1. 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 Indiana University

2. 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 Indiana University

3. 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 Indiana University

4. 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 Indiana University

5. 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 Indiana University

6. 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 Indiana University

7. 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 Indiana University

8. 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: /ncomms5538
4/10/2019
SME Indiana University

9. 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 Indiana University

10. 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) <
Rejected at a high confidence level
C. Amole et al. (ALPHA collaboration)
Nature Comm., doi: /ncomms2787
4/10/2019
SME Indiana University

11. 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 Indiana University

12. 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

13. 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,
S. Sala et al., Phys. Rev. A 94, 2016,
Asymmetric Talbot-Lau configuration : fringe magnification
4/10/2019
SME Indiana University

14. «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 Indiana University

15. 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 Indiana University

16. 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 Indiana University

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

18. 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 Indiana University

19. 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 Indiana University

20. 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 Indiana University

21. 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 Indiana University

22. 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 Indiana University

23. 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 Indiana University

24. 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 Indiana University

25. 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 Indiana University

26. 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.
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 Indiana University

27. 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 Indiana University

28. 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 Indiana University

29. 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 Indiana University

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