High Energy Focusing Telescope (HEFT)

1. High Energy Focusing Telescope (HEFT) Caltech Space Radiation Laboratory Aleksey Bolotrikov, Hubert Chen, Walter R. Cook, Fiona Harrison, Peter Mao, Steve Schindler Columbia Astrophysics Laboratory Jim Chonko, Mario Jimenez-Gerate*, Chuck Hailey, Jason Koglin, David Windt, Haitao Yu Danish Space Research Institute Finn Christensen, Carsten Jensen Lawrence Livermore National Laboratory Bill Craig, Kurt Gunderson, Klaus Ziock *Currently at MIT

2. HEFT Science • Imaging and spectroscopy of 44Ti emissions and non-thermal continuum in young Supernova remnants • Sensitive hard X-ray observations of obscured Active Galactic Nuclei (AGN) • Spectroscopic observations of accreting high-magnetic field pulsars • Galactic Center: observe compact objects in outburst/quiescence

3. Supernova • 44Ti with 68 and 78 keV nuclear transitions. • Synthesized near the mass cut (the boundary between the innermost ejecta and the material that falls back to form the collapsed remnant). • Production and ejection sensitive to explosion mechanism and ejecta dynamics. • Map Density and velocity distribution.

4. Instrument Overview • Conic-approximation Wolter-I optics: 6 m focal length • Thermally Formed Glass Substrate: 300 um thick • Depth-graded W/Si Multilayers: 20 – 70 keV • CdZnTe pixel detector resolution: 1 keV • Effective Area: 250 cm2 @ 40 keV • Over-constrained optics: 1’ HPD • Field of view: 17’ @ 20 keV • Pointing stability: 20”

5. HEFT Flight Assembly

6. Multilayer Coated Glass Optics • Thermally Formed Glass • Reasonable cost • Thin and light weight • Low surface roughness • Mass producible • 8 ovens at Columbia • 1.5 technicians • >1 optics layer/day • W/Si Multilayer Coatings • Enhanced reflectivity with broad energy acceptance • High throughput at DSRI coating facility • ~2 optics layers/day

7. Telescope Assembly Method • Each spacer layer (upper & lower) is individually machined to the precise radius and angle: • Assembly errors do not stack up • < 8” assembly error contribution • Multilayer optic shells are constrained to spacers with epoxy: • Only near net shaped shells are necessary to obtain 1’ HPD performance • Fast and robust assembly process: • Requires 1 tech for 1 layer/day

8. Metrology Comparison

9. Laser Scanner vs. LVDT a) Laser Raw b) LVDT Raw c) Laser Phase Error Removed d) LVDT Phase Error Removed

10. Optics Development 39” Prototype with 200 cm segments 51” Prototype with 200 mm thick glass Example: Example: HPD = 30” HPD = 31”

11. Achievements • Utilized surrogate mounts at Columbia for R&D • Demonstrated < 8” assembly machine error • Demonstrated consistency of X-ray, UV & LVDT metrology methods • Correlated free-standing (Laser) and mounted glass (LVDT) • 1.0’ HEFT prototype optic using 300 mm thick glass substrates • 51” optic using 200 mm thick glass – meets Con-X HXT requirement • 39” optic using short glass segments Research Directions • In-depth data analysis and FEA of glass mounting (with LLNL) • Improve thermal glass slumping process and characterization • New and improved multilayer coatings up to 170 keV (D. Windt) • Collaborate with GSFC on mounting Epoxy Replicated Thermally Formed Glass (W. Zhang) • Next generation substrates: mandrel-less forming, graphite thermo-vacuum forming, VELCRO, Si wafer • Improve assembly machine to ~3” with true Wolter-I parabolic/ hyperbolic geometry