A closed cycle helium cryostat was used for cooling. The cryostat DE-202AG was operated by a temperature controller LS-336 (LAKE SHORE) and the heat produced by the cryostat was removed from the system by a water-cooled helium compressor ARS-2HW. The sample was placed in a custom-made cell consisting of a 3 cm long rod-shaped copper cell of 1 cm diameter, sealed from the exterior with a copper dome and insulated by dynamic vacuum (p < 10 -4 kPa), and connected to the BELSORP-max adsorption instrument with a 1.5 mm copper capillary.