Jerry Sell

Polarization and relaxation of ^209Rn

The study of the nuclear polarization of radon is motivated by the expected large enhancement of sensitivity to a CP-violating electric dipole moment (EDM) in isotopes with octupole deformation or vibrational strength. In preparation for EDM measurements, the polarization of radon by spin exchange with laser-polarized alkali metals is studied. The measurement of the alignment of 209Rn using HPGe detectors to observe the resulting anisotropy in the 337 and 745 keV gamma rays emitted following electron-capture decay of 209Rn to 209At is demonstrated. Radon is polarized via spin-exchange collisions with rubidium atoms in an uncoated Pyrex optical pumping cell. Anisotropy measurements at several temperatures are used to study polarization and relaxation.

Lifetime measurement of the cesium6P3/2level using ultrafast pump-probe laser pulses

Using the inherent timing stability of pulses from a mode-locked laser, we have precisely measured the cesium

Collinear laser spectroscopy of francium using online rubidium vapor neutralization and amplitude modulated lasers

6P_{3/2}

Measurement of gravitational time dilation: An undergraduate research project

excited state lifetime. An initial pump pulse excites cesium atoms in two counter-propagating atomic beams to the

Polarization and relaxation rates of radon

6P_{3/2}

Lifetime measurement of the cesium 6P{sub 3/2} state using ultrafast laser-pulse excitation and ionization

level. A subsequent synchronized probe pulse ionizes atoms which remain in the excited state, and the photo-ions are collected and counted. By selecting pump pulses which vary in time with respect to the probe pulses, we obtain a sampling of the excited state population in time, resulting in a lifetime value of 30.462(46) ns. The measurement uncertainty (0.15%) is larger than our previous report of 0.12% [Phys. Rev. A 84, 010501(R) (2011)] due to the inclusion of additional data and systematic errors. In this follow-up paper we present details of the primary systematic errors encountered in the measurement, which include atomic motion within the intensity profiles of the laser beams, quantum beating in the photo-ion signal, and radiation trapping. Improvements to further reduce the experimental uncertainty are also discussed

Francium developments at Stony Brook

Performing collinear laser spectroscopy on low intensity radioactive beams requires sensitive detection techniques. We explain our apparatus to detect atomic resonances in neutralized (208-210)Fr ion beams at beam energies of 5 keV and intensities of 10(5) s(-1). Efficient neutralization (> or = 80%) is accomplished by passing the beam through a dense Rb vapor. Increased detection efficiency is achieved by amplitude modulating the exciting laser to decrease the scattered light background, allowing fluorescence detection only when the laser is near its minimum in the modulation cycle. Using this technique in a collinear geometry we achieve a background reduction by a factor of 180 and a signal-to-noise increase of 2.2, with the lifetime of the atomic state playing a role in the efficiency of this process. Such laser modulation will also produce sidebands on the atomic spectra which we illustrate.

Collisional Processes in Alkali-Methane Gas Mixtures for Alkali Laser Development

General relativity predicts that clocks run more slowly near massive objects. The effect is small—a clock at sea level lags behind one 1000 m above sea level by only 9.4 ns/day. Here, we demonstrate that a measurement of this effect can be done by undergraduate students. Our paper describes an experiment conducted by undergraduate researchers at Colorado College and the United States Air Force Academy to measure gravitational time dilation. The measurement was done by comparing the signals generated by a GPS frequency standard (sea-level time) to a Cs-beam frequency standard at seven different altitudes above sea level. We found that our measurements are consistent with the predictions of general relativity.