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GBAR Gravitational Behaviour of Antihydrogen at Rest

GBAR Gravitational Behaviour of Antihydrogen at Rest. CERN AD-7 Approved 30/05/2012 14 institutes 48 physicisists. Motivation Principle and goal of the experiment Experimental technique Schedule and perspectives. Motivation.

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GBAR Gravitational Behaviour of Antihydrogen at Rest

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  1. GBAR GravitationalBehaviour of Antihydrogen atRest CERN AD-7 Approved 30/05/2012 14 institutes 48 physicisists • Motivation • Principle and goal of the experiment • Experimental technique • Schedule and perspectives Pascal Debu - CEA Saclay / Irfu

  2. Motivation A direct testof the Equivalence Principlewithantimatter The acceleration imparted to a body by a gravitational field is independent of the nature of the body : Inertial mass = gravitational mass Tested to a veryhighprecisionwithmanymaterials Pascal Debu - CEA Saclay / Irfu

  3. INDIRECT LIMITSTheory and experiments • Limitscanbe put on anydifferentgravitationalacceleration(call itg) for antimatter: • General Relativity: WEP violation → violation of energy conservation • Supergravity: → introduce new gravi-vector and scalarfields not coupled to γto distinguishmG et mG(J. Scherk, Phys. Lett. B (1979) 265) • But : • - Limitsfrom the antimattercontent of ordinarymatter • - It isdifficult to cancel exactlyvector and scalar interactions • (D.S.M.Alveset al SU-ITP-09/36) • CPLEAR: CP violation in K0-K0oscillations measurements as a function of time dependsuponm (A. Apostolakis et al., PhysLett B 452 (1999) 425) • Cyclotron frequencymeasurementof p (H-) et p in the samemagneticfield • R. Hughes and M. Holzscheiter, PhysRevLett 66 (1991) 854 • G. Gabrielse et al. PhysRevLett 82 (1999) 3198 Pascal Debu - CEA Saclay / Irfu

  4. INDIRECT LIMITSTheory and experiments • A direct limit ??? • Arrival time of one (? : 90 % CL) neutrino and 18 antineutrinos • from SN1987a (S. Paksava et al. PhysRev D 39 (1989) 1761) • But, also … • An argument in favor of g g fromcosmology : • Matterantimatterasymmetry in the Universe • Need of darkenergy + darkmatter + inflation • Is there a repulsiveantimatter-matter interaction ??? • (A. Benoît-Lévy, G. Chardin A&A 537 (2012) A78) Pascal Debu - CEA Saclay / Irfu

  5. Past attempts and proposals • - positrons: proposed by W. Fairbank • tests withelectrons: F. Witteborn and W. Fairbank, PhysRevLett 19 (1967) 1049 • antiprotons: PS200 Proposal Los Alamos Report LA-UR 86-260 • Very hard : - antineutrons: hard to slow down T. Brando et al, NucI. Instrum. Methods 180 (1981) 461 - positronium: short life time (142 ns) if n = 1 possibility if n>>1 Pbs: cooling, polarisability, ionisation… A.P. Mills, M. Leventhal, NucI. Instrum. Meth. in Phys. Research. B192 (2002) 102 All theoretical arguments have assumptions (absolute potential, virtual loops, CPT…) No direct measurement available yet To conclude: Pascal Debu - CEA Saclay / Irfu

  6. Outline • Motivation • Principle and goal of the experiment • Experimental techniques • Schedule and perspectives Pascal Debu - CEA Saclay / Irfu

  7. Next simplest system:H Two experiments in preparation H L Principle : parabolic flight AEGIS : deflectometer GBAR : duration of free fall • AEGIS : cold antihydrogen T(H) ~ 100 mK ~ 10 μeV • L = 1 m & vh = 500 m/s →h = 20 µm • GBAR : produce first cold H+→ veryslowHT(H) ~ 10 μK ~ 1 neV - L = 0.1 m & vh = 0.5 m/s →h = 20 cm • Goal : phase 1 : ∆g/g~ 1% ; phase 2 : ∆g/g< 10-3 Pascal Debu - CEA Saclay / Irfu

  8. Gbar : use H+to get H atoms cooling 10 µK detector Laser (t0) H+ gravity detector (t1) • Produce ion H+ • Capture ion H+ • Sympatheticcooling10 µK • Photodetachment of e+ • Time of flight • Errordominated by • temperatureof H+ • Relative Precision on g: h = 1/2 g (t1-t0)2 h = 20 cm ∆t = 202 ms J.Walz & T. Hänsch, General Relativity and Gravitation, 36 (2004) 561. Pascal Debu - CEA Saclay / Irfu

  9. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  10. High intensity slow positrons source ~ 5 x 1011fast e+/s ~ 2 x 108slow e+/s e+/e- selection e+ ~MeV e- 10 MeV e+“slow” : 3 eV target LINAC Moderator e- andγ ~ MeV 300 Hz / 2 μs 0.2 mA Tungsten near primary target εmoderation~ 5 x10-4 Solid neon after e+/e-selector εmoderation ~ 3 10-3 Tungstentargetεe+/e- prod~ 5 10-4 Pascal Debu - CEA Saclay / Irfu

  11. Prototype at Saclay Concrete shielding X rays Slow e+ detection RIKEN Penning trap for e+ e+/e- magnetic separator e- linac 4.3 MeV W target Present slow e+ rate : ~ 4 106 s-1 Extrap. to 10 MeV : ~ 5 107s-1 Target value : ~ 3 108 s-1 (higherenergy, frequency, moderation) Pascal Debu - CEA Saclay / Irfu

  12. H+production e+ trap accumulate ~ 2 1010e+ every p burst ~ 2’ Dump ~1010e+ in Ps converter in < τPs=142 ns Linac 3 108slow e+/s closed geometry to keep density (SiO2 reflects Ps) RIKEN test : 1.3 x1010e- / 75 ns Pascal Debu - CEA Saclay / Irfu

  13. Yield of o-Ps : 30 % !!! Measurement at CERN ~ 3.5 x 105 e+ cm-2s-1 L.Liszkay et al., Appl. Phys. Lett. 92 (2008) 063114 e+ flux x ~1011 Measurement at UCR ~ 5.6 x 1016 e+ cm-2s-1 D. B. Cassidy et al., Phys. Rev. A 81 012715(2011) No loss in conversion efficiency in spite of the 1011intensity factor Pascal Debu - CEA Saclay / Irfu

  14. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  15. RIKEN Multi Ring Trap • Trap now at Saclay: • we start accumulation with pulsed e+ • Simulation: • εtrapping ≈ 50% expected • few 1010 e+ needed The MRT at RIKEN Pascal Debu - CEA Saclay / Irfu

  16. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  17. Cross-sections on Ps H.R.J. Walters and C. Starett, Phys. Stat. Sol. C, 1-8 (2007) J. P. Merrison et al., Phys. Rev. Lett. 78, 2728 (1997) σ ~10-16 cm2 σ ~10-15 cm2 H + Ps  H- + e+ p + Ps  H + e+ } EH = 6 keV in Ps frame 4 102H 1H+ 6 106p 1012Ps/cm2 5 10 20 50 100 Ep [keV] EPs [eV] AD/Elena Facility CERN if fraction of Ps excited to n=3 expect × > 100 2 x1010 e+ from trap Pascal Debu - CEA Saclay / Irfu

  18. Cross-sections on Ps : new results(IRFU & IPCMS Strasbourg) Production of excited from Production of from de-excitation required 30 % Ps(3d)  nb  300 at 1 or 6 keV (100 in GBAR proposal) Pascal Debu - CEA Saclay / Irfu

  19. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  20. Deceleration & focusing of p Methodusedat ISOLDE : 60 keV ion beamsdelivered in 2 keV bunches of < 50 ns p from ELENA drift tube 100 keV 4 mm mrad 1 keV p pulse 1 keV 0.2 m 40 mm mrad Tests with p in preparation at CSNSM - 99 kV - 99 kV switched to 0 V Pascal Debu - CEA Saclay / Irfu

  21. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  22. H+cooling • Segmented RF Paul Trap, welldepth ~1 eV • Sympatheticcoolingusing Be+ ions • Laser cooled Be+ ions • Coulomb interaction of H+and Be+ Cooling laser H+capture trap Be+trap • Be+ Doppler cooling • Temperature ~ 1 mK • Be+ sub-Dopplercooling • Temperature ~ 10 μK Pioneered by NIST group M. D. Barrett, D. Wineland, PRA 68, 042302 (2003) Sympathetic cooling of 9Be+ and 24Mg+ for quantum logic Pascal Debu - CEA Saclay / Irfu

  23. SynopticScheme Pascal Debu - CEA Saclay / Irfu

  24. Free fallmeasurement H+ - Atomstrajectories afterphotodetachement of the excess positron + h = 1/2 g (t1-t0)2+vz0(t1-t0) Aim : measureg to 1 % precison (first phase) ~ 1500 eventsneeded γ γ Pascal Debu - CEA Saclay / Irfu

  25. Efficiencies A few weeks of running to get 1500 events All details in : P. Pérez et al, Proposal CERN - SPSC- 029 (2011) Pascal Debu - CEA Saclay / Irfu

  26. Perspective: beyond 1 % precision Gravitational quantum states of Antihydrogen A. Yu. Voronin, P. Froelich, and V. V. Nesvizhevsky, Phys. Rev. A 83, 032903 (2011) • H Source: • very low temperature • high phase-space density • compact system • Improve the precision on gwith the spectroscopy of gravitational levels of H above the annihilation plane : similarmethod as for UCN neutrons (GRANIT spectrometer) Pascal Debu - CEA Saclay / Irfu

  27. GBAR Schedule • 05/2012: approval by CERN Research Board • 12/2012: start e+ trapping tests • 06/2013: deceleration technique demonstration with protons • 06/2014: Ps production and excitation • 06/2014: detector tests with cosmics • 12/2014: sympathetic cooling demonstration with matter (H2+) • 06/2015: Installation at CERN • 03/2016: Commissionning • 01/2017: AD/ELENA starts and later… first measurements Pascal Debu - CEA Saclay / Irfu

  28. The GBAR collaboration 14 institutes 48 physicisists Varietyof physicsfields Particle Accelerator Plasmas and ions trapping Cold atoms Positronium Material science Cold neutrons Theory Pascal Debu - CEA Saclay / Irfu

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