Resonant detection of axion mediated forces with Nuclear Magnetic Resonance

TL;DR

A method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion.

Abstract

We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 10^9 and 10^12 GeV or axion masses between 10^-6 and 10^-3 eV, independent of the cosmic axion abundance.

Figures (3)

• Figure 1: A source mass consisting of a segmented cylinder with $n$ sections is rotated around its axis of symmetry at a fixed frequency $\omega_{\rm{rot}}$, which results in a resonance between the frequency $\omega = n \omega_{\rm{rot}}$ at which the segments pass near the sample and the resonant frequency $2 \vec{\mu}_{N} \cdot \vec{B}_{ext} /\hbar$ of the NMR sample. The NMR sample has an oblate spheroidal geometry to minimize magnetic gradients while allowing close proximity to the mass. Superconducting cylinders screen the setup from the environment and the NMR sample from the source mass.
• Figure 2: Reach in the coupling vs interaction range plane for the monopole-dipole axion mediated interactions. The band bounded by the red (dark) solid line and dashed line denotes the limit set by transverse magnetization noise of the sample for the specific setup described in the text, for $T_2$ ranging from $1$ s to $1000$ s. The blue (darker) solid line is a future projection obtained by scaling the setup using parameters chosen in Table 1. The blue (darker) dot-dashed line is the projected limit set by the SQUID sensitivity. We limit the integration time in all setups to $10^6$ sec. The shaded band is the parameter space for the PQ axion with $C_f=1$. Additional uncertainties scalaraxioncoupling and model dependence PDG can produce variations of this axion parameter space. Experimental as well as combined experimental and astrophysical bounds are also presented Raffelt:2012spgsgpgermany.
• Figure 3: Reach in the coupling vs interaction range plane for the dipole-dipole mediated interactions between $^3$He nuclei (top) or electrons and $^3$He nuclei (bottom). The red (dark) solid and dashed lines denote the limits set by the source mass described in the text or a liquid $^3$He sample with $T_2=1\hbox{and}1000$ sec, respectively. The ultimate projected sensitivity is shown with the blue (darker) solid line. Integration time is set to $10^6$ sec. Also shown is the PQ axion signal for $C_f=1$. The value of $C_f$ in specific models is discussed in Ref. PDG. Astrophysical and experimental bounds are taken from Ref. Raffelt:2012sp.