Fundamental physics with antihydrogen and antiprotons at the AD. Michael Doser CERN

Transcription

1 Fundamental physics with antihydrogen and antiprotons at the AD Michael Doser CERN

2 What measurements are we talking about? 1) Precise spectroscopic comparison between H and H tests of fundamental symmetry (CPT) 2) Measurement of the gravitational behavior of antimatter tests of the Weak Equivalence Principle 3) other measurements in antihydrogen(-like) systems positronium, protonium, antiprotonic helium,...

3 Experiments at the AD (antiprotons and antihydrogen) Spectroscopy Gravity ALPHA ASACUSA AEgIS GBAR ATRAP ACE Matter-Antimatter interactions BASE... Symmetries... Antimatter manipulations

4 ATRAP & BASE DiSciacca, J. et al. One-particle measurement of the antiproton magnetic moment. Phys. Rev. Lett. 110, (2013) S. Ulmer. et al. Nature 524, (13 August 2015) All measured antiproton-to-h cyclotron frequency ratios as a function of time spin line cyclotron line. (q/m) p /(q/m) p 1 = 1(69) x μp/μp = (factor 6 improvement by BASE in 2017)

5 ASACUSA results (phe+ spectroscopy) rmation Energy (a.u.) + He p By comparing the calculated and experimental phe+ frequencies, the ratio Mp/me can in principle be determined to a fractional precision of < Ionized phe I0 = 0.90 a.u. (24.6 ev) He capture Auger decay - e p 38 Stark mixing ++ He 0 He Radiative 33 e He Nuclear absorption & Annihilation Energy (a.u.) M *~ 38 n0 = m e characteristics of both atom and molecule 0(s) transitions + Neutral phe l M.n Hori et al., Science 04 Nov 2016: Vol. 354, Issue 6312, pp DOI: /science.aaf Ionized phe I0 = 0.90 a.u. (24.6 ev) Auger decay 38 Stark mixing 0 He Radiative Nuclear absorption & Annihilation M *~ 38 n0 = m e n (s) transitions + Neutral phe 40 l 30 example: antiprotonic helium 52 Combining with ATRAP/BASE: Δ(mp,mp), Δ(qp,qp) < (90% CL)

6 Beam formation ASACUSA beam (2014) H ground state hyperfine splitting: N. Kuroda et al., Nature Communications 5, Article number: 3089 (2014) doi: /ncomms4089 Rate: few atoms/hour p e+ Rydberg states? Many still in n>29 Velocity? T~ 100K-1000K? Cusp trap Microwave Sextupole Cavity Magnet H Det. 2. A conceptual experimental setup for the ground-state transition M. Diermaier et hyperfine al., In-beam measurement of the hydrogen hyperfine splitting ents of H atoms with the cusp trap (see the text for more details). (a) TBR: Formation Guiding coils - towards antihydrogen spectroscopy 3D track Focusing detector of low-field. det p a seekers r H t sp cu r lato u cum + ac e p tra (b) Under reasonable assumptions & measuring both transitions to extrapolate to zero field H superconducting -9) appears possible measurement to O(10 cusp magnet (with a rate of ~ 1Hz of ground-state atoms)

7 Antihydrogen production processes ~10 p ~10 e+ radiative recombination γ TBR: 3-body recombination e + RCE: Resonant charge exchange e - Ps* very low rate

8 Antihydrogen production processes TBR: RCE: 3-body recombination e + ALPHA ATRAP AEgIS GBAR Resonant charge exchange e - Ps* ASACUSA p e + Temperature (Te+) Rate ~ Rate (trappable) n (if trapped) Temperature Tp Rate ~ Rate (nps,vps) n (if trapped or slow)

9 ALPHA results (trapping, 1s-2s spectroscopy) G. B. Andresen et al., Nature 468, (02 December 2010) M. Ahmadi et al., Nature 541, (26 January 2017) surviving fraction: 58% 6% further results: microwave transitions in GS H q(h) < 0.71 x 10-9 e trapping of ~ 10 H simultaneously (similar for ATRAP)

10 alternative antihydrogen production method: RCE AEgIS TH ~ Tp GBAR e + TPs ~ 100 K Ep ~ 5 kv e + Ps* + p H * + e - cold H * Ps + p H + e - + Ps + H H + e - hot H +

11 Schematic overview: pulsed horizontal beam of H Schematic overview production: beam charge formation: exchange Stark acceleration measurement: deflectometer e + H* Ps* Ps positronium converter Ps Ps* H* laser excitation H beam [M. K. Oberthaler et al., Phys. Rev. A 54 (1996) 3165] [A. Kellerbauer et al., Phys. Rev. A 54 (1996) 3165] grating 1 grating 2 L L position-sensitive detector H* antiproton trap accelerating electric field atomic beam L L σ a 0 n 4 3 F = - n k E 2 Physics time-of-flight: goals: measurement pulsed of the production gravitational interaction between matter and antimatter, H spectroscopy, beam divergence: ultra-cold p...

12 Two main challenges: more / colder antiprotons Antiproton decelerator ( GeV/c 2 ) AEGIS BASE ALPHA extraction at 5.3 MeV

13 Two main challenges: more / colder antiprotons current methods for trapping them are quite inefficient ELENA to the rescue GBAR BASE ATRAP I & II ASACUSA space for future (anti)atomic physics experiments ALPHA AEgIS extraction at 100 kev

14 ELENA is a tiny new decelerator that: dramatically slows down the antiprotons from the AD increases the antiproton trapping efficiency x 100 allows 4 experiments to run in parallel allows new experiments to come in commissioning started in Nov. 2017

15 Two main challenges: more / colder antiprotons Ultra-cold (~1 µk) Antihydrogen spectroscopy gravity for gravity measurement current lowest p temperature (4.2K) current lowest H temperature (0.5K) (light atom, short wavelength) H atoms in 8 mk using pulsed Lyman-α I.D.Setija et al., PRL 70 (1993) S 2P laser cooling: cw Lyman-α source Eikema, Walz, Hänsch, PRL 86 (2001) 5679

16 Temperature of produced H 2016 (critical for trapping, gravity measurements) TBR: fraction trapped out of fraction made ~ 10-4 challenge inherent in TBR: e + plasma physics trade-off between # and temperature possible increase in cold H rate by laser-cooling Be + to sympathetically cool e + but is cooling efficient enough to counteract heating through p injection? Outlook: 10 s ~ 100 s of trapped H (through stacking)

17 very long-term goals: gravity, spectroscopy in sub-mk traps sympathetic cooling to the rescue GBAR experiment cooling of H + Anion cooling for AEgIS: Os, La, C2 cooling of p J.Walz and T. Hänsch, Gen. Rel. and Grav. 36 (2004) 561 formation of H + (binding energy = ev) how? perhaps through Ps(2p)+H(1s) H + + e - Roy & Sinha, EPJD 47 (2008) 327 sympathetic cooling of H + e.g. In + 20 μk Warring et al, PRL 102 (2009) Fischer et al, PRL 104 (2010) = f (16) nm more than two order 11meV photodetachment at ~6083 cm -1 very weak cooling gravity measurement via TOF TOD best to start at ~ 4K and cool arrow linewidt T D 0.24 µk using the Lyma to Doppler limit ( ) should allow reaching same precision on g as with atoms (10-6 or better)

18 absolute accuracy (GeV) H-H HFS H-H 1S-2S 0 0 K - K mass p-p mass p-p charge/mass p-p magnetic moment e mass e charge Motivation: CPT CPT test of EM interaction ATRAP ASACUSA μ g-factor e g-factor d-d mass 3 3 He- He mass relative accuracy CPT test of strong interaction Inconsistent definition of figure of merit: comparison difficult Pattern of CPT violation unknown (P: weak interaction; CP: mesons) Absolute energy scale: standard model extension (Kostelecky)

19 absolute accuracy (GeV) H-H HFS H-H 1S-2S 0 0 K - K mass p-p mass p-p charge/mass p-p magnetic moment μ g-factor e g-factor 2015 e mass e charge d-d mass 3 3 He- He mass relative accuracy Inconsistent definition of figure of merit: comparison difficult Pattern of CPT violation unknown (P: weak interaction; CP: mesons) Absolute energy scale: standard model extension (Kostelecky) Motivation: CPT ALPHA ATRAP

20 absolute accuracy (GeV) H-H HFS H-H 1S-2S 0 0 K - K mass p-p mass p-p charge/mass p-p magnetic moment μ g-factor e g-factor 2016 e mass e charge d-d mass 3 3 He- He mass relative accuracy Inconsistent definition of figure of merit: comparison difficult Pattern of CPT violation unknown (P: weak interaction; CP: mesons) Absolute energy scale: standard model extension (Kostelecky) Motivation: CPT ASACUSA BASE & ATRAP

21 absolute accuracy (GeV) H-H HFS H-H 1S-2S 0 0 K - K mass p-p mass p-p charge/mass p-p magnetic moment μ g-factor e g-factor 2017 e mass e charge d-d mass 3 3 He- He mass relative accuracy Inconsistent definition of figure of merit: comparison difficult Pattern of CPT violation unknown (P: weak interaction; CP: mesons) Absolute energy scale: standard model extension (Kostelecky) Motivation: CPT ALPHA

22 other measurements with antihydrogen-like atoms & ions... H: charge neutrality... Ps, muonium: gravity (lepton sensitivity) µp: gravity (2 nd generation), antiproton charge radius pp, pd: ions: H + gravity (baryon sensitivity) - Rydberg protonium gravity, CPT (ultra-cold H) ions: H2 +, resp. H2 proton-electron mass ratio μ pn: trapped p + radioisotopes = PUMA

23 Trapping of antihydrogen: ATRAP and ALPHA: large progress in last years main challenge now: enough cold enough constituents small numbers of antihydrogen atoms in the ground state trapped in 2010 first measurement of 1s-2s to in 2016 assuming 1 mk: 1s-2s spectroscopy to ~ (perhaps in a few years) Beams of antihydrogen: ASACUSA: continuous beam (ground state atoms!) and phe + AEGIS: working towards pulsed sub-k beam main challenge now: formation mechanisms and rates, cold enough p low precision gravity measurement and in-flight spectroscopy of HFS to 200 Hz (10-6 ) Trapped antiprotons: to summarize the situation... BASE: conceivable reach: (q/m) p /(q/m) p to 10-12, μp/μp to 10-9 From 2017, new low energy p accelerator ELENA: new experiments, experimental opportunities for many years