Physics Colloquium, October 10, 2006
Precision Mass Measurement: ωcyclotron is not qB/m, does E=mc2? David E. Pritchard

Massachusetts Institute of Technology

We have developed an ion balance that has improved atomic and molecular mass measurement accuracy to ~ 10^-11. It compares the cyclotron frequency of two individual molecular or atomic ions trapped in a uniform magnetic field to find the mass ratio. Besides improving the mass of fundamental particles, this has led to discovery of a correction to the cyclotron resonance formula, a new route to determining the fine structure constant using simple physics, the best measurement of the dipole moment of any charged molecule, recalibration of the x-ray wavelength standard, a possible route to replace the artifact kilogram with an atomic mass standard, and a precise test of E=mc². We can also weigh chemical bonds.

Dr. Pritchard's Web Site

4:00 p.m., Physics Research Building (PRB), Room 1080

Reception at 3:45 p.m., Atrium, PRB