1 B. Flaugher P5 April 2006 The Dark Energy Survey From Scientific Goals to Science Quality Data Brenna Flaugher Fermilab April 2006 P5 Meeting

1B. Flaugher P5 April 2006

The Dark Energy Survey

From Scientific Goals to Science Quality Data

Brenna Flaugher

Fermilab

April 2006 P5 Meeting


DES Science and Technical Requirements

• 5000 deg2 of the So. Galactic Cap in 525 nights (5 yrs)

• photometric-redshifts to z=1.3 with dz < 0.02.

• A small and stable point spread function (PSF) < 0.9'' FWHM median

• A large camera, on the Blanco 4m– 3 deg2 camera with ≥ 2.2 deg FOV

• Data Management system– 300GB/night, automated processing– Publicly available data archive after 1 yr

• Filters, CCDs, Read noise– SDSS g,r,i,z filters; 400 - 1100nm– QE > 50% in the z band (825-1100nm)– Read noise <10 e-

• Optical Corrector with excellent images– Pixel size <0.3” /pixel– < 0.4” FWHM in the i and z bands

The Science Requirements flow to Technical Requirements


The DES Instrument: DECam

3556 mm

1575 mm

Hexapod

Optical Lenses

F8 Mirror

CCDRead out

DECam will replace the prime focus cage on the Blanco

Filters Shutter

Prime Focus Instrument-in optical path-space and thermal constraints


DES: DECam and Data Management

62 2kx4k Image CCDs: 520 MPix8 2kx2k Guide, focus, alignment

DECam will be larger than any existing CCD cameraEach image:

~ 20 Galaxy clusters~ 200,000 Galaxies

Each night ~ 300 GBEntire survey ~ 1 PB

John Peoples is the DES project directorFermilab leads the DECam projectUIUC/NCSA leads the DM project

DES Focal Plane

OUTLINE of this talk•DECam

•project description•cost and schedule

•Data Management•project description•cost and schedule


DES CCDs

LBNL Design: fully depleted 2kx4k CCDs– QE> 50% at 1000 nm, 250 microns thick– 15 m pixels, 0.27”/pixel– readout 250 kpix/sec, readout time ~17sec

DECam / Mosaic II QE comparison

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300 400 500 600 700 800 900 1000 1100

Wavelength (nm)

QE, LBNL (%)QE, SITe (%)

LBNL CCDs in use on WIYN telescope. From S. Holland et al, LBNL-49992 IEEE Trans. Elec. Dev. Vol.50, No 1, 225-338, Jan. 2003

LBNL CCDs are much more efficient than the SITE CCDs in Mosaic II at high wavelengths

To reach redshifts of ~1.3 DES will spend 46% of survey time in z –band

DES CCD design has already been used on telescopes in small numbers (3) SNAP CCDs are the next generation, optimized for space

DES is the 1st

production quantity

application for LBNL

CCDs

z band


CCD Fabrication and Packaging Follow LBNL business model developed for SNAP:• Foundry delivers partially processed wafers to LBNL

(~650 microns thick)

• LBNL finishes wafers (250 microns thick), tests, dices (production rate 5 wafers/month)

FNAL builds up the CCD packages and tests CCD – will match CCD delivery rate

Preconceptual R&D: • 36 Eng. grade 2kx4k CCDs in hand• used to develop focal plane packages, characterize

CCD performance, test CCD readout electronics• Expect 20 more in July 06

Potential Science grade devices expected in Oct. 06

FY07: establish CCD processing and packaging yield

– preliminary est. 25% yield (SNAP devices)– implies 18 months and $1.6M for 70 good devices– CCD yield is a cost and schedule driver

DES Wafers – June 2005!


Front End Electronics: CCD Readout

• FNAL, Barcelona, Madrid, UIUC

• Opportunity for large international contribution: Spanish consortium has submitted a proposal to their funding agencies (~$2M). Would provide ~$0.5M for the production FEE.

• Status:

– UIUC funds used to purchase prototype readout systems

– have already achieved 6.5e noise at 160kpix/sec,

– have a design that fits in 3 temp. controlled crates in PF cage

– need to test readout of multiple CCDs Part of Fermilab Team in the testing lab

LN2 DewarsReadout racks

Filter and shutter controls

3 operational CCDtesting setups


Camera Vessel Prototype

10 slot thermally controlled crate for CCD readout electronics

Cryo and Vacuum controls

Focal plane

Feed-through board for CCD signals

Full size prototype is being built by U. Chicago. It will be ready for CCDs this summerand will be used to test multi-CCD readout


Survey Image System Process Integration (SISPI)

CTIO will upgrade the Telescope Control System (TCS)

Data Management (DM): U. Illinois-Astro/NCSA

U Illinois-HEP (J. Thaler) is leading the SISPI development- similar to HEP-DAQ systems


Optical Corrector Design• Preliminary Design complete (UMich, FNAL, UCL)

– Image quality fwhm: ~ 0.33” (<0.4” required)

• Opportunity now for international collaboration:

– March 05, the UK Consortium submitted a proposal to PPARC to lead the procurement of the optics

– 1.47 M pound proposal to cover cost of polishing, mounting, and alignment of the lenses in the barrel

– P. Doel at U. College London Optical Science Lab will manage the procurement and fabrication

• March 2006, PPARC Council announced that it “will seek participation in DES”

• Additional UK funding ($0.5M ) available through Portsmouth (SRIF3): ~60% of the blanks

• US University funding could cover the rest.• Procurement of the optics is ~2 years • CRITICAL PATH

filter

Dewarwindow

C1 has 940 mmdiameter

C2C3

C4

5 elements, fused silica


• U. Michigan will– handle procurement and testing of

the filters– match SDSS – g,r,i,z and

introduce a well defined cut-off at high wavelength

– design and fabricate or procure a combined filter changer and shutter

DES FiltersDark Energy Camera Filters

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300 400 500 600 700 800 900 1000 1100 1200

Wavelength

%Tra

nsm

itta

nce

925nm 775nm 635nm 475nm

Filter changer will be a cartridge system similar to PanStarrs design


Image Quality:

An observed PSF pattern optical model

= *Elliptical PSF Circular PSF whisker

DESoptics

Primary Mirror

Blanco Primary mirror – excellent figure: D80 <0.25”– radial position controlled by

counterweights– Upgrades in Oct. 05 reduced

the mirror motion from ~1.5mm to < 0.4mm, further reduction expected

24 Radial Supports

3 Hard Points

33 Pressure Pads

Ray tracing model of existing mirror, camera and corrector reproduces PSF patterns seen in data

In this model the primary was misaligned by 0.2 mm x and -0.7 mm y

Primary Mirror Support cell


CTIO and the Blanco Telescope

• Have produced some of the best Weak Lensing measurements

• Cerro Tololo Image Quality Sept-Feb– site median PSF 0.65” FWHM

– Prime Focus (PF) delivered median PSF 0.9” FWHM (used in all DES constraint forecasts)

• DES/CTIO upgrades will stabilize the PSF and should improve the median FWHM:

• DES– focus and alignment sensors on focal plane: generate focus and lateral alignment information with each image

– active control of camera position: hexapods will provide focus and lateral adjustments of corrector + camera system

– improved thermal environment: heat dissipation will be actively controlled

• CTIO is planning additional upgrades to the radial supports


• 2004 Level 0 Image Simulations → DM Challenge 0: Done!– Reformatted SDSS data used to simulate DES images

• 2005-06 Level 1 Catalog &Image Sim. → DM Chal. 1: Done!– 500 sq. deg. catalog; 500 GB of images; FNAL and UChicago computing used

• 2006-07 Level 2 Catalog and Image Sim. In progress– 5000 sq. deg. catalog; 5 TB of images– FermiGrid & MareNostrum SuperComputer (Barcelona)– Higher resolution N-body simulation, more realistic galaxy properties, and more

sophisticated atmosphere and instrument models (noise, ghosts)– Recover input cosmology from catalogs using 4 DES key project methods

• 2007-8 Level 3 Catalog and Image Simulations– Suite of full-DES catalogs (i.e., different input cosmologies)– Synergy with DOE SciDAC proposal (with many DES collaborators) to produce

large cosmological simulations for dark energy studies– 1 year of DES imaging data– Recovery of input cosmologies from catalogs and images– Stress test of full data processing system

DES Simulations Feed DM Challenges


DECam critical paths: CCDs & Optics

CCDs:• LBNL can deliver CCDs at a rate of 20/month after 3 month startup• We need 70 CCDs for the FP including spares• Preliminary yield estimate of 25% implies ~18 months • Cost is ~$23k/wafer, 25% yield implies $1.6M• Construction start of Oct. 07 implies last CCD is finished March ’09• Install last CCD and test full camera ~ 2 months• Ready to ship to Chile ~ May 09

Optics:• Blanks ~ $0.8M , 8 month delivery• Polishing ~ $1.5M, 18 month delivery• Assembly and alignment into corrector ~ 6 months• Ready to ship to Chile ~ 2.75 yrs after procurement begins (Oct. 06 → May 09)


DECam Schedule Dependent on DOE funding and international participation

Opportunity exists to capitalize on international interest in DES • UK consortium would lead and fund procurement of optical elements• Spanish Consortium would lead and fund procurement of production FEE• Important for DOE to provide timely assurance that it intends to proceed

with DES (we will be ready technically to proceed with optics procurement by Aug. 06)

A positive recommendation from P5 would help in this process

DOE Critical Decision Process schedule• FY06 Preconceptual R&D; CD1 Paper review Sept.06

• FY07 R&D, CD2 Review March 07, CD3 Review Sept. 07

• FY08 MIE Construction start

• FY09-10: Assemble and test camera vessel and corrector

– Ship to Chile and install on Blanco , first DES observations Dec. 09


DECam Funding Need Profile (then yr $, Overhead included)

• Total Project Cost: (FY07-FY10) = $19.7 M

• Total DOE Project cost: $16.7 M

• DOE Major Item of Equipment (MIE) total of $12.6 M includes M&S equipment ($7M), technical labor ($5.6M) and a total of ~35% contingency

*Additional $1M in External funds in FY06,Total External Funds = $4M

*

$ M FY07 FY08 FY09 FY10 TOTALACTIVITY R&D CONST CONST CONSTR&D FUNDS (DOE HEP) 4.1 4.1DOE HEP MIE FUNDS 5.8 4.9 1.9 12.6EXTERNAL (Foreign + Univ. Non DOE) 1.0 2.0 0.0 0.0 3.0

TOTAL 5.1 7.8 4.9 1.9 19.7


DES Data Management Project• U. Illinois and NCSA lead the DM project

– Joe Mohr (U. Illinois) is the project leader– Cristina Beldica (NCSA) is the project manager

• DM System Requirements– Reliably transfer ~300GB/night for 525 nights from CTIO to U.Illinois/National

Center for Supercomputing Applications (NCSA)– Automatically process data with built-in quality assurance– Archive the data products and serve the processed data to collaboration – Provide community access to the archive 1 year after images were collected

• DM Team – U Illinois/NCSA, Fermilab and NOAO– Additional DES collaborators

• Deliverables to DES and astronomical community– DM System (High Performance Computing platforms and workstations)

Pipeline middleware Astronomy modules Catalog database Image Archive

– Archived science ready DES data

U Illinois/NCSA DES DM Team


This grid-based, modular and flexible data management system was deployed and tested in Data Challenge 1 (Oct ‘05-Jan ‘06)


DM Schedule and Status

• Pursuing iterative development strategy ‘04-’09

– Yearly data challenges Oct-Jan ‘05-’08– Development targets full delivery in 2009

DC1: base level system in place DC2: data quality, stress test DC3: deploy and test outside NCSA DC4: final validation and stress test

• Data Challenge 1 Results (Oct 1 ‘05-Jan 31 ‘06)

– DM system deployed and tested– Automated reduction (500GB raw reduced

into 5TB)– Catalogued and calibrated 50 million objects– Confirmed photometry and astrometry

Reduced, pseudo-colorDC1 Image


DES DM Funding Sources (then yr $, OH included)

DM System Construction (‘04-’09) $5.1MU Illinois/NCSA (seed funding, incl. 2.5FTE/yr) $1.40M

NOAO (NOAO Science Archive, 1.5FTE/yr) $1.00M

Fermilab* (1.5FTE/yr) $1.00M

Total resources identified to date $3.40M

Pending NSF DES CyberInfrastructure proposal ($1.70M)

• Model is for NSF to fund proposed Data Management system * Contributions by Fermilab scientists (DOE supported)


Conclusions

DES provides the next logical step in both

technology and science– Builds on existing technology and infrastructure, and capitalizes on

collaboration’s experience with large DAQ systems, silicon vertex detectors, and data handling

– 3 deg2 camera: x7 larger area and x7 faster readout than existing Mosaic camera on the Blanco

– 1PB total processed images available to the public; data released 1 year after images taken

– Development and implementation of data analysis techniques for photo-z’s, cluster masses, weak lensing, baryon oscillations, and supernovae are the next steps toward the science of the Stage IV projects of the future (LSST, SNAP)


extras


CCD Requirements

LBNL CCD performance DECam requirements/

Reference Design Pixel array 2048 4096 pixels 2048 4096 pixels Pixel size 15 m 15 m 15 m 15 m (nominal)

<QE (400-700 nm)> ~70% >60% <QE (700-900 nm)> ~90% >80%

<QE (900-1000 nm)> ~60% >50% at 1000 nm Full well capacity 170,000 e- >130,000 e-

Dark current 2 e-/hr/pixel at –150oC <~25 e-/hr/pixel Persistence Erase mechanism Erase mechanism Read noise 7 e- @ 250 kpixel/s < 10 e-

Charge Transfer Inefficiency < 10-6 <10-5 Charge diffusion 8 m < 10 m

Linearity Better than 1% 1%


CCD testing results

• Good news: with 5 thin CCDs tested it looks likely that they can be grouped together

( need more statistics)

• Have all the testing infrastructure running – now need more analysis!

Horizontal Charge Transfer Inefficiency for different voltages


Side view

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Front view

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Isometric view camera end

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Documents

1 B. Flaugher P5 April 2006 The Dark Energy Survey From Scientific Goals to Science Quality Data Brenna Flaugher Fermilab April 2006 P5 Meeting