Cross section of the IMA and trajectories of incident ions and secondary electrons (start electrons and stop electrons). The IMA is a cylindrically symmetric analyzer which consists of an IMA-EA (the upper part) and an IMA-MA (the lower part); (elevation) and (azimuth) represent angles of incident ions. Two dashed lines in IMA-MA indicate the trajectories of secondary electrons, which generate start signals and stop signals for time-of-flight measurement. The straight solid line in the IMA-MA means the trajectories of neutrals, negative ions and high-energy ions that generate stop signals. A solid curve in the IMA-MA represents the trajectories of positive ions reflected by the LEF.
Schematic diagram of the MCP assembly with start electrons and stop particles. Start electrons generate start signals when the charge cloud emitted from the MCP passes through the start grid. The output signals of the resistive anode provide information regarding the azimuthal position of incident ions. Stop particles generate stop signals when the charge cloud hits the center anode.
Calculated (upper) and measured (lower) energy-elevation responses of IMA-EA. Contour lines indicate sensitivity equal to 1, 11, 21, 31…91% of the peak transmission. The angular scanning deflectors and the sensitivity control electrodes were grounded.
Calculated (left) and measured (right) energy-elevation responses of the IMA-EA. Each title of the panels shows the deflection voltage ratio. U (L): indicates that and , where , and denote the voltages applied to the upper deflector, to the lower deflector, and to the inner spherical deflector. Contour lines indicate sensitivity equal to 1, 11, 21, 31…91% of each peak transmission. The energy is normalized with that at and . The sensitivity control electrodes were grounded.
Calculated and measured angular responses of the IMA-EA. Solid curves and diamonds indicate calculation and measurement results, respectively. U (L): indicates that and .
Comparison between the dependence of the deflection angle on the supplied voltage obtained by calculation (solid curve) and by experiment (diamonds). The vertical axis shows the average elevation angle of incident ions. The horizontal axis shows the voltage ratio described as or . A negative (positive) voltage ratio denotes and .
Geometric factor when the upper or lower deflector is supplied with a different voltage. Comparison between the calculated (solid curve) and the measured (diamonds) geometric factor is also shown. The horizontal axis shows the voltage ratio described as or . A negative (positive) voltage ratio denotes and .
Geometric factor under the sensitivity control. Upper panel: , . Middle panel: , . Lower panel: , . The horizontal axis shows the voltage ratio , where indicates the voltage applied to the sensitivity control electrodes. Solid curves and diamonds indicate the calculation and measurement results, respectively.
Measured TOF profiles. Rectangle, plus, star, diamond and triangle marks in the upper panel denote, respectively, the profiles of , , , and beams with incident energy of just before entering the ultrathin carbon foil. Rectangle and cross marks in the lower panel denote, respectively, the profiles of and beams with incident energy of . The vertical scale is normalized by the count measured by a beam monitor.
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