X. Workshop on Resistive Plate Chambers and Related Detectors

The NeuLAND detector for R3B at FAIR will detect high‐energy neutrons and will be based on timing resistive plate chambers. Current RPC detectors for timing purposes often use a common gas mixture, composed of 85% Reclin‐134a, 10% sulfur hexafluoride, and 5% isobutane, which allows the operation of the detector under optimal conditions. Each gas has a series of advantages and disadvantages, which will be briefly listed. Reclin‐134a and sulfur hexafluoride are potent greenhouse gases with high to very high global warming potentials, respectively. The long‐term release of these gases to the atmosphere must therefore be avoided. Due to the considerable gas volume involved in the NeuLAND detector, a closed‐circuit gas recirculation system is proposed for this purpose, consisting of a main circuit with a gas scrubber for the removal of eventual impurities in the gas, a condensation circuit for the recovery of the gas mixture, an injection circuit for the supply of fresh gas, and an on‐line gas‐analysis system based on a quadrupole mass spectrometer. This closed‐circuit system will be presented, and its various subsystems will be described in detail.