Session KP01 - Poster Session III.
POSTER session, Tuesday afternoon, March 23
Exhibit Hall, GWCC
Using a recently constructed atomic beam apparatus, we have undertaken a series of precise atomic structure measurements on the 378 nm 6P_1/2 - 7S_1/2 E1 transition in atomic thallium. This work complements ongoing vapor cell spectroscopy of the thallium 1283 nm M1 transition in this laboratory. These measurements will provide important, independent cross-checks on the accuracy of ongoing calculations of parity nonconservation in thallium. Our atomic beam apparatus consists of a multiple slit oven source and 20 cm oven-to-interaction region distance, which provides a favorable balance of beam density and modest Doppler narrowing. Using a 5 mW external cavity diode laser and an external resonant doubling cavity containing an LBO crystal, we have obtained 4 microwatts of light at 378 nm. In our experiment, we scan the diode laser via a PZT and measure the transmission of UV light through the atomic beam in the vicinity of the transition. With the aid of a calibrated Fabry-Perot cavity this will allow an improved spectroscopic determination of the \sim12 GHz 7S_1/2 state hyperfine splitting as well as the \sim1.6 GHz ^203Tl/^205Tl isotope shift within this transition. Using a precisely constructed electric field plate assembly, and an acousto-optic modulator to frequency shift the diode laser, we are also undertaking a precision Stark shift measurement within the 378 nm transition. Current experimental results will be presented.