| 摘要 |
<p>PURPOSE: To increase the magnetic field gradient of a magnetic detector having a magnetic pole mass made of a weakly magnetic material and improve the particle detecting efficiency of the detector by forming the external surface of the detector in a curved surface which comes into contact at least with a gap and can converge toward the gap. CONSTITUTION: An annular magnet 1 composed of samarium-cobalt, etc., is partially covered with two axial-direction magnetic pole masses 2 and 3 formed of a weakly magnetic material. A gap 4 is left between the masses 2 and 3, and the masses 2 and 3 have external surfaces 5 and 6 having curved cross sections which converge to the gap 4 adjacently to the gap 4. An assembly generates an induced electromagnetic field 7 having a diameter G1 and the displacement or movement of particles to be detected is limited to the line 8 corresponding to both ends of the magnet 1 in the axial direction. Therefore, the converging forms of the surfaces increase the magnetic field gradient and the detecting effect of a magnetic detector thus constituted around the gap and accelerate the holding of the particles to be detected.</p> |
