A majority of experiments will need to be carried out holding a fixed pressure over the length of the reflectivity measurement and this can easily be achieved as well as measuring more normal pressure-area curves. The large NIMA trough has moveable fixed barriers which allow the volume of sub phase to be varied. The troughs both have perspex lids which incorporate neutron transparent quartz windows. This arrangement allows easy alignment of the liquid but prevents a majority of the airborne dust contaminants but it is not a sealed unit. The troughs have the possibility to link to a recirculating heater/cooling bath which has a maximum temperature range of -50 to 200°C.
