NSF Award
2310015
One of the most-successful and best-studied physical theories is the Standard Model (SM), which describes how the universe functions at very small scales. This model has been verified in many different ways over the course of five decades. In principle, such a fundamental theory should be able to predict observations about the universe at large scales, but in a number of notable cases it fails to do so. This suggests an exciting possibility, that there are fundamental features about the universe of which we are unaware. Since these unknown properties have so far evaded detection, discovering them requires experiments with a new level of sensitivity, requiring innovative approaches. Two such experiments leverage recent progress in the production of very low energy “ultracold” neutrons. They are UCNtau, which measures the average time required for a free neutron to decay, and nEDM, a measurement of the charge distribution in an isolated neutron. This project focuses on the development of three techniques designed to enhance the sensitivity of these experiments. The research effort will assemble a cross-disciplinary team to strengthen the synergy between science and technology and will target early undergraduates and pre-college students to more effectively connect practical research experience with the students’ academic work.<br/><br/>The first of three primary research activities to be carried out in this project is the inclusion of empirically-determined magnetic field maps of the UCNτ Halbach array and ab initio simulations of the loaded ultracold neutron (UCN) phase space distribution into a semiclassical spin-tracking Monte Carlo model developed to account for entanglement between spatial and spin degrees of freedom. This goal will ensure that the characterization of systematic effects associated with spin dynamics (depolarization) keeps pace with anticipated improvements in statistical precision. The second core activity is to develop a real-time monitor for the UCNτ effort that will place run-by-run empirical limits on the depolarization rate and serve as a cross-check of the computational model. The third objective is to develop a quantum sensor, based on Nitrogen-Vacancy defects in diamond, optimized to aid in the control and characterization of magnetic and electric fields for nEDM experiments, thereby enhancing the sensitivity with which the neutron electric dipole moment can be measured.<br/><br/>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.
