The recent publication in Phys.Rev.Lett. 126, 141801 Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm says that
A fast pulsed-kicker magnet deflects the muon bunch into a 9-cm-diameter storage aperture, resulting in $\approx 5000$ stored muons per fill.
Considering that those muons are moving with almost the speed of light ($\gamma\approx30)$ and at rest they would only last about $2.2\ \mu s$ on average before decaying, catching one would be no mean feat.
What am I missing?