1. Detectors for the JWST Near Infrared Spectrograph (NIRSpec) B.J. Rauscher 1, P. Strada 2, M.W. Regan 3, D.F. Figer 3, P. Jakobsen 2, S.H. Moseley 1, T. Boeker 2 1 NASA Goddard Space Flight Center 2 ESTEC/European Space Agency 3 Space Telescope Science Institute

2. 8 January 2004AAS, Atlanta, GA A pretty picture is not enough.. Enter NIRSpec Most observations probably detector noise limited!

3. 8 January 2004AAS, Atlanta, GA NIRSpec Modes R=100 (Exploratory spectroscopy, Verify photometric redshifts) –Single Prism 0.6 - 5.0 µm –Micro-Shutter Array or Fixed Slits R=1000 (Emission line diagnostics) –3 Gratings 1.0 - 5.0 µm –Micro-Shutter Array or Fixed Slit(s) R=3000 (Emission line kinematics) –3 Gratings 1.0 - 5.0 µm –Fixed Slit or Integral Field Unit (TBC)

4. 8 January 2004AAS, Atlanta, GA NIRSpec Instrument built by European Industry under ESA Project Leadership Presently Transitioning from Definition to Implementation Phase Two NASA-provided components: –4 x 384 x 175 Micro-Shutter Array –2 x 2k x 2k HgCdTe Detector Array NASA/GSFC to Contribute 2K  4K HgCdTe FPA Readout Electronics Cable Harness

5. 8 January 2004AAS, Atlanta, GA NIRSpec Micro-Shutter Array 4 x 384 x 185 Shutters 9 Square Arcmin of MSA Area Single 200 mas x 450 mas slits >100 objects simultaneously

6. 8 January 2004AAS, Atlanta, GA Focal Plane Array (FPA) Technology 2K  4K FPA comprised of two 2K  2K sensor chip assemblies (SCAs) =0.6–5.0  m HgCdTe detectors FPA passively cooled to T=34–37 K Very successful Phase-A detector development! –Raytheon and Rockwell produced outstanding detectors consistent with requirements – =0.6–5.0  m detectors meet challenging requirements (e.g. total noise =6 electrons rms per t=1000 seconds exposure).

7. Detector Test Results Dark current versus temperature Conversion gain on this and following plots =1.3 e - /ADU

8. Detector Test Results Dark current histogram

9. Detector Test Results Sampled-Up-the-Ramp Dark Signal

10. Use of Reference Pixels Without reference pixels With reference pixels

11. Detector Test Results Total noise versus number of non-destructive reads

12. 8 January 2004AAS, Atlanta, GA Selected highlightes from prototype testing Amplifier glow negligible! —Multiple non- destructive reads averaging down noise. Reference pixels work! —highly effective at removing e.g. Pedestal Drifts. Dark current very low and independent of temperature at T < 40 K

13. 8 January 2004AAS, Atlanta, GA To learn more about JWST detector prototype test results, see Figer, D.F., Rauscher, B.J., Regan, M.W. et al. 2003, “Independent detector testing laboratory and NGST detector characterization project”, Proceedings Of SPIE Vol. 4850, 981

14. 8 January 2004AAS, Atlanta, GA NIRSpec Detector System Test Flow

15. 8 January 2004AAS, Atlanta, GA In Overview FPA vendor delivers fully flight-qualified and characterized Focal Plane Array to NASA/GSFC NASA/GSFC integrates FPA with detector readout system and harness –Harness and readout electronics previously tested at component level NASA/GSFC does system-level test

16. NIRSpec Detector System Test Flow -Part 1 ROIC Screening Detector Layer Screening Hybrid Screening SCA Module Long Perf. Testing (S) Flight Units Test Flow ETUs Test Flow FPA Long Perf. Test Next page FPA Long Perf. Test ROIC Screening Detector Layer Screening Hybrid Screening Next page ROIC Screening Detector Layer Screening Next page Qualification Units Test Flow (Environ. & Unique Tests) ROIC Screening Detector Layer Screening Hybrid Screening Next page GSFC Detector Characterization Lab Cross-Calibration Test Flow Done by FPA Vendor Key: SCA Module Long Perf. Testing (S) Package into FPAs Package into FPAs Hybrid Screening Indep. Char. Tests* *Pending cost/benefit trades Done by TBD

17. NIRSpec Detector System Test Flow - Part 2 ETUs Test Flow Done at Packaging Lead From previous page Done by DCL From previous page Flight Units Test Flow FPA Aliveness Test Flight Environ. Test Flt. Acceptance Tests Done by FPA Vendor Environmental Testing FPA Accept. Test DS Sys.Test FPA Aliveness Test FPE Environ. Tests From previous page Qualification Tests Key: From previous page DCL Cross-Cal. Tests FPE Environ. Tests Qualification Units Test Flow DCL Cross-Calibration FPA Aliveness Test FPA Baseline Perf. Test FPA Aliveness Test FPA Baseline Perf.Test Integrate with FPE & Cable DS Sys.Test Done by TBD

18. Total Noise

19. Detective Quantum Efficiency (DQE)

20. Operability for Science