"Quantitative Analysis of Proton Content in Deuterated Poly(methyl methacrylate) for Thin Neutron Window Material Selection in Ultra-cold Neutron Experiments"

This research investigates the proton content in various fully- deuterated poly(methyl methacrylate) (d-PMMA) samples, dissolved in 99.5% deuterated toluene (d8-toluene), using a novel Nuclear Magnetic Resonance (NMR) spectroscopy quantitative analysis technique. This technique identifies the amount of protons in the polymer via integration of the NMR peaks of the d-PMMA and d8-toluene signal strength calibration, and requires a careful standardized sample preparation protocol.The research focuses on selecting a suitable d-PMMA for use as a thin neutron window material for an experiment that will make the world’s best measurement of the neutron’s electric dipole moment. This experiment will improve our understanding of how matter was formed during the Big Bang. The experiment requires maximum delivery of cold neutrons to inside a cell containing superfluid helium-4 cooled to 0.5 K in order to produce the ultra-cold neutrons (UCNs) needed for the experiment. The ratio of the Hydrogen/Deuteron cross-section of ~12 highlights that material containing hydrogen are much more likely to scatter, absorb, or deflect neutrons. These unwanted processes reduce the number of UCNs needed and produce unwanted background signals.