Progress on Antimatter Interferometry Marco G. Giammarchi Istituto Nazionale Fisica Nucleare – Milano Outline of talk: 1) Theoretical motivation 2) Antiprotons (anti-Hydrogen) 3) Positrons (positronium, Ps) 4/10/2019 SME 2018 - Indiana University

Theoretical movitation 1) Theoretical motivation and method 2) Antiprotons (anti-Hydrogen) 3) Positrons (positronium, Ps) General Relativity is the current Theory of Gravity It is a classical (metric) theory It has never been tested at the level of anti-particles It has no quantum version (approximations in weak field can be quantized with graviton) From the particle physics point of view, it could be mediated by a tensor (spin-2) carrier 4/10/2019 SME 2018 - Indiana University

Gravity and the Particles (CPT) Dynamical meaning The gravitational «charge» According to the WEP CPT Theorem Which means that Would not mean that CPT is broken 4/10/2019 SME 2018 - Indiana University

Gravity and the Particles In many Quantum Gravity models (in the classical static limit), one has : The sign of the Gravi-Vector can be different between Matter and Antimatter Ranges and strength unknowns Graviton Gravi-Vector Gravi-Scalar From the Particle Physics point of view, it could be mediated by a tensor (spin-2) carrier, with the charge being mass-energy. Matter-Matter (e- e-) Antimatter-Matter (e+ e-) Quantum Gravity Scalar attractive gravi-scalar Vector repulsive gravi-vector Tensor (Gravity) graviton Tensor (Antigravity) Repulsive (CPT violating) 4/10/2019 SME 2018 - Indiana University

The Method: Interferometry Moiré, Fraunhofer andTalbot regimes In a sense it’s all Large aperture Far field a x,L Moiré regime x’ Talbot regime Fraunhofer regime Considering the usual expansion, one can define the F parameter F << 1 in the Fraunhofer case F > 1 in the Talbot case 4/10/2019 SME 2018 - Indiana University

Talbot carpets 2 Talbot regime 1 The characteristic pattern of the Talbot effect can be used to make sure the observed effect is the Talbot effect for the specified wavelength Units Talbot length Fringes visibility for the given wavelength 2 Talbot regime 1 Fraunhofer regime setting in when L>>LT «Ballistic» moiré regime 4/10/2019 SME 2018 - Indiana University

Antiprotons (anti-Hydrogen) 1) Theoretical motivation 2) Antiprotons (anti-Hydrogen) 3) Positrons (positronium, Ps) Antiprotons from the CERN Antiproton Decelerator System Multi-step charged particle production (starts with protons at 26 GeV) Charged particles selection Cooling in a dedicated ring 3x107 antiprotons /200 s (100 ns pulse width) with a 5.3 MeV energy 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University Antiproton Deflectometry in AEgIS Energy of the antiprotons degraded down to ~100 keV Moirè deflectometer For protons at this E For laser photons S. Aghion et al. (the AEgIS collaboration) A moiré deflectometer for antimatter, Nature Comm., doi: 101038/ncomms5538 4/10/2019 SME 2018 - Indiana University

Proton-like ions and application(s) Talbot-Lau deflectometer for protons and H-ions as a sensor to detect small fields (Field-Meter) P. Lansonneur et al., Nuclear Instruments & Methods A 862 (2017) 49. 4/10/2019 SME 2018 - Indiana University

Gravitational studies will require Anti-H (ALPHA) The first anti-H gravitational study from a non-interferometric method ALPHA experiment at the CERN AD Trapping of anti-H Releasing anti-H Measuring up-down asymmetry in anti-H annihilation Ratio between gravitational and inertial mass m(g)/m(i) < 70 - 110 Rejected at a high confidence level C. Amole et al. (ALPHA collaboration) Nature Comm., doi: 101038/ncomms2787 4/10/2019 SME 2018 - Indiana University

Positrons (Positronium, Ps) 1) Theoretical motivation 2) Antiprotons (anti-Hydrogen) 3) Positrons (positronium, Ps) QUPLAS: Quantum Interferometry and Gravitation with Positrons and LASers QUPLAS-0) Deflectometry/Interferometry on positrons 4/10/2019 SME 2018 - Indiana University

Positron beam energy: from a few keV up to 20 keV Reference value: 10 keV Intensity: ~ 104 e+/s The de Broglie wavelength One can choose b = c = 33 cm To have a 2 µm periodicity pattern on C Setup preparation Exposure to the e+ beam Integration on the emulsion detector C Given a grating with The Talbot length 4/10/2019 LVS 15 - Indiana University

SME 2018 - Indiana University The detector : Nuclear Emulsions (~µm resolution) S. Aghion et al., JINST 8 (2013) P08013. The method : Asymmetric Talbot-Lau S. Sala et al., J. Phys. B 48, 2015, 195002 S. Sala et al., Phys. Rev. A 94, 2016, 033625 Asymmetric Talbot-Lau configuration : fringe magnification 4/10/2019 SME 2018 - Indiana University

«Asymmetric» Talbot- Lau interferometer: SiNx diffraction gratings Nuclear emulsion Individual positrons SiNx diffraction gratings This configuration was tested as being able to detect a 6-7 micron period pattern S. Aghion et al., JINST 13 (2018) P05013 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University Positronium (electron-positron) is required to study gravitation. Electron (an elementary fermion) Positron (the antifermion) A particle/antiparticle symmetric system) A pure QED system where spin-orbit and hyperfine effects are of the same order Formation of positronoum beam for interferometry and gravitation: n=2, and Rydberg states (AEgIS and other experiments) Rydberg states and Ps flight 4/10/2019 SME 2018 - Indiana University

Thank you for your attention ! Conclusions Anti-protons: deflectometry done, interferometry to be done Anti-hydrogen: beam still to be formed Positrons: deflectometry/interferometry under study Positronium: incoherent beam made Thank you for your attention ! 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University Backup slides 4/10/2019 SME 2018 - Indiana University

Progress on Antimatter Interferometry Marco G. Giammarchi Istituto Nazionale Fisica Nucleare – Milano Q U P L A S QUantum Interferometry, decoherence and gravitational studies with Positrons and LASers Outline of talk: Basic quantum model of diffraction Fraunhofer and Talbot regimes Incoherence effects Other effects and Decoherence Positrons and Positronium experiments Home of the Experiment: L-NESS Laboratory of the Milano Politecnico in Como 4/10/2019 SME 2018 - Indiana University

The QUPLAS Collaboration Università degli Studi di Milano and Infn Milano S. Castelli, S. Cialdi, M. Giammarchi*, G. Maero, S. Olivares, M. Romè, S. Sala Politecnico Como (Milano) M. Bollani (IFN-CNR), M. Leone, M. Lodari, R. Ferragut Albert Einstein Center – Laboratory for HEP – University of Bern A. Ariga, T. Ariga, A. Ereditato, C. Pistillo, P. Scampoli 4/10/2019 SME 2018 - Indiana University

Introduction to the concept of Quantum Interferometry of Ps The typical structure of a Quantum Mechanical Experiment Preparation : e+ beam Ps beam Target Laser (excitation) First grating Detection : Recording interference pattern Projection on measurement eigenstates Preparation Detection Interaction Propagation Interference Non – ideality : Incoherence Non – ideality : Decoherence 4/10/2019 SME 2018 - Indiana University

The Talbot-Lau Effect (and Talbot «carpets») Incoherence Talbot length The Talbot case G1 revival Generates coherence Interference Pattern at C Incoherence The Fraunhofer case A B C Collimator 4/10/2019 SME 2018 - Indiana University

Talbot carpets 2 1 Fraunhofer regime setting in when L>>LT The characteristic pattern of the Talbot effect can be used to make sure the observed effect is the Talbot effect for the specified wavelength Units Talbot length Fringes visibility for the given wavelength 2 1 Fraunhofer regime setting in when L>>LT «Ballistic» moiré regime 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University Particle Decay γ Positronium states that are useful : ortho-Ps Decay probability in flight : Ps γ γ The 3-gamma decay of ortho-Ps actually removes the particles from the beam It does not «blur» the interference pattern in general So, it is a kind of «attenuation factor» related to a loss of unitarity 4/10/2019 SME 2018 - Indiana University

Positrons and Positronium experiments Basic quantum model of diffraction Fraunhofer and Talbot regimes Incoherence effects Other effects and Decoherence Positrons and Positronium experiments Why experiments with positrons and Ps ? A new type of interferometry Positron is a fundamental lepton It is the antiparticle of the electron Ps is the most fundamental atom The QUPLAS program QUPLAS-0) Positron Interferometry QUPLAS-I) Positronium Interferometry QUPLAS-II) Ps gravity e+,e-,Ps interferometry and gravity Will describe mostly QUPLAS-0 here 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University QUPLAS - 0 Interferometry with positrons Interferometry with electrons (in the same apparatus) Comparison A new CPT test The positron/electron beam : T = 10 keV (typical) The detector : Nuclear Emulsions (~µm resolution) The gratings (~µm thickness): SiNx based substrates Electron Beam Litography S. Aghion et al., JINST 8 (2013) P08013. 4/10/2019 SME 2018 - Indiana University

The facility: the Como continuous positron beam The VPAS Laboratory at the L-Ness Politecnico di Milano at Como Center. (R. Ferragut) Slow positron beam. 1. Radioactive source; 2. Electrostatic optics; 3. Sample chamber; 4. HpGe detectors; 5. Cryostat; 6. High voltage protection cage; 7. Power suppliers; 8. Detector electronics. http://www.como.polimi.it/positron Original intensity of the source: 50 mCi Current intensity: ~ 13 mCi Tungsten moderator  reduces the energy from the beta spectrum down to a few eV Electrostatic transport  positron beam 4/10/2019 SME 2018 - Indiana University

Positron beam energy: from a few keV up to 20 keV Reference value: 10 keV Intensity: ~ 4 x 104 e+/s The de Broglie wavelength One can choose b = c = 33 cm To have a 2 µm periodicity pattern on C Setup preparation Exposure to the e+ beam Integration on the emulsion detector C Given a grating with The Talbot length 4/10/2019 SME 2018 - Indiana University

QUPLAS - I Positronium Quantum Interferometry concept Why? Positron Interferometry Electron Interferometry Positronium Interferometry An elementary fermion The relevant antifermion The bound fermion-antifermion system (also, the simplest atom) Problems to face : Positronium is a neutral atom Positronium has a very short lifetime Detection of the interference pattern is not going to be easy. Ionization required. Excitation on Rydberg state is necessary. Laser excitation required. 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University QUPLAS - II Positronium Gravity : why? Answer : to test the Weak Equivalence Principle (test of General Relativity) Universality of Free Fall Matter Weak Equivalence Principle tested on many different systems Torsion Balance Measurement 10-13 level reached Antimatter g not measured Antihydrogen program at CERN (e. g. The AEgIS experiment) Aiming at 1% accuracy Positronium Matter/Antimatter system ? 4/10/2019 SME 2018 - Indiana University

SME 2018 - Indiana University 4/10/2019 SME 2018 - Indiana University