1. HESSI Imaging Capability Pre Environmental Review Brian R. Dennis GSFC Tuesday, February 29, 2000

2. Brian R. Dennis 2/29/2000 Pre Environmental Review HESSI Imaging Confidence that Imaging will work within specifications –Grids and Telescope Initial Alignment –Grid characterization measurements – optical, X-ray, and mechanical –Shims under grid mounts to align field of view to telescope axis –CMM measurements of grids & trays at ETH in Zurich –Alignment of trays on telescope tube using CMM at PSI Confirmation of Alignment –TMS measurements of grids 1 – 8 and both trays at PSI –Gridlet test for grids 1 – 6 at PSI –Direct optical confirmation for grids 6 - 9 –Tilt test for grids 1 – 6 at PSI –TMS measurements at SSL Imaging Simulation Test at SSL

3. Brian R. Dennis 2/29/2000 Pre Environmental Review HESSI Imaging Confidence that Imaging will work within specifications Solar Aspect System (SAS) - Functional SAS solar exposures at PSI with 3 CCD’s –<0.5 arcsecond (1  ) spatial resolution verified Functional electrical tests on spacecraft at SSL –Baseline read-out speed = 128 Hz –Dark level negligable (<1 ch – 0.5 mV) –Not affected by any noise source on spacecraft SAS generated ACS signal for S/C (redundancy for FSS) tested at PSI SAS Alignment Optical axis measurements of SAS lenses at Fisba (Switzerland) to 2 – 3  m CMM measurements of SAS CCD pixels and lens fiducials at ETH in Zurich

4. Brian R. Dennis 2/29/2000 Pre Environmental Review HESSI Imaging Roll Angle System (RAS) – Functional CCD RAS provided by PSI Exposed to stars at the Jungfraujoch in Switzerland –Sensitivity confirmed with m~0 stars –PSF 0.52 pixels (1 sigma) – Required 1 arcminute roll angle accuracy achieved Functional electrical tests on spacecraft at SSL –RMS noise @17C = 0.3mV (0.7 ch.) – baseline m2 star gives 12 chs. –Increase trigger efficiency by summing (2-4) spatial pixels –Transmitting selected matrix in time and space around star signal Redundant PMT RAS provided by SSL RAS Alignment Confidence Optical axis determined at PSI relative to tooling balls –Stable to <1 arcminute through vibration Portable CMM alignment measurements of CCD RAS on spacecraft at SSL Optical alignment measurement of PMT RAS on spacecraft at SSL

5. Brian R. Dennis 2/29/2000 Pre Environmental Review HESSI Imaging Confidence that telescope will survive environmental tests Vibration and thermal cycling of all grids and mounts at GSFC Telescope vibration and thermal cycling at Contraves in Switzerland CCD RAS vibration at PSI and thermal cycling at PSI and SSL PMT RAS tests at SSL Plans for checking imaging capability after environmental tests TMS measurements of grids 1 – 8 and grid trays SAS functional electrical tests with photodiode stimulators CCD RAS CMM alignment measurement & functional electrical tests with lasers for star simulation & photodiodes for Earth albedo simulation

6. Brian R. Dennis 2/29/2000 Pre Environmental Review X-Ray Grid Characterization Results Typical On-Axis Fractional Transmissions Cd 109 Data

7. P A U L S C H E R R E R I N S T I T U T Laboratory for Astrophysics Principle of Twist Monitoring System TMS Rear Grids: 4 Laser DiodesFront Grids: 2 Annuli 3mm Dia Interference Pattern on CCD Camera

8. Brian R. Dennis 2/29/2000 Pre Environmental Review TMS SUMMARY

9. Brian R. Dennis 2/29/2000 Pre Environmental Review History of TMS Results

10. Brian R. Dennis 2/29/2000 Pre Environmental Review Gridlet Test Setup

11. Brian R. Dennis 2/29/2000 Pre Environmental Review GRIDLET TEST Objective is to verify relative twist of the front and rear grids. Any subsequent changes in twist can be monitored by the TMS. Method: –Cd 109 source is located behind a ‘gridlet’ located in front of imager –Two side-by-side detectors measure X-ray transmission through subcollimator. –Motion of the source perpendicular to slits modulates the observed count rates. –Grid twist is indicated by difference in modulation phase as seen by twin detectors. –Modulation is due to 2 nd harmonic response of front grid. Results are completely independent of GSFC grid characterization data. Modulation phase is independent of any test setup misalignments. Test-setup misalignments affect only the amplitude of the modulation.

12. Brian R. Dennis 2/29/2000 Pre Environmental Review GRIDLET TEST RESULTS

13. Brian R. Dennis 2/29/2000 Pre Environmental Review GRIDLET TEST RESULTS

14. Brian R. Dennis 2/29/2000 Pre Environmental Review GRIDLET TEST RESULTS

15. Brian R. Dennis 2/29/2000 Pre Environmental Review GRID TILT TEST –Objective is to measure the angle between the direction of maximum grid throughput and the imager axis. –Tilt test results verify: Correct calculation and installation of shims; Flatness of trays; Absence of tilt due to grid-frame distortion. –Test setup is same as for gridlet test, except: Gridlet tray is removed. Source displacement steps are ~cm, instead of ~microns Slit over detector to limit range of angles –Correct tilt is confirmed if maximum count rate is achieved when source is positioned on subcollimator axis.

16. Brian R. Dennis 2/29/2000 Pre Environmental Review RESULTS OF SEPTEMBER 1999 TILT TESTS AT PSI

17. Brian R. Dennis 2/29/2000 Pre Environmental Review Tilt Test Results

18. Brian R. Dennis 2/29/2000 Pre Environmental Review HESSI Imaging Simulation Test

19. Brian R. Dennis 2/29/2000 Pre Environmental Review Imaging Simulation Test Results Single gaussian source, 2 arcseconds wide, 10,000 photons/s/collimator for 4 s Test ImageOutput Image