I present the construction of a low-velocity intense source (LVIS) of laser-cooled neutral strontium using permanent ring magnets. The LVIS consists of a magneto-optical trap from which cold strontium is extracted in a well-collimated beam. I also present the development and implementation of a full suite of low-noise, high-bandwidth laser control electronics including a microcontroller unit. This microcontroller remotely controls and monitors the current driver, temperature controller, and PID lock circuit for each diode laser simultaneously. The current driver output is accurate to within 2 micro-amps and repeatable to with a few nano-amps. The noise spectral density of the current driver hits a floor of 10^(-10) amps per root Hz at ~50 Hz and has a modulation bandwidth of ~50 MHz. The PID lock-circuit includes a scan-balancing option that we have used to scan an AR coated laser diode ~30 GHz mode-hop free. I describe the construction of an 80 mW frequency doubled 461 nm laser system using PPKTP for cooling and trapping neutral strontium in the LVIS. The LVIS, the electronics systems, and the 461 nm laser system represent major milestones on the way to producing a matter-wave interferometer using Sr-87 ions. The interferometer is based on an optical Raman transition between the hyperfine ground states of the Sr-87 ion. The ions will be produced by exciting the strontium LVIS beam to an auto-ionizing state in the continuum. In the interferometer two half-pi pulses of light and one pi pulse will be delivered to the ions to split and recombine their wave functions. I present calculations of the predicted sensitivity and a discussion of the possible applications. I present a method for locking a 407.8 nm laser to the 5s doublet S J=1/2 to 5p doublet P J=3/2 strontium ion transition in a neutral vapor. I present calculations for the necessary vacuum levels for the experiment and describe the preparation and assembly of the vacuum apparatus. The major vacuum system consists of two connected elastomer sealed chambers: one at 10^(-7) Torr and the other at 10^(-10) Torr separated by a region of low conductance. I present a Sr vapor cell constructed from standard CF fittings that allows the strontium to be heated to ~730 C, which can also be run as a thermal beam. I present a method for protecting the viewports on small-form alkali-earth vapor cells using lead or indium foil during the evaporation of oxide layers. Finally, I report on the current status of the experiment as well as detail future work on the apparatus.
College and Department
Physical and Mathematical Sciences; Physics and Astronomy
BYU ScholarsArchive Citation
Erickson, Christopher Joseph, "Development of a Strontium-87 Ion Interferometer" (2011). Theses and Dissertations. 2750.
strontium, matter-wave, interferometry, LVIS, charged particle, cold atoms, magneto-optical trap, MOT, laser cooling