Update to Near Infrared System for SNAP

1
Update to Near Infrared System for SNAP

• Vic Scarpine
• FNAL SNAP Electronics Meeting
• March 11, 2003

2
Topics

• SNAP NIR Overview
• Visit to University of Michigan
• What is Michigan doing?
• Discussions on NIR issues
• What can Fermilab do?

3
NIR System Concept

• 150 NIR Megapixels
• 36 (2k ? 2k) 18 mm HgCdTe detectors (0.34 sq.
  deg)
• 3 special bandpass filters covering 1.0 1.7 mm
  in NIR
• T 140?K (to limit dark current)

HgCdTe
4
NIR System Performance Goals





5
Risk Assessment Presented to DOE

• Read Noise
• Initial measurements of 1.7m devices have noise
  problem
• Additional production runs may be needed
• Hope that WFC3 solves this problem or
• May be to modify readout strategy to achieve
  required read noise
• Intrapixel Variation
• May not be acceptable for photometry
• Rockwell may be able to sculpt electric field
• Simulation shows dithering is a solution but
  needs to be measured
• How do you spec this for a vendor?

6
Risk Assessment Presented to DOE

• Qualification Testing
• Need to define characterization and qualification
  of large number of HgCdTe devices
• To obtain 44 science grade devices need to test
  at least several hundred devices
• For NSGT 25 devices they are planning three large
  test and qualification facilities

7
SNAP NIR Players

• Greg Tarle, Univ of Michigan NIR RD
  coordinator
• Univ of Michigan - have begun to set up HgCdTe
  evaluation facility
• Number of professors, research scientists,
  post-docs, grad student
• 3-4 full-time equivalent
• Univ of Indiana working with Michigan on
  filters and quantum efficiency measurements
• LBL development of readout electronics??
• Don Figer infrared detectors consultant at
  Space Telescope Science Institute
• Rockwell HgCdTe FPA supplier. Possible readout
  chip.
• Ratheon developing HgCdTe FPA
• Others??? Caltech/JPL/UCLA?

8
Main NIR RD Activities

• Establish a facility for testing and
  characterizing NIR FPAs at University of Michigan
• Study detector read noise and reduction with
  multiple reads
• Study intrapixel variations and impact on
  photometry
• Develop mechanical and thermal concept for NIR
  imager
• Develop plan for testing and qualifying large
  numbers of HgCdTe FPAs
• Produce RD phase deliverables
• Produce realistic cost and schedule estimates for
  CDR
• SNAP RD Plan

9
Michigan Infrared Detector Lab

• Comparative testing and evaluation of industrial
  supplied HgCdTe FPAs
• Characterize read noise, dark current and quantum
  efficiency
• Study intra-pixel variations and impact on
  photometry
• Determine optimum sampling strategy for reducing
  RMS read-out
• Establish facilities for receiving and
  qualifying NIR FPAs
• Optimize calibration techniques and strategies
• Develop mechanical and thermal concept for NIR
  imager in an integrated focal plane

10
Michigan Infrared Detector Lab

• Lab being established
• dewar/vacuum system built
• Low noise DAQ electronics purchased and being
  integrated
• Testing multiplexers to debug system and set
  noise floor
• Need to acquire science grade FPA ()
• Test setup 100K

11
U of M Visit - Issues

• New question about Rockwell FPA pixel stability
• Dark current appears function of readout time
• Is this charge trapping effect?
• If so them has many effects i.e. linearity,
  image lag
• Rockwell vs Ratheon
• Rockwell has made 1.7m for WFC3
• Ratheon has made 2k x 2k, 2.5m for VISTA
• Both want gt 500K for development of SNAP 2k x
  2k 1.7m prototypes
• Time to receive first science grade test FPA
  critical
• U of M may purchase and reimbursed by DOE
• Not clear why they cant get one of the WFC3
  rejects for testing

12
U of M Visit - Issues

• Electronics Readout Chip
• Use LBL CCD chip?
• Rockwell may develop readout chip
• Will this meet SNAP requirements?
• Not sure if Raytheon making a chip
• Other players???
• Does FNAL have an interest here? Can we do a
  better job?
• Political Question
• Will NIR completely end up in NASAs hands?

13
U of M Visit - Issues

• Device characterization and testing plan
• Question of how to spec and measure NIR FPA
  parameters
• Intrapixel variance
• Pixel stablility
• Scientific Issues Tim McKay
• Should the NIR format be re-evaluated for non-SN
  science?
• Are the filters optimized?
• Is SNAP pushing 1.7m too hard?
• Backing off may have small effect on SN search
  but allow for more imaging time?

14
What can Fermilab do for NIR?

• Develop a test and qualification site
• Fermilab experience in detector measurements
• About a year away - allows time to setup test
  system
• Already too many players?
• 100K and few full-time equivalent
• Simulation
• Study optimizing NIR detectors for science
• Clustering, weak lensing
• FNAL astrophysicist involvement
• Detector simulation?
• Intrapixel variation, dithering, charge-trapping
• Fermilab can help now

15
Ongoing HgCdTe Characterization Efforts

• Detector Characterization Lab (DCL) at Goddard
  Space Flight Center (PI Ed Cheng)
• The DCL currently supports the characterization
  of HgCdTe detectors for the Hubble Space
  Telescope Wide Field Camera 3 instrument.
• NASA has funded four laboratories to develop and
  assess the quality of NGST prototype detectors
• The University of Hawaii Laboratory (PI Donald
  Hall) will develop and characterize HgCdTe
  detectors manufactured by Rockwell Scientific.
• The University of Rochester Laboratory (PI
  William Forrest) will develop and characterize
  InSb detectors made by Raytheon Infrared
  Operations.
• The Independent Detector Testing Laboratory (PI
  Don Figer) at Space Telescope Science Institute
  and the Johns Hopkins University will
  characterize both HgCdTe and InSb detectors in a
  comparative hardware setup.
• The Laboratory at NASA Ames Research Center (PI
  Craig McCreight) is developing and characterizing
  SiAs mid-infrared detectors.

16
What can Fermilab do for NIR?

• Readout chip development
• Fermilab has lots of ASIC experience
• Use Fermilab ASIC experience someplace in SNAP
• If interested then when do we start?
• Investigate non-HgCdTe technologies
• Look into issues for making large format InGaAs
  FPAs compile information
• Is it too much development time for SNAP?
• Are there other players looking down this road?

17
E-Mail from Michael Levi to John Marriner Dear
John, Just to correct an important issue in your
write-up, I need to point out that there is
another major axis in the NIR area. We have
"married the Michigan effort to a major
Caltech/JPL/UCLA effort in the NIR. The Caltech
group is heavily involved in the development and
testing of the commercial readout chip as well as
involved with JPL UCLA in the development (and
deploying on telescopes) of the detector
technology. In the next two years the issue with
the detector development is a solid-state physics
problem as opposed to straight-out testing. The
NIR detectors do not currently meet our
specifications and we had to bring NIR experts in
to work on this aspect. The development of a
second axis was a management decision to bring in
world-class experts in NIR. So, the FNAL
interest in this area would be a third effort --
thus would require a careful coordination of
interests, skills, and timing. Thanks for
listening, Michael