OVERVIEW OF RECENT WORK ON LASER EXCITATION OF POSITRONIUM FOR THE FORMATION OF ANTIHYDROGEN

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1 OVERVIEW OF RECENT WORK ON LASER EXCITATION OF POSITRONIUM FOR THE FORMATION OF ANTIHYDROGEN Anti-Apple g? g? Pauline Yzombard (1), on behalf of the AEgIS (2) collaboration (1) Laboratoire Aimé Cotton, Bâtiment 505, Orsay, France (2) AD-6: AEgIS, C.E.R.N. Route de Meyrin 385, 1217 Meyrin, Switzerland Earth

2 OUTLINE I. AEgIS experiment II. Positron and laser systems III. Recent works Ps(n=3) laser excitation Ps Rydberg IV. Future works: toward a colder H beam 2 MARCH 9 - LEAP PAULINE YZOMBARD

3 I. AE gis COLLABORATION Stefan Meyer Institute University of Genova University of Milano University of Padova University of Pavia CERN Institute of Nuclear Research of the Russian Academy of Science Max-Planck Institute Heidelbert Politecnico di Milano University College London Czech Technical University University of Bergen University of Bern University of Brescia Heidelberg University ETH Zurich University of Lyon 1 University of Oslo University of Paris Sud University of Trento INFN sections of: Genova, Milano, Padova, Pavia, Trento

4 I. AEGIS ANTIMATTER EXPERIMENT: GRAVITY, INTERFEROMETRY, SPECTROSCOPY Main goal: Measurement of g with 1% precision on antihydrogen. Challenges: - Production of a bunched cold beam of antihydrogen - Measurement of vertical beam deflection (10 μm drop over 1 m) via moiré deflectometer. p trap moiré deflectometer g? Anti- Apple Aghion, S. and al. Nat. Commun vol (2014) Earth e+ Ps convertor Cf. Talk of Daniel Krasnicky Overview of latest results from AEgIS 4 MARCH 9 - LEAP PAULINE YZOMBARD

5 I. AEGIS - PRINCIPLE Anti-hydrogen formation via Charge exchange process with Ps* Principle demonstrated by ATRAP collaboration Ps* produced via Cs* collisions on positrons trapped plasma C. H. Storry et al., Phys. Rev. Lett. 93 (2004) ] 93 (2004) Interests: Pulsed H production (time of flight Stark acceleration) Narrow and well-defined H n-state distribution Colder production than via mixing process expected MARCH 9 - LEAP PAULINE YZOMBARD Rydberg Ps* Long lifetime + large cross section σ a 0 n 4 5 H formation enhanced

6 II. POSITRON AND LASER SYSTEMS - POSITRON SYSTEM Positron system Efficient transfer of positrons into the main traps - cf Talk of Daniel Krasnicky Overview of latest results from AEgIS Studying positrons and Positronium physics in a dedicated test chamber AEgIS zone 6 MARCH 9 - LEAP PAULINE YZOMBARD

7 II. POSITRON AND LASER SYSTEMS - POSITRONIUM FORMATION Sketch of the e + system - parameters given for 2015 PbWO e+ / 0.15s 22 Na 11mCi e+ / 3min 3.3keV e+ bunch implanted SEM image: Silica-based nano- porous target Mariazzi S et al., Phys. Rev. B 2010, 81,

8 II. POSITRON AND LASER SYSTEMS - POSITRONIUM FORMATION Ps formation sketch 3.3keV Production of Ps in the test chamber τ = 142ns SSPALS (single shot positron annihilation lifetime spectroscopy) ( * ) measurements Average of 10 single shots. S. Aghion et al. Nucl. Instru. Meth. in Phy. Res Sect. B 362:86 92, (*)Cassidy D B et al., NIMB 2007, 580,

9 II. POSITRON AND LASER SYSTEMS - LASER SYSTEM Ps Internal energy n Rydberg n=3 n=2 n=1 continuum ~1700 nm In front of the test chamber: Energy 1.3mJ, pulse 4ns, waist 10mm 205 nm In front of the test chamber: Energy 60µJ, pulse 2ns, waists 6mmx8mm A dedicated laser system: conceived to be broadband σ ~ 110GHz - to cover Doppler broadening and magnetic mixing (Zeeman effect, at 1 T) inside the main trap 9 MARCH 9 - LEAP PAULINE YZOMBARD

10 1064 nm III. RECENT WORKS- POSITRONIUM = 3 LASER EXCITATION n Ps Internal energy continuum Test chamber n=3 excitation + photoionization Aghion S et al., PRA, submitted Feb.2016 n=3 n=2 photoionization Si0 2 nanoporous target Gamma detector o-ps cloud e+ preliminary 205 nm n=1 MARCH 9 - LEAP PAULINE YZOMBARD EM conditions: B = 250 Gauss E = V/cm (Area laser OFF Area laser ON) S(%)= Area laser OFF 10

11 III. RECENT WORKS- POSTRONIUM = 3 LASER EXCITATION n - e+ implantation energy 3.3keV - Target at room temperature - excitation-ionization S(%) laser at resonnace 15.5% Scan of the n=3 transition preliminary -3P excitation line centered at ±0.02 nm Predicted: nm - From this measurement: We extrapolate an average temperature of the excited o-ps : T ~1300K ± 200 K (Doppler broadening) 11 MARCH 9 - LEAP PAULINE YZOMBARD Aghion S et al., PRA, submitted Feb.2016

12 III. RECENT WORKS- POSITRONIUM RYDBERG EXCITATION (VIA =3 STATE) n Ps Internal energy continuum Rydberg excitation (n=1 n=3 n = 15 transition) Scan of the Rydberg transitions n Rydberg n= nm nm preliminary n=17 n=16 n=15 n=2 205 nm preliminary n=1 12 MARCH 9 - LEAP PAULINE YZOMBARD Aghion S et al., PRA, submitted Feb.2016

13 IV. FUTURE WORK TOWARD COLDER H - Sympathetic Cooling of p with laser cooled anions Atomic anions studied: Os -, La - An alternative project: laser cooling of molecular anions, as C 2 - P. Yzombard et al. Phys. Rev. Lett. 114, MARCH 9 - LEAP PAULINE YZOMBARD

14 IV. FUTURE WORK - TOWARD A POSITRONIUM LASER COOLING? - Focusing Ps beam via Doppler cooling Improving the H formation = having a better solid angle Laser focusing MARCH 9 - LEAP PAULINE YZOMBARD 14

15 IV. FUTURE WORK - TOWARD A POSITRONIUM LASER COOLING? - Focusing Ps beam via Doppler cooling Ps Internal energy n=3 n=2 n=1 continuum 2P 243 nm 1S Challenge: short Ps lifetime (~142ns) Interest: lightest atom (µ =2 m e ) implies a huge recoil energy for each scattered photon (~1500m/s or 0.3 K) Laser development: a long pulse 243nm has to be implemented (pulse ~30ns to 200ns) MARCH 9 - LEAP PAULINE YZOMBARD 15

16 IV. FUTURE WORK - TOWARD A POSITRONIUM LASER COOLING? -1D Doppler cooling? Ps Internal energy n=3 continuum Probing time Probing time Simulations: Ps 1D velocities distributions, probed for different timing during laser cooling B = 0 T. n=2 2P Probing time n=1 1S 243 nm Simulation parameters Legend: Velocities range excited by laser Probing time Ps velocities distributions (m/s) 1D P L w L Γ L δ L T 3D (Ps cloud) 5000W 7mm 50GHz 2.5cm K MARCH 9 - LEAP PAULINE YZOMBARD 16

17 CONCLUSION AND OUTLOOK Recent works in Ps physics: First measurements of n=3 Ps laser excitation Proof of Rydberg excitation with our dedicated laser system major step to form H via charge exchange process Future developments for laser works: getting a colder p plasma (sympathetic cooling via cold anions) or/and focusing Ps beam (Doppler cooling) MARCH 9 - LEAP PAULINE YZOMBARD 17

18 THANK YOU FOR YOUR ATTENTION MARCH 9 - LEAP PAULINE YZOMBARD 18

19 APPENDIX Simulation code Anions laser cooling MARCH 9 - LEAP PAULINE YZOMBARD 19

20 Algorithm - simulations Absorption-emission processes calculated using rate equations -> taking account : Laser detuning d, linewidth G laser, saturation and Doppler effects. L e e G e G f f d W Rabi L f G= 1/lifetime = natural linewidth G laser (FWMH) Total linewidth G tot = G+ G laser +G f +G e Einstein Rate equations r (h/2p)w Rabi =-<e q e r f>e laser I = e 0 c E laser2 /2=2 Power/(p waist 2 ) PHYSICAL REVIEW A 69, (2004) Rate Absorption

21 Algorithm - simulations -All levels and transitions needed (n=1->n=2) -gravity, magnetic field and recoil photons -Dipole moment aligned on local field local laser polarization. => Kinetic Monte Carlo + Verlet Internal state (population) KMC Solve exactly the rate equations. Better than standard (Metropolis) Monte Carlo P(t+dt)~P(t)+G dt External state (position) Verlet Verlet algorithm to drive the particles motion

22 Anions cooling? 22 Cooling Os -? Cooling La -? => Heidelberg, Ger. A. Kellerbauer C 2 - Cooling C 2 -?

23 electrons Studied Molecules: Candidate?

24 C 2 - Sisyphus cooling 24 Cooling C 2- - several simulations in Penning traps. P. Yzombard et al. Phys. Rev. Lett. 114, Penning-like trap configuration