The MicroBooNE detector is a Liquid Argon Time Projection Chamber. It consists of 170 tonnes of liquid Argon, which need to be kept at 87 Kelvin (-186 ˚C or -303 ˚F) in a big cryostat. Submerged in the argon, a cathode powered to up to -100 kV is creating an electric field across a field shaping cage. Opposite the cathode, very fine wires are strung just 3 mm apart in three planes -- over 8,000 wires in total!
When a neutrino interacts with an argon nucleus in the TPC, it produces charged particles. These charged particles ionise the surrounding argon atoms, which means that some of the electrons in the argon atoms separate from the argon nuclei. The electrons, being negatively charged, then drift in the electric field towards the wire planes. The movement of the charge induces a signal in the wires, which is read out using special electronics. Putting all these signals together, scientists are able to reconstruct where the charged particles from the interaction went, and calculate some of their properties, such as their energy and momentum. This helps in identifying which type of particles are involved and whether what is observed stems from a neutrino interaction.