Assembly of the XENONnT TPC
The Freiburg crew and the XENONnT.
XENONnT will soon be the largest and most sensitive detector for WIMP dark matter. Its "heart" is the TPC (time projection chamber) which records the light and charge signals created by particle interactions in the liquid xenon (LXe) target. The design of the full TPC was co-led by Freiburg and the so-called field cage was designed, optimized and largely built by Freiburg. The field cage ensures that the electric field across the LXe target is as homogeneous as possible to move ionization charges from the interaction point to the top of the detector, while maintaining the original (x,y) coordinates.
The field cage was optimized by means of detailed electric field simulations and in-depth prototyping. Its large copper components were all machined in Freiburg (and many other Teflon (PTFE) and stainless steel parts as well). After an intense cleaning campaign to remove radioactive impurities from the material surfaces the XENONnT TPC was installed at the Italian LNGS laboratory end of February 2020. The photo shows the Freiburg crew in the cleanroom (also under Freiburg's responsibility) around the field cage. From left to right: Francesco, Marc, Sebastian, Jacques (Chicago), Arianna. The field cage consists of PTFE refectors (white) surrounded by field shaping elements made of copper (orange). Not all field shaping elements are installed at the point the photo was taken.
