Johannes Schulz IKP Uni Münster

Design of a 2-phase Xe TPC for electron drift length measurements (pdf)

The XENON-Project searches for WIMPs by looking for nuclear recoil signals induced in a 2-phase xenon TPC. WIMPs hitting Xe-atoms produce electrons and scintillation light in the liquid. The electrons are forced by an electric field to drift towards the surface, where they are extracted and accelerated causing scintillation light in the gas. The light signals can be detected by 2 arrays of PMTs at the bottom and on top of the TPC. The signals of the PMTs give the x- and y-coordinate of the event, the time between the first and the second light pulse gives the z-coordinate allowing a 3D position reconstruction. A small TPC with 80mm diameter and 200mm hight will be integrated in our cryogenic purification system. The light readout will be done by 14 UV-sensitve Hamamatsu R8520-06-AL PMTs. The first TPC-setup will allow a drift length of 170mm and can stepwise be upgraded to 1000mm later on. The drift length measurements can indicate the level of electronegative impurities in the Xe.