X-ray detection by an on-chip coil integrated superconducting tunnel junction

An on-chip coil integrated superconducting tunnel junction (OC2-STJ) was used for x-ray detection by applying the magnetic field produced by a superconducting microstrip coil integrated into the superconducting tunnel junction chip. The fabricated OC2-STJ chip was mounted in a cooling capsule attached to the mixing chamber of a compact 3He–4He dilution refrigerator. The OC2-STJ chip was held at a constant temperature in the capsule against the Joule heat generated in the current feed line of the strip coil during the detection operation. Stable operation of the OC2-STJ was demonstrated without using the usual external electromagnets.