= Faraday cup
{c}
{wiki}
A <Faraday cup> collects beam <electric charge> on a conducting <electrode> and measures the resulting <electric current> or accumulated <electric charge>. For complete collection of <particles> carrying known <electric charge> $q$, $Q=Nq$ and $I=q\,dN/dt$, providing a direct relation between the electrical <signal> and particle delivery.
The collector intercepts the beam. Its geometry and applied fields must account for escaping <secondary electrons>, which alter the net <electric charge> left on the cup. Background <electric currents> and incomplete collection also affect the inferred particle number. <Faraday Cup by the ALPHA experiment>[ALPHA experiment: Faraday-cup counting of stored electron and positron plasmas]{ref}
Back to article page
