Suppose you replaced the standard collimator on an Anger camera with one that has only one hole with diameter d positioned at the center of the camera—i.e., at x = 0 and y = 0. Let the object be a small radioactive point source that is placed 20 cm away from the camera face in direct alignment with the center of the camera.
(a) When a gamma ray photon goes through the collimator hole, the camera produces a response. Explain in words what happens to this photon and what sequence of events takes place in order to produce the X and Y signals and the Z-pulse.
(b) Suppose the X signal is held constant until the next photon hits the camera (so it is a piecewise constant signal X(t) in time.) Draw X(t) when the hole has a small diameter [call this X1(t)] and then draw X(t) when the hole has a larger diameter [call this X2(t)]. Account for all effects that change when you increase the hole diameter and draw the signals on the same vertical and horizontal scales with clear labels.
(c) Would you expect the sequence of Z-pulses to change when the hole diameter (of this single hole) is increased? Explain your answer.
(d) If you double the hole diameter, what must you do to the hole length in order for the camera to have the same sensitivity?
