Low field flux creep in niobium superconducting wires

Using a SQUID magnetometer we have measured flux creep in superconducting persistent current loops made of niobium and niobium-titanium wire. The observed creep is 4 orders of magnitude less than that reported in niobium alloys above H _c1, but 2 to 4 orders of magnitude larger than reported for trapped flux in niobium tubes well below H _c1 A novel ‘ soak ’ technique, which eliminates the need for a persistent current and precise temperature regulation, is described.