currents: 1 fA Frequency (Hz)

• In thermal equilibrium: – Particles short noise in parallel – Appear as a dip in detector spectrum – Width of the dip -> number of particles 2 1 R  q  ∆ν =   ⋅ N 2π m  D 

H. Nagahama et al., Rev. Sci. Instrum. 87, 113305 (2016) Measurement configuration

Extract antiprotons and H - ions, compare cyclotron frequencies

Park Precision Park Reservoir electrode trap electrode trap

Measure & ⇒

antiproton H- ion

ν, / /2π / ν, / /2π / Measure & ⇒ , 1 2 Comparison of H-/antiproton cyclotron frequencies: One frequency ratio per 4 minutes with ~ 6 ppb uncertainty Rtheo = 1.001 089 218 754 2(2) G. Gabriesle et al., PRL 82 , 3199 (1999). 12 Proton to Antiproton Q/M: Physics

/ 1 1 69 10 / • In agreement with CPT conservation • Exceeds the energy resolution of 6521 frequency ratios previous result by a factor of 4. S. Ulmer, et al., Nature 524 , 196 (2015)

• Constrain of the gravitational anomaly for antiprotons: 10 daysidereal 20 8 , ,̅ -9 3 1 / , 6 - 1)/10 0

theo 4 /R

Our 69 ppt result sets exp (R 2 a new upper limit of -20 (a.u.) Output Lock-In

0 0 4 8 12 16 20 24 10000 100000 1 8.7 10 Time (h) Time (s) • Set limit of sidereal (diurnal) variations in • Conclusion: proton/antiproton charge-to-mass ratios Matter and Antimatter clocks run at the same frequency to < 0.72 ppb/day hω L Spin up

Very very Continuous Stern hard work Gerlach Effect

̅ ̅ ̅/̅ Spin down 2 / Straight- Image Current foward Measurements r B

14 Larmor Frequency – extremely hard Measurement based on continuous Stern-Gerlach effect .

Energy of magnetic dipole in Φ μ ⋅ Frequency Measurement Leading order magnetic field ρ Spin is detected and analyzed via correction 2 an axial frequency measurement

This term adds a spin dependent quadratic axial potential -> Axial frequency becomes a function of the spin state

μ Δν~ : α ν ν - Very difficult for the proton/antiproton system. ~ 0.3 / - Most extreme magnetic conditions ever applied to single particle. S. Ulmer, et al. PRL 106, 253001 (2011) ∆~170 Single Penning trap method is limited to the ppm level Next Step: The Double Penning-Trap Method

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spin probability flip spin 0.0

-0.1 -0.003 0.000 0.003 0.006 0.009 0.012 ν ν L/ c

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0.0 spin flip probability probability flip spin

-0.1 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 0.012 ν /ν L c 1.) measure cyclotron Initialize the spin state 2.) drive spin transition at particle transport analyze the spin state

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0.2 spin up spin up 0.2 0.2 spin up 0.2 spin up (Hz) (Hz) (Hz) (Hz) z,0 z,0 z,0 z,0 ν ν ν ν

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no spin-flip in PT spin flipped in PT

-0.2 -0.2 -0.2 -0.2 spin down axial - frequency axial axial - frequency axial axial - frequency axial spin down spin down - frequency axial spin down -0.4 -0.4 -0.4 -0.4 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 measurement measurement measurement measurement measures spin flip probability as a function of the drive frequency in the homogeneous magnetic field of the precision trap The holy -grail : single antiproton spin flips

C. Smorra et al., Phys. Lett. B 769, 1 (2017)

• First non-destructive observation of single antiproton spin quantum transitions. The Magnetic Moment of the Antiproton

3000-fold improvement in g factor difference G. Schneider et al. , Science 358 , 1081 (2017)

̅ . 2 2 2

.

C. Smorra et al. , Nature 550 , 371 (2017) 18 The Antiproton Magnetic Moment A milestone measurement in antimatter physics

Mainz effort started

BASE approved

ASACUSA 1E-3 exotic ATRAP

) BASE pbar

+g single Penning traps p 1E-6 {

> 3000 )/(g pbar

-g BASE multi-Penning traps p 1E-9 { reached proton limit (BASE Mainz) 2(g

principal limit of current method 1E-12 1985 1990 1995 2000 2005 2010 2015 2020 CERN COURIER, 3 / 2018. C. Smorra et al., Nature 550 , 371 (2017). year BASE achievements since 2011

Observation of spin flips with Most precise proton Precise CPT test with : Most precise antiproton comparison of cyclotron frequencies a single trapped proton g-factor measurment g-factor measurment S. Ulmer, et al., Nature 524, 196 (2015)

H. Nagahama, et al., Nature Comms. 8, 14084 (2017) C. Smorra et al. , Nature 550 , 371 (2017)

S. Ulmer, et al., PRL 106, 253001 (2011) A. Mooser, et al., PRL 110, (2013) / 1 1 69 10 Application of the double / Penning-trap technique g/2 = 2.792 846 5 (23) g/2 = 2.792 847 350 (9) Rexp,c = 1.001 089 218 755 (64) (26) A. Mooser et al. , Nature 509 , 596 (2014). To be improved by another First direct high precision factor of 10 to 100 Sixfold improvement compared to measurement of the proton previous measurement magnetic moment. Reservoir trap for antiprotons C. Smorra, et al., Int. Journ. Mass Spec. 389, 10 (2015). g/2 = 2.792 847 344 1 (42) g/2 = 2.792 847 344 62 (82) Idea: Enable operation with A. Mooser, et al., PLB 723, 78 (2013) antiprotons independent of 350-fold improvement compared G. Schneider et al., Science 358 , 1081 (2017). accelerator run times. to previous measurement

Partly comparable work by J. DiSciacca, G. Gabrielse et al.. (ATRAP/TRAP collaboration) Thanks for your attention!

S. Ulmer J. Devlin E. Wursten T. Higuchi RIKEN RIKEN/CERN CERN / RIKEN RIKEN / Tokyo

P. Blessing J. Schaper J. Harrington M. Borchert S. Erlewein GSI & RIKEN RIKEN / Hanover MPIK/RIKEN Hannover/RIKEN MPIK/RIKEN

K. Blaum, Y. Matsuda, C. Ospelkaus, W. Quint, J. Walz, Y. Yamazaki

C. Smorra M. Bohman M. Wiesinger A. Mooser G. Schneider RIKEN MPIK/RIKEN RIKEN/MPIK RIKEN/MPIK RIKEN/Mainz

Funding: RIKEN / Max Planck Society / ERC Advanced / Helmholtz Gemeinschaft / DFG / C-TCFS Planned Developments – Sympathetic Cooling of pbars • Current antiproton magnetic moment measurements are limited by particle preparation time and particle mode temperature • Expect: With traditional methods another 50-fold improvement is possible, afterwards: limit of traditional methods will be reached!

Effort at University of Mainz New Method The Vision Couple protons/antiprotons 5 trap design implemented and sympathetically to laser x x A B cooled 9Be + ions and imprint simultaneous detection of 9Be + ion and

s Doppler temperatures to the 0 A B

Potential Depth Potential (a.u.) proton in common endcap trap was antiproton Distance (a.u.) demonstrated. Was demonstrated Publication: K. R. Brown, C. for 9Be + ions in Paul Ospelkaus, Y. Colombe, A. C. C. Smorra, A. Mooser, M. Bohman, M. Wiesinger et al. Wilson, D. Leibfried, D. J. traps – implement Wineland, Nature 471 , 196 (2011). same in Penning traps Effort at University of Hannover and PTB Current Time Budget Laser Time Budget >100-fold improved Recent dramatic progress: antiproton cooling Detection of a single laser cooled 9Be + ion, in a Penning trap system time seems to be in which is fully compatible with the reach BASE trap system at CERN

M. Niemann, J. M. Cornejo, C. Ospelkaus et al. Summary and Outlook

• Performed a 69 p.p.t. - test of CPT invariance with baryons by comparing proton/antiproton charge-to-mass ratios • Performed the most precise measurement of the proton magnetic moment with a fractional precision of 0.3 p.p.b. • Performed the most precise measurement of the antiproton magnetic moment with a fractional precision of 1.5 p.p.b. • Feasibility to improve Q/M comparison by factor of 5 to 10 demonstrated.

0.6 0.6

0.5 0.5 0.4 BASE 2016 0.4 BASE 2017 0.3 0.3

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0.1 0.1 spin flip probability spin probability flip 0.0 0.0 spin flip probability probability flip spin

-0.1 -0.1 -0.003 0.000 0.003 0.006 0.009 0.012 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 0.012 ν /ν L c ν ν L/ c What inspires experiments with antimatter?

1. scenario supported by 1. Hubbles law 2. Discovery of CMWB with a black body spectrum of 2.73(1)K, by far too intense to be of stellar origin . 3. BBN scenario describes exactly the observed element abundances as found in «cold» stellar nebulae .

2. Using the models which successfully describe 1., 2. and 3.:

Prediction Observation Baryon/ Ratio 10 -18 Baryon/Photon Ratio 10 -9 Baryon/Antibaryon Ratio 1 Baryon/Antibaryon Ratio 10000

Following the current Standard Model of the Universe our predictions of baryon to photon ratio are wrong by about 9 orders of magnitude while our baryon/antibaryon ratio is wrong by about four orders of magnitude . Antimatter and Dark Matter

• Given our current understanding of the Universe there are several problems

• Energy content of the universe has yet to be understood . • We even do not understand why these 5% of baryonic matter exist.

Search for time-base signatures in Could these problems be related? antimatter data, mediated by / antiproton coupling: Single Trap – Double Trap – Triple Trap

single-trap method 0.6

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multi-trap method 0.6

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0.3 Cooling Maintenance Measurement Shuttling Cooling Maintenance Measurement Shuttling

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0.0 spin flip probability flipspin probability two years compared to two months… -0.1 -0.002 0.000 0.002 0.004 0.006 0.008 0.010 0.012 ν ν L/ c Systematics

calculate measure T / calculate measure / calculate measure / calculate measure / calculate measure / calculate measure / constrain measure / constrain measure / simulate / constrain

this dominant error is not present in double trap measurements. classical trap shifts shifts induced by 2 particle approach Has been estimated with the conservative 95% C.L.