Abstract: A double-wall cryostat formed by the interconnection of an inner wall and an outer wall in their upper part, the walls defining therebetween a hermetic enclosure in which there is disposed a detector element connected by an electrical connection to circuits outside said enclosure, wherein the two walls are each provided in their upper part with a flexible sealing element, the two sealing elements cooperating by contact for ensuring the hermetic interconnection of the two walls and the electrical connection, formed by fine conductor wires enclosed between two thin flexible insulating bands, extends out of the hermetic enclosure between said sealing elements.