418 Chapter 6. Scintillation Detectors and Photodetectors
current and the anode current. How much voltage this current corresponds to
if the equivalent resistance of the output circuit is 100 Ω. Assume the quantum
and collection efficiencies to be 40% and 80% respectively.14.An APD has a gain of 100 and is used to measure photon intensity from a
laser light having mean wavelength of 2.2μm. If the quantum efficiency of the
APD is 0.56, compute its responsivity. Also calculate the photocurrent if the
incident photon flux is 2. 5 × 1011 s−^1.
15.Compute the relative change in the mean gain of an APD if the hole-to-electron
ionization rate ratio changes from 0.001 to 0.1. The APD has a gain of 100 at
u=0.001.
16.Compute the average photocurrent flowing through an APD having a gain of
50 and responsivity of 10 if it is exposed to a 4.8eV photon beam of intensity
1. 6 × 108 s−^1.