A purity monitoring system for liquid argon calorimeters

Abstract For liquid argon calorimeters electronegative impurities dissolved in the medium degrade the detector response and deteriorate the energy resolution, especially at high energies. A concept for a purity monitoring system for liquid argon calorimeters has been developed and is presented here. Special combined monitors of 241 Am- and 207 Bi-cells are used to monitor the concentration of impurities. The working principle as well as results from test measurements are discussed.