Design Configurations Reducing Space Radiation Noise in Ultra-Sensitive Infrared Sensors*

This paper evaluates considerations in minimizing disruptions of scientific data in ultra-sensitive Infrared (IR) spaced-based telescopes by ions in space radiation and neutrons produced when ions react with the nuclei in high Z metallization.. Results of proposed designs are based on a model developed at Boeing. The components modeled are the spectra of the ions in cosmic rays and solar flares, the transport of the primary ions and secondary particles produced including neutrons, the generation electron hole pairs (EHPs) in the focal point array (FPA), and a component modeling transfer of EHPs from generation to recombination. Results indicate noise levels above 100 EHPs by secondary particles alone per pixel in solar flares and extra-galactic sources; these observations agree with empirical data sources. IR astronomical observatories now have a noise level of 100 electrons/pixel indicating the need of detailed radiation transport models; in near future designs where the pixel pitch reduces from 25 to 5 microns, the pixel noise levels are estimated to be as low as 10 electrons/pixel.