“Old wine in new wineskins:” Upgrading the liquids reflectometer instrument user control software at the Spallation Neutron Source

Abstract

The Liquids Reflectometer (LR) Instrument installed at the Spallation Neutron Source (SNS) enables observations of chemical kinetics, solid-state reactions, phase-transitions and chemical reactions in general [1]. The ability of the instrument to complete measurements quickly and therefore process many samples is a key capability inherent in the system design [2]. Alignment and sample environment management are a time consuming and error prone process that has led to the development of automation in the control software operating the instrument. In fact, the original LR user interface, based on the Python scripting language, has been modularized and adapted to become the standard interface on many other instruments. A project to convert the original Python [3] implementation controlling the LR instrument into the modular version standardized at SNS was undertaken in the spring of 2012. The key features of automated sample alignment and robot-driven sample management system enable the instrument to reduce the manual labor required to prepare and execute observations, freeing up precious time for analysis and reporting activity. We present the modular PyDas control system [4], its implementation for the LR, and the lessons learned during the upgrade process.