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Detector Characteristics

The current detector is a Hawaii-2 array fabricated by Teledyne Imaging Sensors (FPA number 109). The measured properties of the science detector array are given in the table below. The FLAMINGOS-2 dark current is set by the properties of the HAWAII-II array. The quantum efficiency of the array as measured by Teledyne is 65.6% at J and 49.8% at K.

The read noise of FLAMINGOS-2 is a function of both the HAWAII-II chip and the MCE-4 electronics. The mean RMS read noise for a single CDS pair, referenced to a single read, is between 11.6 e- to 14.3 e- depending on the VRESET value used. For multiple reads, the read noise drops more slowly than 1/√(nreads), which is the theoretical ideal expectation; this is in keeping with the results of other groups with HAWAII-II Fowler sampling. An effective read noise of <5 e- RMS is achieved for nreads of 8 or higher.

The array linearity is illustrated in this plot, which shows the linearity of laboratory data obtained in the Ks band. The FLAMINGOS-2 detector/electronics response is linear to <0.5% over the range from ~4000 ADU to ~22,000 ADU. Saturation is reached at ~35,000 ADU.


 

Detector Characteristics
Array Hawaii-II (HgCdTe) FPA 109
Pixel format 2048x2048 18-micron pixels
Spectral Response 0.9 - 2.4 microns
Dark Current 0.5 e-/s/pix
Read noise (single CDS pair) 11.7 ± 0.2 e-
Read noise (nreads ≥ 8) < 5 e-
Gain 4.44 ± 0.35 e-/ADU
Well depth 155,400 e-
Quantum efficiency ~ 65.6% in J band