Axion Production and Detection Using a Dual NMR-type Experiment

TL;DR

This paper proposes a dual NMR experiment setup to produce and detect axions via nuclear spin interactions, demonstrating potential to surpass astrophysical bounds on axion-nucleon coupling with feasible device configurations.

Contribution

It introduces a novel dual NMR method for axion detection, leveraging axion field gradients and frequency tuning to enhance sensitivity beyond current astrophysical constraints.

Findings

Detection sensitivity surpasses astrophysical bounds with 15-day integration.

10 cm NMR devices can achieve similar sensitivity in just 1 hour.

Probes a wide axion mass range up to inverse source distance.

Abstract

Axions that couple to nuclear spins via the axial current interaction can be both produced and detected using nuclear magnetic resonance (NMR) techniques. In this scheme, nuclei driven by a real oscillating magnetic field in one device act as an axion source, which can drive NMR in a nearby spin-polarized sample interrogated with a sensitive magnetometer. We study the prospects for detecting axions through this method and identify two key characteristics that result in compelling detection sensitivity. First, the gradient of the generated axion field can be substantial, set by the inverse distance from the source. In the near zone, it reduces to the inverse of the source's geometric size. Second, because the generated axion field is produced at a known frequency, the detection medium can be tuned precisely to this frequency, enabling long interrogation times. We show that the experimental sensitivity of a pair of centimeter-scale NMR devices operating over a 15-day integration time can already surpass existing astrophysical bounds on the axion-nucleon coupling. A similar sensitivity can be achieved with 10 centimeter-scale NMR devices with only 1 hour of integration time. These dual NMR configurations are capable of probing a wide range of axion masses, up to values comparable to the inverse distance between the source and the sensor.