# Dark Matter Search Results from the Complete Exposure of the PICO-60 C$_3$F$_8$ Bubble Chamber

## TL;DR

This paper reports the final results from the PICO-60 bubble chamber dark matter detector, setting new constraints on WIMP interactions with protons, with improved sensitivity and larger exposure at lower energy thresholds.

## Contribution

It presents the complete exposure data from PICO-60 with enhanced analysis techniques, providing the most stringent limits on certain WIMP-proton cross sections to date.

## Key findings

- Set new leading limits on WIMP-proton spin-dependent cross section.
- Achieved larger fiducial volume through improved event identification.
- Enhanced sensitivity at lower energy thresholds.

## Abstract

Final results are reported from operation of the PICO-60 C$_3$F$_8$ dark matter detector, a bubble chamber filled with 52 kg of C$_3$F$_8$ located in the SNOLAB underground laboratory. The chamber was operated at thermodynamic thresholds as low as 1.2 keV without loss of stability. A new blind 1404-kg-day exposure at 2.45 keV threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 keV. This increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. These results set the most stringent direct-detection constraint to date on the WIMP-proton spin-dependent cross section at 2.5 $\times$ 10$^{-41}$ cm$^2$ for a 25 GeV WIMP, and improve on previous PICO results for 3-5 GeV WIMPs by an order of magnitude.