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Trapping and Probing Rare Isotopes
We trap and probe atoms of rare isotopes,
and explore related scientific problems in the realm of physics and beyond.
Testing time-reversal symmetry in atoms and nuclei.
We are searching for a permanent electric-dipole moment (EDM) of the Ra-225 (t1/2 = 15 d) atom. A positive finding would signify the violation of time-reversal symmetry (T). This experiment provides an outstanding opportunity to search for new physics beyond the Standard Model. We have succeeded in realizing laser trapping and cooling of radium atoms (both Ra-226 and Ra-225) for the first time ever. At present, we are developing the techniques and apparatus needed for the EDM measurements with cold Ra-225 atoms.
Studying exotic nuclear structure
Helium-8 (He-8) is the most neutron-rich matter that can be synthesized on earth: it consists of two protons and six neutrons, and remains stable for an average of 0.2 seconds. Because of its intriguing properties, He-8 has the potential to reveal new aspects of the fundamental forces among the constituent nucleons. We have recently succeeded in laser trapping and cooling this exotic helium isotope, produced at the GANIL cyclotron facility in northern France, and have performed precision laser spectroscopy on individual trapped atoms. Based on atomic frequency differences measured along the isotope chain He-3 – He-4 – He-6 – He-8, the nuclear charge radius of He-8 has been determined for the first time. The result can now be compared with the values predicted by a number of nuclear structure calculations and is testing their ability to characterize this loosely-bound halo nucleus.
Radio-krypton dating – from dream to practice
The Atom Trap Trace Analysis (ATTA) method has revolutionized our ability to measure radiokrypton isotopes, Kr-81 (t1/2 = 229,000 yr) and Kr-85 (t1/2 = 10.8 yr), in samples of natural material. This in turn opens the door to a wide range of new applications in the Earth sciences. Kr-81 measurements of groundwater samples from the Nubian Aquifer in the Western Desert of Egypt showed residence times approaching one million years. At present, we are developing the next generation instrument, ATTA-3, which is expected to further reduce sample sizes required for radiokrypton analysis of groundwater and glacial ice.
Other Research Projects
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Counting Individual Ca-41 Atoms with a Magneto-Optical Trap
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Search for Helium-like Strangelets in the Earth's Atmosphere
We acknowledge the support of DOE, Office of Nuclear Physics, and NSF, Division of Earth Sciences.
