Collaborative Research: MRI: Development of Apparatus for the Cold Molecule Nuclear Time-Reversal EXperiment (CeNTREX)

This project will support the purchase of equipment and parts needed to construct the apparatus for a new experiment known as CeNTREX, the Cold molecule Nuclear Time-Reversal experiment. CeNTREX is a collaborative effort to detect evidence for new types of fundamental forces and particles, through precise measurements of magnetic resonance signals from nuclei embedded in the polar molecule thallium fluoride. The goal of the CeNTREX experiment is to detect a particular deformation in the shape of an atomic nucleus, known as a nuclear Schiff Moment. This will advance the progress of science because a Schiff Moment along the spin axis of a nucleus can arise only in the presence of fundamental interactions that are not symmetric under reversal of the direction of time. Interactions of this type can be mediated by new, as-yet undetected, particles that are predicted to occur in some theoretical models that extend the current Standard Model of particle physics. A Schiff Moment of size large enough to be detected with the projected sensitivity CeNTREX could indicate the existence of new particles with mass well above that of the heaviest known particles - and even beyond the reach of the Large Hadron Collider (LHC). Hence, CeNTREX will provide one of the few known ways to search for physics beyond the Standard Model associated with particles too massive to be created at the LHC. An experiment with the fundamental discovery potential of CeNTREX can also capture the interest of the general public and raise the level of excitement about science. In addition, design and construction of the CeNTREX apparatus will provide opportunities for training several young scientists in instrumentation development. This type of precision measurement science exposes students to a wide range of intellectual and technical subfields, and provides unusually broad training in experimental physics that benefits development of the scientific workforce of the nation.

The existence of an asymmetric charge distribution such as an electric dipole moment (EDM) or a Schiff moment (SM) along a particle's angular momentum axis requires violation of time reversal (T) symmetry, which is equivalent to the more widely-discussed phenomenon of CP violation. Observation of an EDM or SM within a few orders of magnitude of current limits would be evidence for phenomena outside the Standard Model of particle physics theory. Furthermore, there are strong motivations from particle theory and cosmology to expect an EDM or SM in this experimentally-accessible range. Discovery of an EDM or SM could illuminate the mechanism responsible for the observed matter-antimatter asymmetry of the universe, which remains one of the grand challenges of cosmology and particle physics. Moreover, new physics at the TeV scale (the range of energy not being explored at the LHC), carrying new CP-violating phases, naturally give rise to EDM and SM near the current experimental limits. Hence any advance in sensitivity to SMs pushes the frontier of particle physics in a manner complementary to current efforts at the Large Hadron Collider. The CeNTREX apparatus will be developed by integrating a wide array of subsystems - many custom designed and built - including vacuum systems, a molecular beam source, lasers, optical control and detection systems, microwave control and transmission systems, precise magnetic field measurement and control systems, and high voltage systems. The conceptual design of CeNTREX builds from recent advances using the properties of diatomic molecules to amplify signals due to new fundamental forces, and in precisely detecting and manipulating molecules. This novel apparatus will use a cryogenic beam of diatomic molecules to make the world's most sensitive measurement of a SM. Detailed estimates of the first-generation measurement using CeNTREX are projected to yield a 30-fold increase in sensitivity, relative to the current state of the art, to certain types of time-reversal symmetry violating interactions that could be responsible for the cosmological matter-antimatter asymmetry in the Universe.

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.