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AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy C. Canali INFN sez. Genova 11° ICATPP Como, 8 October 2009

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The AEGIS Collaboration LAPP, Annecy, France D. Sillou Queens U Belfast, UK G. Gribakin, H.R.J.Walters INFN Firenze, Italy G. Ferrari, M. Prevedelli, G. Tino CERN M. Doser, A. Dudarev, D. Perini (+ support from T. Eisel, F. Haug, T. Niinikoski) INFN Genova, Italy C. Canali, C. Carraro, V. Lagomarsino, G. Manuzio, G. Testera, S. Zavatarelli MPI-K Heidelberg A. Fisher,A. Kellerbauer, U. Warring, C. Kirchhoff Inst. Of Phys., Heidelberg, Germany M. Oberthaler INFN Milano, Italy I. Boscolo, N. Brambilla,F. Castelli, S. Cialdi, L. Formaro, A. Gervasini, M. Giammarchi, F. Leveraro, A. Vairo INR Moscow, Russia A.S. Belov, S. N. Gninenko, V. A. Matveev, A. V. Turbabin ITEP Moscow, Russia W. M. Byakov, S. V. Stepanov, D.S. Zvezhinskij New York Univ. USA H.H. Stroke Univ. Oslo, Norway O. Rohne, S. Stapnes INFN Pavia-Brescia, Italy G.Bonomi, A. Fontana, A. Rotondi, A. Zenoni Czech Tech. Univ, Prague, Czech Republic V. Petracek, D. Krasnicky, M. Spacek IRNE Sofia, Bulgary N. Djurelov INFN Padova-Trento, Italy R.S. Brusa, D. Fabris, M. Lunardon, S. Mariazzi, S. Moretto, G. Nebbia, S. Pesente, G. Viesti ETH Zurich, Switzerland S.D. Hogan, F. Merkt Qatar University I. Y. Al-Qaradawi Politecnico Milano, Italy G. Consolati, A. Dupasquier, R. Ferragut, P. Folegati, F. Quasso La. Aime Cotton, Orsay, France L. Cabaret, D. Comparat INP Minsk, Belarus G. Drobychev UCBL Lyon, France P.Nedelec

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Physical Motivations: why antimatter? Gravity and antimatter AEGIS: measuring g on antihydrogen Overview Measuring g on H Conclusions AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy

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Antimatter system: WEP test General Relativity test Gravity: Spectroscopy on antihydrogen CPT: relative precision Magnetic moment (g - 2) e - e + (g μ - μ + (q/m) e - e + Mass differencef K 0 K 0 Charge/mass (q/m) pp [P. B. Schwinberg et al., Phys. Lett. A 81 (1981) 119] [R. S. Van Dyck, Jr. et al., Phys. Rev. Lett. 59 (1987) 26] [G. Gabrielse et al., Phys. Rev. Lett. 82 (1999) 3198] [Y. B. Hsiung, Nucl. Phys. B (PS) 86 (2000) 312] [G. W. Bennett et al., Phys. Rev. Lett. 92 (2004) ]

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We need neutral (cold) antimatter: Charged particles are extremely sensitive to electric fields: we need a neutral system… High precision spectroscopy: The frequency of the 1S-2S transition in hydrogen has been measured with high precision: f = (46) Hz Gravity measurement: Anti-hydrogen! [M. Niering et al., Phys. Rev. Lett. 84 (2000) 5496]

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General relativity is a classical (non quantum) theory! Tensor Newton, always attractive Vector repulsive between like charges Scalar always attractive The non-Newtonian terms could (almost) cancel out if a b and v s, but would produce a striking effect on antimatter Matter-matter:matter-antimatter: [T. Goldman, M. Nieto Phys. Lett 112B (1982)] [ E. Fischbach, C. Talmadge The search for Non Newtonian Gravity Springer]

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PS210 first H-bar Dirac equation ATHENA first cold H-bar ATRAP Fermilab 1932 Positron discovery 1955 Antiproton discovery AEGIS proposal ATRAP2 ALPHA Wow!… so, lets start the experiment! 1927

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PS210 first H-bar Dirac equation ATHENA first cold H-bar ATRAP Fermilab 1932 Positron discovery 1955 Antiproton discovery AEGIS proposal ATRAP2 ALPHA 1999 The AD – Antiproton Decelerator ADPS Protons Antiprotons

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protons 26 GeV/c from PS 3.5 GeV/c GeV/c Delivered to experimental areas: 10 7 antiprotons delivered every ~85 s 0.1 GeV/c 200 ns bunches AD ring Stochastic & electron cooling ASACUSA ATHENA ATRAP 1999 The AD – Antiproton Decelerator

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AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) 2007: proposal submitted 2008: experiment approved by CERN 2009: start building … asacusa alpha atrap aegis

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B= 1 T H prod. region 100 mK Positronium Production region Moiré deflectometer Positrons trap AD side p entrance Stark accelerator Positrons from accumulator Antihydrogen production based on: Penning traps Confinement in vacuum of charged partcles: B-Field radial confinement E-Field axial confinement B=1T

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Goal: first direct measurement of Earths gravitational acceleration g on antimatter p catching and cooling positrons accumulation Antihydrogen production Beam formation g measurement 0s100s time B=1T

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5kV Electron plasma p catching and cooling From AD: 10 7 antiprotons delivered every ~85 s 0.1 GeV/c 200 ns bunches 10 4 antiprotons in trap [athena] electron cooling of antiprotons Resistive cooling Sympathetic cooling with negative ions (?) GOAL: > mK

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e+ bounch Ps production (bound state e + e - ) Ps excitation (Double laser pulse n=1 n=3 n=25) H-bar production (Charge exchange Ps + p H + e) Stark acceleration

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e+ slowing down and Ps formation Ps thermalize within target (eV) Ground state Ps emitted in vacuum High Yield (30-50%) Precise timing (few tens ns) Production of positrons from a Surko-type source and accumulator 22 Na radioactive source (40 mC) 10 8 e + every 200 s e + accumulator & positronium production

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dye laser 1064 nm, 4 ns 135 mJ nm 6 mJ PPLN 2 cm PPLN 4 cm 3 mJ nm Etalon 615 nm OPA OPG Q-switched Nd:YAG laser 3 mJ 1670 nm 205 nm n = 1 n = 2 n = 3 n = 35 positronium excitation Two laser steps: n Ps = 1 n Ps = 3 n Ps = 3 n Ps = 20 … 40 (tunable) >10 6 Rydberg positronium atoms are expected

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Antihydrogen production occur via charge exchange process: Large cross section ~ a 0 n Ps 4 σ = cm 2 Antihydrogen state related to initial Ps* state Produced antihydrogen has the same temperature of antiprotons (100 mK): Low energy H! [C. H. Storry et al., Phys. Rev. Lett. 93 (2004) ]

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Δv of several 100 m/s within about 1 cm Electric fields: few 100 V/cm (limited by field ionization) Already working with Rydberg hydrogen! [E. Vliegen & F. Merkt, J. Phys. B 39 (2006) L241] The beam is produced using a stark accelerator: H is in Rydberg state Interactions between electric dipole moment and a non-uniform electric field:

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How to measure g? Produce an horizontal antihydrogen beam, velocity few 100 m/s Horizontal flight path about 1 m Vertical gravity deflection : m/s Poor beam collimation: beam size after flight: several cm H vhvh L h Gravity measurement with ordinary matter have been performed with a Moirè deflectometer: σ(g)/g = 2×10 -4 [M. K. Oberthaler et al., Phys. Rev. A 54 (1996) 3165]

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40 cm 20 cm L s 30 cm (distance antihydrogen source-first grating) Grating distance L 40 cm Grating size: 20 x 20 cm 2 Grating period: a=80 μm Grating transparency 30% Detector resolution 10 μm G1G2Detector Only classical interactions

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Binning (grating period) V h = 600 m/s x counts Montecarlo results

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V h = 400 m/s V h = 600 m/s x counts

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V h = 400 m/s V h = 600 m/s V h = 300 m/s x counts

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V h = 400 m/s V h = 600 m/s V h = 300 m/s V h = 250 m/s x counts

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T: time of flight between the two gratings a: grating period Measurement of g to 1%: 10 8 e + in s 5x10 6 Rydberg Ps antiprotons captured and cooled to 100 mK rate: 10 3 H / AD cycle 10 5 antihydrogen athoms (2-3 settimane).

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Conclusions ( & ambitions): Gravity on antimatter has never been tested AEGIS could perform the first measure of this kind never performed An antihydrogen beam open the way to new experimental possibilities Trapping antihydrogen & spectroscopy, atomic fountain, BEC, High precision g-meas. … AEGIS will use already well-know techniques together with innovative schemes Members of AEGIS are already working on this…

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Thanks for your attention

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The g measurement Send the antihydrogen beam through the deflectometer: t 0 defined within sec Send the antihydrogen beam through the deflectometer: t 0 defined within sec For every antihydrogen measure the vertical position x and the arrival time on the detector For every antihydrogen measure the vertical position x and the arrival time on the detector Few tens antihydrogen/cycle; flight time ms; Few tens antihydrogen/cycle; flight time ms; The large beam velocity spread makes pileup negligible The large beam velocity spread makes pileup negligible Reconstruct the flight time T between the 2 gratings Reconstruct the flight time T between the 2 gratings Group together Hbar having T in a proper interval (T 1,T 2 ) : make a T 2 distribution symmetric Group together Hbar having T in a proper interval (T 1,T 2 ) : make a T 2 distribution symmetric Build the 1 period arrival position distribution N(x/a) : about 10 3 detected particles Build the 1 period arrival position distribution N(x/a) : about 10 3 detected particles Use a phase tracking algorithm to find the shift Use a phase tracking algorithm to find the shift Find g by fitting the relation Find g by fitting the relation x/a 10 m resolution Infinite resolution N(x)

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Capture and cooling of antiprotons p catching and cooling positrons accumulation Antihydrogen production Beam formation g measurement From AD: 10 7 antiprotons delivered every ~85 s 0.1 GeV/c 200 ns bunches Catching: Degrader foil Reflecting and trapping in Penning trap (5kV) 10 4 antiprotons in trap [athena] Cooling: previously loaded plasma with 10 7 electrons electrons quickly cool down by cyclotron radiation electron cooling of antiprotons Resistive cooling Sympathetic cooling with negative ions (?)

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Recombination experiments: ATHENA & ATRAP antiprotons positron plasma Core idea: trapping in the same region and e + [C. Regenfus, NIM A 501 (2003) 65] Cylindrical Penning trap

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Diocotron jump of positrons P-bar catching region P-bar cooling region B=5T B=1T

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