Modeling energy transport through the hot-electron microcalorimeter

We present numerical simulations of the diffusion of energy through the hot-electron microcalorimeter. This detector uses a normal-insulator-superconductor tunnel junction to measure the energy deposited by X-ray photons in the normal electrode. The photon energy is converted into heat stored by electrons and is detected as a change in the current flowing through the junction. We show that a measurement of only the pulse height can cause errors in the deduced photon energy, and that a numerical correction based on either the fall or rise time of the pulses can be used to deduce both the original photon energy and the location of the absorbed photon.