A CIRCULAR MICROCHANNEL PLATE (MCP), A SECONDARY-ELECTRON MULTIPLIER WHICH DETECTS AND AMPLIFIES ELECTRONS IN TWO-DIMENSIONS. IT COMPRISES OF TWO CHANNELLED PLATES COATED IN A SEMICONDUTOR SUBSTANCE. WHEN A VOLTAGE IS APPLIED ACROSS THE INPUT-SIDE AND OUTPUT-SIDE ELECTRODES OF THE MCP, A POTENTIAL GRADIENT IS BUILT-UP ALONG THE CHANNEL DIRECTION. IF AN INCIDENT ELECTRON STRIKES AN INNER WALL ON THE INPUT SIDE, A NUMBER OF SECONDARY ELECTRONS ARE EMITTED. THESE SECONDARY ELECTRONS ARE ACCELERATED BY THE POTENTIAL GRADIENT AND TRAVEL ALONG A PARABOLIC PATH DETERMINED BY THE INITIAL VELOCITY. THEY THEN COLLIDE WITH THE OPPOSING WALL SURFACE, CAUSING SECONDARY ELECTRONS TO BE EMITTED AGAIN. IN THIS MANNER, THE ELECTRONS COLLIDE REPEATEDLY WITHIN THE CHANNEL AS THEY PASS TOWARDS THE OUTPUT SIDE. THE RESULT IS A LARGE MULTIPLICATION OF THE INCIDENT ELECTRON. THE MCP IS USED AS A DETECTOR FOR PARTICLES IN MASS SPECTROMETRY.

CLASSIFICATION HAS BEEN DETERMINED IN ACCORDANCE WITH THE FOLLOWING:- GENERAL INTERPRETATIVE RULES (GIR)S GIR 1 HAS BEEN USED TO CLASSIFY THIS PRODUCT BY THE TERMS OF HEADING 8541 FOR DIODES, TRANSISTORS AND SIMILAR SEMICONDUCTOR DEVICES; PHOTOSENSITIVE SEMICONDUCTOR DEVICES, INCLUDING PHOTOVOLTAIC CELLS WHETHER OR NOT ASSEMBLED IN MODULES OR MADE UP INTO PANELS; LIGHT-EMITTING DIODES; MOUNTED PIEZOELECTRIC CRYSTALS GIR 6 HAS BEEN USED TO CLASSIFY THE GOODS TO SUBHEADING LEVEL 8541 40 FOR PHOTOSENSITIVE SEMICONDUCTOR DEVICES, INCLUDING PHOTOVOLTAIC CELLS WHETHER OR NOT ASSEMBLED IN MODULES OR MADE UP INTO PANELS; LIGHT-EMITTING DIODES CN 854140 90 FOR OTHER THAN LIGHT-EMITTING DIODES, INCLUDING LASER DIODES TARIC 85414090 90 FOR OTHER THAN ELSEWHERE SPECIFIED IN THIS COMMODITY CODE