Calculation of the output charge cloud from a microchannel plate

Abstract

The imaging performance of microchannel plate (MCP) detectors of photons and charged particles depends on the angular and energy distributions of the electrons in the output charge cloud. Measurements of these distributions are sparse and do not cover the full range of MCP operating parameters (input current, bias voltage, electrode design, channel length and channel diameter).Our two dimensional Monte Carlo model of the avalanche process in a single microchannel yields the output energy distribution of electrons (EDOE) and angular distribution of electrons (ADOE) for arbitrary channel geometries. The model has been validated by comparison with the available experimental data and used to examine the (a) effects of current saturation and (b) novel output electrode geometries. r

Preliminary Demonstration of an IonCCD as an Alternative Pixelated Anode for Direct MCP Readout in a Compact MS-Based Detector

“…Finally the depth of the nickel-based electrode penetration into the channel from the entrance and exit faces ('endspoiling') is twice the channel diameter (~20 μm). It has been calculated that the electrode endspoiling has an important influence on the output energy and angular distributions of electrons, (EDOE) and (ADOE), respectively [11].…”

“…The versatility of the MCP makes it a gain-producing element of choice for energetic particles (ionic and neutral species), electrons, X-rays, and from UV to IR when used with appropriate photocathodes. The broad descriptive work of MCPs can be found in early work [5][6][7][8][9][10][11][12][13][14][15][16].…”

Diagnostic Testing and NIKE Experiments

“…In addition, one needs some parameters that are not obtained from theory or tabulation but that are instead based on the extensive experimental work of Fraser and collaborators [7,8]. These include the escape probability for an a secondary electron at the surface, P,(O), the average energy required to create a secondary electron, e, and the secondary electron escape length, L,.…”

Monte Carlo simulations of microchannel plate detectors. I. Steady-state voltage bias results

“…In previous Monte Carlo simulations, 15,16,17,18 the possibility of the incoming electrons' elastic reflection was neglected. In our simulations, we found elastic scattering to be an important effect, particularly for low-bias voltages.…”

“…Scholtz et al 18 found that the following equation produced a good fit to the reflected fraction of secondary electrons vs. primary electron energy data:…”