Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada Canada’s National Laboratory for Particle and Nuclear Physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules ALPHA-g: Precision Antimatter Gravity Measurement with a Magnetic Trap Makoto C. Fujiwara LEAP 2016 Kanazawa, Japan TRIUMF – Canada’s National Lab for Particle & Nuclear Physics, Vancouver *Disclaimer: views expressed here are my own

Introduction Motivations: “Big Picture” –MCF: arXiv: Antimatter gravity experiments –Dropping atoms in a trap ALPHA-g overview –Goals –TPC –Laser cooling Implications of anti-H charge neutrality test –Charge & Mass of positron Summary & Prospects LEAP 2016: Outline Makoto Fujiwara

Seeing antimatter drop: “Textbook” experiment Antimatter Gravity Makoto Fujiwara, TRIUMF3

ATHENA’s anti-H annihilation event (Nature, 2002): now on the cover of textbook! $ on Amazon.com Textbook Experiment 4Makoto Fujiwara, TRIUMF

Seeing antimatter drop: “Textbook” experiment Ambitious efforts: –AEGIS, GBAR, Positronium, Muonium… I had been scared of even thinking about gravity, because of its technical difficulties, until… Antimatter Gravity Makoto Fujiwara, TRIUMF5

Annihilation event after 1000 s confinement Nov Makoto Fujiwara, TRIUMF6

Trapping time increased by x5000 “Game changer” Confinement of Antihydrogen for 1000 s Nature Physics, July 2011 Makoto Fujiwara

Gravity Measurement in a magnetic trap Now plausible due to long confinement time “cooling to temperatures where gravitational effects could become apparent.”

Motivations for Anti-H measurements Makoto Fujiwara

Atomic hydrogen: one of best studied systems –1s-2s level: (10) Hz  –Hyperfine splitting: (1) Hz ~ Antihydrogen (anti-H): produced in large quantities by ATHENA, ATRAP (2002) Comparison of H and anti-H –Compelling regardless of theoretical motivations Gravitational force on Antimatter: never been measured directly: –c.f. very lose limit by ALPHA Anti-H Motivations (experimental) Makoto Fujiwara

What is Particle Physics? (e.g. Grossman) “Simple answer”: The Standard Model, including a Higgs, works extremely well! Theoretical Motivations: “Big Picture” Peter Higgs July 4, 2012 Makoto Fujiwara

Many open issues with SM, which motivated “New Physics” at the TeV scale “Naturalness” problem of Higgs mass very serious –Quantum corrections in SM require Higgs mass to be naturally heavy, like GeV –A “small” mass 125 GeV requires fine-tuning to O(30) – Motivation for Beyond SM theories (Susy, Extra Dim…) Issues with the Standard Model Makoto Fujiwara No new physics yet at LHC – Hopefully x2 energy, or precision expt’s will solve this! (750 GeV?) – Simple BSM models ruled out – Cosmological Constant even greater fine-tuning O(120) – Anthropic Principle our last resort?

is (technically) unnatural … “Pen standing without any balance” Makoto Fujiwara

Perhaps time to stop and think: “L=?” really the right question to ask? Is (effective) Quantum Field Theory the correct description of Nature? Test of CPT and General Relativity with Anti-H would challenge fundamental framework of physics Motivations Makoto Fujiwara

Antimatter Gravity in a magnetic trap H Very cold anti-H in a vertical trap –Anti-H “gas” will sag due to gravity –If anti-H cooled to ~mK 1/2kT=mgh Vertical trap ： h~1 m –Position sensitive detection via annihilations Challenges –Only few anti-atoms at a time –(anti)hydrogen inconvenient Light mass Transitions in deep UV –Magnetic fields μΔB = mgh; ΔB~20 Gauss for h=1 m Vertical trap

1.Sagging of trapped “gas” 2.Slow release of Hbars 3.Anti-atomic “fountain” 4.Many Others General approaches Makoto Fujiwara

1. Gravitational Sagging examples Simple counting a)Open top lid; Count how many left b) Open bottom lid; Count how many left Counts in (a) depend on anti-H Temperature and mg. –High energy tail come out, but those with kT < mgh stay trapped –Sign measurement should be immediate, if anti-H cold enough H 17Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012

2. Slow release Use time info to get anti-H energy info –Late time  colder  more sagging Measure h distribution as function of time Many variations possible: e.g. –Dump top and bottom lids at same time –Compare separate dump of top vs bottom, in different order –Combine with counting measurement in (1) H 18Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012

Possible gravity technique [ALPHA, Nature Comm., 4, 1785 (2013)] – Anti-H released by ramping down magnetic trap – Late time events: colder, more sensitive to (anomalous) gravity First attempt Gravity x 100 ~10000% measurement of gravity  Limit on a new force coupled to anti-baryon/lepton

3. Anti-atomic Fountain Launch anti-H into drift region –E.g. by raising bottom of trap well –Still need radial confinement in drift region Counting annihilations on top vs bottom; Time-of-flight with time zero via: –E.g. fast ramping of the trap Basis for anti-atom interferometry H Drift region Trap region 20Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012

Antimatter Interferometry Sep 16, 2014 Makoto Fujiwara Δφ = (k eff ⋅ g) T 2 systematics Mulle et al., PRL 112, (2014)

New Project ALPHA-g Makoto Fujiwara

A new device being proposed by ALPHA: 1: Measurement of sign of g Should be “immediate” once anti-H is trapped 2. Free fall of cooled anti-H 1% to sub % measurement 3. Development towards antimatter-wave interferometry Eventually ? 4. Precision microwave spectroscopy Requirements more compatible than ALPHA-2 ALPHA-g Overview Makoto Fujiwara

24 ALPHA-g Experimental Concept A long (~ 2m) vertical trap –Anti-H production region Production, trapping, & cooling –Measurement region Sagging of anti-H “gas” Anti-atomic “fountain” Anti-atomic interferometry uW spectroscopy Some key components –SC Magnets & Cryostat –Beam lines –Tracking detector (TPC) –Cosmic veto (SiPM) –Cooling laser –Magnetometry MCP/ Probes MCP/ Probes RF resonator pbar e+ Laser, uW TPC Trigger/veto H External Magnet Anti-H prod & cooling ~0.5 m Meas. Region ~1.5 m Internal coils &cryostat

Detector requirements Tracking: Key for ALPHA successes! –Annihilation position to several mm Limited by multiple Scat. –Good pattern recognition –Cosmic rejection based on event topology –Unusual magnetic fields –Large area coverage –Uniform efficiency –Other options considered  Radial Drift Time Projection Chamber! Cosmic veto: – Cosmic rejection via time of flight – Magnetic fields – Few 100 ps time resolution  Scintillator + SiPM – Prototype with PMT: ~200 ps resolution: – Large area SiPM under development 25

Radial TPC (Amaudruz, Henderson, etc) Makoto Fujiwara 1/8 Prototype Garfield ++ Calculation

TCP: GEANT4 simulations (Andrea Capra, Scott Menary) Makoto Fujiwara See Poster P48 Simulated resolutions Very powerful pattern recognition!

ALPHA-g in AD zone

Towards Anti-H Laser Cooling Laser cooling simulation [Donnan, MCF, Robicheaux, J. Phys. B. 46, (2013)] –Cooling on 1 dimension –Use coupling of degrees of freedom for 3-D cooling –Cooling from ~500 mK to ~20 mK in few 100 sec Anti-H energy Time evolution (0-200 s) Laser cooling –Provides cold, high density, spatially confined sample –Good for gravity and spectroscopy! Pulsed Lyman-alpha spectroscopy –High transition rate –Sensitive detection

Anti-H Charge Measurements Makoto Fujiwara

Makoto C. Fujiwara / U. Tokyo JHF-Pbar Workshop, Feb Experimental Limits on |  Q  Q| e－e－ e+e+ p + p Positronium + cycl. freq.   p atom   SF6 gas    pHe atom   (BASE cycl freq: 7x   ) ALPHA: <10 -9 limit on e+ charge: ~10 -9 (40 fold improv’t)  <7x ASACUSA “Weak link": e+ charge PDG 2014

4. What about e+ mass? Makoto Fujiwara I have issues with PDG [1] and Fee et al.[5]: 1.“assumption that the Ps Rydberg is exactly half of the hydrogen one” does not make sense 2.It seems FEE93 assumed incorrect sensitivity between Δfreq(1s-2s) and Δm e+ /m e 3.e+ mass & charge should be treated independently, as for Pbar mass and charge [6, 7] 4.Not clear if the limit is 90% CL rather than 1σ PDG 2014

Fee et al [5] –Freq(1s-2s) measured to 2.6 x ; agree with (then) theory to 8x –This is taken to be set (linearly) Δm e+ /m e to 8x10 -9, a value adopted by PDG [1] –However, Freq(1s-2s) ∞ Reduced mass(Ps); Hence Δm e+ ~ 2 x Δf(1s-2s); Mass limit should be 1.6 x (rather than 8x10 -9 ) e+ e- charge equality is assumed –Relaxing this (as for pbar), Δm e+ dominated by e- e+ cyclotron comparison: 1.3 x New QED calculations [8]; agreement at 4.7 x – Theory: (0.6) MHz New [8] – Expt: (3.2) MHz Fee et al [5] 5. Issues with previous derivation Makoto Fujiwara

Before ALPHA –Δm e+ /m e+ ~ –ΔQ e+ /Q e+ ~ 3x10 -8 (Pbar mass, charge anomaly negligible) Cf: PDG 2014 –Δm e+ /m e+ ~ 8 x10 -9 (Our results x10 worse) –ΔQ e+ /Q e+ ~ 4 x Positron charge & mass before ALPHA Makoto Fujiwara Cyclotron Ps(1s-2s) Preliminary

After ALPHA-1 [3] –Both Δm e+ /m e+ and ΔQ e+ /Q e+ improved marginally ~ x2 7. Positron Charge & Mass after ALPHA-1 Makoto Fujiwara Cyclotron Ps(1s-2s) ALPHA-1 Preliminary

After ALPHA-2 [4] –Ignore pbar charge & mass anomaly (4x ) –ΔQ e+ /Q e+ ~ 7x (1σ), 40-fold improvement over pre-ALPHA –Δm e+ /m e+ ~ ±2x10 -8, ~5 fold improvement –But central value shifted due to disagreement between theory and exp in Ps(1s-2) 8. Positron Charge & Mass after ALPHA-2 Makoto Fujiwara ALPHA-1 ALPHA-2 Ps(1s-2s) Preliminary Cyclotron

Analysis so far assumed δm pbar /m pbar, δQ pbar /Q pbar << δm e+ /m e+, δQ e+ /Q e+ Next generation Anti-H exp’ts can no longer assume this. In general, need 4 independent measurements to determine m pbar, Q pbar, m e+, Q e+. Possibilities: 9. Antiproton Mass & Charge MeasurementLeading order dependence Current precision (1 σ ) Near future prospects Pbar/p cyclotronQ pbar / m pbar 7× Base: ? Pbar Hem pbar Q pbar 2 4× ASACUSA: ? e+/e- cyclotronQ e+ /m e+ 1.3×10 -7 Harvard ? Ps(1s-2s)(m e+ /2) Q e+ 2 5×10 -9 ETH: 5× ? Anti-H (charge)Q pbar + Q e+ 7× ALPHA: ? Anti-H (1s-2s)m e+ Q pbar 2 Q e+ 2 -ALPHA: ? Note: muon to electron charge known to 2x10 -9 from Muonium [9]

ALPHA-g: new proposed device by ALPHA collaboration –Antimatter gravity measurements with increasing precisions –Detailed design in progress –Wish to make the first sign measurement before CERN’s long shutdown (LS2)!  collaborators Summary Makoto Fujiwara

ALPHA Collaboration ALPHA 16 institutions, ~40-50 physicists ALPHA 16 institutions, ~40-50 physicists Makoto Fujiwara

Canada’s National Laboratory for Particle and Nuclear Physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules Thank you! Merci! 4004 Wesbrook Mall | Vancouver BC | Canada V6T 2A3 | Tel | Fax | Makoto Fujiwara

Back up slides Makoto Fujiwara

“Anti-CPT theorem” Greenberg 2002 –In local field theories, CPT violation comes with Lorentz violation (in flat space time) Antimatter and Standard Model Extension Lorentz evenLorentz odd CPT even CPT odd SM Most of BSM EFT (e.g. SME) EFT (e.g. SME) Beyond EFT Well tested in Matter expt’s Matter-Antimatter Comparisons meeting

Colder Hbars come out later Data agree with simulated energy distribution Temperature diagnosis for future cooling studies Released energies very cold: – Claiming the potential hill; adiabatic cooling Kinetic energy of trapped Hbars: Nature Phys Simulated kinetic energy distribution Release of trapped Hbar at t=0 Standard simulation Release energies

Radial Drift TCP: Electron drift in gas (Henderson, Lu) 44