Large Dynamic Range Ion Spectrometer (LDRIS)

1. Large Dynamic Range Ion Spectrometer (LDRIS) Single microchannel plate Thin-window silicon photodiode -3 kV Gain 105 500 Single MCP -2 kV Fast, thin-window photodiode Total Gain/Ion = 5x107 Ammeter Reset Digital Output Controller, Data I/O Ammeter: converts charge deposited over a short accumulation interval to a digital word, which is the output. The accumulation register in the ammeter is cleared after each accumulation.

2. Large Dynamic Range Ion Spectrometer (LDRIS) • The LDRIS detector substantially extends the dynamic range of incident ion flux, allowing larger geometric factors that provide unprecedented, statistically significant measurements of low ion fluxes. • LDRIS uses a clocked ammeter circuit that is simpler in design and uses fewer resources than conventional CEM and MCP detectors. • 2) Problems of pulse pileup and gain saturation due to high ion fluxes in CEM and MCP detectors is eliminated using the current design. • 3) LDRIS has demonstrated (a) the ability to count individual ions and (b) a dynamic range approximately 100 times that of a conventional MCP detector. • Detection of Individual Ions: • Oscilloscope traces of detection of three individual detected ions • Custom electronics will greatly reduce noise Single microchannel plate Thin-window silicon photodiode • Gain of LDRIS as a function of input beam current: • Gain measured for both single particle mode (using oscilloscope) and sensitive ammeter. • Single MCP has unexpected nonlinear gain at high beam currents, allowing more headroom in nonlinear amplifier • MCP detector limited to about 10-12 A; LDRIS can measure at least 10-10 A, demonstrating an extension of dynamic range by a factor of at least 100.