  The identification of helium nuclei at LHCb is achieved using a method based
on measurements of ionisation losses in the silicon sensors and timing
measurements in the Outer Tracker drift tubes. The background from photon
conversions is reduced using the RICH detectors and an isolation requirement.
The method is developed using $pp$ collision data at $\sqrt{s}=13\,{\rm TeV}$
recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an
integrated luminosity of $5.5\,{\rm fb}^{-1}$. A total of around $10^5$ helium
and antihelium candidates are identified with negligible background
contamination. The helium identification efficiency is estimated to be
approximately $50\%$ with a corresponding background rejection rate of up to
$\mathcal O(10^{12})$. These results demonstrate the feasibility of a rich
programme of measurements of QCD and astrophysics interest involving light
nuclei.
