Observation of gravitationally induced vertical striation of polarized ultracold neutrons by spin-echo spectroscopy

TL;DR

This paper introduces a spin-echo spectroscopy method for ultracold neutrons that leverages gravitationally induced vertical striation to accurately analyze neutron energy spectra and magnetic field gradients, aiding precision physics experiments.

Contribution

The paper presents a novel combination of spin-echo spectroscopy with gravitationally induced vertical striation for ultracold neutrons, enabling precise energy spectrum reconstruction and magnetic field gradient measurement.

Findings

Reconstructed neutron energy spectra using spin-echo signals.

Achieved magnetic field gradient measurement accuracy of 1.1 pT/cm.

Demonstrated gravitationally induced vertical striation in UCNs.

Abstract

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a $|B_0|=1~\text{\mu T}$ magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCN of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of $1.1~\text{pT/cm}$. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.