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Ph. D. Defense

Ph. D. Defense. Committee: Chair: J. H. Edgar Advisor: B. D. DePaola Member: C. L. Cocke Member: C. D. Lin Member: P. M. A. Sherwood Presenter: Hai T. Nguyen. MOTRIMS: Magneto-Optical Trap Recoil Ion Momentum Spectroscopy. Hai Nguyen, Richard Br é dy, Xavier Fl é chard,

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Ph. D. Defense

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  1. Ph. D. Defense • Committee: • Chair: J. H. Edgar • Advisor: B. D. DePaola • Member: C. L. Cocke • Member: C. D. Lin • Member: P. M. A. Sherwood • Presenter: Hai T. Nguyen

  2. MOTRIMS: Magneto-Optical Trap Recoil Ion Momentum Spectroscopy Hai Nguyen, Richard Brédy, Xavier Fléchard, Alina Gearba, How Camp, Takaaki Awata, Johnathan Sabah, Kyle Wilson, and Brett DePaola.

  3. OUTLINE • Reviews of Cold Target Recoil Ion Momentum Spectroscopy • Motivation • Experimental Setup • Results • Conclusion and Outlook

  4. For charge transfer: COLTRIMS: Principles • Cold Target Recoil Ion Momentum Spectroscopy is a technique in which information about the collision is obtained through the measurement of the momentum transferred to the ionized target (atom/molecule). p P’ p q P p p r || p r ┴ r Q: energy defect : Scattering angle (Lab frame) Prll , Pr: parallel and perpendicular recoil momentum components PP , PP’ : projectile momentum before and after the collision Vp: projectile velocity nc: number of transferred electrons

  5. COLTRIMS: Pros & Cons • Pros: • This technique allows kinematically complete experiments. • The good resolution in the measured longitudinal recoil ion momentum allows accurate determination of the inelasticity in the collision and therefore identification of the different collision channels by their different Q-values. • Cons: • Ultimately, in COLTRIMS, the resolution is limited by the temperature of the target (>100 mK) traditionally delivered by a supersonic jet. • Problematic for collisions with excited target.

  6. MOTIVATION • Collisions with excited target (~ 20%). • Resolution is no longer limited by target temperatures (~ 130mK). • Cross-section measurements provide rigorous test for theory.

  7. EXPERIMENTAL SETUP

  8. EXPERIMENTAL RESULTS • Results Obtained: • Energy dependent Cs+ + Rb (5l), l = s and p • Energy dependent Na+ + Rb (5 l), l = s and p • MOTRIMS probes MOT excited state fractions • Systems with energetically degenerate channels (Dual beam method) • Li+ + Rb • K+ + Rb • Rb+ + Rb • Results will be shown for: • 7 keV Na+ + Rb (5l), l = s and p • Na+ + Rb (5l)compare with theory • MOT excited state populations • Rb+ + Rb(5l), l = s and p

  9. 5s-3p 5p-3p 5p-4s 5s-3s RESULTS7 keV Na+ + Rb (5l), l = s and p

  10. RESULTS7 keV Na+ + Rb (5l), l = s and p Laser off

  11. MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

  12. RESULTS7 keV Na+ + Rb (5l), l = s and p

  13. RESULTS7 keV Na+ + Rb (5l), l = s and p

  14. RESULTS7 keV Na+ + Rb (5l), l = s and pCompared to calculation

  15. ENERGY-DEPENDENT RESULTSCompared to calculation

  16. ENERGY-DEPENDENT RESULTSCompared to calculation 5s-3p 5p-3p (keV mrad) (keV mrad)

  17. MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

  18. MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

  19. MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

  20. 3 5p 2 1 0 2 5s 1 MOTRIMS as a probe7 keV Na+ + Rb (5l), l = s and p

  21. Other Collision System: Difficulty

  22. RESULTS7 keV Rb+ + Rb (5l), l = s and p s5s-5p/s5p-5s = 2.95 ± 0.05

  23. RESULTS7 keV Rb+ + Rb (5l), l = s and p

  24. RESULTS7 keV Rb+ + Rb (5l), l = s and p s5s-5p/s5p-5s = 2.95 ± 0.05 DCS for resonant channels are more forwardly peaked 5s-5s Oscillatory Structure 5p-5p No Oscillatory Structure

  25. SUMMARY • ‘Simultaneous’ measurements of excited state fraction and relative cross sections. • Kinematically complete collisions study for alkali ion – trapped atoms including energetically degenerate systems. • MOTRIMS is a powerful tool for ion-atom collisions. • Using MOTRIMS as a probe at MOT dynamics under some perturbation.

  26. THANKS • Committee Members • MOTRIMS Group • JRML Support Staff: • Kevin Carnes, Scott Chainey, Charles Fehrenbach, Bob Geering, Bob Krause, Vince Needham, Al Rankin, Carol Regehr, and Mike Wells.

  27. Questions & Answers • Cooling and Trapping • Optics Layouts • Experimental Setup • Analysis • Excited State Formula? • Others Systems

  28. DAVLL Sat abs O I /2 REPUMP Com AOM 80MHz Blocker F=40cm TRAPPING OPTICS F=40cm /2 O I TRAP Sat abs DAVLL Q&A SIMPLE OPTICS LAYOUT

  29. Q&A SIMPLE OPTICS LAYOUT l /2 PBS l /4 Mirror Mirror From AOM l /4 l /2 l /4 Mirror PBS l /4 TRAPPING OPTICS l /4 Mirror Mirror l /4 Mirror

  30. Mass a.u. 2 keV s 5 keV s 7 keV s 6 8.268E-5 8.548E-5 8.623E-5 23 7.538E-5 8.086E-5 8.232E-5 39 7.087E-5 7.801E-5 7.991E-5 85 6.162E-5 7.216E-5 7.497E-5 133 5.442E-5 6.761E-5 7.112E-5 -- Q&A Projected TOF

  31. Independent of excited state measurements: Q&A RESULTS7 keV Na+ + Rb (5s, 5p)

  32. 3 5p 2 1 0 2 5s 1 Q&A Cooling and Trapping B + - Rb VZ z Optical frequency m = +1 m = 0 j=1  m = -1 + - LASER m = +1 m = -1 z j= 0

  33. Q&A RESULTS7 keV Li+ + Rb (5l), l = s and p

  34. Q&A RESULTS7 keV Li+ + Rb (5l), l = s and p

  35. Q&A Multi-Projectile Source

  36. Q&A Probe: 7 keV Na+ + Rb (5l) Known

  37. Q&A 7 keV Li+ + Rb (5l) Known Results

  38. Q&A Cross Sections 7 keV Li+ + Rb Waiting for TC-AOCC results

  39. Q&A 7 keV Li+ + Rb Scattering Angle Information

  40. Q&A 7 keV Li+ + Rb Scattering Angle Information • Grouped scattering angle information are hard to extrapolate (Rb + Rb). • Theoretical Comparison not trustworthy. • Using a weighted method to deduce individual channel scattering angle information.

  41. Q&A 7 keV Li+ + Rb Scattering Angle Information Laser on Laser off

  42. Q&A 7 keV Li+ + Rb Scattering Angle Information

  43. Q&A RESULTS6 keV Cs+ + Rb (5l), l = s and p

  44. Q&A RESULTS6 keV Cs+ + Rb (5l), l = s and p

  45. Q&A SINGLE CAPTURE IN 6 keV Cs+ + Rb (5l), l = s and p • Recoil ion PSD image

  46. Q&A RESULTSEnergy dependent Cs+ + Rb (5l), l = s and p

  47. Q&A Excited State Fraction Formula?

  48. Specific Example: 87Rb MF Levels! MF Levels! F=3 -3 -2 -1 0 +1 +2 +3 15 10 6 3 1 52P3/2 F=2 F=1 5 8 9 8 5 F=0 Trapping Laser F=2 52S1/2 -2 -1 0 +1 +2 F=1 So, What’s the Problem!? Q&A So, What’s the Problem!?

  49. Here’s the problem! Here’s the problem! So, What’s the Problem!? Q&A So, What’s the Problem!? Beam Symmetry? I2 = 0.45 mW / cm2 B-Field Gradient? I1 = 0.50 mW / cm2

  50. Preliminary Results Q&A Preliminary Results

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