One-dimensional Trench-MWPC detector for the D20 powder diffractometer at the Institut Laue–Langevin

The instruments at the Institut Laue–Langevin (ILL) dedicated to powder and single-crystal diffraction are those requiring the most challenging neutron detectors in terms of angular resolution. Two of these instruments (XtremeD and D16) have been collecting diffraction data since 2023 using large-area two-dimensional curved position-sensitive neutron detectors based on the Trench-MWPC (multi-wire proportional chamber) design. In these detectors, 2D neutron diffraction images are obtained through the coincidence detection of signals which are read out individually on the anode wires and cathode blades of the Trench-MWPC structure. These 3 He-filled detectors combine high angular coverage, high spatial resolution and high count rate capability. More recently, a one-dimensional version of the Trench-MWPC was implemented in the position-sensitive detector developed for the D20 high-intensity powder diffractometer at the ILL. In this detector, diffraction line profiles are obtained by the individual read out of signals from anode wires only. Since the cathode electrodes are not segmented, the mechanical design and fabrication of 1D Trench-MWPC detector modules are greatly simplified compared with the 2D version. The new D20 Trench-MWPC detector provides an angular resolution of 0.1° and an angular coverage of 160°. The design, fabrication and characterization of this 1D Trench-MWPC detector are presented in this article.