The Effects of Charge Persistence in Aladdin III InSb Detectors on Scientific Observations

Charge persistence is signal that remains on a detector array after the illumination source has been removed. It is a characteristic of many types of photo detectors but is particularly prominent in near-infrared arrays that utilize Indium Antimonide (InSb) as a photosensitive material. Persistence can be a significant issue for a scientific observation with the potential of reducing the quality of the data. We have studied the properties of persistence for an Aladdin III array from Raytheon which is installed in the Keck Observatory’s adaptive optics camera, NIRC2. In this paper we discuss the types of observations that are at risk from persistence effects. We present data on the characteristics which include the following results: 1) the level of persistence is more strongly influenced by incident flux than that of fluence (flux x integration time), 2) the persistence is wavelength independent, 3) the persistence level is not reduced by continuous reset-reads of the array or “flushing”, 4) the determination that the persistence decay scales with a power law and is proportional to 1/t.