Directional detection of keV proton and carbon recoils with MIMAC

TL;DR

This paper demonstrates a new method with the MIMAC detector to measure the direction of keV-range nuclear recoils, advancing the potential for detecting low-mass dark matter particles through directional detection.

Contribution

The study introduces a technique to reconstruct the direction of neutron-induced nuclear recoils at keV energies, achieving angular resolution below 16 degrees, enabling directional detection of low-mass dark matter.

Findings

Achieved angular resolution better than 16° for proton recoils at 4 keV.

Achieved angular resolution better than 16° for carbon recoils at 5.5 keV.

First detector to measure keV-range nuclear recoil directions without incoming particle restrictions.

Abstract

Directional detection is the dedicated strategy to demonstrate that DM-like signals measured by direct detectors are indeed produced by DM particles from the galactic halo. The experimental challenge of measuring the direction of DM-induced nuclear recoils with (sub-)millimeter tracks has limited, so far, the maximal directional reach to DM masses around $100~\rm{GeV}$. In this paper, we expose the MIMAC detector to three different neutron fields and we develop a method to reconstruct the direction of the neutron-induced nuclear recoils. We measure an angular resolution better than $16^\circ$ for proton recoils down to a kinetic energy of $4~\rm{keV}$ and for carbon recoils down to a kinetic energy of $5.5~\rm{keV}$. For the first time, a detector achieves the directional measurement of proton and carbon recoils with kinetic energies in the keV range without any restriction on the direction of the incoming particle. This work demonstrates that directional detection is around the corner for probing DM with masses down to $\mathcal{O}(1~\rm{GeV})$.