Progress

Analyzed cracking behaviour of Argon solid. Cracks are reproducible and arise due to the contraction of Argon as substrate cools. Shards of with surface area of 1 mm² can maintain transparency over multiple days.

Installed CCD camera to observe transparency across entire substrate during and after growth. Transparency across whole cyrogenic Argon solid is maintained at 95% across multiple days.

Designed an Einzel lens system used to focus the ions transported by the ion guide onto the cryogenic argon crystal. The middle element of the lens allows either for the transmission of the ions or the deflection of the ions onto a Faraday cup for counting.

Began experiments to analyze Ar purification techniques in a dedicated vacuum chamber. Our goal is to obtain impurity levels lower than 1 part in 10¹².

Detected fluorescence spectrum (averaged over 18 hours) of the sapphire substrate on which Ar crystals are grown. The substrate was illuminated during this time by a 500-mW frequency-doubled Nd:YAG laser. The fluorescence peak at 694 nm is due to Cr impurities in the sapphire, with the other features being due to spectral impurities in the Nd:YAG laser light.

Probed microscopic changes in Argon solid surface topology by observing the speckle pattern created by laser light as it scatters through an evaporating argon crystal as it is heated from 20 to 200 kelvin. Two hours of this experiment is captured in the video below.

Grew an 360-μm-thick argon cryogenic solid over a period of 4.5 hours at a rate of just under 6 interference fringes (1.5 μm) per minute. Below is a snapshot of the first half hour of growth.

Connected Hexapole Ion Guide to Commercial Electrospray Ion Source. Transported BaF⁺ ions with near-100% efficiency to end of hexapole guide by using angular deviations in the ion path to reduce on-axis neutrals. Differential pumping in the transfer system permitted chamber pressures on the order of 10^-8 torr.

Published article describing hyperfine structure of oriented polar molecules and details proposed EDM³ experimental method.

Inserted coldhead into vacuum system and create first cryogenic Ar solid.

Acquired and tested three laser systems: an external-cavity diode laser with a wavelength tunable from 790 to 870 nm for spectroscopy of BaF embedded in solid Ar, a stabilized HeNe (632 nm) for interferometry, and a Nd:YAG green laser with a power of 500 mW for photoluminescence.

Completed vacuum system to house the experiment.

First attempt at Ar annealing.

Finished renovation on new 2000 square-foot laboratory space.

Observed isotopically pure ¹³⁸Ba¹⁹F from an electrospray source.