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GMOS-S Array (Hamamatsu)

The upgraded GMOS-S detector array will consist of three ~ 2048x4176 Hamamatsu chips arranged in a row. Two of the detectors (CCDr and CCDg) will have an enhanced red response, these CCDs are referred to by the ITC as "Hamamatsu Red". The right-most CCD (CCDb, the blue end of spectral dispersion dispersion) in the focal plane array has improved blue response in addition to red response very similar to the Hamamatsu Red CCDs. This third CCD is referred to by the ITC as "Hamamatsu Blue". The orientation of the CCDs will remain unchanged and will continue to support the Nod and Shuffle observing mode. The plot below gives the anticipated QE comparison to the current E2V CCDs in GMOS-S. These QE plots are taken from general Hamamatsu information and lab measurements done in Hilo. See the Status and Availability webpage for more details.

 

 
QE Comparison for the GMOS-S CCDs upgrade. 

 

The table below summarizes some of the expected Hamamatsu detector/controller characteristics.

Array Hamamatsu
Pixel format ~ 6144x4176 pixels
Array layout Three ~ 2048x4176 chips in a row with ~ 1mm gaps
Pixel size 15 microns square; 0.0809 arcsec/pixel
Spectral Response approx 0.36 to 1.03 microns [ Hamamatsu Red data / Hamamatsu Blue data / plot ]
Bias level not yet available
Flat field response not yet available
Readout time not yet available
Chip CCDr CCDg CCDb
Chip ref no. BI5-36-4k-2 BI11-33-4k-1 BI12-34-4k-1
Dark current not yet available not yet available not yet available
Full Well ~185,000 e- ~177,000 e- ~177,000 e-
Fringing at 900nm not yet available not yet available not yet available

 

Values we be updated as detectors are characterized.

Readnoise and Gain Values

The table below will give gain/read-noise values for the new GMOS Hamamatsu CCDs operating with the SDSU controller once the detectors have been characterized. The values are averaged over all 12 amps. The full table of read-noise and gain values at all settings and for all amps is not yet available.

Readout Gain Resulting average
rate level Gain (e-/ADU) noise (e- rms)
Slow Low 5.86 3.97
Fast High 1.96 7.67
Fast Low 7.17 5.55

The Slow Read / High Gain mode will not be offered for the Hamamatsu CCDs as it has been deemed to be of little scientific use. Slow Read / Low Gain is the primary mode for science use. Fast Read / Low Gain may be of use, for example, with acquisition observations or for time resolved observations. Fast Read / High Gain is expected to be used primarily for very bright targets.