1. A Stark decelerator for ammonia molecules Ruth Buning Master research project February 23, 2007

2. Outline Why decelerate? Why decelerate? Why ammonia? Why ammonia? Neutral polar molecules in E fields Neutral polar molecules in E fields The machine The machine Slow ammonia Slow ammonia

3. Why decelerate? Transit-time broadening Transit-time broadening

4. Even higher resolution.. Fountain, clock Fountain, clock

5. Ammonia, NH 3 Proton-electron mass ratio 

6. Fountain

7. Goals in this work Build a Stark decelerator Build a Stark decelerator Characterize it Characterize it Decelerate NH 3 to a few m/s Decelerate NH 3 to a few m/s How can we produce and detect as much slow NH 3 as possible? How can we produce and detect as much slow NH 3 as possible?

8. Dipole in E field Stark shift:

9. Stark shift in ammonia Low-field seekers High-field seekers

10. Dipole in E field (2)

11. Deceleration

12. Setup

14. Molecular beam Supersonic expansion Supersonic expansion Few % NH 3 in Xe Few % NH 3 in Xe Valve cooling Valve cooling

15. The decelerator

16. Time to switch

18. Detection 2+1 REMPI 2+1 REMPI Density in detection region Density in detection region

19. Measurements Wavelength scan Wavelength scan TOF (time of flight) scan TOF (time of flight) scan

20. Spectrum

21. TOF profile

24. Optimization Beam quality Beam quality Ammonia percentage Ammonia percentage Temperature Temperature Backing pressure Backing pressure Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

25. Optimization Beam quality Beam quality Ammonia percentage5 % Ammonia percentage5 % Temperature Temperature Backing pressure Backing pressure Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

26. Optimization Beam quality Beam quality Ammonia percentage5 % Ammonia percentage5 % Temperature-50 o C Temperature-50 o C Backing pressure Backing pressure Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

27. Optimization Beam quality Beam quality Ammonia percentage5 % Ammonia percentage5 % Temperature-50 o C Temperature-50 o C Backing pressure Backing pressure Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

28. Backing pressure

29. Clusters

30. Optimization Beam quality Beam quality Ammonia percentage5 % Ammonia percentage5 % Temperature-50 o C Temperature-50 o C Backing pressure0.5 bar Backing pressure0.5 bar Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

31. Valve opening

32. Optimization Beam quality Beam quality Ammonia percentage5 % Ammonia percentage5 % Temperature-50 o C Temperature-50 o C Backing pressure0.5 bar Backing pressure0.5 bar Valve opening Valve opening Detection efficiency Detection efficiency Laser power Laser power Laser focus Laser focus

33. Laser power

34. Slow ammonia (1)

35. Slow ammonia (2)

38. Slow ammonia (3)

42. Slow ammonia (4)

43. Conclusions Stark decelerator operational Stark decelerator operational Down to 25 m/s Down to 25 m/s Adaptations Adaptations Differential pumping Differential pumping Focusing Focusing -> Molecular fountain -> Molecular fountain