Abstract
An ac calorimeter was constructed for measurements below room temperature. A cryostat was designed while modifying that for adiabatic calorimetry for highly stable thermal condition. Temperature control comparable to that in adiabatic calorimetry was achieved. Chopped-light was introduced to the cryostat through optical fiber, and lead to the sample through a fused-quartz rod. The cryostat is applicable to general physical measurements keeping its capability for thermal control.
