| 摘要 |
<p>The imaging system uses a radiation detector (1) consisting of a drift chamber (12) and a multiwire proportional chamber both filled with gas. The source of radiation (S) produces a divergent beam which passes through a longitudinal slit (F) to give a flat beam in the plane of the slit. In a direction orthogonal to this plane, the chambers of the detector (1) have the drift space (12) of the electrons containing the cathode (11), a converter, a proportional multiplication anode (13) and a second cathode (14) placed next to the anode (13). The last 2 electrodes (13,14) are made of wire conductors extending in 2 planes parallel to the illumination beam in roughly orthogonal directions to allow a 2D location of the electron in the plane. The voltage applied to the wires forming the second cathode (14) varies according to position, to compensate for the variation in gain in amplification due to the divergence of the wires forming the anode (13).</p> |
