CCD Mosaics at CTIO and SOAR.

1. 2Kx4K 2Kx4K 2Kx4K 2Kx4K 2Kx4K 2Kx4K 2Kx4K 2Kx4K One Arcon 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). CCD Mosaics at CTIO and SOAR. 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 KPNO’s 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 < 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 and four ARCONs shown SDSU-2 ctrlr. Shielded cable Dewar 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 (@ 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 < 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-Mosaicand 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, @ 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 QE> 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 NOAO’s 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 @ 4 channel ea. 2 @ 2 channel ea. 2 @ 2 channel ea. 12 @ 12 channel ea. Controller – Dewar connection Direct (connector–connector) 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 ,H+SW rails per 1/2H-reg Wiring inside dewar Constantan & Cu wires Constantan & Cu wires flex Wires (Constantan&Cu), flex Detector cooling Radiative/conductive, LN2 LN2 Cryotiger Cryocooler Chip mount material; heater Al; emb. Nickel-Chromium wire Invar; embedded pwr-Rs 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 @ 2 e/ADU 10 µV/e, 3.1e @ 2 e/ADU 3 µV/e, <10e 1.8 µV/e, 5.9 e @ 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 (VJD=26V) 23.2V,10V,-4.7VOG1& -3.7VOG2 Detector issues Slow parallels => long readout Output amp glow for high V_OD Treat to improve QE and cosmetics PSF = f (V_backside_bias =< 80V)