# Presentation: 775060

## NIR Program Overview

- Gregory Tarlé
**SNAP Internal Review**
**Lawrence Berkeley National Laboratory**
**Berkeley, CA**
**Tuesday, November 11th 2003**

## SNAP NIR Science Drivers

**SNAP NIR Science Drivers**

- Biggest change in the overall design of SNAP since its conception  importance of the Near Infrared Focal Plane
- Reflects essential role of NIR observations in core SNAP science
- Tracing the effect of dark energy through cosmic time requires probing to high-redshift
- Rest frame optical shifts into NIR after z=0.9
- Large wavelength coverage provides important constraints on systematic errors
- Substantially enhances auxiliary science

## NIR allows observation of SNe rest frame optical to high redshift

**Simulated SNAP observations of high redshift SNe**

**NIR allows observation of SNe rest frame optical to high redshift**

## NIR Science Drivers

**Signal-to-noise ratio**
**Noise should be dominated by unavoidable zodiacal light ******** limits on dark current and read noise**
**Signal levels should be sufficient to allow precise observation of SNe near peak at ****z >1.5 ******** limits on quantum efficiency**

**Spatial and wavelength coverage**
**Wavelength coverage to overlap CCDs and allow B and V restframe observations to z>1.5 ******** sensitivity from 1.0 to ******** ****1.7 ********m**** **
**NIR data for all SNe to constrain systematic errors ******** focal plane to match CCDs**

## NIR enhances auxiliary science

**SNAP surveys are unique**
- Depth
- From the disk to z=10
- Depth in the time domain
- R~27 in each epoch
- Broad multiband wavelength coverage including NIR
- 9 bands = Low resolution spectroscopy (R~7)
- Photometric redshifts
- Available in time domain
- Lyman- to z~13
- Image quality: very small and stable PSF
- Photometric stability

**Some**** of the topics impacted:**
**Galaxy studies**: evolution and clustering, a census of R, I, z, and J band dropout galaxies
**Galaxy clusters**: identification of high redshift galaxy clusters, faint and small constituents
**High-z quasar studies**: mapping the quasar luminosity function to z=10, probing the structure of reionization
**Transient**: GRBs, QSO/AGN, outer solar system objects
**Cool stars in the Milky Way**
**Strong Lensing**
**Targets**: Identification of targets for NGST, CELT, etc...

## NIR System Performance Specifications

| Field of View | - match CCD FoV- every SN in every color | ~ 0.3 degrees |
| --- | --- | --- |
| Plate Scale | achieve photometric accuracy with at most2 x 2 dithering  | 0.17 / pixel |
| Wavelength band | - overlap with CCD- reach into decel. phase- restframe B to z=1.7 | 0.9 - 1.7 μm |
| Read Noise | photometry is zodiacal light limited  | < 5 e-   |
| Dark Current | photometry is zodiacal light limited | < 0.02 e- / pixel / sec |
| QE | adequate S/N out to z=1.7 within time constraints | > 60% |
| Filters | cover NIR band with redshifted restframe B | 3 |

## NIR Progress

- NIR team assembled (Caltech, IU, JPL, UCLA, UM)
- Laboratory facilities in place and tested
- Two competing vendors for HgCdTe FPAs (Rockwell Science Center (RSC) and Raytheon Vision Systems (RVS)
- Alternative sensor technology (InGaAs) under investigation
- Detector procurement and development program in place
- Active program of device characterization under way

- Over the last year the SNAP infrared program has crystallized  with several important developments:

## Tests to be Performed

- _FPA sensitivity_     - readout noise
- 	- dark current
- 	- relative and absolute quantum efficiency
- _FPA uniformity_ 	- inter-pixel variations
- 	- intra-pixel variation
- 	- gain
- 	- linearity
- _FPA stability_	- latent charge
- 	- thermal stability

- _NIR Detector Characterization Laboratories at Michigan, JPL, and Caltech/UCLA:_ facilities for the complete optical and electrical characterization of infrared detectors (Focal Plane Arrays) for the SNAP R&D phase.
- Goal: Meet science requirements by measuring / demonstrating

- _Challenge!_ Measure at a few e- level

- _Challenge!_ Measure micron size spatial resolution

## Dark Current

- 2

- SB-301 mux: Dark Current (295K)

- 0

- 80

- 120

- 40

- Signal (adu)

**Slope = 0.002**

- SNAP specification for dark current is
- < 0.02 e-/pix/sec at 140K
- 1.7 μm cutoff devices for Hubble’s WFC3
- achieve DC < 0.1 e-/pix/sec at 150K
- Rule of thumb: factor of 7-10 reduction in
- dark current for every 10K

- System sensitivity demonstrated using multiplexers:
- DC for multiplexers is measured at 0.002 e-/pixel/sec at 295K.
- Conversion gain based on DC from thermal e**-** is 0.65 e**-**/adu.
- We are ready to characterize DC for HgCdTe FPAs!

## Quantum Efficiency

- QE measurement for SNAP is ready
- Set-up developed by IU and installed at UM.
- Absolute calibration of 200W lamp to 5% (ultimately 3% expected).
- Uniformity 0.5% across full 2k FPA
- Source will be also be used for inter-pixel and gain measurements.

-  SNAP requires QE > 60%
-  WFC3 devices have QE > 70% for
-   1.2 to 1.7m range

**Uniformity of 200W **
**   ****calibrated lamp**

## Read Noise

**Read Noise**

**Read Noise sensitivity demonstrated using multiplexers:**
- Series of consecutive CDS reads (texp=0) at 140K
- RN for RVS SB-301 mux is 3.5 adu
- Gain ranges from 0.65 to 1.4 e-/adu
- 0.65 is measured at 295K using thermal e-
- 1.4 e-/adu uses photo e- at 140K
- RN is ~ 5 e- for mux, reduced to < 2 e- with multiple samples

-  SNAP specifications for read noise of < 10 e-
-     reduced to 5 e- using Fowler-4 sampling
-          - multiple samples reduce noise as N
-  WFC3 read noise is near 25 e- (CDS reads)
-  Noise was reduced to 12 e-, but QE was
-     very poor
-          - dark current/stability remained good
-  Believe high read noise is linked to material
-     junction or surface region
-          - 2 new  lots are budgeted to increase QE for
-                the low noise process

- SB-301 multiplexer noise

- We are ready to characterize DC for HgCdTe FPAs!

## Intra-Pixel Variations

- SNAP NIR is undersampled by a factor of 1.5 at 1.7m to 2.5 at 1m .
- 22 dithering should correct photometry errors due to undersampling (See Bernstein PASP 2001)
- SNAP NIR performance target for photometry: ~2% overall statistical,    ~ 2% relative systematic is challenging and requires understanding of intra-pixel variation

- We must:
- Measure the intra-pixel variationfor SNAP HgCdTe’s
- Demonstrate the ability tocorrect this with a 2x2 dither pattern
-         - Achieve 2% photometry
-         - Reconstruct diffraction limited
-           seeing of SNAP optics in NIR

- Intra-pixel sensitivity of PACE HgCdTe measured by Gert Finger

## Measuring Intra-pixel variation

**Measuring Intra-pixel variation**

**‘**Spot-o-matic’ for intra-pixel variation measurements developed
- Based on LBL design, adapted to NIR at UM
- Design specs:
- Spectral Range: up to 1800 nm
- Resolving Power: 1.1 μm
- Depth of focus: 4 μm
- Working distance: 3.1 cm
- Bench tests show spot with FWHM = 4 μm Currently upgrading system with automated x, y, z stage

- Fiber opticsource

- Collimatingtube lens

- Focusing objective

- Target photodiode
- w/knife edge

- We are ready to measure Intra-pixel variation for HgCdTe FPAs

## Other Measurements

- _Persistence_
- 	An increase in DC following exposure and reset has been seen in shortwave WFC3  devices. RSC believes they can control this. For SNAP we
- must measure DC vs. time following saturation
- must explore the effect of multiple resets and increased reset time
- _Inter-pixel variation _will be tested using QE light source, uniform to 0.5%
- _Temperature sensitivity_ of all parameters will be measured.
- _Controller noise specifications_ will be derived from Mux transfer function (needed to specify electronics).

## Device Delivery Schedule 2003

| Device | Manufacturer |  | Grade | size | Initial Site | Delivery Date |
| --- | --- | --- | --- | --- | --- | --- |
| H1RG | RSC | mux | engin. | 1k  1k | UM | in hand |
| VIRGO-2k | RVS | mux | engin. | 2k  2k | UM | in hand |
| VIRGO-1k | RVS | mux | engin. | 1k  1k | UM | in hand |
| VIRGO-1k(2.5 μm cutoff) | RVS | FPA | near science | 1k  1k | UM | in hand |
| H2RG | RSC | mux | engin. | 2k  2k | UM | in hand |

- We have contracted with RVS, RSC and Sensors Unlimited to provide a progression of devices over the next two years intended to meet SNAP science specifications.
- RSC will build on its WFC3 experience with shortwave FPAs and H2RG mux developed for NGST. RVS has launched an aggressive program to produce and mate 1.7 μm material to its VIRGO-2k (SB301) mux building on their VISTA experience.

## Device Delivery Schedule 2004

| Device | Manufacturer |  | Grade | size | Initial Site | Delivery 
Date |
| --- | --- | --- | --- | --- | --- | --- |
| H2RG | RSC | FPA | engin. | 2k x 2k | Caltech | March 2004 |
| H2RG | RSC | FPA | engin. | 2k  2k | UM | April 2004 |
| VIRGO-1k | RVS | FPA | engin. | 1k  1k | Caltech/UCLA | April 2004 |
| InGaAs/H1RG | SU/RSC | FPA | engin | 1k x 1k | JPL | April 2004 |
| VIRGO-1k | RVS | FPA | engin. | 1k  1k | UM | May 2004 |
| H2RG | RSC | FPA | engin. | 2k  2k | UM | July 2004 |
| VIRGO-2k | RVS | FPA | science | 2k x 2k | Caltech/UCLA | Aug. 2004 |
| VIRGO-1k | RVS | FPA | engin. | 1k  1k | UM | Aug. 2004 |
| VIRGO-2k | RVS | FPA | science | 2k  2k | UM | Sep. 2004 |
| H2RG | RSC | FPA | science | 2k  2k | Caltech | Nov. 2004 |
| H2RG | RSC | FPA | science | 2k  2k | UM | Dec. 2004 |

- Devices will be exchanged between labs for concurrence testing

## Facilities

- Michigan & IU

## NIR Team Key Personnel - UM

| Personnel | Activity | FTE |
| --- | --- | --- |
| Michigan |  |  |
|     Greg Tarlé | NIR Coordinator | 40% |
|     Carl Akerlof | NIR lab (optics)  | 10% |
|     Myron Campbell | NIR lab (electronics)  | 10% |
|     David Gerdes  | NIR lab (electronics), software development  | 20% |
|     Timothy McKay  | SNAP science planning  | 20% |
|     Wolfang Lorenzon  | NIR lab planning, SNAP simulations  | 10% |
|     Bruce Bigelow | Participate in the conceptual design of the focal plane array.  | 100% |
|     Sen. Engin. Tech. | Support of design, fabrication and testing of various components required for operation of the IR devices  | 100% |
|     Shawn McKee | SNAP simulations, software pipeline  | 20% |
|     Michael Schubnell | NIR lab lead, SNAP simulations  | 100% |
|     Andrew Tomasch | NIR lab (mechanical, thermal)  | 100% |
|     Matthew Brown | Characterization of the FPA device, SNAP simulations  | 50% |

## NIR Team Key Personnel - Caltech/UCLA

| Personnel | Activity | FTE |
| --- | --- | --- |
| Caltech |  |  |
|     Keith Taylor | Management and oversight | 10% |
|     Roger Smith | Technical leadership, planning & reporting | 55% |
|     Dani Guzman | Electronic interfacing detector testing | 90% |
|     Marco Bonati | Controller software, SIDECAR & detector
testing, test automation. | 70%
 |
|     Ernest Croner  | Electronic fabrication, wiring, Cryovac support | 30% |
|     EE (new position) | Rockwell detector testing. | 90% |
|     ME | Detector mounts, design Automated Test Dewar | 35% |
| UCLA (subcontract to Caltech) |  |  |
|     Ian McLean | Management and oversight | 10% |
|     Detector Engineer TBD | Raytheon Detector testing.  | 90% |
|     Mike Spencer | Electronics Engineer | 30% |
|     George Brims | Systems Engineer | 30% |

## NIR Team Key Personnel - IU

| Personnel | Activity | FTE |
| --- | --- | --- |
| Indiana University |  |  |
|      Stuart Mufson | Management and oversight | 20% |
|       Nick Mostek | Device characterization - QE measurements | 50% |

| Personnel | Activity | FTE |
| --- | --- | --- |
| JPL |  |  |
|     Dave Cole | Lead | 50% |
|     Peg Frerking | Management oversight | 10% |
|     Mike Seiffert | technical help as needed     | 10% |
|     Technician | device characterization | TBA |

**NIR Team Key Personnel - JPL**

## NIR Milestones

| Mux testing complete | Dec. 2003 |
| --- | --- |
| Instrumentation complete | Feb. 2004 |
| Begin EG testing | Feb. 2004 |
| Begin SG testing | March 2003 |
| EG testing complete | Sep. 2004 |
| Mission Concept Report | Dec. 2004 |
| ZDR/DRR | Dec. 2004 |
| SG testing complete | Feb. 2005 |
| Conceptual Design Report | Sept.  2005 |

## Deliverables

| Draft science driven requirements for NIR | Feb. 2004 |
| --- | --- |
| Draft Integration & Test Plan for NIR | Sept. 2004 |
| Test packets for EG devices  | Sept. 2004 |
| Final science driven requirements for NIR | Nov. 2004 |
| Test packets for SG devices  | Mar. 2005 |
| Production of draft Interface Control Document | Mar. 2005 |
| Final Integration & Test Plan for NIR | Aug. 2005 |
| Detector Characterization plan | Aug. 2005 |
| Production of final Interface Control Document | Sept. 2005 |

## R&D Schedule Milestones

## Summary

**NIR System**
**Essential for core science mission**
**A critical role in reducing systematic errors**
**Substantially enhances auxiliary science **
**NIR R&D Program leading to CDR**
**Solid NIR team established **
**Laboratory facilities in place and tested**
**Competition established among vendors to develop SNAP HgCdTe technology**
**Develop and characterize devices that will meet SNAP science requirements**
**Establish NIR Science Driven Requirements**
**Develop Conceptual Design of NIR system**
**Detector Characterization Plan**
**Develop I&T plan**
**Cost and Schedule**