Speaker
Description
Charge sharing deteriorates the spatial and spectral performance of spectroscopic imaging systems which exploit the small-pixel effect, such as HEXITEC. As charge sharing may be produced by multiple non-exclusive physical processes, a diverse range of charge carrier behaviours exist within charge sharing events – with each multipixel event containing process-specific spatial and spectral distortions. The performance of generalised methods of charge sharing correction are therefore limited by their one-size-fits-all approach. Traditional, generalised charge sharing correction results in either significant sensitivity loss when using Charge Sharing Discrimination (CSD), or significant energy and spatial resolution loss when using Charge Sharing Addition (CSA). These limitations represent a key barrier preventing high-performance spectroscopic imaging within low flux applications.
Shape analysis of multipixel events exploits event-shape-specific energy information to infer the charge carrier behaviour and interaction process most-likely to be responsible for a given multipixel event. This allows existing process-specific methods for spectral and spatial reconstruction to be applied only to events, or portions of multipixel events, which require correction.
Event shape analysis was carried out at 141 keV. This indicated >99.6% of events resulted from 10 event shapes. The most-likely charge carrier behaviours for each high-likelihood event shape was determined. Current methods for spectral and spatial reconstruction were adapted for effective application within HEXITEC data. Event-shape-specific charge sharing correction was carried out for 2-pixel events, producing process-specific images which were combined to create a final reconstructed image. This new approach to charge sharing correction achieved significant sensitivity improvements when compared to CSD (17.3M vs 8.7M total image counts), reduced energy resolution loss in comparison to CSA (0.7% vs 1.2% at 141 keV) and improved spatial resolution when compared to either CSD or CSA (500 μm vs 580 μm FWHM).