New Heat-Capacity Measurements of the Possible Order-Disorder Transition in the 4/7-phase of 2D Helium

We have developed a new heat-capacity measuring system with ZYX graphite that is known to have much better crystallinity than Grafoil and started data collection. We report preliminary data as well as a detailed description of instrumentation including a mechanical heat-switch operated by hydraulic pressure of superfluid 4He.