First non-zero measurement of a nuclear electric dipole moment

TL;DR

This study reports the first non-zero measurement of a nuclear electric dipole moment using a novel supercurrent-based method, providing new insights into nuclear properties and fundamental symmetries.

Contribution

It introduces a new experimental technique for measuring nuclear electric dipole moments and presents the first non-zero measurement of $^{181}$Ta's EDM.

Findings

Measured $^{181}$Ta EDM as $(3.39 imes 10^{-32}) e ext{cm}$ with high statistical significance.

Estimated upper limit for $^{207}$Pb EDM at $1.2 imes 10^{-31} e ext{cm}$.

Detailed theory, experimental setup, and implementation of the novel measurement method.

Abstract

This paper reports the first non-zero measurement of a nuclear electric dipole moment using a novel method based on the rate of change of a supercurrent first proposed in 2016~\cite{https://doi.org/10.48550/arxiv.1604.02152} and fleshed out in this current paper. The theory, experimental concept and implementation are described in detail. The non-zero nuclear electric dipole moment measured with over 1000 hours of data was that of $^{181}$Ta producing a best value $|d_\text{e}^\text{Ta}|=(3.39\pm0.31_\text{stat})\cdot10^{-32}e\cdot\text{cm}$ and $|d_\text{e}^\text{Ta}|=(3.39\pm3.18)\cdot10^{-32}e\cdot\text{cm}>0$ at 99.985\%CL. There is an uncertainty on the value of overall multiplicative parameters such as the self-inductance of the superconducting circuit ($\pm4\%$), the mutual inductance between the SQUID pickup coil and the sample wire ($\pm15\%$), and the magnitude of the solenoid current ($\pm5\%$). An upper-limit was estimated for the control element, $^{207}$Pb, $|d_\text{e}^\text{Pb}|\lesssim1.2\cdot10^{-31}e\cdot\text{cm}$ at 95\%CL.