Graham Lochead YAO 2009 Towards a strontium pyramid MOT Graham Lochead Durham University

Graham Lochead YAO 2009 Colleagues Strontium Rydberg experiment Matt Jones Supervisor James Millen PhD student

Graham Lochead YAO 2009 Outline Overview of strontium –Structure and uses Our experiment –Aims and achievements Pyramid MOT –What is a pyramid MOT? –Why is it beneficial? –Our design Progress so far Summary

Graham Lochead YAO 2009 Overview of strontium Alkaline-earth element Atomic number 38 Two electrons in outer shell Four stable isotopes: 84 Sr 0.6% I=0 boson 86 Sr 9.9% I=0 boson 87 Sr 7% I=9/2 fermion 88 Sr 82.5% I=0 boson

Graham Lochead YAO 2009 Overview of strontium: Electronic structure 1S01S0 1P11P1 1D21D2 461 nm  /2  = 32 MHz 3P3P nm  /2  = 7.5 kHz 412 nm 698nm  /2  = 1 mHz 87 Sr 1 S 0 ground state – no x optical pumping Low decay rate to xxmeta-stable state 3 P 2 Broad linewidth for 1 S P 1 transition Intercombination line x for further cooling

Graham Lochead YAO 2009 Cold atomic uses for strontuim Ultracold atomic plasmas Optical lattice clocks From Killian et al., physics/

Graham Lochead YAO 2009 Durham strontium experiment Ultracold Rydberg state strontium atoms in an optical lattice

Graham Lochead YAO 2009 Aims of our experiment Two stage cooling to make ultracold Optical lattice from two counter-propagating beams from same laser (532nm) Excite to a Rydberg state Observe following dynamics Aims

Graham Lochead YAO 2009 Experimental setup

Graham Lochead YAO 2009 Achievements Single stage cooling to a MOT at 461nm Labview computer control setup MCP tested

Graham Lochead YAO 2009 How does the pyramid MOT fit in?

Graham Lochead YAO 2009 What is a pyramid MOT? Normal (6 beam) MOTPyramid MOT Three pairs of counter- propagating beams Single beam with four mirror creating the same optical geometry K. J. Weatherill PhD thesis (2007)

Graham Lochead YAO 2009 Pyramid MOT function Used as cold atomic source

Graham Lochead YAO 2009 Benefits of a pyramid MOT Size – much smaller than a Zeeman slower Simpler to build than complex magnetic field in ZS Simpler optical alignment than 2D mot or funnel No thermal atoms disrupting experiment

Graham Lochead YAO 2009 Our pyramid MOT design First strontium pyramid MOT Based on dispensers Novel design

Graham Lochead YAO 2009 The novelty in our design Source of hot atoms above mirrors to load MOT Hot strontium reacts with glass – coating mirrors Problem Solution Dispensers below mirrors Slits where mirrors meet in corners

Graham Lochead YAO 2009 Novel design

Graham Lochead YAO 2009 Progress so far Everything designed and ordered Waiting for chamber and mount

Graham Lochead YAO 2009 Dispenser cell Dispensers used before to create a non- pumped, buffer gasless reference cell E. M. Bridge, et al. Rev. Sci. Instrum. 80, (2009)

Graham Lochead YAO 2009 Second generation dispenser cell New cell becomes optically thick Saturated absorption spectroscopy in new cell

Graham Lochead YAO 2009 Summary 1S01S0 1P11P1 1D21D2 3P3P