PM: Search for New Physics Beyond the Standard Model through Precision Isotope Shift Measurements

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

High-precision experiments at low energies offer compelling opportunities to search for new physics beyond the Standard Model of particle physics. It is proposed to set improved bounds for a new fundamental force by performing precision measurements of isotope shifts (minute perturbations in the colors of light emitted by atoms due to changes in the number of neutrons in the nucleus). By comparing isotope shifts measured on different colors of light emitted by the same element, it is possible to search for new particles that signal a new fundamental force. The proposed work will unite research and educational goals by training undergraduate and graduate students, and strive to increase the participation of underrepresented groups. In particular, it is proposed to improve high-precision isotope shift spectroscopy in Yttervium (Yb) by four orders of magnitude to search for a new boson that couples to quarks and leptons in the intermediate mass range of 100 eV to 100 MeV (divided by the square of the speed of light). In this approach, a nonlinearity in a so-called King plot, which compares isotope shifts for two different transitions, provides sensitivity to physics beyond the Standard Model, as well as to previously inaccessible nuclear effects. Spectroscopy will be performed on three different transitions in laser-cooled and trapped Yb+ ions, where the precision will be improved by four orders of magnitude from the current level of 1 kHz to ∼ 0.1 Hz. This will not only enable the observation of previously inaccessible nuclear effects, but also push the limit for the coupling of the new boson to standard matter into a previously untested range. The sensitivity to new physics can be dramatically improved if additional isotopes can be made available. Therefore, an extraction and trapping apparatus will be developed that will be used to trap and measure the unstable 166Yb isotope, and provide the capability to measure other unstable isotopes at accelerator facilities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.