Modeling the impact of preflushing on CTE in proton irradiated CCD-based detectors

Abstract

A software model is described that performs a "real world" simulation of the operation of several types of charge-coupled device (CCD)-based detectors in order to accurately predict the impact that high-energy proton radiation has on image distortion and modulation transfer function (MTF). The model was written primarily to predict the effectiveness of vertical preflushing on the custom full frame CCD-based detectors intended for use on the proposed Kepler Discovery mission, but it is capable of simulating many other types of CCD detectors and operating modes as well. The model keeps track of the occupancy of all Phospho- rous-Silicon (P-V), Divacancy (V-V) and Oxygen-Silicon (O-V) defect centers under every CCD electrode over the entire detector area. The integrated image is read out by simulating every electrode-to-electrode charge transfer in both the vertical and horizontal CCD registers. A signal level dependency on the capture and emission of signal is included and the current state of each electrode (e.g., barrier or storage) is considered when distributing integrated and emitted signal. Options for performing preflushing, preflashing, and including mini-channels are available on both the vertical and horizontal CCD registers. In addition, dark signal generation and image transfer smear can be selectively enabled or disabled. A comparison of the charge transfer efficiency (CTE) data measured on the Hubble space telescope imaging spectrometer (STIS) CCD with the CTE extracted from model simulations of the STIS CCD show good agreement.Index Terms-Charge-coupled device (CCD), charge transfer efficiency (CTE), preflushing, proton.

Radiation effects on photonic imagers-a historical perspective

“…Even if the CTI is known, the effect on imaging performance still has to be calculated. Several authors [102], [103] have developed models for predicting CCD performance for particular operating conditions, but care is still needed to extrapolate results to other situations. Even for high signal applications, where CTI damage is reduced, CCDs are restricted to displacement damage doses below 5 10 MeV/g.…”

Found! A CCD that meets space astrometry requirements

“…A simulated CCD is instantiated using specific parameters such as pixel size, row shift timing, dark current, etc. Electrons are transited across the simulated CCD, with trap capture and release calculations at each time step calculated using a method derived from Philbrick's [12] treatment, with some modifications. The electrons are then "read out" as part of the shifting process, and can be post-processed in a fashion similar to actual CCDs readouts.…”