1. DARK ENERGY SURVEY (DES) Francisco Javier Castander Serentill All material borrowed from DES collaboration IEEC/CSIC

2. Announcement of Opportunity Blanco Instrumentation Partnership Develop a major instrument for Blanco 4m CTIO Submit a science, technical & management plan Community instrument Up to 30% of Blanco 4m for 5 years commencing in 2007 or 2008 Letter of intent March 15, 2004 Proposals August 15 2004

3. The Science Case for the Dark Energy Survey James Annis For the DES Collaboration

4. The Dark Energy Survey We propose to make precision measurements of Dark Energy –Cluster counting, weak lensing and supernovae –Independent measurements by mapping the cosmological density field to z=1 –Measuring 300 million galaxies –Spread over 5000 sq-degrees using new instrumentation of our own design. –500 Megapixel camera –2.1 degree field of view corrector –Install on the existing CTIO 4m

5. Cosmology in 2004 Combine to measure parameters of cosmology to 10%. We enter the era of precision cosmology. – Confirms dark energy (!) 2003 Science breakthrough of the year WMAP measures the CMB radiation density field at z=1000 Sloan Digital Sky Survey measures the galaxy density field at z < 0.3

6. The Big Problems: Dark Energy and Dark Matter Dark energy? Who ordered that? (said Rabi about muons) Dark energy is the dominant constituent of the Universe Dark matter is next The confirmation of Dark Energy points to major holes in our understanding of fundamental physics 1998 Science breakthrough of the year 95% of the Universe is in forms unknown to us

7. Dark Energy 1.The Cosmological Constant Problem Particle physics theory currently provides no understanding of why the vacuum energy density is so small:  DE (Theory) /  DE (obs) = 10 120 2.The Cosmic Coincidence Problem Theory provides no understanding of why the Dark Energy density is just now comparable to the matter density. 3.What is it? Is dark energy the vacuum energy? a new, ultra-light particle? a breakdown of General Relativity on large scales? Evidence for extra dimensions? The nature of the Dark Energy is one of the outstanding unsolved problems of fundamental physics. Progress requires more precise probes of Dark Energy.

8. One measures dark energy through how it affects the universe expansion rate, H(z): H 2 (z) = H 2 0 [  M (1+z) 3 +  R (1+z) 4 +  DE (1+z) 3 (1+w) ] matter radiation dark energy Note the parameter w, which describes the evolution of the density of dark energy with redshift. A cosmological constant has w =  1. w is currently constrained to ~20% by WMAP, SDSS, and supernovae Measurements are usually integrals over H(z) r(z) =  dz/H(z) Standard Candles (e.g., supernova) measure d L (z) = (1+z) r(z) Standard Rulers measure d a (z) = (1+z)  1 r(z) Volume Markers measure dV/dzd  = r 2 (z)/H(z) The rate of growth of structure is a more complicated function of H(z) Measuring Dark Energy

9. DES Dark Energy Measurements New Probes of Dark Energy –Galaxy Cluster counting 20,000 clusters to z=1 with M > 2x10 14 M  –Weak lensing 300 million galaxies with shape measurements –Spatial clustering of galaxies 300 million galaxies Standard Probes of Dark Energy –Type 1a Supernovae distances 2000 supernovae

10. Supernova Type 1a Supernovae magnitudes and redshifts provide a direct means to probe dark energy –Standard candles DES will make the next logical step in this program: –Image 40 sq-degree repeatedly –2000 supernovae at z < 0.8 –Well measured light curves SCP Essence LSST DES SNAP 2000 20052010 2015 2020 SDSS Current projects CFHLS PanStarrs Proposed projects

11. New Probes of Dark Energy Rely on mapping the cosmological density field Up to the decoupling of the radiation, the evolution depends on the interactions of the matter and radiation fields - ‘CMB physics’ After decoupling, the evolution depends only on the cosmology - ‘large-scale structure in the linear regime’. Eventually the evolution becomes non-linear and complex structures like galaxies and clusters form - ‘non-linear structure formation’. z = 30 z = 0

12. Spatial Clustering of Galaxies The distribution of galaxy positions on the sky reflects the initial positions of the mass Maps of galaxy positions are broken up in photometric redshift bins The spatial power spectrum is computed and compared with the CMB fiducial power spectrum. The peak and the baryon oscillations provide standard rulers. DES will –Image 5000 sq-degrees –Photo-z accuracy of  z < 0.1 to z = 1 –300 million galaxies Cooray, Hu, Huterer, Joffre 2001 LSST DES SNAP 2000 20052010 2015 2020 Planck SDSSWMAP PanStarrs

13. Weak Lensing D s distance to source D l distance to lens D ls distance from lens to source Light path Background galaxy shear maps Lensing galaxies Weak lensing is the statistical measurement of shear due to foreground masses A shear map is a map of the shapes of background galaxies

14. Weak Lensing Shear maps(z) Galaxy map z = 1/4 z = 1/2 z = 3/4 DeepLensCFHLS The strength of weak lensing by the same foreground galaxies varies with the distance to the background galaxies. –Measure amplitude of shear vs. z –shear-galaxy correlations –shear-shear correlations DES will –Image 5000 sq-degrees –Photo-z accuracy of  z < 0.1 to z = 1 –10-20 galaxies/sq-arcminute LSST DES SNAP 2000 20052010 2015 2020 Planck SDSSWMAP PanStarrs

15. Peaks in the Density Field Clusters of galaxies are peaks of the density field. Dark energy influences the number and distribution of clusters and how they evolve with time. 2 Mpc 16 Mpc

16. Cluster Masses Our mass estimators –Galaxy count/luminosity –Weak lensing –Sunyaev-Zeldovich The South Pole Telescope project of J. Carlstrom et al. DES and SPT cover the same area of sky Self calibration –Mass function shape allows independent checks –Angular power spectrum of clusters –Allows an approach at systematic error reduction SZ Optical Lensing X-ray Mass

17. Cluster Counting Locate peaks in the density field using cluster finders –Red sequence methods –SZ peaks DES will –Image 5000 sq-degrees –Photo-z accuracy  z = 0.01 to z = 1 –20,000 massive clusters –200,000 groups and clusters z = 0 1 3 z N LSST DES SNAP 2000 20052010 2015 2020 Planck SDSSWMAP PanStarrs Low mass High mass Very massive 13.7  log M < 14.2 14.2  log M 14.5  log M

18. We aim at ~5% precision on Dark Energy Cluster Counting Weak Lensing Supernova The Planck satellite will provide tighter input CMB measurements, and the constraints will improve slightly. w w w  DE MM MM Joint constraints on w and w a are promising: initial results suggest  w a ~ 0.5.  w ~ 5% and   DE ~ 3%

19. The Dark Energy Survey We propose the Dark Energy Survey –Construct a 500 Megapixel camera –Use CTIO 4m to image 5000 sq-degrees –Map the cosmological density field to z=1 –Make precision measurements of the effects of Dark Energy on cosmological expansion: Cluster counting Weak lensing Galaxy clustering Supernovae 5000 sq-degrees Overlapping SPT SZ survey 4 colors for photometric redshifts 300 million galaxies

20. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Design of the Dark Energy Survey James Annis

21. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Science Goals to Science Objective To achieve our science goals: –Cluster counting to z > 1 –Spatial angular power spectra of galaxies to z = 1 –Weak lensing, shear-galaxy and shear-shear –2000 z<0.8 supernova light curves We have chosen our science objective: –5000 sq-degree imaging survey Complete cluster catalog to z = 1, photometric redshifts to z=1.3 Overlapping the South Pole Telescope SZ survey 30% telescope time over 5 years –40 sq-degree time domain survey 5 year, 6 months/year, 1 hour/night, 3 day cadence

22. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DARK ENERGY SURVEY (DES) Science Goal: measure w=p/ρ, the dark energy equation of state, to a precision of δw ≤ 5%, with Cluster Survey Weak Lensing Galaxy Angular Power Spectrum Supernovae

23. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DES: Requirements Science Goals Cluster Survey Weak Lensing Galaxy Angular Power Spectrum Supernovae Science Requirements redshifts, area, filters, limit mag, red image quality, area photometry, area, limit mag repeat, area, filters, red

24. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Science Requirements 1.5000 sq-degrees Significantly overlapping the SPT SZ survey area To be completed in 5 years with a 30% duty cycle 2.4 bandpasses covering 390 to 1100 nm SDSS g,r,i,z z modified with Y cutoff 3.Limiting magnitudes g,r,i,z = 24,24,24,23.6 10σ for small galaxies 4.Photometric calibration to 2% 1% enhanced goal 5.Astrometric calibration to 0.1” 6.Point spread function Seeing < 1.1” FWHM Median seeing <= 0.9” g-band PSF can be 10% worse Stable to 0.1% over 9 sq- arcminute scales From chapter 3 of NOAO proposal; version 3 of requirements. Version 4, under review, will be a formal science requirements document.

25. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Limiting Magnitude Limiting magnitude (10σ for small galaxies) was set by flow down of science goals: ½ L* cluster galaxies at redshift 4000A break leaving blue filter –g,r,i,z = 22.8,23.4,24.0,23.3 –Complete cluster catalog Galaxy catalog completeness –g,r,i,z = 22.8,23.4,24.0,23.6 –Simple selection function Blue galaxy photo-z at faint mags –g,r,i,z = 24.0,24.0,24.0,23.6 –Photo-z for angular power spectra and weak lensing 0 redshift 1.5 Mag of ½ L* galaxy photo-z – spectro-z i = 23-24 Red Galaxy

26. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Galaxy Cluster Redshifts the distribution of the number of clusters as a function of redshift is sensitive to the dark energy equation of state parameter, w. four filters (griz) track 4000 Å break. Need z band filter to get out to redshift >~ 1 DES data will enable cluster photometric redshifts with dz~0.02 for clusters out to z~1.3 for M > 2x10 14 M  Theory

27. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Photometric Redshifts Resulting limiting magnitudes give very good photometric redshifts Monte Carlo simulations of photometric redshift precision –Evolving old stellar pop. SED –Redshifted and convolved with filter curves. Noise added. –Polynomial fit to photo-z –For clusters, averaging all galaxies in the cluster above limiting magnitude. Template fit for photo-z These are sufficient to achieve our science goals. ½ L*2 L* 1.0x10 14 M 0 Clusters Red galaxies

28. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO The Footprint Requirements Overlap with SPT SZ survey Redshift survey overlap Footprint -60 <= Dec <= -30 SDSS Stripe 82 + VLT surveys Overlap targetRight Ascension (deg) Declinatio n (deg) Area (sq. deg.) SPT-60 to 105 -75 to -60 -30 to -65 -45 to –65 4000 SDSS Stripe 82-50 to 50-1.0 to 1.0200 Connection region 20 to 50-30 to –1.0800 DIRBE dust map, galactic coordinates

29. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Survey Strategy I Design decision 1: area is more important than depth –Image the entire survey area multiple times Design decision 2: tilings are important for calibration –An imaging of the entire area is a tiling –Multiple tilings are a core means of meeting the photometric calibration requirement: offset tilings, not dithers Design decision 3: substantial science with year 2 data –We will aim for substantial science publications jointly with the public release of the year 2 data.

30. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Survey Strategy II Year 2 –g,r,i,z 100 sec exposures –g,r,i,z =24.6, 24.1, 23.6, 23.0 –Calibration: abs=2.5% rel=1.2% –Clusters to z=0.8 –Weak lensing at 12 gals/sq-arcmin Year 5 –z 400 sec exposures –g,r,i,z =24.6, 24.1, 24.3, 23.9 –Calibration: abs=<2% rel=<1% –Clusters to z=1.3 –Weak lensing at 28 gals/sq-arcmin Two tilings/year/bandpass In year 1-2, 100 sec/exp In year 3, drop g,r and devote time to i,z: 200 sec/exp In year 5, drop i and devote time to z: 400 sec/exp If year 1 or 2 include an El Nino event, we lose ~1 tiling, leaving three tilings at the end of year 2. This is sufficient to produce substantial key project science.

31. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DES Time Allocation Model September: 4 bright+ 4 dark nights 22 nights October: 4 bright+ 5 dark nights 22 nights November: 4 bright+ 4 dark nights 22 nights December: 4 bright+ 4 dark nights 21 nights Telescope shut down Dec 25, 31 January: 4 bright+ 5 dark nights 11 nights and the 2 nd half of all nights February: 3 bright+ 3 dark nights 11 nights and the 2 nd half of all nights March – August all none T otal 257 nights 108 nights Time to the Community and to the Dark Energy Survey

32. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Time Allocation Analytic calculation of time available –30 year CTIO weather statistics –5 year moving averages –Calculate photometric time –Can complete imaging survey and time domain survey with 3 sq-degree field of view camera Simulations of observing process –Use mean weather year –Survey geometry –Observing overhead –NOAO time allocation model –High probability of completing core survey area in time allocated Probability of obtaining 8 tilings per year over survey area. Dark is 100%, light yellow ~50% => DES time allocation model just sufficient to achieve science objective. CTIO mean weather year

33. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Photometric Calibration Strategy Calibrate system response –Convolve calibrated spectrum with system response curves to predict colors to 2% –Dedicated measurement response system integrated into instrument Absolute calibration –Absolute calibration should be good to 0.5% –Per bandpass: magnitudes, not colors –Given flat map, the problem reduces to judiciously spaced standard stars Relative calibration –Photometry good to 2% –Per bandpass: mags, not colors –Use offset tilings to do relative photometry Multiple observations of same stars through different parts of the camera allow reduction of systematic errors Hexagon tiling: –3 tilings at 3x30% overlap –3 more at 2x40% overlap –Aim is to produce rigid flat map of single bandpass –Check using colors Stellar locus principal colors

34. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Survey Simulation We plan a full scale simulation effort –Led by Huan Lin –Centered at Fermilab and Chicago –Using analytic, catalog and full image simulation techniques Over 4 years –Underway, starting with photometric redshift simulations Use the simulations in 3 ways: –Check reduction code Mock data reduction challenge Chris Stoughton –Prepare analysis codes Mock data analysis challenge Josh Frieman –Prepare for science Survey simulations –Jim Annis Catalog level simulations –Lin, Frieman, students for photo-z and galaxy distributions –Risa Weschler’s Hubble Volume n-body –Albert Stebbins’s multi-gaussian approximation –Mike Gladder’s empirical halo model Image level simulations –Erin Sheldon for weak lensing –Doug Tucker and Chris Stoughton Terapix skyMaker Massey’s Shapelets code

35. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Survey Planning Summary We have well defined science goals and a well defined science objective –A 5000 sq-degree survey substantially overlapping the SPT survey –A time domain survey using 10% of time The science requirements are achievable. –A good seeing, 4 bandpass, 2% calibration, i ~ 24 survey Multiple tilings of the survey area the core of the survey strategy and photometric calibration. The survey can be completed using: –22 nights a month between September and October –21 nights in December –22 half nights a month in January and February

36. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DES Instrument Project OUTLINE Science and Technical Requirements Instrument Description Cost and Schedule Prime Focus Cage of the Blanco Telescope We plan to replace this and everything inside it

37. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DES Instrument Reference Design 3556 mm 1575 mm Camera Filters Optical Lenses Scroll Shutter The Reference Design represents our current design choices and may change with more analysis 1.2.1 CCDs 1.2.2 CCD Packaging 1.2.3 Front End Electronics 1.2.4 CCD Testing 1.2.5 Data Aquisition 1.2.6 Camera Vessel 1.2.7 Cooling 1.2.8 Optics 1.2.9 Prime Focus Cage 1.2.10 Auxiliary Components 1.2.11 Assembly and Testing Instrument Construction Organization

38. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Optics Design 2.2 deg. FOV Corrector –5 powered elements (Fused Silica) –one aspheric surface (C4) four filters – griz needed for DES –others can be used More details of the design in the next talk (Steve Kent) Cost for the glass ~ 660k$ Cost for figuring ~ $1M ~ 1.5 yr delivery Corrector

39. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Dark Energy Survey: Optical Design and Issues 2.2 Deg. Field of View Corrector Requirements Performance Issues Steve Kent, Fermilab, for the DES Collaboration Dark Energy Survey BIRP, Aug 12, 2004

40. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO 2.2 Deg. Field of View Corrector ● 14 requirements total – 0.39 to 1.1 μ (SDSS filter bandpasses) – Scale 17.7 arcsec/mm – Field size 450 mm diameter (2.2 degrees) – D80 < 0.64 arcsec everywhere (FWHM <.4 arcsec) – No ADC (Atmospheric Dispersion Corrector) – Minimize ghosting – Space for filter, shutter – Design choices should minimize procurement, fabrication schedule.

41. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Gladders may11 design Features: Flat focal plane Five lenses + Filter (including dewar window) All fused silica One aspheric surface Largest diameter 1.1 meters Flexibility spacing elements Low distortion (<1%) Good ghosting properties star halos exit pupil image Filter Shutter C1 C2 C3 C4 C5 Filter

42. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO CCDs Reference Design: LBNL CCDs –QE> 50% at 1000 nm –2k x 4k –15 micron pixels –250 microns thick –fully depleted (high resistivity) –back illuminated –4 side buttable –readout 250 kpix/sec –2 RO channels/device –readout time ~17sec –fringing eliminated –PSF controlled by bias voltage R&D on LBNL CCDs nearly finished. LBNL CCDs have been used at LICK and on the WIYN Telescope and on the Mayall

43. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO CCD QE and Read noise Read noise for a recently finished DALSA 2k x 4k 250 kHz → 7e- To get redshifts of ~1 we spend ~50% of survey time in z-band. LBNL CCDs are much more efficient in the z band than the current devices in Mosaic II

44. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO CCD Wafers: Existing masks have 2/wafer to be cost efficient we will make new masks with 4/wafer CCD Acquisition Model Reference Design Acquisition Model Order CCDs through LBNL – good relationship with commercial foundry Foundry delivers wafers to LBNL (~650 microns thick) LBNL –applies backside coatings for back illuminated operation –oversees thinning (~ 250 microns thick) and dicing –tests all devices on cold probe station LBNL delivers all tested, unpackaged devices to FNAL FNAL packages and tests CCDs Prepared to package ~ 160 CCDs (spares, yield)

45. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Packaging CCD Packaging will be done at Fermilab LICK and LBNL have already successfully packaged small quantities. We are developing a working relationship with R. Stover at LICK (we visited in July) to learn packaging techniques CCD Packaging is very similar to building the components of silicon vertex detectors. Fermilab has built many vertex detectors for CDF and D0, and is contributing to CMS CCD packaged at LBNL Invar Foot AlN circuit board Wirebonds to CCD

46. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Packaging and Testing Process Packaging and testing keep up with anticipated CCD delivery rate of 20/month (5 wafers). Packaging: –one CCD takes ~ 1 week to complete –Plan to have capabilities to start 2/day Testing: –estimate 2 days/CCD –3 identical test stands needed to keep up with 5 CCDs/week LBNL cold probe test results will guide which CCDs to package 1 st Assume 60 good devices from production run and up to 18 good devices from preproduction run

47. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO CCD Test Stand and Acceptance Criteria Testing –linearity, full well depth, QE, CTE, readnoise, dark current Testing and acceptance criteria will be defined as we gain experience with LBNL CCDs Will also consider impact of acceptance criteria on community Multiple tilings reduces impact of bad regions Study with 100 consecutive bad columns found ~1.5% of tiling area was imaged less than 3 times after 5 complete tilings

48. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Camera Reference Design Focal Plane 62 2k x 4k CCDs for main image, 4-side buttable, 15 micron pixels 8 1k x 1k CCDs for guiding and focus Camera Design Focal Plane feed through board Frontend electronics

49. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Camera Vessel Vacuum feed through board brings signals out of cryostat Camera is separated into two spool pieces: one for signal feed throughs one for cooling and vacuum services Removal of cooling spool piece allows access to back of focal plane and cables Cooling/ Vacuum spool piece

50. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Cooling and Integration Reference Design has LN2 reservoir inside cryostat Fill from recondensing dewars on floor investigating alternative: Gifford-McMahon cryo coolers on cooling spool piece which condense N2 directly into reservoir Will fully assemble prime focus cage at FNAL and test all systems together (corrector, focal plane, cooling, data acquisition, data management....) before shipping to Chile

51. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Front End Electronics and DAQ Large focal plane implies long cables between CCD and electronics crates Reference design has clock drivers and preamps as part of the cable assembly Goals are noise < 5 e-, linearity <0.25%, support a readout rate of 250 kpix/sec Reliable operation requires careful consideration of internal and external components Minimize heat generated in the PF cage by locating DAQ off telescope off the cage

52. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Data Acquisition DAQ Parameters 62 (+4) 2k x 4k (1k x 1k) 2 250 kHz (17 s) 971 MB 57 MB/s 4 1k x 1k 2 1 MHz (0.5 s) 8 MB 16 MB/s # CCDs Pixels/CCD Amps/CCD Digitization rate Bytes/image Data rate FE  DAQ Image CCDs Guide CCDs DES data rates are relatively high by astronomy standards, but not for particle physics. We will use the Monsoon data acquisition system, developed by NOAO. We will modify it to separate digital and analog functionality. Using Monsoon shortens development time and enables collaboration with NOAO and other Monsoon users.

53. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO DES Modifications: ADCs will reside on the telescope. The rest of the electronics will be off the telescope. Save space and power on the telescope. Reduce noise (ADCs are closer to the CCDs). Save money. Data Acquisition We will modify this part. Monsoon architecture:

54. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO We Can Do This! The Silicon facility at Fermilab has experience building the Run 0, I, & II silicon vertex detectors: °Micron precision assembly ° Wirebonding ° Thermal Management ° Cleanrooms Building a CCD focal plane uses many of the same skills, but has many fewer devices. LBNL has extensive experience with CCD development and packaging for SNAP/JDEM UIUC has experience building large, high rate data acquisition systems at SLAC, Fermilab, and Cornell. U Chicago has experience with optical design and optical systems on SDSS ° DES does not depend on pioneering development work. ° The main issues are cost, schedule, and integration. The DES collaboration has assembled a team of experienced scientists, engineers, designers and technicians

55. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Schedule Milestones Optics and CCDs are the most Challenging tasks CCDs: Preproduction run: FY05, Production run: FY06 and FY07 Optics: Order glass in FY06, Figuring/polishing in FY07 Fully Commissioned by June 2009!

56. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Total Cost profile in Then Yr $ (excluding institutional overhead) The Reference Design represents our current choices for meeting the science goals Total cost for the Instrument project is $18.4 M excluding institutional overheads and 22.5M$ with overhead in then year $. We will be ready for observations by June 2009. This schedule is funding limited.

57. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Instrument Project Organization

58. Brenna Flaugher for the DES Collaboration BIRP Meeting August 12, 2004 Tucson Fermilab, U Illinois, U Chicago, LBNL, CTIO/NOAO Conclusions We have a strong collaboration with a wide variety of skills that cover all aspects of this project With this collaboration we can complete the instrument and start survey operations on the telescope in 2009