Canadas National Laboratory for Particle and Nuclear Physics
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 LEAP 2016 Kanazawa, Japan Makoto C. Fujiwara TRIUMF – Canada’s National Lab for Particle & Nuclear Physics, Vancouver *Disclaimer: views expressed here are my own 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
LEAP 2016: Outline • Introduction • Motivations: “Big Picture” – MCF: ar. Xiv: 1309. 7468 • 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 Makoto Fujiwara
Antimatter Gravity • Seeing antimatter drop: “Textbook” experiment Makoto Fujiwara, TRIUMF 3
Textbook Experiment • ATHENA’s anti-H annihilation event (Nature, 2002): now on the cover of textbook! • $107. 28 on Amazon. com Makoto Fujiwara, TRIUMF 4
Antimatter Gravity • 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… Makoto Fujiwara, TRIUMF 5
Annihilation event after 1000 s confinement Nov. 2010 Makoto Fujiwara, TRIUMF 6
Confinement of Antihydrogen for 1000 s Trapping time increased by x 5000 “Game changer” 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
Anti-H Motivations (experimental) • Atomic hydrogen: one of best studied systems – 1 s-2 s level: 2 466 061 413 187 035 (10) Hz Dn/n~10 -15 – Hyperfine splitting: 1 420 405 751. 768 (1) Hz ~10 -12 • 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 Makoto Fujiwara
Theoretical Motivations: “Big Picture” • What is Particle Physics? (e. g. Grossman) • “Simple answer”: The Standard Model, including a Higgs, works extremely well! Makoto Fujiwara Peter Higgs July 4, 2012
Issues with the Standard Model • Many open issues with SM, which motivated “New Physics” at the Te. V scale • “Naturalness” problem of Higgs mass very serious • No new physics yet at LHC – Quantum corrections in SM require Higgs mass to be naturally heavy, like 1019 Ge. V – A “small” mass 125 Ge. V requires fine-tuning to O(30) – Motivation for Beyond SM theories (Susy, Extra Dim…) Makoto Fujiwara – Hopefully x 2 energy, or precision expt’s will solve this! (750 Ge. V? ) – Simple BSM models ruled out – Cosmological Constant even greater finetuning O(120) – Anthropic Principle our last resort?
“Pen standing without any balance” is (technically) unnatural … Makoto Fujiwara
Motivations 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 Makoto Fujiwara
Antimatter Gravity in a magnetic trap • Very cold anti-H in a vertical trap – Anti-H “gas” will sag due to gravity – If anti-H cooled to ~m. K 1/2 k. T=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 H Vertical trap
General approaches 1. 2. 3. 4. Sagging of trapped “gas” Slow release of Hbars Anti-atomic “fountain” Many Others Makoto Fujiwara
1. Gravitational Sagging examples • Simple counting a) Open top lid; Count how many left b) Open bottom lid; Count how many left H • Counts in (a) depend on anti-H Temperature and mg. – High energy tail come out, but those with k. T < mgh stay trapped – Sign measurement should be immediate, if anti-H cold enough Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012 17
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. H – Dump top and bottom lids at same time – Compare separate dump of top vs bottom, in different order – Combine with counting measurement in (1) Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012 18
First attempt 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 ~10000% measurement of gravity Limit on a new force coupled to anti-baryon/lepton Gravity x 100
3. Anti-atomic Fountain • Launch anti-H into drift region Drift region H Trap 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 Makoto Fujiwara, ALPHA-TRUMF Workshop, June 8, 2012 20
Antimatter Interferometry Mulle et al. , PRL 112, 121102 (2014) systematics Δφ = (keff⋅g) T 2 Sep 16, 2014 Makoto Fujiwara
New Project ALPHA-g Makoto Fujiwara
ALPHA-g Overview • 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 10 -6? 4. Precision microwave spectroscopy • Requirements more compatible than ALPHA-2 Makoto Fujiwara
Internal coils &cryostat ALPHA-g Experimental Concept • A long (~ 2 m) vertical trap MCP/ Probes TPC Meas. Region ~1. 5 m H Anti-H prod & cooling ~0. 5 m pbar e+ Laser, u. W External Magnet Trigger/veto RF resonator – Anti-H production region Production, trapping, & cooling – Measurement region • Sagging of anti-H “gas” • Anti-atomic “fountain” • Anti-atomic interferometry • u. W spectroscopy • Some key components – – – SC Magnets & Cryostat Beam lines Tracking detector (TPC) Cosmic veto (Si. PM) Cooling laser Magnetometry 24
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 + Si. PM – Prototype with PMT: ~200 ps resolution: – Large area Si. PM under development 25
Radial TPC (Amaudruz, Henderson, etc) 1/8 Prototype Garfield ++ Calculation Makoto Fujiwara
TCP: GEANT 4 simulations (Andrea Capra, Scott Menary) Very powerful pattern recognition! Simulated resolutions See Poster P 48 Makoto Fujiwara
ALPHA-g in AD zone
Towards Anti-H Laser Cooling • Laser cooling – Provides cold, high density, spatially confined sample – Good for gravity and spectroscopy! • Pulsed Lyman-alpha spectroscopy – High transition rate – Sensitive detection Laser cooling simulation [Donnan, MCF, Robicheaux, J. Phys. B. 46, 205302 (2013)] – Cooling on 1 dimension – Use coupling of degrees of freedom for 3 -D cooling – Cooling from ~500 m. K to ~20 m. K in few 100 sec Anti-H energy Time evolution (0 -200 s)
Anti-H Charge Measurements Makoto Fujiwara
3. Experimental Limits on |d. Q/Q| PDG 2014 Positronium + cycl. freq. - e 4 10 8 SF 6 gas 10 21 (BASE cycl p+ freq: 7 x 10 11) p atom 2 10 5 e+ “Weak link": e+ charge ? p p. He atom 10 7 ALPHA: <10 -9 limit on e+ charge: ~10 -9 (40 fold improv’t) <7 x 10 -10 ASACUSA Makoto C. Fujiwara / U. Tokyo JHF-Pbar Workshop, Feb 16 2002
4. What about e+ mass? PDG 2014 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 FEE 93 assumed incorrect sensitivity between Δfreq(1 s-2 s) and Δme+/me 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 Makoto Fujiwara
6. Positron charge & mass before ALPHA • Before ALPHA Preliminary C yc lo tro n – Δme+/me+ ~ 10 -7 – ΔQe+/Qe+ ~ 3 x 10 -8 (Pbar mass, charge anomaly negligible) Ps(1 s -2 s) Makoto Fujiwara Cf: PDG 2014 – Δme+/me+ ~ 8 x 10 -9 (Our results x 10 worse) – ΔQe+/Qe+ ~ 4 x 10 -8
7. Positron Charge & Mass after ALPHA-1 • After ALPHA-1 [3] Preliminary C yc lo tro n – Both Δme+/me+ and ΔQe+/Qe+ improved marginally ~ x 2 ALPHA-1 Ps(1 s -2 s) Makoto Fujiwara
8. Positron Charge & Mass after ALPHA-2 C yc lo tro n • After ALPHA-2 [4] Preliminary Ps(1 s -2 s) ALPHA-2 ALPHA-1 Makoto Fujiwara – Ignore pbar charge & mass anomaly (4 x 10 -10) – ΔQe+/Qe+ ~ 7 x 10 -10 (1σ), 40 -fold improvement over pre-ALPHA – Δme+/me+ ~ ± 2 x 10 -8, ~5 fold improvement – But central value shifted due to disagreement between theory and exp in Ps(1 s-2)
9. Antiproton Mass & Charge • Analysis so far assumed δmpbar/mpbar, δQpbar/Qpbar << δme+/me+, δQe+/Qe+ • Next generation Anti-H exp’ts can no longer assume this. • In general, need 4 independent measurements to determine mpbar, Qpbar, me+, Qe+. Possibilities: Measurement Leading order dependence Current precision (1σ) Near future prospects Pbar/p cyclotron Qpbar / mpbar 7× 10 -11 Base: 10 -11 ? Pbar He mpbar Qpbar 2 4× 10 -10 ASACUSA: 10 -10 ? Qe+/me+ 1. 3× 10 -7 Harvard ? (me+/2) Q e+2 5× 10 -9 ETH: 5× 10 -10 ? Qpbar + Qe+ 7× 10 -10 ALPHA: 10 -12 ? me+ Qpbar 2 Q e+2 - ALPHA: 10 -11 ? e+/e- cyclotron Ps(1 s-2 s) Anti-H (charge) Anti-H (1 s-2 s) Note: muon to electron charge known to 2 x 10 -9 from Muonium [9]
Summary • 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 (LS 2)! collaborators Makoto Fujiwara
ALPHA Collaboration 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! Makoto Fujiwara BC | Canada V 6 T 2 A 3 | Tel 604. 222. 1047 | Fax 604. 222. 1074 | www. triumf. ca 4004 Wesbrook Mall | Vancouver
Back up slides Makoto Fujiwara
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