Millicharged dark matter detection with ion traps

TL;DR

This paper proposes using ion traps to detect millicharged dark matter particles, leveraging their low background noise and high sensitivity to set new constraints on dark matter properties.

Contribution

The study introduces a novel application of ion traps for dark matter detection, providing significantly improved constraints on millicharged particles compared to previous methods.

Findings

Existing ion trap measurements set new bounds on millicharged dark matter.

Ion traps can detect energy depositions as low as neV.

Future experiments could explore even larger parameter space.

Abstract

We propose the use of trapped ions for detection of millicharged dark matter. Millicharged particles will scatter off the ions, giving a signal either in individual events or in the overall heating rate of the ions. Ion traps have several properties which make them ideal detectors for such a signal. First, ion traps have demonstrated significant isolation of the ions from the environment, greatly reducing the background heating and event rates. Second, ion traps can have low thresholds for detection of energy deposition, down to $\sim \text{neV}$. Third, since the ions are charged, they naturally have large cross sections for scattering with the millicharged particles, further enhanced by the low velocities of the thermalized millicharges. Despite ion-trap setups being optimized for other goals, we find that existing measurements put new constraints on millicharged dark matter which are many orders of magnitude beyond previous bounds. For example, for a millicharge dark matter mass $m_Q=10~\textrm{GeV}$ and charge $10^{-3}$ of the electron charge, ion traps limit the local density to be $n_Q \lesssim 1 \, \textrm{cm}^{-3}$, a factor $\sim 10^8$ better than current constraints. Future dedicated ion trap experiments could reach even further into unexplored parameter space.