First direction sensitive search for dark matter with a nuclear emulsion detector at a surface site

TL;DR

This paper reports the first direction-sensitive dark matter search using a nuclear emulsion detector at sea level, demonstrating the detector's potential for particle tracking and dark matter detection in an unshielded environment.

Contribution

It introduces a novel use of nuclear emulsion films for directional dark matter searches and demonstrates their effectiveness in an unshielded, surface environment.

Findings

No dark matter signal was observed, consistent with background models.

Excluded certain dark matter cross-sections at specific masses.

First directional dark matter search with a solid-state tracking detector.

Abstract

Fine-grained nuclear emulsion films have been developed as a tracking detector with nanometric spatial resolution to be used in direction-sensitive dark matter searches, thanks to novel readout technologies capable of exploiting this unprecedented resolution. Emulsion detectors are time insensitive. Therefore, a directional dark matter search with such detector requires the use of an equatorial telescope to absorb the Earth rotation effect. We have conducted for the first time a directional dark matter search in an unshielded location, at the sea level, by keeping an emulsion detector exposed for 39 days on an equatorial telescope mount. The observed angular distribution of the data collected during an exposure equivalent to 0.59 g days agrees with the background model and an exclusion plot was then derived in the dark matter mass and cross-section plane: cross-sections higher than $1.3 \times 10^{-28}$ cm$^{2}$ and $1.7 \times 10^{-31}$ cm$^2$ were excluded for a dark matter mass of $10$ GeV$/c^2$ and $100$ GeV$/c^2$, respectively. This is the first direction sensitive search for dark matter with a solid-state, particle tracking detector.