A Novel Single-ion Monitoring System Based On Coincident Measurement Of Both Position And Time

Single-ion monitoring is a key requirement in many energetic heavy-ion experiments.For example,in laboratory simulation of the single event effect（SEE）of semiconductor devices under heavy ion bombardments,the ion flux and the arrival position of individual ions on the device surface are key parameters for evaluating the cross sections of various SEE processes.The measurement precision of these parameters directly affects the calculation accuracy of related SEE cross sections.On the other hand,the measurement of the ion arrival time is helpful to the correlation analysis of SEE events.In this work,a two-dimensional position-sensitive and timing monitor of individual ions has been developed based on the coincident measurement of both position and time.When energetic heavy ions pass through a solid foil,secondary electrons are generated on both sides of the foil.They are guided by parallel electrostatic and magnetic fields to corresponding detectors.Both the hitting position and the arrival time of the secondary electrons on corresponding detectors can be measured.The penetrating position and time of incident ions through the foil are obtained by coincident measurement of both the electron-detecting position and time.Background events usually do not pass through this position-timing dual coincidence.The monitor is composed of a 6μm thick aluminum foil,a pair of electrode arrays,a pair of microchannel plate（MCP）detectors installed face to face,and a set of magnetic components.The electrode arrays create a uniform electrostatic field for the monitor.The magnetic components create a uniform magnetic field.The MCP detector employs a copper wire anode with no insulating surfaces and integrates four spectroscopy amplifiers and a timing amplifier,which are all designed in this work.The spectroscopy amplifiers collect anode charge and give the particle position information.The timing amplifier obtains the particle time information from the detector high-voltage circuit.It is tested with an ²⁴¹Amαsource.A position resolution of 1.0 mm and an event-recording time resolution of 50 ns have been realized.It has been proven that the monitor can discriminate true events from heavy background radiations.The performance of the monitor fulfills the requirements of laboratory SEE experiments.