Optimizing Spin Dressing Sensitivity for the nEDMSF Experiment

Abstract

nEDMSF aims to measure the neutron electric dipole moment ($d_n$) with unprecedented precision. In this paper we explore the experiment's sensitivity when operating with an implementation of the critical dressing method in which the angle between the neutron and Helium-3 spins (${\varphi }_{3n}$) is subjected to a square modulation by an amount ${\varphi }_d$ (the "dressing angle"). Several parameters can be tuned to optimize sensitivity. We find roughly 10% improvement over a previous estimate, resulting primarily from the addition of a waiting period between the $\pi /2$ pulse that initiates $d_n$-driven ${\varphi }_{3n}$ growth and the start of ${\varphi }_{3n}$ modulation. We find negligible further improvement by allowing ${\varphi }_d$ to vary continuously over the course of a run, and no degradation resulting from the addition of an in situ background measurement into each ${\varphi }_{3n}$ modulation sequence. A complete simulation confirms a 300 live-day sensitivity of $\sigma =1.45\times 10^{-28}e\cdot \mathrm{cm}$. At this level of sensitivity, ${\sigma }_{{\varphi }_{3n0}}=1\mathrm{mrad}$ precision on the initial $n{/}^3\mathrm{He}$ angle difference is not negligible.

10 pages, 1 figure

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