Speaker
Dr
John Blanchard
(Helmholtz-Institut Mainz, Germany)
Description
xions and axion-like particles (ALPs) are well-motivated dark matter candidates, but are challenging to detect experimentally.
Current experiments such as ADMX (the Axion Dark Matter eXperiment) are based on the coupling of ALPs to electromagnetic fields, and practical experimental considerations (e.g. constraints on microwave cavity size) typically limit such searches to axion/ALP masses greater than about $10^{-6}$~eV.
The Cosmic Axion Spin Precession Experiment (CASPEr) tackles the problem from a new direction by using nuclear magnetic resonance (NMR) techniques to search for nuclear spin precession caused by background axion/ALP dark matter.
CASPEr is naturally divided into two main efforts, based on the two couplings between axions and nuclear spins: CASPEr-Wind searches for the ``axion wind'' effect -- the direct coupling of nuclear spins to the relative momentum of the ALP field, and CASPEr-Electric searches for the oscillating nuclear electric dipole moment caused by the QCD axion.
Under appropriate experimental conditions, both of these couplings behave analogously to RF magnetic fields, in that they can induce measurable spin precession if the frequency of oscillation of the axion field (corresponding to the axion mass) is equal to the nuclear Larmor frequency.
By sweeping the applied magnetic field from $\sim$10$^{-5}$ to 14.1~T, CASPEr will be able to probe the ALP parameter space for masses between $\sim$10$^{-12}$ and $6.9\times 10^{-7}$~eV.
Current efforts in the technical design and construction of CASPEr will be discussed.
Primary author
Dr
John Blanchard
(Helmholtz-Institut Mainz, Germany)
