Implementation of a Digital Gaussian Filter to Restore Resolution of the PLATYPUS Reflectometer
James Spedding, Nick Hauser, P. Van Esch · 2024
Following its commissioning in 2019, the PLATYPUS reflectometer at the Australian Centre for Neutron Scattering, ANSTO, demonstrated a significant degradation in detector resolution from7 mm full-width half-maximum. The PLATYPUS reflectometer uses a Monoblock Aluminium Multitube detector that was designed and fabricated at Institut Laue-Langevin and uses the charge division method for positional determination. After the cause of degraded resolution was determined to be electrical noise, a digital fourth-order low-pass Gaussian filter was applied to pre-processed preamplifier signals to remove high frequency components. The digital filtering method, also devised at Institu Laue-Langevin, was implemented purely in firmware and software and was successful at improving the resolution to 4 mm full-width halfmaximum. The results indicate the technique has limitations but also highlight the convenience and flexibility of the digital approach to pulse-processing.