Our Group Studies Fundamental Physics through Astrophysical Techniques

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Our Group Studies Fundamental Physics through
Astrophysical Techniques
Postdocs Claire Cramer Andrea Loehr Armin
Rest Brian Stalder Michael Wood-Vasey
Grad Students Will High Gautham Narayan 2
graduated 2008James Battat Arti Garg
Undergrad Students JJ Blair Kenny Gotlieb
Engineering Staff Peter Doherty, Research
Engineer John Oliver, Senior Electrical
Engineer Nathan Felt, Electrical
Engineer Steve Sansone, Machine Shop
Supervisor Sarah Harder, Electronics
Technician
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Why Astrophysical methods?

• Much effort in contemporary physics goes into
  finding evidence for physics beyond the standard
  model. The most robust evidence for new physics
  (to date) comes from astrophysical observations.
  We operate where the signal is non-zero.
• The benefit vs. cost curve in astrophysics is
  steep. Successive generations of instrumentation
  provide a major improvement in figure of merit.
• Scale of projects remains modest, compared to
  accelerator experiments. While the size of an
  astrophysical project is growing steadily, one
  student or one postdoc can have a major impact,
  and can assume a major leadership role. Great
  training ground!

The primary objectives of the High Energy
Physics (HEP) program are to explore the
fundamental interactions of matter and energy,
including the unknown "dark" forms of matter and
energy that appear to dominate the universe to
understand the ultimate unification of
fundamental forces and particles to search for
possible new dimensions of space and to
investigate the nature of time itself.
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Survey Figure of Merit

• Number of objects detected per unit time, to
  given SNR

PanSTARRS
better
LSST
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Projects

• Studying the nature of Dark Energy with type Ia
  supernovae
• ESSENCE project measure the value of w, the
  equation of state parameter.
• Studying the nature of Dark Energy using the
  abundance of galaxy clusters with redshift.
• Optical observations of candidate galaxy clusters
  detected with Sunayev-Zeldovich distortions of
  the microwave background.
• Building a high-efficiency multiband imager for
  Magellan for this.
• Studying the nature of the Dark Matter
• SuperMACHO project, a search for microlensing of
  LMC stars
• Probing the flattening of the Milky Ways dark
  matter halo with RR Lyrae stars
• Testing the foundations of gravity on all scales
• Tests of foundations of gravity on solar system
  and Galactic scales
• Improving the precision of astronomical
  calibration
• Detector-based metrology for instrumental
  sensitivity
• Real-time measurements of atmospheric
  transmission
• Precise determination of line-of-sight extinction
  through the Galaxy.
• R D for next-generation systems
• LSST Calibration schemes camera engineering
  data acquisition system detectors

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Group Publications in Past 12 Months

• Retrieved 20 abstracts, Total citations 418
• 1. Observational Constraints on the Nature of
  Dark Energy First Cosmological Results from the
  ESSENCE Supernova Survey, 9/2007, Astrophysical
  Journal
• 2. Scrutinizing Exotic Cosmological Models Using
  ESSENCE Supernova Data Combined with Other
  Cosmological Probes, 9/2007, Astrophysical
  Journal
• 3. The ESSENCE Supernova Survey Survey
  Optimization, Observations, and Supernova
  Photometry, 9/2007, Astrophysical Journal
• 4. Testing for Lorentz Violation Constraints on
  Standard-Model-Extension Parameters via Lunar
  Laser Ranging, 12/2007, Physical Review Letters
  
• 5. Constraining Cosmic Evolution of Type Ia
  Supernovae, 10/2007, ArXiv e-prints,
• 6. Evidence for Distinct Components of the
  Galactic Stellar Halo from 838 RR Lyrae Stars
  Discovered in the LONEOS-I Survey, 5/2008,
  Astrophysical Journal
• 7. Linking optical and infrared observations with
  gravitational wave sources through variability,
  12/2007, ArXiv e-prints
• 8. Toward More Precise Survey Photometry for
  PanSTARRS and LSST Measuring Directly the
  Optical Transmission Spectrum of the Atmosphere,
  10/2007, Publications of the Astronomical
  Society of the Pacific
• 9. The Apache Point Observatory Lunar
  Laser-ranging Operation Instrument Description
  and First Detections, 1/2008, Publications of
  the Astronomical Society of the Pacific
• 10. Calibration of LSST Instrument and Data,
  12/2007, Bulletin of the AAS
• 11. Time Dilation in Type Ia Supernova Spectra at
  High Redshift, 8/2008, Astrophysical Journal

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Past Years Publications, cont.

• 12. Solar system constraints on the
  Dvali-Gabadadze-Porrati braneworld theory of
  gravity, 7/2008, Physical Review D,
• 13. Dark-Matter-Induced Weak Equivalence
  Principle Violation, 7/2008, ArXiv e-prints
• 14. Large Synoptic Survey Telescope From Science
  Drivers To Reference Design, 6/2008, Serbian
  Astronomical Journal
• 15. Constraints on Lorentz Violation with
  Precision Measurements of the Lunar Orbit,
  4/2008, BAPS
• 16. Investigating the Distinct Components of the
  Galactic Stellar Halo RR Lyrae from the LONEOS-I
  Survey, 3/2008, American Astronomical Society
  Meeting Abstracts,
• 17. LSST Survey Strategy 12/2007, Bulletin of
  the American Astronomical Society,
• 18. The First Lunar Ranging Constraints on
  Gravity Sector SME Parameters, 10/2007, ArXiv
  e-prints,

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Accomplishments

• Measured Equation of State parameter of dark
  energy,
• W ?1.0 to 10
• Developed technique for robust real-time
  determination of photometric redshifts of
  clusters of galaxies.
• Completed full design of PISCO camera system, now
  in construction
• Used precise solar system data to constrain novel
  gravity ideas and to brand new upper bounds on
  Lorentz violation
• Devised a completely new approach to the
  calibration of astronomical apparatus

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Joint Limits on w favor ?1

• From Wood-Vasey et al, astro-ph/0701041
• Combines ESSENCE and SNLS and nearby and HST
  supernovae
• BAO limits from Eisenstein et al
• Complementarity of techniques
• Different systematics

(Assumes flat Universe)
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The Calibration Challenge for Optical Astronomy.
Stubbs Tonry, ApJ, 2006
Atmospheric transmission
Instrumental Throughput
Stubbs et al, ASPC, 2007
Stubbs et al, PASP, 2007
Spectroscopy
Imaging
Lidar
Modeling
And then add ? dependent attenuation in the
Galaxy
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Detectors are better characterized than any
celestial source!
Spectrum of Vega NIST photodiode QE
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Atmospheric Transmission
www.cea.berkeley.edu/mlampton/
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The Atmosphere Varies
June 1991
March 1982
Burki et al 1995
Atmospheric extinction during photometric nights
at La Silla
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Aerosols and Water are the main concerns

• Variation in aerosol size and shape distribution
  and density produces variation in extinction.
  This is reasonably smooth in wavelength.
• Variation in atmospheric water content produces
  variable absorption, highly structured in
  wavelength.
• For water, exploit the fact that stellar spectra
  are spectrally smooth in NIR.

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Why do we care, and what really matters here?

• Comparing SN fluxes from different redshifts
  requires knowing the relative instrumental
  response vs. wavelength, across the entire field
  of view. Next-generation projects require flux
  precision at the 1 level. Standard practice
  (SDSS) is 5.
• Determining colors of galaxies, i.e. knowing flux
  ratios in different optical passbands at the 1
  level, is required in order to extract
  photometric redshifts for galaxies for weak
  lensing and other observational cosmology probes.
  
• So we need to understand, characterize and
  correct for instrumental response effects, for
  time-varying atmospheric scattering, and for
  Galactic exinction.
• Our goal is flux ratios at 1 or better, with an
  overall scale factor that can be at the 10 level
  or worse. We dont care about ergs/sec/nm/cm2
• This requires 1) precise full-system calibration,
  2) real-time monitoring of atmospheric
  transmission, 3) correcting for Galactic
  extinction

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3 talks follow

• Claire Cramer, postdoctoral fellow, Precision
  Calibration
• Mr. Will High, graduate student, Galaxy Cluster
  as DE Probes.
• Mr. John Oliver. LSST electronics RD.

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Calibration for Precision Photometry
Harvard Chris Stubbs Claire Cramer Peter
Doherty Gautham Narayan Will High
NIST Keith Lykke Steve Brown John Woodward
Allan Smith
LSST David Burke Kirk Gilmore
IFA, Hawaii John Tonry
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Calibration Concept

• We improve upon traditional celestial calibration
  sources by
• Measuring a source with a known spectrum, namely,
  a narrowband tunable laser
• Compare the system response (telescope
  throughput) to a known detector (NIST-calibrated
  photodiode)
• In a related (but separate) effort, continuously
  monitoring the atmosphere during acquisition of
  astronomical data

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Wavelength Calibration Procedure

• Illuminate full telescope aperture with
  monochromatic light
• Take a calibration flat while monitoring input
  light with calibrated photodiode
• Normalize flat to flux seen by photodiode
• Move to the next wavelength and repeat, until
  entire visible spectrum is spanned
• Construct wavelength-dependent response for each
  pixel in the telescopes CCD camera
• End result
• measurement of relative system throughput,
  including telescope mirrors, corrector optics,
  filters, and detector

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Proof of concept 2006 CTIO test
CTIO Blanco 4m
preamp
integrator
light projected on telescopes flat field screen
NIST photodiode
fiber link
beam launch optics
Opotek laser, tunable from 400 nm to 2 ?m
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CTIO results
normalized data filter transmission
throughput (arb. units)
throughput (arb. units)
calibration data scaled detector QE
wavelength (nm)
wavelength (nm)
fused silica blank in filter holder, pinhole
camera imaging flat-field screen onto photodiode
R filter throughput
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Next step

• Develop a system for permanent installation at
  PS1,
• which will function as a prototype for the LSST

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Technical challenges

• Broad wavelength coverage, 350-1100 nm
• Illumination must be uniform to 10 over 2m
  diameter spot (8m for LSST!)
• Screen must fit into the telescope dome!

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An emissive screen side emitting fibers
fiber sits in milled grooves
frosted acrylic diffuser
side-emitting fiber
reflective back plate
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A reflective scheme reverse telescope with
diffuser
tunable source
hacked DLP digital projector, optical fiber
diverging mirrors
transmissive screen
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DLP Technology for Image Flattening
ants leg
MEMS mirror
TI digital light processing 106 micron-sized
mirrors independently addressed create grayscale
image
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Transferring uniform radiance
reciprocal
Integrating sphere CCD
camera
Flat, by def. Non-uniform
Iteratively flattened
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Current Status

• Functioning prototype in the lab
• Image flattening software complete
• Tests with tunable light source underway
• Full-scale test on Haleakala, Fall 2008

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Summary and Outlook

• In the field
• Proof-of-principle test at CTIO in 2006
• Full-scale test of DLP projector and reverse
  telescope at PanSTARRS by the end of 2008
• Functioning calibration system permanently
  installed in 2009
• In the lab
• Flat screen prototype development and testing,
  2007-8
• Idea factory for how best to harness DLP
  technology for the LSST
• DLP-fed fiber bundle?
• Engineered diffusers?
• Collimating reflector array?
• LSST prototyping, 2009-10

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Galaxy clusters as dark energy probes
Virgo cluster Image credit Rainer Zmaritsch
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Galaxy clusters as dark energy probes
(Cluster baryon fraction, Vikhlinin et al. 2003)

• Cluster abundance cluster as a function of
  mass and redshift
• Exponential sensitivity to dark energy
• Highly complementary to type Ia supernovae and
  CMB tests
• A necessary component of modern dark energy
  measurements (DETF)
• Multi-wavelength, global effort underway

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SZ effect The best known way to discover clusters

• Sunyaev-Zeldovich
• Eg, South Pole Telescope
• Images of diffuse cluster gas
• Signal is redshift independent at high redshift
  for clusters above a constant mass threshold
• Corollary SZ gives no redshifts
• Redshift follow-up needed, opticalIR
• Precision dark energy measurement not possible
  without redshifts

(L. van Speybroeck)
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PISCO The optimal cluster redshift follow-up

• PISCO enables the dark energy science in the
  first place
• Maximal cluster photons per unit time
• 6.5 m class telescope
• Dichroic beamsplitting without traditional glass
  filters
• Red-sensitive CCDs with optimized AR coatings
• Field of view matched to size of high redshift
  clusters
• Maximal cluster redshifts per unit time
• Fast, online calibration and analysis
• No need for extra standard star observations
• Adaptive exposure times, traveling salesman
  cluster list sorting
• Minimal redshift errors (read highly
  competitive)
• Sub-percent
• Cluster ellipticals are incredibly abundant and
  uniform
• Main sequence stars are incredibly abundant and
  uniform
• Minimal cost
• Ground-based, on existing telescope
• Simple and innovative design using mature
  technology

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PISCOs unique optical design
Path of Light
Magellan telescope

• Key features
• Four focal planes
• Three dichroics
• One shutter
• No glass filters (sort of)
• Great acronym

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PISCOs status

• Most glass blanks on hand
• CCDs on hand
• Electronics ready
• August 20 Assembled cubes ready for testing
• August 27 Final assembly of 3 cubes
• August 29 Ready for pickup

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PISCOs unique survey strategy

• Fast, online photometric calibration without
  standard stars
• Adaptive exposure times
• Traveling salesman cluster list sorting

Stellar locus calibration
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PISCOs unique survey strategyProof of concept
Abell 3675 redshift 0.1383 g 120s i 60s z 120s

• Magellan 6.5m
• LDSS3, griz
• 26 known clusters
• Wish list of new clusters

1
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PISCOs unique survey strategyProof of concept

• Magellan 6.5m, LDSS3
• Data calibration in about a minute per cluster
• Cluster detection and redshift analysis in a
  matter of seconds
• Residual rms of
• dz 0.01
• dz/(1z) 0.8-0.9
• No evidence for unknown systematics
• Makes optimal use of telescope time well know
  whether to integrate longer or slew to next
  target.

Redshift Out
Residual
Redshift In
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Blanco Cosmology Survey

• Another piece of our cluster endeavor
• Blanco 4m telescope at Cerro Tololo, Chile
• griz, to roughly redshift 1, 1 mag deeper than
  Sloan
• 100 deg2 planned, ½ completed in 3 yr
• PI Joe Mohr of IUIC
• Weak gravitational lensing by clusters
• Full coverage by South Pole Telescope, other
  wavelengths
• http//cosmology.uiuc.edu/BCS/

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Cluster Cosmology Summary

• Our cluster redshift program fits very neatly
  into the global cluster cosmology effort
• PISCO is a key component
• Necessary and optimal cluster redshift follow-up
• We can follow up on cluster redshifts faster than
  anyone else
• We can follow up on the highest-redshift clusters
• BCS data on hand
• SZ observations well under way
• PISCO-prototype data from Magellan on hand
  reduced
• PISCO construction well under way
• Poised for new discoveries

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LSST Camera Electronics

• John Oliver (Camera Electronics Project Manager)
• Nathan Felt, Sarah Harder
• Harvard University
• Paul OConnor, Veljko Radeka
• Brookhaven National Laboratory
• Mitch Newcomer, Rick Van Berg (Electronics System
  Engineer)
• University of Pennsylvania
• Klaus Honscheid
• Ohio State University
• Jim Bensinger, Kevan Hashemi
• Brandeis University
• Mike Huffer
• Stanford Linear Accelerator Center

Aug 2008 DOE site visit
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Focal Plane Readout - The Challenge

• Large (huge) focal plane ? 201 Sensors _at_ 16
  Mpixels each ? 3.2 Gpixels
• High speed readout ? 15 sec exposures, 2 sec
  read
• Low read noise, sky shot noise dominated gt 5 e
  rms
• Leakage current 1 e/sec/pixel ?Sensor temp -
  100C
• High dynamic range ? Full well 100,000 e ( gt
  16 bits)
• High crosstalk immunity 80 db
• Fully synchronous readout across entire focal
  plane
• Large number of sensor pads (signals) ?
  150/sensor 30,000 pads total
• High vacuum environment ? contamination control
• Minimization of vacuum feedthroughs
• Very compact packaging

Aug 2008 DOE site visit
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FPA Readout Strategy

• Fundamental tradeoff between read speed read
  noise (noise 1/SQRT(Tint) ? lt 500 kpix/sec
• 16 Mpixels sensors with 16 segments (ports) /
  sensor ? 500 kHz readout _at_ 2 second read
• Raft based sensor electronics package ? 9
  sensors x 16 ports 144 ports (channels) per
  raft
• Entire electronic package located within
  cryostat to avoid 30k electrical feedthroughs
  (penetrations)
• Electronics division
• Front End ? Analog signal processing (cryo zone
  -100C)
• Back End ? A/D conversion, data collection, raft
  control, io to CCS DAQ (cold zone -40C)
• 21 rafts ? 3,200 readout CCD output ports
• Data output on one optical fiber per raft ? 144
  Mpixels/2 sec ?1.4 Gbps on fiber
• All raft electronics controlled by single
  Timing Control Module for focal plane
  synchronicity ? Timing/Control Module (Brandeis)

Aug 2008 DOE site visit
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Camera Electronics Distribution
Cryostat

• Timing Control Module
• Shutter Controller
• Filter Controller
• Thermal Controllers
• Electromechanical Actuator Control

• Power Conditioning
• Ethernet hub
• Thermal controllers
• Vacuum controllers

Data Fibers
Power cooling
Ethernet
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Camera Overview (Drawing courtesy M. Nordby SLAC)
Utility Trunk
Cold Plates
Raft Control Crate (RCC)
Cryostat outer cylinder
Focal Plane fast actuators
Raft Tower (Raft with Sensors FEE)
L3 Lens in Cryostat front-end flange
Filter Changer rail paths
Shutter
L1/L2 Housing
Filter in stored location
L1 Lens
Camera Housing
L2 Lens
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Filter in light path
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Front End Functionality - ASICs

• Dual Slope Integration for signal processing
• Transmits signals as differential analog to Back
  End Electronics (BEE)
• 8 channel signal processing ASICs
• ASPIC chip ? LPNHE/IN2P3 Paris
• Clock level translation
• Conversion of logic level signals (LVDS) to CCD
  Clock levels (programmable)
• 8 channel ASIC (HV CMOS process)
• Sensor Control Chip ? ORNL/UTennesee
• Slow controls, FPA thermal control (temp sensors
  heaters to maintain 0.1C stability)

Aug 2008 DOE site visit
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Back End Functionality (Raft Control Crate)

• Video A/D , D/A, temp sensing (processing), slow
  controls, Data Fiber Interface to DAQ
• A/D Conversion (BEBs)
• 18 bit commercial ADCs in chip scale ( 7mm x
  7mm) packages
• 144 packages per raft
• D/A conversion slow controls (BEBs)
• Programmable CCD bias levels
• Programmable CCD Clock Hi/Lo levels
• Raft Control Module (RCM)
• Detailed readout control Slave to Timing
  Control Module
• Data fiber controller/driver (Xilinx Rocket
  i/o)
• Engineering interface (debug port)

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Packaging
Front End
Back End
Raft mount points
Sensor Packages
Back End Boards
Raft
Flex cables and Thermal Straps
FEE Boards
Raft Control Crate, Raft Control Module
FEE cage
Aug 2008 DOE site visit
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Project Status

• BEB Ver 1.0
• Developed tested in FY 06 07
• 1.8 ADC counts pedestal width _at_ 500 kpix/sec
• BEB Ver 2.0
• Full 24 channels/board (144 channels/crate)
• Design completed
• Fabrication Aug-Sep 08
• Test Fall 08
• RCM
• Design in progress
• Fabrication Fall 08
• Test 4th Qtr 08
• RCC Mechanical/Thermal design
• Design completed, to be fabricated at Harvard
  Fall 08
• System integration FY 09

Aug 2008 DOE site visit
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BEB Ver 2.0
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