1. Brenna Flaugher FNAL All Experimenters Meeting June 2008 1 Dark Energy Survey Motivation Dark Energy is the dominant constituent of the Universe Dark Matter is next 95% of the Universe is in Dark Energy and Dark matter for which we have no understanding 1998 and 2003 Science breakthroughs of the year

2. Brenna Flaugher FNAL All Experimenters Meeting June 2008 2 Probes of Dark Energy: Map the cosmological density field The rate of growth of structure is determined by the amount and distribution of dark matter, dark energy and by the expansion rate of the universe z>30z=0 Count the Galaxy Clusters as a function red shift and cluster mass Measure the spatial clustering of galaxies as a function of red shift (angular power spectrum) Measure the distortion in the apparent shape of galaxies due to intervening galaxy clusters and associated clumps of dark matter (weak lensing) Use supernovae as standard candles to measure the expansion rate

3. Brenna Flaugher FNAL All Experimenters Meeting June 2008 3 Cluster of Galaxies: Largest gravitationally bound objects Size ~ 10 25 cm ~ Megaparsec (Mpc); Mass ~ 10 15 Msun What is the cluster redshift? What is the cluster mass? not completely different from jet clustering in collider physics but also have depth (red shift) info. SDSS data

4. Brenna Flaugher FNAL All Experimenters Meeting June 2008 4 The Dark Energy Survey (DES) Proposal: –Perform a 5000 sq. deg. survey of the southern galactic cap –Measure dark energy with 4 complementary techniques New Instrument (DECam): –Replace the PF cage with a new 2.2 FOV, 520 Mega pixel CCD camera + optics Time scales: –Inst. Construction 2008-2011 –Survey: 525 nights during Oct.–Feb. 2011-2016 Funding: –DOE, NSF, STFC (UK), Ministry of Education and Science (Spain), FINEP (Brazil), and the 11 Collaborating Institutions Use the Blanco 4M Telescope at the Cerro-Tololo Inter-American Observatory (CTIO)

5. Brenna Flaugher FNAL All Experimenters Meeting June 2008 5 The DES Instrument: DECam To meet the DES science requirements, within the allocated time period DECam must have: 3 sq. deg. field of view (~ 0.5 meter diameter focal plane) excellent optical image quality red sensitive CCDs (from LBNL) g,r,i,Z,Y filters low noise electronics (readout with < 10 e noise!) cryogenic cooling system DECam Focal Plane 62 2kx4k Image CCDs: 520 MPix 8 2kx2k Alignment/focus CCDs 4 2kx2k Guide CCDs

6. Brenna Flaugher FNAL All Experimenters Meeting June 2008 6 DES Timeline 2004: Fermilab and National Optical Astronomy Observatory (NOAO) approvals –April: 1 st presentation to the FNAL PAC –July: Stage 1 approval by the FNAL director, –September: NOAO approved the DES proposal 2005: Nov. DOE approved CD-0 (Mission Need) for a ground based DE project 2006: P5 and the Dark Energy Task Force –April: DES presentations to P5 –July: Dark Energy Task Force report recommended projects like DES –July/Sept. P5 recommendation to proceed with DES. Reiterated this in 2008 2007: May CD-1 NSF/DOE Review of DES; Oct. CD-1 approval 2008: Jan. CD-2/3a NSF/DOE Review of DES –CD-2 approval for DECam April 29 th (Baseline cost and schedule) –CD-3a approval for DECam May 19 th (Construction start, long lead procurements) –CD-3b review scheduled for Sept. 2008

7. Brenna Flaugher FNAL All Experimenters Meeting June 2008 7 DECam overview CCD focal plane is housed in a vacuum vessel (the imager) which is supported by the barrel LN2 is pumped from the telescope floor to a heat exchanger in the imager: cools the CCDs to -100 C CCD readout electronic crates are mounted to the outside of the Imager and are actively cooled (UIUC). Filter changer (8 filter capacity) and shutter form one mechanical unit (UMichigan). Hexapod provides focus and lateral alignment capability for the corrector-imager system Barrel supports the lenses and imager DECam weighs about 4 tons (load limit is ~ 6 tons)

8. Brenna Flaugher FNAL All Experimenters Meeting June 2008 8 DECam Project Key People Wyatt Merritt is DECam deputy project manager Level 2 managers –CCDs: Tom Diehl and Juan Estrada –Front End Electronics: Terri Shaw, Spanish coordinator: Manel Martinez (Barcelona) –Optics: Peter Doel (University College London) –Opto-Mechanical: Andy Stefanik –SISPI (~ DAQ): Jon Thaler (UIUC) and Klaus Honscheid (OSU) –Survey Planning and Simulations: Huan Lin and Jim Annis Andy and Terri are also the mechanical and electrical project engineers, respectively STFC has committed funds for polishing of the lenses (~ $2.5M) Spanish funding agencies committed funds for the FEE; the preproduction boards are already in fabrication All the universities kicked in cash for early R&D and the lens blanks

9. Brenna Flaugher FNAL All Experimenters Meeting June 2008 9 Current Work at Sidet: CCD Packaging and Testing

10. Brenna Flaugher FNAL All Experimenters Meeting June 2008 10 Future work at Sidet (Lab A): Telescope Simulator

11. Brenna Flaugher FNAL All Experimenters Meeting June 2008 11 Conclusions By April 2011 (< 3 years from now!) we plan to have 62 DECam CCDs in a new camera on the Blanco April 2008 –1 DECam CCD –with prototype electronics –in a small test dewar –on the CTIO 1m (next to the Blanco)

12. Brenna Flaugher FNAL All Experimenters Meeting June 2008 12 Extras

13. Brenna Flaugher FNAL All Experimenters Meeting June 2008 13 Cerro Tololo Inter-American Observatory

14. Brenna Flaugher FNAL All Experimenters Meeting June 2008 14 DES Participating Institutions Fermilab University of Illinois at Urbana-Champaign University of Chicago Lawrence Berkeley National Laboratory University of Michigan NOAO/CTIO Spain-DES Collaboration: Institut d'Estudis Espacials de Catalunya (IEEC/ICE), Institut de Fisica d'Altes Energies (IFAE), CIEMAT-Madrid: United Kingdom-DES Collaboration: University College London, University of Cambridge, University of Edinburgh, University of Portsmouth, University of Sussex The University of Pennsylvania Brazil-DES Consortium The Ohio State University Argonne National Laboratory 12 participating institutions and >100 participants DES Funding from DOE, NSF, STFC (UK), Ministry of Education and Science (Spain), FINEP (Brazil), and the Collaborating Institutions

15. Brenna Flaugher FNAL All Experimenters Meeting June 2008 15 Baseline Obligations and Funding Tables for DOE funds (overhead included, then yr $) FY07 Funding includes $0.77M of carry-over from the R&D proposal and funds spent before Aug.1 (EVMS reporting started) FY08 Funding is $5.5M from FNAL, 0.1M from UIUC Base Grant Obligations Funding

16. Brenna Flaugher FNAL All Experimenters Meeting June 2008 16 Blank inspection at Corning C2 The next step, polishing, will remove only ~ 1 mm per side C1

17. DES Forecasts: Power of Multiple Techniques Assumptions: Clusters:  8 =0.75, z max =1.5, WL mass calibration BAO: l max =300 WL: l max =1000 Statistical+photo-z systematic errors only Spatial curvature, galaxy bias marginalized, Planck CMB prior Factor 4.6 relative to Stage II w(z) =w 0 +w a (1–a) geometric geometric+ growth DETF Figure of Merit: inverse area of ellipse Stage II not included here

18. Brenna Flaugher FNAL All Experimenters Meeting June 2008 18 Forecast Constraints DES+Stage II combined = Factor 4.6 improvement over Stage II combined Large uncertainties in systematics remain, but FoM is robust to uncertainties in any one probe, and we haven’t made use of all the information. Further detail of these forecasts is contained in the Dark Energy Science Program. DETF FoM

19. Brenna Flaugher FNAL All Experimenters Meeting June 2008 19 DES Photometric Redshifts Measure relative flux in grizY filters and track the 4000 A break Estimate individual galaxy redshifts with accuracy  (z) < 0.1 (~0.02 for clusters) Good detector response in z band filter needed to reach z~1.5 Elliptical galaxy spectrum