CCD Mosaics at CTIO and SOAR.

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CCD Mosaics at CTIO and SOAR.
Ricardo E. Schmidt, CTIO / NOAO
SDW2005, Taormina.
Abstract Mosaics based on 2K x 4K CCDs are
briefly reviewed.  An 8Kx8K mosaic of SITe002A
CCDs is in use at the 4m Blanco telescope.  At
the SOAR 4.1 m telescope E2V 44-82 CCDs are used
in an 4Kx4K Imager and another 4Kx4K mini-mosaic
utilizing CCID20 detectors will be employed by
the Goodman Spectrograph.  A 62 CCD mosaic
incorporating high resistivity CCDs from LBNL is
part of the Dark Energy Camera project that
should be available at the 4m Blanco telescope by
2009. Each of these four types of 2K x 4K CCDs
have two output amplifiers and 15 micron pixels.
SOAR IMAGER 4k x 4k Mini-Mosaic of E2V CCDs
4m BLANCO 8K x 8K MOSAIC-2 (Imager).
A Mini-Mosaic made of two CCD44-82 detectors
covers a 5.5 x 5.5 arcmin FOV at 0.08 / pix on
the SOAR 4.1m telescope. It includes twin
filter wheels -5 positions ea.- and a fast
linear shutter. This Imager started operations
in 2004.
8 three-side buttable SITe002A CCDs are used by
Mosaic-2 to cover a FOV of 36 x 36, at a scale
of 0.27/ pix. Its shutter and a 14-filter
track running in a loop over the dewar top- are
both pneumatically actuated. This wide field
Mosaic Imager has been in regular use for the
past 6 years at the 4m Blanco telescope and is
typically scheduled 120 nights per year.
Mosaic-2 is a copy of KPNOs Mosaic-1. However
to read out Mosaic-2 uses 16 channels whereas
Mosaic-1 uses 8 channels. One Mosaic image
represents 140 MB of data. The peak QE for
SITe002As is 85 at 600 nm the CCDs run at -95
oC. Fringing is lt 5 in the I band, there is
some low level crosstalk which gets successfully
removed, there are no after-images. Grounding
CCDs are wired to the corresponding Arcon star
point -at the Arcon backplane (multilayer planar
PCB)- and are isolated from the detector mount
and dewar.
Dewar
Shielded cable
SDSU-2 ctrlr.
Dewar and four ARCONs shown
M83 This SOI 5x5 arcminutes color image,
obtained on February 16th 2005, is composed of
two sets of 0.7 arcsec FWHM images taken at the
B, V and R filters. A 20 arcseconds shift was
applied between the two sets of observations in
order to eliminate the central gap of the CCDs
mosaic in the final image.
A LabVIEW based GUI called ArcVIEW is used with
this Imager. ArcVIEW uses a Client / Server
scheme and runs in a Linux environment on a PC.
An image binned 4x4 is read out in 6 sec (_at_ RON
of 3.8 e).
Heat exchanger
2xCCD44-82 (E2V) 3 edge buttable, CCD44-82s have
an extra FET to buffer the output stage (hence 2
drain voltages). Setting V_OD too high causes
amplifier glow. This CCD has two Outputs Gates
and also a Dump Drain.
8K x 8K Mosaic
At the telescope images show fringing of lt 2 in
the I band. No after- images are seen.
SOAR Goodman Spectrograph
DECAM on 4m BLANCO
Feed through bd.
P.I. Chris Clemens
(UNC). With Long-slit Multi-slit capabilities
it uses a 4k x 4k Mini-Mosaic and covers an
effective FOV of 7.2 diameter on SOAR, at a
scale of 0.15 / pix. Observing will start in
2005.
Dark Energy Camera, a collaboration -lead by
Fermilab- to build a 62 CCD Imager. DECAM will
be used for a 5000 sq. deg. survey to
constrain the Dark Energy parameter w to
5. DECAM observing to start in 2009.
CCID20
Collimator
62 CCD Imager, FOV 2.2 deg diam and active area
diameter 448 mm, _at_ 0.27/pix on 4m Blanco PF.
Frontend electronics
Articulated Camera
LBNL high resistivity, n-type silicon CCD which
can be fully depleted. Clock and bias voltages
are reversed in sign from conventional CCDs.
This 4 side buttable, back illuminated CCD has a
QEgt 50 at 1000 nm. These CCDs 1) Use a
buried p-channel 2) Use substrate bias
voltage to fully deplete substrate and
control PSF 3) Require special erase
procedure The CCDs will be packaged by Fermilab.
DEWAR FOR GOODMAN
Controller
This system is optimized for the UV/Blue. The
CCID20 requires sequencing of reset and drain
voltages on power up and power down of the
two, the output drain should be the last to be
turned on and the first to be turned off. The
CCID20 uses high resistivity bulk silicon
thinned to 40 µm and hence there is an asociated
red QE boost and less fringing due to larger
thickness. This 3 side buttable CCD is
back-illuminated but not MPP. For the CCID20 we
get a lowest noise of 1.9 e- at a conversion gain
of 0.4 e- / ADU. We treated the CCID20 with dry
air plus heat to solve some cosmetic problems and
to get an increased QE.
Cryotiger
2 x CCID20
The DECAM instrument will replace the Blanco 4m
Prime Focus Cage
NOAOs Monsoon controller will be used to read
out the 62 CCDs. 18 CCDs will be treated as 6
groups of 3, with the assumption that the same
clock rails can be applied to groups of 3 CCDs.
oTCCD will be read for each CCD and used for QE
corrections.
A scroll shutter design is being tested.
MOSAIC-2
SOAR IMAGER
GOODMAN SPECT.
DECAM
2K x 4K CCDs with 15 micron pixels
8 x SITe 002A
2 x E2V CCD44-82
2 x MIT/LL CCID20
62 x LBNL 2Kx4K
CCD technology (all w. 2 output amps)
Thinned, n-channel
Thinned, n-channel
Hi Rho (40 µm), n-chan.
Hi Rho (250 µm), p-chan.
Controller
4 x ARCON
SDSU-2
SDSU-2
4 x MONSOON
Video boards (total)
4 _at_ 4 channel ea.
2 _at_ 2 channel ea.
2 _at_ 2 channel ea.
12 _at_ 12 channel ea.
Controller Dewar connection
Direct (connectorconnector)
0.5m cable
1.2m cable
0.7m cable
Controller cooling
Passive
Liquid coolant
Liquid coolant
Liquid coolant (rack)
Electronics inside dewar
None
None
None
t.b.d.
Shared signals
Clock rails per 3 CCDs
RGL/R, DD/RDL per H-reg
RG per H-reg, PU/L per CCD
LGA/B ,HSW rails per 1/2H-reg
Wiring inside dewar
Constantan Cu wires
Constantan Cu wires
flex
Wires (ConstantanCu), flex
Detector cooling
Radiative/conductive, LN2
LN2
Cryotiger
Cryocooler
Chip mount material heater
Invar embedded pwr-Rs
Al emb. Nickel-Chromium wire
Invar 8x FETs on PCB
Invar pwr-Rs
Times (dwell, pixel, readout) for bin 1x1
3.6 µs, 14 µs, 100s
1 µs, 3.7 µs, 20 s
1 µs, 3.7 µs, 20s
1 µs, 4 µs, 20s
CCD responsivity, RON
5 µV/e, 3.8 e _at_ 2 e/ADU
10 µV/e, 3.1e _at_ 2 e/ADU
3 µV/e, lt10e
1.8 µV/e, 5.9 e _at_ 2.4 e/ADU
Typical biases V_OD, V_RD, V_OG
25 V, 14.3 V, 2 V
18.5 V, 12.7 V, -1 V
-22 V, -12.5 V, 2.2 V
(VJD26V) 23.2V,10V,-4.7VOG1 -3.7VOG2
Detector issues
Slow parallels gt long readout
Output amp glow for high V_OD
PSF f (V_backside_bias lt 80V)
Treat to improve QE and cosmetics