| Neil Shafer-Ray | |
| Title: | Professor |
| Education: | B.A. 1986 Massachusetts Institute of Technology |
| Ph.D. 1990 Columbia University | |
| Office: | 123 Nielsen Hall |
| Phone: | 405-325-3961, ext. 36123 |
| Email: | |
| Research Home Page |
Our group currently covers three research areas: The first is an effort to use a novel resonance technique to measure the electron's electric dipole moment. The second is an effort to use recently developed techniques in cooling and trapping to create a source of ultracold nitric oxide molecules.
It is well known that an electron carries a magnetic moment, m=μBgS,that is proportional to its spin. (Here μB is the Bohr magneton and g the dimensionless "g-factor".) In the early 1950's Purcell and Ramsey suggested that the electron may also carry an electric dipole moment leading to an interaction
U = - μB(gS·B + gEDMS·E/c)
Whereas the g factor is known to be a bit larger than 2, current experiments limit |gEDM μB/c| to less than 10-27e cm. A major focus of our group is to either measure or place an even smaller limit on the value of gEDM. To do so we are observing magic values of electric field for which the magnet moment of the molecule PbF vanishes. If the electron has a dipole moment, this electric field value will be different for the case of a magnetic field parallel to an electric field and the case of a magnetic field anti-parallel to an electric field. Measurement of a non-zero electric dipole moment would help differentiate between competing models of Particle Physics and could help explain mechanisms for CP violation that might have led to a matter-dominated Universe.
Cold populations of gas phase molecules contained by non-uniform electro-magnetic fields are of great importance to many fields, including precision measurement, navigation, time standards, and quantum computing. Our group is working with the Abraham laboratory to create an ultracold source of nitric oxide molecules. Here slow moving nitric oxide molecules are optically pumped into a trap state using pseudo continuous laser radiation. This creates a relatively hot (~1 K) population of trapped molecules. The temperature is then reduced with a second optical pumping scheme (demonstrated for atoms by the Raizen group at the University of Texas Austin.) The goal of this research is to create a dense source of NO molecules at a temperature below 1 mK.
Representative Publications:
- P. Sivakumar, C.P. McRaven, M. Rupasinghe, T. Yang, N.E. Shafer-Ray, T. Sears, and G. Hall, "Pseudo-continuous resonance enhanced multiphoton ionization: Application to the determination of the hyperfine constants of 208Pb19F," Molecular Physics, 108, 927 (2010).
- C.P. McRaven, P. Sivakumar, and N.E. Shafer-Ray, "Experimental Determination of the Hyperfine States of the 207Pb19F molecule," Phys. Rev. A, 054502 (2008).
- Milinda Rupasinghe and N.E. Shafer-Ray, "Effect of the geometric phase on the possible measurement of the electron’s electric dipole moment using molecules confined by a Stark gravitational trap," Phys. Rev. A, 78, 033427 (2008).
- Bryan J. Bichsel, Michael A. Morrison, Neil Shafer-Ray, and E. R. Abraham, "Experimental and theoretical investigation of the Stark effect for manipulating cold molecules: Application to nitric oxide," Phys. Rev. A, 75, 023410 (2007).
- Neil Shafer-Ray, "Possibility of zero-g-factor paramagnetic molecules for measurement of the electron's electric dipole moment," Phys. Rev. A, 73, 034102 (2006).