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Home , Antiprotonic helium

Laser spectroscopy of antiprotonic helium

M. Hori1, H. A. Khozani1, A. Sótér1, R.S. Hayano2, Y. Murakami2, H. Yamada2, D. Horváth3, L. Venturelli4

1Max Planck Institute of Quantum Optics, Garching, Germany 2University of Tokyo, Japan 3Wigner Institute, Budapest, Hungary 4INFN Brescia

Moriond 2017 Long-lived in helium

Ar Number of recorded Time elapsed until (us) Ne

PS205 experiment (1993)

Number of recorded annihilations Time elapsed until annihilation (us)

Masaki Hori MPI for Quantum Optics 2 Metastable antiprotonic helium (p̄He+)

Electron in 1s orbital. Attached with 25-eV ionization potential. Auger emission suppressed.

Antiproton in a ‘circular’ Rydberg orbital n=38, l=n-1 with diameter of 100 pm.

Localized away from the nucleus. The protects the during collisions with helium atoms. τ ∼ 4 µs

Masaki Hori MPI for Quantum Optics 3 Precision measurements of p̄He+ transition frequencies and companions with QED calculations yields:

Antiproton-to-electron mass ratio to precision of 8 × 10-10

Assuming CPT invariance, electron mass to 8 × 10-10

Combined with the cyclotron frequency of antiprotons in a Penning trap by TRAP and BASE collaborations, antiproton and proton masses and charges to 5 × 10-10 → Consistency test of CPT invariance

Bounds on the 5th force at the sub-A length scale……

Masaki Hori MPI for Quantum Optics 4 Ionic Atomic Energy states states levels of

v=1 v=0 v=2 + v=4 v=3 42 p̄ v=5 He -2.6 41 40 n=33 39 M* -2.8 38 n 0 ~ = 38.3 me 32 37 Level energy (a.u.) -3.0 36

31 35 Stark -3.2 mixing Auger 34 Radiative decay 30 33 Metastable p 4He+ -3.4 4 Auger-dominated p He+

4 ++ 29 32 Ionized p He -3.6

n=31 Nuclear 28 absorption -3.8 l = 30 31 32 33 34 35 36 37 38 39 40 41

Masaki Hori MPI for Quantum Optics 5 Calculated two-photon transition frequency (n,l)=(36,34)→(34,32)

Non-relativistic energy 1 522 150 208.13 MHz mα4 order corrections -50320.64 mα5 order corrections 7070.28 mα6 order corrections 113.11 mα7 order corrections -10.46(20) mα8 order corrections -0.12(12) Transition frequency 1 522 107 060.3(2) Uncertainty from alpha charge radius +/-0.007 Uncertainty from antiproton charge radius < 0.0007

Korobov, Hilico, Karr, PRL 112, 103003 (2014). Korobov, Hilico, Karr, PRA 89, 032511 (2014). Korobov, Hilico, Karr, PRA 87, 062506 (2013).

Masaki Hori MPI for Quantum Optics 6 One-loop self-energy correction in atomic units for two-center system

V.I. Korobov, J.-P. Karr, L. Hilico

Masaki Hori MPI for Quantum Optics Two-loop QED contributions

V.I. Korobov

Masaki Hori MPI for Quantum Optics 8 Theoretical precision compared to other atoms

Antiprotonic He (n,l)=(33,32)→(31,30) 2 145 054 858.100(200) MHz

Experimental precision (Korobov 2014)

Uncertainty due to mα7 QED Uncertainty due to helium on this digit charge radius (to be improved by muHe experiment)

Hydrogen 1s-2s 2 466 061 413.18 MHz (Parthey et al. 2014)

Uncertainty due to proton charge radius on these digits

Masaki Hori MPI for Quantum Optics Laser spectroscopy method Formation e-

He+

pHe+

laser p

Laser excitation Auger pHe++ emission of e-

Charged pions signal the resonance antiproton condition between laser and atom. annihilation

Masaki Hori MPI for Quantum Optics 10 Sub-Doppler two-photon spectroscopy

(n, ℓ) We reduced broadening using two- photon excitation of antiproton with ν1 laser counter-propagating laser beams of unequal wavelength. virtual state Δνd ν2 laser (n-1, ℓ-1)

(n-2, ℓ-2)

By tuning virtual intermediate state of antiproton within 10 GHz of a real state, Laser transition probability enhanced by >1000x.

Masaki Hori, MPI for Quantum Optics, Germany 11 CERN

A beam of 3 million antiprotons of kinetic energy 5.3 MeV are provided every minute to ATRAP, ALPHA, AEGIS, ASACUSA, BASE, (GBAR)

Figure 3: Ad possible modifications Experimental setup Experimental setup p

Achromatic Identical laser beam transport system laser 1

RF quadrupole decelerator

laser 2 Heterodyne spectrometer

Frequency SHG/THG comb ULE cavity crystal Ti:S ampli

fi cw seed er laser Pulsed laser

Ti:S oscillator

Masaki Hori, MPI for Quantum Optics, Germany 13 Two-photon spectroscopy results

3

2 Single-photon spectroscopy of (n,l)=(36,34)-(35,33) 1

0 3

2 Two-photon spectroscopy

Signal intensity (arb.u.) 1 (n,l)=(36,34)-(34,32) 0 -1 0 1 Laser frequency offset (GHz)

Masaki Hori, MPI for Quantum Optics, Germany 14 Reduction of Doppler width by buffer gas cooling

4 (A) (B) (C) (D) 3

2

1

0 Signal intensity (arb.u.) -2 0 2 -2 0 2 -2 0 2 -2 0 2 Laser frequency offset (GHz)

Cooled 2×109 p̄He+ atoms to ~1.5 K Experiment took over 4 years of data. Resolved hyperfine structure in single-photon resonance

Masaki Hori, MPI for Quantum Optics, Germany 15 Experiment-theory 2-photon comparison

35

Nature 475 484 (2011)

Theory 1 522 107 060.3(2) MHz Experiment 1 522 107 062(4)(3)(2) MHz

Masaki Hori, MPI for Quantum Optics, Germany 16 Comparison between experimental and theoretical transition frequencies of 13 single-photon resonances

Masaki Hori, MPI for Quantum Optics, Germany 17 Antiproton-to-electron mass ratio 2016

Antiproton-to-electron mass ratio 1836.1526734 (15)

Science 354, 610 (2016)

Masaki Hori, MPI for Quantum Optics, Germany 18 -5 10 Experimental and theoretical precisions -6 10 LEAR experiments

Relativistic corrections -7 10 AD construction

Two-loop QED RFQD beam -8 10 Frequency comb, laser chirp correction Complex-coordinate rotation Two-photon -9 spectroscopy 10 CODATA98 proton/electron mass ratio 6 CODATA2010 Buffer gas cooling -10 10 7 Precision on (anti)proton-to-electron mass ratio

-11 10 1995 2000 2005 2010 2015 Years

Masaki Hori, MPI for Quantum Optics, Germany 19 BASE and ATRAP recent results

r B

Larmor frequency measured by continuous Stern Gerlach effect

ATRAP collab. PRL 110, 130801 (2013)

BASE collab. Nat. Comm. 8, 14084 (2017) !"# = 2.792 846 5 (23) Nature 524, 196 (2015)

Masaki Hori, MPI for Quantum Optics, Germany 20 ALPHA 1s-2s laser spectroscopy @ 243 nm

Nature 541, 506 (2016)

ATRAP, AEGIS, ASACUSA-CUSP, GBAR also show lots of progress!

Masaki Hori, MPI for Quantum Optics, Germany 21 New experiment on pionic helium＠PSI

First laser spectroscopy of an e- atom containing a meson He++

π-

Negative pion in a ‘circular’ Rydberg orbital n=16, l=n-1 with diameter of 100 pm. τ ∼ 7ns ! Localized away from the nucleus. The electron protects the antiproton during collisions with ordinary helium atoms.

22 Summary

Sub-Doppler two-photon laser spectroscopy of antiprotonic helium atoms. Measured 3 two-photon transitions to a precision of 2.3 ppb.

Collisional buffer gas cooling of antiprotonic helium atoms to T=1.5 K. Measured 13 single-photon transitions.

Agreed with 3-body QED calculations. Determined the antiproton-to- electron mass ratio as 1836.1526734 (15).

Laser spectroscopy of metastable pionic helium, experimental runs 2014-2015, observation of first laser induced pion transition………..

Masaki Hori, MPI for Quantum Optics, Germany 23 Backup slides