LArTPCs

Liquid Argon Time Projection Chambers (LArTPCs)

Liquid argon time projection chambers are becoming more and more important in neutrino physics. Their capability to produce striking images of neutrino interactions, akin to those detected in bubble chamber detectors, makes them an excellent tool to unravel the mysteries that may be hidden by neutrinos. 

The construction of a LArTPCs is relatively simple. You need a volume of liquid argon which is encased by an electric field created by the cathode and anode. When a neutrino interacts with an argon atom within the detector, charged particles are produced, which go on to ionise the argon producing free electrons and scintillation light; the uniform electric field causes these electrons to drift towards a grid of wire planes, on which these electrons are collected as charge. The origin positions of the drifting electrons can then be reconstructed, knowing the position of the point on the wire planes at which they were detected, and the time taken for the electrons to arrive. And these can be combined into an image of the whole interaction. 

At the same time, scintillation light is detected by photomultiplier tubes, which can indicate if the interaction was in time with the neutrino beam being sending neutrinos. By using both signals, it is able to depict photographic-like 3D images for particle interactions down to the scale of millimetres.

LArTPC experiments: