AEGIS. Antimatter Experiment: Gravity, Interferometry, Spectroscopy. C. Canali INFN sez. Genova (AEgIS COLLABORATION)

Transcription

1 AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy C. Canali INFN sez. Genova (AEgIS COLLABORATION) 46 Rencontres de Moriond 26 March 2011

2 LAPP, Annecy, France D. Sillou Queen s U Belfast, UK G. Gribakin, H. R. J. Walters U of Qatar, Doha, Qatar I. Al-Qaradawi L. V. Jorgensen INFN Firenze, Italy G. Ferrari, M. Prevedelli CERN, Geneva, Switzerland J. Bremer, G. Burghart, M. Doser, A. Dudarev, T. Eisel, F. Haug, D. Perini INFN Genova, Italy C. Canali, C. Carraro,,. Krasnický, V. Lagomarsino, G. Testera,R. Vaccaro ne, S. Zavatarelli MPI-K, Heidelberg, Germany A. Kellerbauer, U. Warring U of Heidelberg, Germany P. Bräunig, F. Haupert, M. K. Oberthaler U of Lyon, France P. Nédélec INFN Milano, Italy I. Boscolo, F. Castelli, S. Cialdi, M. Giammarchi, M. Sacerdoti, D. Trezzi, F. Villa Politecnico di Milano, Italy G. Consolati, R. Ferragut, A. Dupasquier INR, Moscow, Russia A. S. Belov, S. N. Gninenko, V. A. Matveev New York U, USA H. H. Stroke Laboratoire Aimé Cotton, Orsay, France L. Cabaret, D. Comparat U of Oslo, Norway J. P. Hansen, O. Rohne, H. Sadake INFN Padova, Trento, Italy G. Nebbia, R. S. Brusa, S. Mariazzi L. Di Noto, INFN Pavia/Brescia, Italy G. Bonomi, L. Dassa, A. Fontana, C. Riccardi, A. Rotondi, A. Zenoni Czech Technical U, Prague, Czech Republic V. Petráček INRNE, Sofia, Bulgaria N. Djourelov ETH Zurich, Switzerland S. D. Hogan, F. Merkt TCP2010 April 12-16, 2010 Saariselkä C. Canali

3 AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy Physical Motivations: why antimatter? Gravity and antimatter The AEgIS experiment Goals: Measure g on antihydrogen Antihydrogen spectroscopy CPT test Methods: Produce an Hbar beam Moirè deflectometer

4 AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy Physical Motivations: why antimatter? Gravity and antimatter The AEgIS experiment Goals: Measure g on antihydrogen Antihydrogen spectroscopy CPT test Methods: Produce an Hbar beam Moirè deflectometer

5 What do we know about gravity and antimatter? apple anti apple g =9.81..m/s 2 g =9.81..m/s 2 g =?? m/s 2 Earth CPT anti Earth CPT is useless Weak equivalence principle for antimatter

6 Weak equivalence principle (for antimatter) General relativity is the fundamental theory of the gravitation It is a non quantum theory (classical) Many efforts to get a quantum theory differences between matter and antimatter would of course violate the weak equivalence principle (WEP), a cornerstone of General Relativity Indirect limits about antimatter: g H g g H x 10 x=6,7,8. M. Nieto et al Phys. Rep. 205 (5) 221 (1991) M. Charlton et al Phys. Rep (1994) R. Hughes Hyp. Int.76 3 (1996) Xiv: v1 [hep-th ] 28 Aug 2008 arxiv: v1 [hep-ph] 23 Jul 2009

7 Precision 1,00E+00 1,00E-01 1,00E-02 1,00E-03 1,00E-04 1,00E-05 1,00E-06 1,00E-07 1,00E Newton Pendulum Stevin Drop Tower MATTER-MATTER 1910 Southern EXPERIMENTS Torsion balance Equivalence Principle tests 1,00E-09 1,00E-10 1,00E-11 1,00E-12 1,00E-13 1,00E Shapiro lunar laser Year 1999 Baebler torsion balance MiniSTEP, MICROSCOPE, Galileo Galilei 10-17??

8 AEGIS Antimatter Experiment: Gravity, Interferometry, Spectroscopy Physical Motivations: why antimatter? Gravity and antimatter The AEgIS experiment Goals: Measure g on antihydrogen Antihydrogen spectroscopy CPT test Methods: Produce an Hbar beam TO DO LIST: produce antihydrogen make an horizonally travelling H-bar beam measure its horizontal deflection over 1m horizontal path Moirè deflectometer

9 The antiproton decelereator (AD) at cern Protons Antiprotons Every 200s: 10 7 antiprotons delivered every ~85 s 0.1 GeV/c 200 ns bunches AD PS

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

11 e+ accumulator Rydberg positronium Diluition cryostat 100 mk 1m Antihydrogen Production/study Penning traps Positronium production Moire deflectometer Monte carlo simulation Laser Particle detectors Positronium spectroscopy Plasma physics Position Sensitive detector

12 Positrons from Accumulator 22 Na source 5T magnet Pbar capture Pbar cooling (4kK 1T magnet Pbar cooling (100mK) Deflectometer (g meas.) 1m Antiprotons from AD 1m Antihydrogen / anihilations detectors Position sensitive detector

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

14 H-bar production (Charge exchange Ps *+ p H* + e) Stark acceleration 100mK antiprotons (4K actual record ) F 3 2 nk E Ps excitation (Double laser pulse n=1 n=3 n=25) e+ bounch Ps production (bound state e + e - )

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

16 supplementary gratings for optical interferometry active area of 68cm 2 Philippe Bräunig Group of Prof. Markus Oberthaler Kirchoff Institute for Physics, Heidelberg aegis@matterwave.de Gravity measurement with ordinary matter have been performed with a Moirè deflectometer: σ(g)/g = [M. K. Oberthaler et al., Phys. Rev. A 54 (1996) 3165]

17 20 cm G1 G2 Detector 40 cm 40 cm L s Grating distance L 30 cm (distance antihydrogen source-first grating) 40 cm Grating size: 20 x 20 cm 2 Grating period: a=80 μm Grating transparency 30% Detector resolution <10 μm Only classical interactions

18 Antihydrogen athoms are detected one by one Time of flight is measured (v)

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

20 x V h = 600 m/s V h = 400 m/s g=9.81 m/s 2 counts

21 x V h = 600 m/s V h = 400 m/s V h = 300 m/s g=9.81 m/s 2 counts

22 x V h = 600 m/s V h = 400 m/s V h = 300 m/s V h = 250 m/s g=9.81 m/s 2 counts

23 dx a gt a 2 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 10 5 antihydrogen athoms (2-3 weeks).

24 Direct measurement of gravity acceleration of neutral antimatter system 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.

25 A journey of a thousand miles starts with a single step 老子 Lǎozǐ (c. 4th century B.C.) Chinese philosopher

26 The g measurement 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 Few tens antihydrogen/cycle; flight time ms; The large beam velocity spread makes pileup negligible 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 Build the 1 period arrival position distribution N(x/a) : about 10 3 detected particles Use a phase tracking algorithm to find the shift Find g by fitting the relation 2 N(x) 10 m resolution T Infinite resolution x/a T w w w w w a 0.4 N det g det det det det det w T rad m m m m

27 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 (?)

28 140 mm Recombination experiments: ATHENA & ATRAP Core idea: trapping in the same region p and e + positron plasma p e H p 2e H e antiprotons π 511-keV γ Silicon micro strips (inner) π Cylindrical Penning trap (outer) CsI crystals π 511-keV γ [C. Regenfus, NIM A 501 (2003) 65]

29 5kV p catching and cooling Electron plasma GOAL: > mk 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 (?)

30 e + accumulator & positronium production Production of positrons from a Surko-type source and accumulator 22 Na radioactive source (40 mc) 10 8 e + every 200 s 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)

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

32 Antihydrogen production occur via charge exchange process: p Ps * H * e Large cross section ~ a 0 n Ps 4 σ = 10-9 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) ]

33 The beam is produced using a stark accelerator: H is in Rydberg state Interactions between electric dipole moment and a non-uniform electric field: Δv of several 100 m/s within about 1 cm F 3 2 nk E 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]