Scattering and the prediction of Quantum Efficiency and response time characteristics

Abstract

Quantum Efficiency from photocathodes and Yield from diamond secondary emitters are affected by scattering during electron transport in bulk material. The emission distribution is required to predict how current density and emittance from these sources affect beam transport in Particle-in-Cell codes, particularly MICHELLE. Monte Carlo is used to augment a standard Three-Step-Model (TSM) based model used for photocathodes, and to model secondary emission inside the thin film diamond flake in a Diamond Current Amplifier. In both, how electron bunches generated within the semiconductor material evolve under band bending and transport change how many are emitted, and consequently the temporal characteristics and phase space distribution of the emitted bunch are likewise changed. We describe the status of the emission models, how scattering changes the temporal characteristics, and progress in developing simple models to account for the effects of scattering in a manner appropriate for incorporation into MICHELLE.