Plato meeting MSSL Wed+Thur 15+16/Oct/08

1. Plato meeting MSSL Wed+Thur 15+16/Oct/08 UK interests/activities Alan Smith and Dave Walton UCL/MSSL

2. Agenda Wednesday • Organisation of project, System Group • Organisation of ‘focal plane’ WP (UK+Spain) • CCD characteristics and procurement • CCD optimal operating temperature • Characterisation, CCD, FPA, ... Thursday • Tour of lab • Front end electronics • FPA interface definitions • AOB

3. UK groups with hardware interests • MSSL • Leicester University • RAL • Astrium Proposal submitted to STFC: • Awaiting bridging grant • Proposal presentation/decision meeting with STFC 24/Sep/08 • Final outcome expected in November

4. Plato proposal to STFC identifies 9 workpackages for UK • Preparation: UK exoplanet community • Preparation: UK asteroseismology community • CCD specification and characterisation • Impact of L2 environment • Front end electronics • AIV for focal planes • Calibration • End-to-end simulation • Data processing Baseline Flexible to the needsof the consortium

5. Themes

6. WP3. CCD Specification and characterisationUK lead: MSSL Review PDD CCD spec wrt: • science performance • Manufacturability • Cost • Schedule • packaging Gaia CCD at MSSL

7. CCD Specs: see e.g. Payload Definition Doc (PDD) • Flight: 28 telescopes, 4 CCDs per telescope • Each CCD 3584x3584 18µm pixels • Full-frame (except for 2 bright-source telescopes using same chip but frame transfer) ~150 CCDs

8. CCD specs (continued) • 4-phase IФ • Back-illuminated, AR coated, wavelength range TBC, ~400-1000nm • 2 readout ports, ~4Mpix/s, <20e- rms • SiC package (TBC) with flexi • 2- or 3-side buttable, metallisation of bus lines

9. CCD open issues • Integration of JFET (or even controller and/or readout electronics) into CCD package • Operating temperature: baseline 170K, higher T easier to implement but need to assess effect on trap/release

10. CCD characterisation • Prototype • Design verification • In depth charaterisation • Sub-pixel characterisation • Calibration process trials • General optimisation including FEE • CCD (E2V) • Acceptance testing • CCD (MSSL) • Delta acceptance (tbc) • Characterisation • Optimisation • Focal Plane • Noise, alignment • Function • Telescope • PSF • Function • Spacecraft • Co-alignment • Function • In-flight • Characterisation • Linearity (including Full-Well domain) • Full-Well • Noise • CTE • Responsivity • Gain • Flat field • Vs • Temperature • Drive voltages • Wavelength

11. WP7. CalibrationUK lead: MSSL • Develop overall scheme to integrate calibration at all levels and be complementary to in-flight calibration practicalities

12. WP6. AIV for focal planesUK lead: MSSL • Study verification (Test) strategy at Payload level, to be consistent with calibration strategy (see WP7)

13. WP8. End-to-end simulationUK lead: MSSL • Co-ordination with Denmark • Definition of CCD performance model • Definition of focal plane performance model • Consideration of model requirements wrt post-launch analysis.

14. WP4. Impact of L2 environment on CCD performanceUK lead: Leicester University • CCD Requirements study • L2 environment study: radiation and dust • Impact of environment on CCD, shielding • Review of previous and current studies/missions • Scientific impact of above assessments • Dose: Ionising ~8 Krad(Si) Non-ionising ~5e9 p cm-2

15. WP5: Front end electronicsUK lead: MSSL • Analysis and decomposition of Science Requirements and PDD • Generation and assessment of FEE design options • Analysis of compatibility of optimum design wrt Science Requirements and payload constraints • Support to Spain’s thermo-mechanical design work PEM, developed for ESA Gaia contract with RAL, Astrium

16. Front end electronics • Integrated in CCD package? • 16-bit, 4Mpix/s, 2 ports per CCD. Described in PDD as “modest extension” to existing components, but suitable rad-hard ADC may be a challenge • Integral non-linearity important for photometry • Differential non-linearity important for small deltas (asteroseismology and transits). GATTI scaling may be required.