Detector Characteristics for Mount Hamilton Facility Instruments

Comparison of CCD's in Hamilton Spectrograph Dewars 4, 6 and 8
Dewar 6 and 8 CCDs are 2048x2048 with 15um pixels, but their performance characteristics differ significantly. Dewar 6 has somewhat better blue response and is much less susceptible to particle events. Dewar 8 has excellent red response and narrower line profiles (narrow-slit fwhm of about 1.45 pixels as compared to about 2.2 for dewar 6), but particle events are much more common and tend to leave longer trails. Compare 30-minute darks.

Dewar 4 CCD is 4096x4096 with 12um pixels. It is less susceptible to particle events than Dewar 8 and has narrower line profiles than Dewar 8. Dewar 4 shows fringing in the red (21.3% at 8000A, and 54.8% at 10000A).

Dewar 6 shows some fringing in the red, and has a few bad columns; Dewar 8 has no fringing and no bad columns. Their respective read noise and dark current are given in the following table; their QE's are plotted below.

Dewar 4 Dewar 6 Dewar 8
Type E2V Back Illuminated CCD
4096x4096
12um pixels
Type Lick3 L4-9-00AR
Thin 2048x2048
15um pixels
Type LBNL 2048x2048
hz back CCD
15um pixels
Read noise 5.7 e- slow
10.1 e- fast
Read noise 8.7 e- slow
10.1 e- fast
Read noise 3.8 e-
Dark current 2 e-/pixel/hour @-80c
Dark current 16 e-/pixel/hour @-118c
Dark current 40-57 e-/pixel/hour @-135c
N.B. The QE for dewar 8 in the above plot was measured at -115 c. QE may be slightly lower at lower temperatures. (stats courtesy of the Lick Detector Lab)