1. Monochromatic ion and electron beams by ionization of cold atoms Daniel Comparat Laboratoire Aimé Cotton, CNRS, UPR3321, Bât. 505, Univ Paris-Sud, Orsay, 91405 FRANCE

2. Experiments in the « Cold atoms and molecules group » Cesium Magneto-Optical Trap (P. Pillet, H. Lignier, D. Comparat) -Cold cesium molecules (formation, vibrational cooling, trapping,..) Cs,Ytterbium MOT: (D. Comparat, P. Cheinet, P.Pillet) Cold Rydberg atoms (dipole blockade, plasma ….) Stark & Zeeman (mol.) decelerators (P. Pillet, J. Robert) CERN : antigravity, antihydrogen, Ps spectroscopy: (L. Cabaret, D. Comparat) Production of ion and electron sources from cold atoms (P. Pillet, D. Comparat) - +

3. Outline  Electron and ion sources  Laser cooled sources  Ion beam project  Electron beam project  Outlook

4. Outline  Electron and ion sources  Laser cooled sources  Ion beam project  Electron beam project  Outlook

5. Ion (focused) source applications Sputtering Array of holes Microlens FIB pattern FIB image of a Al sample Test surface with various sizes tin (Sn) balls Ion and Electron Beam induced deposition Secondary particles: M 0,M +,M -,… 10/02/11 Imaging Deposition

6. Electron source applications Particle accelerator, Televisions, … Electron spectrometers: EELS (Electron Energy Loss Spectroscopy) Imaging + Scanning microscope Electron irradiation: Mass spectrometry, Sterilization, Desorption Linking or breaking polymers http://ehs.virginia.edu/ehs/ehs.rs/rs.images/sem.coutesy.iowa.state.jpg

7. Ion source 7nm Limitations: few element possible Ga, In, Cs, Bi, Au, Si, + Alloys… Gallium pollution Wide energy-spread ∆E=5eV A single wide-spread technology (LMIS) Liquid Metal Ion Source Electron sources Limitations: Wide energy-spread ∆E=0.3eV Monochromators limits flux and brightness Complex Optics (chromatism) to focus Several wide-spread technologies Thermionic (LaB 6 ) Photocathode Cold emission Plasma

8. Current (pA –  A) Emittance (normalized)  x,y : phase space Brightness (A m -2 sr -2 eV -1 ) amount current in a spot, invariant along the beam path no interactions, aberrations Energy spread  E: it limits the energy resolution and the focusing properties Important source parameters Angle x’= v x /v z z Position x 

9. Important source parameters TypeLMISGas Field Ion. Source PlasmaTrap (Penning) I max (nA)10000.01100000.01 B (A m -2 sr -1.eV -1 ) 10 5 -10 6 10 9 10 3 10 5 From: J. Vac. Sci. Technol. A 23 1498 (2005) + Handbook of Charged Particle Optics (2008) U=10 keV, I=1 nA  spot size ~ 0.1 µm U=1 eV, I=10 µA  spot size ~100 µm Gun :TungstenLaB 6 SchottkyCFEG Brightness (A.m -2 sr -1 eV -1 )10 4 10 5 10 7 10 8 Cathode energy spread (eV)10.50.4 0.3 ∆E=5eV

10. Outline  Electron and ion sources  Laser cooled sources  Ion beam project  Electron beam project  Outlook

11. Point source / colimated source Want small A, small  I ~ 1 nA A ~ 100 nm 2 E ~ 1-10 5 eV  E ~1eV Needs: Mono-Energy (∆E < 0.1 eV) spectroscopy-chemistry-focus Brightness B r = I/(A  E) : amount of current in a spot New: Small area A Coulomb explosion Large  eV Ions + Electrons - Conventional sources Large area A ~ 1 mm 2 No Coulomb explosion Small  meV -+ LARGE SOURCE

12. G. Freinkman, A. V. Eletskii, and S. I. Zaitsev, Microelectron. Eng. 73, 139 (2004). Ionization of COLD ATOMS ! A A+A+ Laser k B T e 1 K ~ 0.1 meV OTHER ADVANTAGES: Low energy E for less damage Less aberrations (cheaper electrostactic optics)

13. Ultracold plasma evolution Ultracold plasma production 0 ns 1 ns 100 ns 1 µs 5 µs heating of electrons heating of ions expansion T ions ~ 1 K T e - ~ 50 K 1 K ~ 0.1 meV Partial Rydberg recombination Physics Reports 449 (2007) 77 – 130 A A+A+ Laser k B T e In principle 1 K ~ 0.1 meV not ultracold!

14. Temperature [K] 10 3 10 34 10 28 10 4 10 3 Density [m] -3 10 2 10 5 10 4 10 9 10 6 10 7 10 8 Nebulises Solar Corona FlamesAuroras ITER 10 1 Inside Sun 10 10 22 Neutral plasmas ultra - cold Correlated Plasmas Γ≥1 plasma screen Interstellar Space Magnetosphere Kinetic Plasmas Γ= E pot /E cin <1 confined: magnetic, inertial, gravitationnal L aser M éga J oule Ultra-cold plasma - - + - Rydberg atom Neon Laser Brown dwarfs Trapped Ions “dusty” Disordered induced heating Three body recombinaison T ions ~ 1 KT e - ~ 50 K

15. Proposal for ultracold electron sources from MOT Pulsed extraction 1MV/cm in 1ns B > 10 9 A.rad -2 m -2 V -1 Claessens BJ, van der Geer SB, Taban G, Vredenbregt EJ, Luiten OJ. PRL 95, 164801 (2005)  e - diffraction, FEL or accelerator input Rb MOTValues Density 10 18 m -3 Volume 1 mm 3 Temperature1 mK Atom Number10 9 (/s)

16. Several Elements (alkali, rare gaz, …) B > 10 6 A.rad -2 m -2 V -1 I ~ 1 nA Focused <10nm at 1keV cf. FIB 30keV

17. Emittance at quantum limit: Cs 0.1nm sub-ps resolution For 100eV beam µeV dispersion B ~ 10 15 A.rad -2 m -2 V -1 I ~ 0.5 pA Cs + e-e- n~800 E~0.1V/cm R = n 2 a 0 ~ 1µm Rydberg + ionization using chirped ns pulse

18. MCP  size of beam Recent realizations Eindhoven (E. Vredenbregt) Rb MOT: electron pulse PRL 105, 034802 (2010)

19. NIST (J. McClelland) Cr ion Li ion 2011 New J. Phys. 13 103035

20. Melbourne (R. Scholten) Nature Physics 7 785 (2011).

21.  U 10 K) Beam Energy as low as 1 eV E acc All internal (average space charge) potential has been converted into kinetic energy 1nA differential voltage problem: ~30µm Example on low energy dispersion

22. Limitations Low flux well bellow 1nA MOT ~ 10 7 -10 9 atoms/s  I < 1nA Better to use atomic beams 2D-MOT ~ 10 9 -10 11  I < 10nA atomic beams ~ up to 10 14  I < 1µA Pulsed behaviour ( advantage to play with time dependent fields ) Directly ionize atoms (need lots of laser power  pulsed laser) UltraCold Plasma formation NIST PRL 83, 4776 (1999) Better to use Rydberg atoms Our PRL 85 4466 (2000) Needs typically 10 000 lower laser power  CW laser possible Possibility to solve the differential voltage problem ?

23. Outline  Electron and ion sources  Laser cooled sources  Ion beam project  Electron beam project  Outlook

24. Ion source: Coldjet V0V0 V0V0 0 1 Recirculating oven Beam Creation 2 Optical Molasses: Beam Collimation 3 2D-Mot: Beam Compression 4 Laser excitation to Rydberg state 5 Field Ionization Extraction 6 To FIB ionic optics 1234-5 Longitudinale speed(m/s)300 Divergence (mrad)270.3 Flux (at/s)10 13 10 12 Diameter (mm)180.2-1

25. 80°C ≤ 250°C Silica wick Copper Crucible Stainless Steel Candelstick 1 mm Adjustable diameter (2 mm) Pailloux, Review of Scientific Instruments, Volume 78, Issue 2, pp. 023102-023102-6 (2007). 1) Recirculating oven. Beam Creation

26. 2-3 Beam Collimation + compression 4 m long!! 1 cm

27. 2-3 Beam Collimation + compression Compression is not standard for a beam with speed v>100 m.s -1 1995: Pierre Pillet (Cs) transversal compression for v z < 150 m.s -1 3 cm interaction zone 100 mW laser power Fluorescence of a cesium atomic beam compressed (a) without optical pumping and (b) with optical pumping

28. Stress and different thermal coefficients New system with Viton ring Screen and crucible Water cooling Screen Coldjet chamber 10 cm long compression zone 500 mW laser power  we hope to collimate and compress all velocity v < 200 m/s

29. NEW IDEA: Sisyphus cooling Cool with only 100 photon absorption  LASER COOLING FOR MOLECULES Blue detuned: dressed state

30. 4. Ionization: excitation to Rydberg state Previous experiments: Near threshold laser ionization Our experiment: Field ionization of Rydberg atoms Current 1 nA  E > 1kV/cm (waist >10µm)   V = E*waist > 1 Volt TOO HIGH!!! Rydberg atoms field ionized at a given electric field E = 1 /16n 4 Ionization at a given position  No differential voltage problem Better excitation efficiency (  exc /  ion = 10 4 for n=30) Choice of the extraction field (n-dependent) with reduction of space charge effects n~30

31. Ionization or Rydberg studies in cold atomic sample (Cs MOT) 6s 1/2 6p 3/2 7s 1/2 np 3/2 MOT lasers @852nm Laser diode @1470nm CW Ti:Sa laser @750-830nm Ions or Rydberg atoms Trapping Lasers MCPs Laser Diode Ti:Sa Laser Ions np 0,20,40,60,81,01,21,41,6 Time (µs) For 300ns TiSa creating np states + field ionization Cs + e-e- R = n 2 a 0 ~ 1µm

32. Study in electric field: C 3 /R 3 M. Mudrich et al. PRL 95 233002 (2005) Control of ion kinetic energy (Ice-Rydberg ) ? Controled ionization: novel ultracold plasma production Study in zero electric field: C 6 /R 6 M. Viteau et al. PRA 78 040704 (2008) Collisions Rydberg/Rydberg Penning Ionization Formation of an ultra-cold plasma 45 44 43 Collisions Rydberg/atomes Black body ? 39 40 41 n=39,40,41 np ns (n+1)s ss’ pp E R  n=43,44,45 ns (n+1)s np N. Vanhaecke et al. PRA 71 013416 (2005) T. Pohl et al. EPJD 40 45 (2006)

33. 18.5 kV -21.4 kV Exctraction electrodes Field ionization area Rydberg excitation lasers Atomic Beam 5. Field Ionization. Electrodes design Rydberg excitation in flat electric field  No energy shift Extraction to avoid aberrations

34. 6 To FIB ionic optics Evaluation of the performances diameter, dispersion angle, energy spread, minimum spot size Optimizing Cc and Cs Secondary Ion Mass Spectroscopy (chemical analysis) Smaller probe better lateral resolution Low energy extraction (~100 eV) Better depth resolution

35. Expected performancies He-tip Cold atom source Focused Ion Beam FIB @ 30keV Plasma Spot Diameter (nm) 0.1 1 10 100 1000 10 -4 0.01 1 100 Beam Current (nA)

36. Outline  Physical ideas and goals of the project  Experience at LAC: cold atoms, cold Rydberg and cold plasma  Ion beam project  Electron beam project  Outlook

37. The electron source Laser setup + Control electronics 2D-MOT + Electron optics Host experiment UHV - 2D cesium MOT - Flux ~ 10 10 - 10 11 atoms/s => up to 10nA current - Flexible setup, to be connected to existing experiments - Electron Energy Loss Spectroscopy + Microscope (LPS, A. Gloter) - Controlled breaking of molecular bonds (ISMO, A. Lafosse) Optical fibers

38. The electron source: 2D MOT

39. Theoretical study: focusing 8 eV Beam   E < 10 meV Focused on ~ (10 nm) 2 equivalent to 10 5 µA on (1mm) 2 >10 3 times that of a standard gun 10pA e - current General Particle Tracer ®

40. High current: Limitation due to charge effects 1µm 10 cm Equally spaced Gaussian random Uniform random 2 cm Ex: I > 1 nA   E> 10meV Stochastic space charge effect B 10 3 10 4 10 5

41. … Distance R R min  laser … B A Blockade sphere radius:    laser ~V dip-dip    R min 3 A B How to create ordered particles: Dipole blockade Dipole (n 2 )-Dipole(n 2 ) interaction dipole-dipole shift Rydberg Lukin et al. PRL 87 037901 (2001) Nearby atoms are not excited Journal of the Optical Society of America B 27, A208 (2010)

42. No excitation of two atoms at R = 3.6  m Probability to excite 2 atoms at the same time Nature Physics 5, 115 (2009). Does not work at 18 µm distance Probability to excite 1 atoms R 0 11 0 Sin  AB

43. Electric field: control (blockade) of Rydberg excitation 7s 300ns Ti:Sa V dd    R 3    laser n Ryd  laser /   Vogt et al. PRL 99 073002 (2007) Permanent dipole e-e- Cs + F e-e- µ µ R Journal of the Optical Society of America B 27, A208 (2010)

44. Expected performances Gun :TungstenLaB 6 SchottkyCFEG 2-D MOT Source Brightness (A.m -2 sr -1 eV -1 )10 4 10 5 10 7 10 8 > 10 8 Cathode energy spread (eV)10.50.40.3< 0.01 T electrons (MOT / beam) < 10K10 K ~ 1 meV T electrons (Tungsten) ~ 2000 K limited space charge effects:  E ~ 16 meV/nA demonstrated with photoionization of effusive atomic beams (H. Hotop) Review of Scientific Instruments, 72, 4098, (2001).

45. Laser cooling = collimation Rydberg = excitation + Field ionization Improve focus limit (10µm)x(∆E/E) Huge domain of applications and improvement for: Spectrometers, irradiation, induced chemistry Imaging Sputtering, deposition CONCLUSION: High flux of (ordered) ions/electrons By field Rydberg ionization of cold atoms or molecules Futur:Industrial product? Implantation of N atoms from Cooling of CN molecules 2016 2011

46. The Team The LAC team: Guyve Khalili, Yoann Bruneau, Joshua Gurian, Andréa Fioretti, Pierre Pillet, Daniel Comparat The Orsay Physics Team: Leïla Kime, Bernard Rasser and Pierre Sudraud + the collaboration with the University of Pisa Nicolo’ Porfido, Francesco Fuso, Andréa Fioretti Other collaborations: A. Gloter, C. Colliex (LPS, Orsay) A. Lafosse (ISMO, Orsay) COLDBEAMS conference: Nîmes, France, Oct 1-3 Marie Curie Industry-Academia Partnerships and Pathways: FP7-PEOPLE-2009-IAPP European Reseach Council: ERC-StG- COLDNANO