Experimental Nuclear Physics, Fundamental Symmetry Tests

Research Interests

My research interests in experimental nuclear physics involve low-energy, high-precision tests of fundamental symmetries as probed in experiments utilizing ultracold neutrons (UCN). The driving central theme of our research in these fundamental neutron physics experiments is the search for new physics beyond the Standard Model of particle physics. We are currently involved with two such initiatives. First, we are carrying out a high-precision measurement of the neutron beta-asymmetry at a new UCN source developed at the Los Alamos National Laboratory. A value for this asymmetry, combined with the neutron lifetime, permits an extraction of the CKM quark-mixing matrix element V_ud. The goal is to perform a high-precision test of the unitarity of the CKM matrix. Second, we are involved with a new U.S.-based search for the neutron electric dipole moment (EDM). The existence of a neutron EDM requires violation of the Time-Reversal Symmetry (T-violation). Additional sources of T-violation, equivalent to CP-violation, are needed to explain the fundamental question of the origin of the baryon asymmetry of the universe. This experiment will be conducted at the Spallation Neutron Source at Oak Ridge National Laboratory.

I am also interested in measurements of the distribution of charge within the (neutral) neutron. Future measurements to the smallest length scales ever will be conducted at the Jefferson Laboratory.

Career History

• B.S. in Physics, Massachusetts Institute of Technology (1999)
• Ph.D. in Physics, Massachusetts Institute of Technology (2003)
• Postdoctoral Scholar, California Institute of Technology (2003-2008)
• Assistant Professor, University of Kentucky, (2007 - )

• R.W. Pattie, Jr. et al., "First measurement of the neutron beta asymmetry with ultracold neutrons", Phys. Rev. Lett. 102, 012301 (2009).
• B. Plaster et al., "A solenoidal electron spectrometer for a precision measurement of the neutron beta asymmetry with ultracold neutrons", Nucl. Instrum. Methods Phys. Res. A 595, 587 (2008).
• R. Schmid, B. Plaster, and B.W. Filippone, "Motional spin relaxation in large electric fields", Phys. Rev. A 78, 023401 (2008).
• T.M. Ito et al., "A multiwire proportional chamber for precision studies of neutron beta decay angular correlations", Nucl. Instrum. Methods Phys. Res. A 571, 676 (2007).
• B. Plaster et al., "Measurements of the neutron electric to magnetic form factor ratio G_En/G_Mn via the ²H(e,e'n)¹H reaction to Q² = 1.45 (GeV/c)²", Phys. Rev. C 73, 025205 (2006).
• J.W. Martin et al., "New measurements and quantitative analysis of electron backscattering in the energy range of neutron beta-decay", Phys. Rev. C 73, 015501 (2006).
• R. Madey, A. Yu. Semenov, S. Taylor, B. Plaster et al., "Measurements of G_En/G_Mn from the ²H(e,e'n)¹H reaction to Q² = 1.45 (GeV/c)²", Phys. Rev. Lett. 91, 122002 (2003).