METHOD AND DEVICE FOR DETECTING MAGNETIC BODY CONCENTRATION

PROBLEM TO BE SOLVED: To measure the concentration of the extremely small amount of a magnetic body element constituent contained in a substance instantly without any contact. SOLUTION: A substance 1 is passed in a pipeline 2 consisting of non- magnetic body, first, a contained magnetic body constituent is magnetized by a magnetic field application means 3, and then only a magnetic field due to the magnetized magnetic body constituent is detected by magnetic measurement means 8 and 10 containing a magnetic sensor 8 due to a superconductive quantum interference element(SQUID). In one example, a magnetic shield 4 prevents an external magnetic noise(Mo) from entering the magnetic sensor 8 and the pipeline 2 being placed near the magnetic sensor 8. In another example, the SQUID that is adjacent to the pipeline and the SQUID that is away from the pipeline are provided in the magnetic sensor 8 and a difference between the both SQUID outputs is obtained by the measurement circuit 10, thus canceling the external magnetic noise(Mo).