Characteristics of the Hubble Space Telescope's radiation environment inferred from charge-collection modeling of Near-Infrared Camera and Multi-Object Spectrometer dark frames

Abstract

Dark frames from orbiting infrared detector arrays are analyzed using a charge-collection model to investigate the effects of secondary and primary particle environments in infrared detectors and related electronics. The effects of different components of the primary and secondary environments are assessed by examining trends with time and pixel-to-pixel charge correlations. I. INTRODUCTION U SE OF sensitive infrared detectors in space poses significant challenges for the astronomy, military, and radiation-effects communities. These devices are designed to respond to the low levels of ionization deposited by infrared photons. This high detector sensitivity, coupled with the faintness of infrared sources typically observed by these detectors, necessitates that detectors operate at cryogenic temperatures, where charge mobilities are low and charges can become metastably trapped. As such, infrared detectors are susceptible to a rich variety of radiation effects that can be caused not just by proton-induced nuclear recoils and heavy ions but also by single low-LET (so-called minimum-ionizing) particles in the radiation environment [1]-[3]. Moreover, the faintness of most infrared sources of interest means that observations are often of long duration so there is ample opportunity for radiation effects to corrupt detector readings. Previous studies have reported significantly higher-than-expected rates of radiation-induced contamination in images Manuscript

Cosmic-ray-related Signals from Detectors in Space: The Spitzer/IRAC Si:As IBC Devices

“…The excess of hits below the minimum average ionizing particle yield (towards the left of Figure 5) has also been observed for the HST NICMOS HgCdTe arrays (Ladbury et al 2002) and the Gaia CCDs (Crowley et al 2016). To first order, this behavior is due to the statistical nature of ionization loss by an energetic particle, which proceeds by discrete interactions and hence is subject to statistical fluctuations.…”

“…Predicting and modeling the performance of such space missions depends on a thorough understanding of these spurious signals for the specific detector type employed. Information about this behavior has been summarized for the bolometers on Herschel (Horeau et al 2012), the CCDs on Gaia (Crowley et al 2016), the detectors on the Infrared Space Observatory (ISO) (Heras et al 1998(Heras et al , 2003, the Si:As IBC devices on Akari (Mouri et al 2011), and for NICMOS on the Hubble Space Telescope (HST) (Ladbury et al 2002). Preliminary studies are also available for the Spitzer IRAC detectors (Patten et al 2004;Hora et al 2006).…”

Proton-induced secondary particle environment for infrared sensor applications

“…The detector array pixels had significant charge sharing (particle-induced cross-talk) between the struck pixel and the neighboring pixels. Charge sharing by diffusion from the hit pixel to neighboring pixels appears to be an important mechanism in large-format IR detector arrays for the single-particle environment [2], [3]. For this experiment, the authors want to determine the total charge in each hit, including the charge in the struck pixel and the charge that spreads to neighboring pixels.…”

“…The higher than expected transient Manuscript rate was attributed to secondary particles and delta electrons. In addition, the possible role of secondary particles in the performance of the near-infrared camera multi-object spectrometer (NICMOS) camera has been studied [2]. NASA's James Webb Space Telescope (JWST) Program is investigating potential transient effects on prototype FPA hardware through modeling and testing [3].…”

Radiation-induced charge collection in infrared detector arrays

“…After considerable data processing and interpretation, onorbit data from a HgCdTe FPA in the NICMOS camera on the Hubble Space Telescope provides a rich data source for cosmic ray induced transients [11]. Fig.…”