# Presentation: 125599

## Instrument R&D

**Chris Bebek**
**Lawrence Berkeley National Laboratory**
**11 November 2003**

## Requirements development
Instrument walk through
R&D plan and goals
R&D management
Organization
CDR preparation
Schedule
Summary

- Instrument walk through
- R&D plan and goals
- R&D management
- Organization
- CDR preparation
- Schedule
- Summary

**Overview**

- Internal Review

- C. Bebek 11/11/03

## Requirements Flowdown(as perceived to drive R&D efforts)

## Science-Driven Requirements to Instrument Concept

**Instrument**
- A large  FOV  (0.7 sq. deg. ).
- Observation cadence commensurate with SNe evolution (every 4 days).
- Allocation of time for photometry and follow up spectroscopy (60/40).

**Measurement Program**
- Discover and follow light curves evolution of Type Ia SNe from z=0.3 to 1.7.
- Capture spectrum near peak luminosity.
- ~2000 well measured SNe

- Internal Review

- C. Bebek 11/11/03

## Science-Driven Requirements to Instrument Concept

**Photometry**
- Rest frame F. U, B, V, (R)-band light curves.
- Rest frame B-band measurement to 2% at peak.
- K-correction.
- Rest frame multi-color evolution.
- Malmquist bias (early detection).
- Rise time (fused 56Ni).
- Peak-to-tail luminosity ratio (C/O ratio).

**Photometer**
- Wavelength coverage from 350 nm to 1700 nm.
- Use two plate scales to cover the wavelength range to obtain time efficient photometry.
- 9 filters.
- Required S/N(epoch) versus magnitude achieved with appropriate duration and number of exposures.
- Zodiacal light - limited measurements.

- Internal Review

- C. Bebek 11/11/03

## Science-Driven Requirements to Instrument Concept

**Science-Driven Requirements to Instrument Concept**

**Spectroscopy**
- UV metalicity features – strength and location.
- S and Si features
- SII 5350Å line, 	w = 200Å
- SII “W” shape, 	w =   75Å
- SiII 6150Å line, 	w = 200Å
- Ejecta velocity, 15Å.
- Host galaxy z.

**Spectrograph**
- Wavelength coverage from 350 nm to 1700 nm.
- S/N = 20.
- Resolution ~100 ().

- Internal Review

- C. Bebek 11/11/03

## Space Ops Impacts onInstrument Concept

- Reliability
- Avoid moving parts
- No coolers; passive, radiative cooling
- No filter wheel
- Allow a shutter
- Avoid multiple focal planes
- Eliminate multiple adjuster sets
- Coalesce visible, NIR, and spectrograph into one focal plane
- Eliminate dichroics
- Cosmic rays
- Proton rate is ~4/s/cm2, after shielding.
- CCD impact is about 3% of pixels are contaminated per 100 s of exposure time.
- Long integrations  need to be broken into a sequence of short exposures (say 300 s for photometry and 1000 s for spectroscopy).

- Internal Review

- C. Bebek 11/11/03

## Instrument Working Concept

**Instrument Working Concept**

- Internal Review

- C. Bebek 11/11/03

## Focal Plane Concept

- All instruments coalesced on one focal plane.
- Common 140K operating temperature.
- “Bolted” to telescope structure.
- Photometer sensors in one focal plane, example.
- 36 2k x 2k, 18 μm HgCdTe NIR sensors.
- 36 3.5k x 3.5k, 10.5 μm CCD sensors
- Spectrograph mounted to focal plane.
- Two channel spectrograph with light access port in the focal plane.
- Objects dropped into spectrograph light port by steering the satellite.
- Fixed filter mosaic
- 3 NIR bandpass filter types organized in 3 x 3 arrays.
- 6 visible bandpass filter types organized in 6 x 6 arrays.
- Guide off the focal plane during exposures.
- 4 regions of star guider CCDs.

- Internal Review

- C. Bebek 11/11/03

## Focal Plane Concept

**Focal Plane Concept**

- Guider

- Spectrograph
- port

- Visible

- NIR

- Focus star
- lamps

- Calibration lamps

- Spectrograph

- Thermal links

- Focus star
- projectors

- Calibration projectors

- rin   =   6.0 mrad (129 mm)
- rout = 13.0 mrad (284 mm)

- Internal Review

- C. Bebek 11/11/03

## R&D Plan and Objectives

## R&D Plan and Objectives

- The R&D period concentrates on:
- Paper studies to eliminate or better understand the identified risks.
- A limited, focused hands-on R&D program to mitigate risk.
- Expose and documenting all interface areas with other subsystems.
- Produce a preliminary project cost and schedule.
- R&D Major objectives:
- SNAP NIR detector characterization, specifications, and acquisition plan.
- SNAP visible detector characterization, specifications, and production plan.
- Filter set and mounting concept.
- Spectrograph image slicer prototype characterization.
- Instrument readout electronics concept.
- Detector readout ASIC core prototypes.
- Shutter concept.
- Particle shield performance study and refined mass estimate.

- Internal Review

- C. Bebek 11/11/03

## Detector R&D

- SNAP contemplated because low wavelength cutoff NIR detectors and extended red response CCDs were are on the horizon.
- Rockwell MBE 1.7 m HgCdTe for WFC3
- LBNL CCDs
- A DOE review in July 2002 recommended that
- Augment the NIR group
- Development alternate sources for LBNL CCDs
- We have done this, and more

- Internal Review

- C. Bebek 11/11/03

## R&D Sensors Specs

|  | Visible | NIR | Units |
| --- | --- | --- | --- |
| Wavelength | 350-1000 | 900-1700 | nm |
| <Quantum efficiency> | 80(400-800 nm) | 60 | % |
| Read noise (multiple reads) | 4 | 5 | e |
| Dark current | 0.005 | 0.02 | e/s/pixel |
| Pixel size | 9-12 | 18-20 | μm |
| Format (approx) | 4k x 4k | 2k x 2k |  |
| Readout time | 30 | 30 | s |

|  | Visible | NIR | Units |
| --- | --- | --- | --- |
| Wavelength  coverage | 350-980 | 980-1700 | nm |
| <Quantum  Efficiency> | 80 | 60 | % |
| Read Noise | 2 | 5 | e |
| Dark  Current | 0.001 | 0.02 | e/s/pixel |
| Pixel size | 9-10 | 18-20 | μm |
| Format (approx) | 1k x 1k | 1k x 1k |  |

*Photometer*

*Spectrograph*

- Internal Review

- C. Bebek 11/11/03

## NIR Detectors

- Internal Review

- C. Bebek 11/11/03

## NIR  Photometer

- Function
- Photometry from 1000 nm to 1700 nm.
- Effort
- Develop 1.7 m cutoff detector availability – warm telescope
- Establish facility for testing and characterizing NIR FPAs.
- Characterize devices
- Linkages
- Instrument mechanical engineering group
- Instrument electronics
- Filter group
- Calibration group

- Internal Review

- C. Bebek 11/11/03

## NIR Detector Plan

- Establish large format 1.7 μm cutoff detectors
- Explore detector technology options
- Establish competitive vendor environment
- We have sought to broaden both our technology and vendor pool.
- Rockwell – MBE HgCdTe
- Raytheon – LPE HgCdTe
- Sensors Unlimited/Rockwell – InGaAs
- First MCT engineering parts in January / InGaAs < May
- Iteration decision in summer 2004
- CDR technology and vendor(s) decision in late 2005

- Internal Review

- C. Bebek 11/11/03

## NIR Detector Roadmap

- Internal Review

- C. Bebek 11/11/03

## NIR Detectors Testing

- Characterization
- University of Michigan – HgCdTe
- Electrical and optical characterization
- Pin hole projector for intra-pixel response
- Cal Tech w/ UCLA as subcontractor – HgCdTe
- Electrical and optical characterization
- Long term, automated production testing
- JPL – InGaAs
- Plenary talk by Greg Tarle
- Breakout presentations by Mike Schubnell and Roger Smith

- Internal Review

- C. Bebek 11/11/03

## Visible Detectors

**Visible Detectors**

- Internal Review

- C. Bebek 11/11/03

## Visible Photometer

**Visible Photometer**

- Function
- Photometry from 350 nm to 1000 nm.
- Effort
- Push LBNL CCD technology to conclusion
- Establish backup CCD fabrication site
- Explore alternative technologies
- Complete optical performance measurements
- Develop device packaging
- Derive a cost model.
- Linkages
- Instrument mechanical engineering group
- Instrument electronics
- Filter group
- Calibration group

- Internal Review

- C. Bebek 11/11/03

## Visible Detector Development

**Visible Detector Development**

- Technology development
- LBNL/DALSA CCDs
- LBNL CCD technology at a traditional CCD vendor – in negotiation
- Silicon PIN diode hybrids – Rockwell (Raytheon)

- SNAP v1 CCDs
- 3512 x 3512, 10.5 m

- RSC HyVisi
- 2k x 2k, 18 m

- Internal Review

- C. Bebek 11/11/03

## Visible Detector Roadmap

- Internal Review

- C. Bebek 11/11/03

## Visible Detector Testing

- Characterization
- LBNL
- General device characterization
- PSF measurements
- Radiation – protons and 60Co
- Yale
- Packaging
- Radiation testing beyond protons
- Plenary talk by Natalie Roe
- Breakout presentations by Steve Holland and Charles Baltay

- Internal Review

- C. Bebek 11/11/03

## Filters

**Filters**

- Internal Review

- C. Bebek 11/11/03

## Filters

- Activity
- Univ. of Indiana is working with a vendor to deposit filters on silicon sensors.
- Michigan will examine issues for suspending discrete filters.
- Effort
- Concept for mechanical mounting discrete filters.
- Several cycles of direct deposition of filters on silicon wafers and CCDs.
- If successful, move on to NIR deposition.
- Linkages
- Visible group
- NIR group
- Focal plane mechanics
- Calibration group

- Internal Review

- C. Bebek 11/11/03

## Filters

- 4” silicon wafer with V-band filter

- Discrete filter mounting

- Chuck Bower breakout talk

- Internal Review

- C. Bebek 11/11/03

## Spectrograph

**Spectrograph**

- Internal Review

- C. Bebek 11/11/03

## Spectrograph

- Function
-   = 100 spectroscopy from 350 to 1700 nm
- Effort
- Optics train design
- Focal plane sensor selection
- Slicer technology development
- Calibration procedures studies
- Linkages
- Focal plane mechanics
- Instrument electronics
- Calibration group

- Details in Anne Ealet plenary and Eric Prieto breakout talks.

- Internal Review

- C. Bebek 11/11/03

## Spectrograph

**France supplied item**
**concept design and system engineering - LAM**
**calibration, simulation and ground segment - CPPM **
**Will seek to maintain common electronics and readout architecture.**
**Will seek to maintain common detector technology, but not necessarily same format.**

- Internal Review

- C. Bebek 11/11/03

## Electronics

**Electronics**

- Internal Review

- C. Bebek 11/11/03

## Electronics Overview

- Sensor front-end electronics
- Warm vs cold trade-offs
- Commonality across systems
- Observatory control unit
- Capture functional requirements
- Configuration
- Control/monitor
- Data flow
- Mass memory
- No data on-board data processing
- Compression studies at FNAL
- Instrument mechanisms
- Space craft interface

- Details in Mike Sholl and Henrik von der Lippe plenaries and Jean-Pierre Walder breakout talks.

- Internal Review

- C. Bebek 11/11/03

## Electronics Methodology

- Block diagram

- Top level of an essential model used to capture functional requirements and interoperability of subsystems.
- Visible and NIR sensors
- Spectrograph
- OTA mechanics
- Calibration group
- Spacecraft thermal
- Spacecraft telemetry
- Spacecraft controls

- Internal Review

- C. Bebek 11/11/03

## OCU Functional Requirements

**CPU****	****	**
**	****Decode ground command packets****	**
**	****Decode SC discrete signals****	**
**	****Send discrete signals to SC****	**
**	****Transfer database set points to systems****	**
**	****Execute science data observation plan****	**
**	****Execute telescope focus observation plan****	**
**	****Configure mass memory per exposure****	**
**	****Generate data headers per exposure and insert in mass memory****	**
**	****(Execute focal plan star guider algorithm)****	**
**	****(Compress data)****	**
**	****(Thermal control algorithm)****	**
**	****Supervise housekeeping data collection for S-band transmission****	**
**	****Host subsystem databases****	**
**1553****	**
**	****Receive data packets from S-band**
**	****Pass house keeping packets to S-band**
**	****Pass instrument data packers to S-band, on occasion, eg, focus data**
**	****Pass focal plane star guider information to ACS**
**	****Receive ACS information and insert in science data stream**
**SC-instrument discrete signals****	**
**	****What simple signals do we want to receive and/or exchange with SC?**
**Mirror actuators****	**
**	****Open the door**
**	****Command secondary hexapod**
**	****Read secondary hexapod position**
**	****Command tertiary hexapod (option)**
**	****Read tertiary hexapod position (option)**
**Focus support****	**
**	****Control Shack-Hartman lamps**
**Shutter****	**
**	****Program shutter motion, eg, rate, blade-to-blade gap**
**	****Execute shutter cycle**
**	****Record shutter motion time-angle profile**
**Filter wheel control (option)****	**
**Calibration lamps****	**
**	****Power control broad band lamp**
**	****Power control spectral lamps**
**	**

**	****Monitor lamp power**
**	****Control lamp shutter**
**Focal plane star guider****	**
**	****Guide star database**
**	****Load guide star(s) coordinates into centroid hardware**
**	****Set centroid hardware parameters**
**	****Configure sensors readout**
**	****Receive data streams**
**Power supplies****	**
**	****Control power supplies**
**	****Monitor power supplies**
**	****Control power routing to sub-systems**
**Visible****	**
**	****Operation modes database**
**	****Load/read DACs**
**	****Load/read timing parameters**
**	****Load/read operating mode**
**	****Execute read mode (synchronous across devices)**
**	****Monitor sensor temperature**
**	****Monitor remote generated voltages**
**	****Receive data streams**
**NIR****	**
**	****Operation modes database**
**	****Load/read DACs**
**	****Load/read timing parameters**
**	****Load/read operating mode**
**	****Execute read mode (synchronous across devices)**
**	****Monitor sensor temperature**
**	****Monitor remote generated voltages**
**	****Receive data streams****	**
**Spectrograph****	****	**
**	****Operation modes database****	**
**	****	****Visible**
**	****	****NIR**
**	****Load/read DACs****	**
**	****	****Visible**
**	****	****NIR**
**	****Load/read timing parameters****	**
**	****	****Visible**
**	****	****NIR**

**	****Load/read operating mode****	**
**	****Execute read mode****	**
**	****	****Shutter (if present)**
**	****	****Visible**
**	****	****NIR**
**	****Monitor sensor temperature****	**
**	****	****Visible**
**	****	****NIR**
**	****Monitor remote generated voltages****	**
**	****	****Visible**
**	****	****NIR**
**	****Receive data streams****	**
**	****	****Visible**
**	****	****NIR**
**	****Command actuators****	**
**	****Command internal calibration lamps (if any)****	**
**Data compression****	****	**
**	****Load/read compression parameters****	**
**	****Monitor compression performance per sensor****	**
**	****Enable/disable sensor science data streams****	**
**	****Forward data to mass memory****	**
**Mass memory****	****	**
**	****Configure write slots for sensor incoming data****	**
**	****Configure read slots for data to transmitter****	**
**	****Monitor ECC rates****	**
**	****Enable/disable redundant elements (if relevant)****	**
**	****Insert headers and relevant house keeping data****	**
**Thermal control****	****	**
**	****Heater set points database****	**
**	****Configure heater elements****	**
**	****Record temperature sensors****	**
**	****Elements****	**
**	****	****Primary mirror**
**	****	****Secondary mirror**
**	****	****Tertiary mirror**
**	****	****Folding mirror**
**	****	****Telescope structure and mounting struts**
**	****	****Focal plane and mounting struts**
**	****	****Thermal links**
**	****	****Radiator(s)**
**	****	****Electronics boxes**

- Internal Review

- C. Bebek 11/11/03

## Detector Front-end Electronics

**Detector Front-end Electronics**

- Goal to mount electronics, cold at the focal plane
- Photons to bits on serial cable per detector.

- Required development
- Rockwell SIDECAR for NIR
- SNAP CDS+ADC for CCD
- CCD clocking-bias system
- DC-DC power supplies

- Internal Review

- C. Bebek 11/11/03

## Detector Front-end Electronics

- Internal Review

- C. Bebek 11/11/03

## Focal Plane Guider

**Focal Plane Guider**

- Function
- Provide fine guiding during exposures
- Telescope/instrument I&T
- Effort
- Trades and concepts by spacecraft group
- Star catalog survey for candidate stars
- Detector area vs magnitude vs ACS update rate
- Linkages
- Instrument mechanics
- Instrument electronics
- Attitude control system

- Internal Review

- C. Bebek 11/11/03

## Shutter and Calibration 

- Internal Review

- C. Bebek 11/11/03

## Shutter

- Multifunction
- Normal exposures of well determined time
- Fast exposures for calibration on bright objects
- Flat illumination surface for calibration lamps
- Effort
- Concept
- Drive mechanism research
- Linkages
- Calibration group
- Attitude control system

- Internal Review

- C. Bebek 11/11/03

## Function
OTA I&T support
On-orbit focusing
Detector stability
Filter monitoring
Absolute  calibration for spectrograph
Effort
Capture calibration group needs
Explore lamp technology

- OTA I&T support
- On-orbit focusing
- Detector stability
- Filter monitoring
- Absolute  calibration for spectrograph
- Effort
- Capture calibration group needs
- Explore lamp technology

- Shack-Hartman light sources

- Lamp

- Fiber optic

- Lens

**Calibration Support Hardware**

- Internal Review

- C. Bebek 11/11/03

## Mechanical/Thermal

## Thermal/Mechanical Mounts

**Thermal/Mechanical Mounts**

- Multifunction
- Kinematic mounts
- Thermal isolation
- Effort
- Concept
- Prototype construction and characterization
- Linkages
- OTA mechanics

- Internal Review

- C. Bebek 11/11/03

## Radiator

**Radiator**

- Function
- Provide passive cooling for focal plane sensors
- Provide passive cooling for spectrograph sensors
- Provide passive cooling for focal plane electronics
- Provide passive cooling for thermal shield
- Effort
- Concept
- Linkages
- OTA mechanics

- E.g., thermal links

- Internal Review

- C. Bebek 11/11/03

## Shield

**Shield**

- Multifunction
- Charged particle attenuator
- Thermal vessel
- Light shield
- Back-scattered light absorber
- Contamination control
- Effort
- Concept
- Particle attenuation study at FNAL
- Linkages
- OTA mechanics
- Additional shielding studies for spectrograph and backside of focal plane, in general.

- Internal Review

- C. Bebek 11/11/03

## R&D Studies and Trades

- Separate visible, NIR, and spectrograph focal planes.
- Small FOV NIR configurations.
- Shutterless operation.
- Filter wheel configurations and fixed filters.
- Filter placement – on or off sensors
- Filter number optimization.
- Telemetry bandwidth, solid state recorder, data compression
- Data storage and telemetry bandwidth versus orbit type, orbit period, exposure time, and relative fraction of spectrograph time.
- Single or double channel spectrographs with prisms or gratings.
- Electronics development – warm vs cold operation
- Precision guiding schemes using the focal plane.
- Shield – charge particle attenuation efficiency vs mass
- Shutter concept development
- Exposure time and number of exposures to set limits on sensor dark current and readnoise and to provide sufficient dithering information.
- Thermal loads
- Calibration support hardware
- I&T support hardware

**√**

**√**

**√**

**√**

**√**

**√**

**√**

- Internal Review

- C. Bebek 11/11/03

## Project Management

## Instrument Management

- Management activities
- Oversee R&D technical activities
- Receive Level 2 science requirement.
- Generate instrument concept specifications
- Derive instrument component requirements
- Assemble component specifications into instrument level specifications
- Validate against Level 2 science requirements.
- CDR planning and execution

| Personnel | Activity | FTE |  |
| --- | --- | --- | --- |
|  |  | FY04 | FY05 |
| Chris Bebek  | Instrument lead | 1.00 | 1.00 |
| Natalie Roe | Deputy lead | 0.60 | 1.00 |
| S. Virostek | Lead engineer  | 0.75 | 1.00 |
| TBN | Dep. Proj. Eng. |  | 0.75 |

- Internal Review

- C. Bebek 11/11/03

## Institutional R&D Responsibilities

- Internal Review

- C. Bebek 11/11/03

## CDR Preparation

- Convert working concept to a conceptual design
- Interface Control Documents - drafts
- Discover and document interfaces amongst instrument systems.
- Discover and document interfaces with other systems.
- Integration and test planning - drafts
- I&T plan development for instrument.
- I&T plan development with telescope and spacecraft.
- Project preliminary cost and schedule
- Cost and schedule *conventional *components.
- R&D results will define cost and schedule of *custom* items.
- Identify long lead procurement items.

- Internal Review

- C. Bebek 11/11/03

## Examples of Interfacesto Other Systems

**Examples of Interfaces****to Other Systems**

- _Optical Telescope Assembly_
- Optical parameters
- Mechanical mount
- ICD
- I&T plan

- _Calibration group_
- Shutter
- Filters
- Readout
- RFD

- _Simulation_
- Provide sensor
-  characteristics
- data

- _Telemetry_
- Command
- Monitoring
- Science data
- ICDs
- I&T plan

- _Bus power_
- ICD
- I&T plan

- _Atitude Control System_
- Star guider
- ICD
- I&T plan

- ICD:	Interface Control Documents I&T:	Integration and Test Plans
- RFD:	Requirements flow down

- Internal Review

- C. Bebek 11/11/03

## R&D Cross Links Index

**R&D Cross Links Index**

**From**

**To**

- This is a work in progress to document the interactions during R&D, and eventually during construction,  of the instrument subsystems among themselves and of the instrument with other SNAP systems.

- Internal Review

- C. Bebek 11/11/03

## R&D Schedule Milestones

- Internal Review

- C. Bebek 11/11/03

## Summary

- We have a limited scope R&D program to mitigate technology risks in
- visible and NIR detectors
- spectrograph image slicer
- custom integrated circuits
- Other activities center on concept development for CDR preparation
- More details in:

_*Plenary talks*_
- Visible detectors	N. Roe
- NIR detectors	G. Tarle
- Spectrograph	A. Ealet
- Electronics	H. von der Lippe

_*Breakout session*_
-  Filters	C. Bower
-  CCD development	S. Holland/C. Baltay
-  NIR detectors 	M. Schubnell/R. Smith
-  Spectrograph 	E. Prieto
-  ASIC development 	J-P Walder

- Internal Review

- C. Bebek 11/11/03

## Backup material

## R&D Schedule Milestones

- Internal Review

- C. Bebek 11/11/03

## R&D Schedule Milestones

- Internal Review

- C. Bebek 11/11/03

## R&D Schedule Milestones

- Internal Review

- C. Bebek 11/11/03

## R&D Schedule Milestones

- Internal Review

- C. Bebek 11/11/03