The CCDs to be purchased are the Marconi (formerly EEV) 42-20. The detailed CCD procurement specification is available on-line as pdf or html.

The current CCD functionality is as follows:
 

CCD size	2048 pixels in the spectral direction
	1024 in the spatial direction
Pixel size	13.5µm square
Dark signal	The device is an MPP (Muliti pinned phase) device (also known as IMO - inverted mode operation). The CCD is expected to be operated at around -50 degrees C (TBC). A graph showing the predicted dark current, at the start and end of the mission, can be found here.
Electronic readout noise	about 8 electrons rms (corresponds to approximately 1 DN)
Quantum Efficiency	around 80%. The final QE will depend on the backside treatment adopted
Full well	About 90k electrons.

Notes:

There will be two readout amplifiers - one at each end of the serial readout register (see diagram below)

Readout rate - It is hoped that we can achieve 500khz (2µs per pixel)

no supplmentary buried channel is possible with the MPP device

Reading out the CCD

See the diagram below. There are two ways in which the CCD can be readout:

1. Define Window 1 (from 0 to 1023 pixels) which will be readout to the left hand amplifier A and define Window 2 (from 1024-2047 pixels) which will be read out to the right hand amplifier B;
2. Define Window A (from 0 to 2048 pixels) which can be readout either to the left hand amplifier A or to the right hand amplifier B.

The above diagram shows how the windows will be defined on the Marconi 42-20 CCD

This page was last changed on 23 May 2000

This page is maintained by Chris McFee