Journal Article

Laboratory and In-Flight Measurements at 10a\55A K of InSb Near-Infrared Detector Performance for the Warm Mission of the AKARI Satellite

Kaneda, Hidehiro, Wada, Takehiko, Ishihara, Daisuke, Oyabu, Shinki, Mori, Tatsuya

2011

Overview

The warm mission phase of AKARI, the Japanese infrared astronomical satellite, has started after its 180A liter liquid helium cryogen was exhausted. Since then, we have conducted near-infrared observations with the Infrared Camera (IRC), while the telescope is slowly warming up. To explore the possibility of continuing observations at higher temperatures, we evaluate the performance of the InSb detector array, a flight backup model for the IRC, in a laboratory at various operating temperatures between 10A K and 55A K. By combining the laboratory measurements with the in-flight measurements of the AKARI/IRC detector array, we consistently derive the changes of relative sensitivity, dark current, total noise, and the number of hot pixels with operating temperature. All of them show small changes in a range of temperature from 10A K to 40A K. However, at temperatures above 40A K, the dark current and the number of hot pixels start to increase rapidly, while the relative sensitivity decreases and the total noise increases gradually. We obtain the dependence of the performance on bias voltages to suggest an optimal operation for a future AKARI warmer phase.