1. Studying our cold Rydberg gas James Millen

2. Level scheme (5s 2 ) 1 S 0 461nm 32MHz (5s5p) 1 P 1 (5sns) 1 S 0 (5snd) 1 D 2 Continuum ~413nm Studying our cold Rydberg gas – group meeting 17-08-09

3. Experimental sequence (see last group meeting) Studying our cold Rydberg gas – group meeting 17-08-09 Strontium loaded into MOT from Zeeman slowed beam MOT beams provide first excitation photon Laser at 412nm provides second photon, always on Electric field plates direct charge onto MCP Average heavily on oscilloscope Timing and read-out via LabView

4. Studying our cold Rydberg gas – group meeting 17-08-09 Spectrum

5. Line analysis Can use quantum defect analysis to try and identify series δ = n – n*n* = √(R sr /T n ) T n = E ion - E 1 S 0 δ=3.27 1 D 2 δ=2.38 Studying our cold Rydberg gas – group meeting 17-08-09

6. Acquisition Studying our cold Rydberg gas – group meeting 17-08-09

7. High resolution Studying our cold Rydberg gas – group meeting 17-08-09 These spectra were taken using laser scan, requires >100 averages… Can instead step the laser in frequency, and read out every time, limited by wavemeter accuracy.

8. Stark effect Studying our cold Rydberg gas – group meeting 17-08-09 Our field plates can create a uniform electric field

9. Mysteries/Problems (I) Studying our cold Rydberg gas – group meeting 17-08-09 Our ion signal is tied to the number of atoms in our MOT:

10. Mysteries/Problems (I) Studying our cold Rydberg gas – group meeting 17-08-09 The ions hang around for a very long time…

11. Mysteries/Problems (II) Studying our cold Rydberg gas – group meeting 17-08-09 How many Rydberg atoms are we creating?

12. Mysteries/Problems (III) Studying our cold Rydberg gas – group meeting 17-08-09 How are we making ions‽ We make up to ~4 Vcm -1 @ n = 85 the field for ionisation is ~ 6Vcm -1 @ n = 50 the field for ionisation is ~ 50Vcm -1 Collisions? Black body ionisation? Need to avoid building up charge

13. “Stark shuttering” Studying our cold Rydberg gas – group meeting 17-08-09

14. www.stemnet.org.uk www.direct.gov.uk/sciencesowhat