The most effective way of looking for alpha particles is with a scintillation counter.
From the economist.com
The filters were then collected and air dried, and radioactivity was measured by scintillation counter and analyzed by using SigmaPlot.
From the nature.com
It will shoot low-energy X rays at the ground, causing silver on the surface to fluoresce, and will measure the fluorescence on a scintillation counter.
From the time.com
Silver atoms that are caught in the penetrating beam capture neutrons and briefly become unstable isotopes, emitting gamma rays that can be recorded by the snooper's scintillation counter.