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Future Imaging/Spectroscopy Approaches to High Energy Solar Science

Future Imaging/Spectroscopy Approaches to High Energy Solar Science. G.J. Hurford Space Sciences Lab University of California, Berkeley. Annapolis 5-August 2010. Some Key Science Issues to which Imaging/Spectroscopy might be relevant. Directivity Are accelerated electrons and ions beamed?

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Future Imaging/Spectroscopy Approaches to High Energy Solar Science

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  1. Future Imaging/Spectroscopy Approaches to High Energy Solar Science G.J. Hurford Space Sciences Lab University of California, Berkeley Annapolis 5-August 2010

  2. Some Key Science Issuesto which Imaging/Spectroscopy might be relevant • Directivity • Are accelerated electrons and ions beamed? • Coronal Sources • What are the properties of the acceleration site? • What is the role and properties of trapping in the corona? • Ions • What are the spatial characteristics of ion acceleration and propagation?

  3. Three Approaches to measuring Directivity • Imaging Polarimetry • Requires high sensitivity and well-conceived instrumentation • Directivity • Requires cross-calibrated measurements with good spectral resolution from 2 or more vantage points • At least one measurement should be imaging/spectroscopy • Instrumentation does not require exceptionally high angular resolution or sensitivity • Albedo • Requires good image quality and high spatial resolution at hard x-ray energies • Yields directivity and footpoint height

  4. Coronal Sources • Requires ability to cleanly separate coronal sources from bright footpoint sources • Requires ability to measure multiple size scales • Good quality imaging spectroscopy is essential • Options • High dynamic range • Limb occultation

  5. Ion Imaging • Priorities: • Neutron capture line (2.2 MeV) • Electron bremsstrahlung continuum (<100 t o > 300keV) • Annihilation line (511 kev) • Prompt lines • Requires much more sensitivity • Requires low background • Excellent spectral resolution is highly desirable but may not be essential • Needs moderately good (~10”) spatial resolution • ENA imaging • High sensiivity required • Moderate spatial resolution (~1 arcminute)

  6. Wish List • Maintain current strengths • Excellent absolute and co-location accuracy • High spectral resolution and uniformity of response • Hard X-rays • Much better dynamic range • Somewhat higher angular resolution (~1”) • Gamma-rays • Much better angular resolution (<10”) • MUCH better sensitivity and background suppression • ENA imaging capability • Sensitivity to Magnetic fields

  7. Enabling Technologies for New Flare Observations • Focusing optics • Direct imaging - Christe will discuss • Digital correlators enable radio imaging/spectroscopy -Steven White discussed • Ge detectors with 3-D positioning • Grid technology  subarcsecond HXR imaging  compact collimators • CZT and other pixelated detector capability • TRL of booms – Albert Shih will discuss application • Advances in on-board and ground data systems • Steady progress in polarization instrumentation - McConnell • Etc, etc

  8. Enabling Technologies for New Flare Observations • Focusing optics • Direct imaging - Christe will discuss • Digital correlators enable radio imaging/spectroscopy -Steven White discussed • Ge detectors with 3-D positioning • Grid technology  subarcsecond HXR imaging  compact collimators • CZT and other pixelated detector capability • TRL of booms – Albert Shih will discuss application • Advances in on-board and ground data systems • Steady progress in polarization instrumentation - McConnell • Etc, etc

  9. 3D-Germanium Detectors • Germanium detectors • 7.5cm × 7.5cm × 1.5cm • Orthogonal strips on opposite faces • 0.5-mm pitch • Locate each energy deposition to ~0.1 mm3 • Compton-scatter track reconstruction • Gives time, energy, location and directional information on each photon 9

  10. GRIPSGamma-Ray Imaging Polarimeter for Solar flaresP.I. Bob Lin, UCB First balloon flight: spring 2012 Shih will discuss adaptation to s/c Multi-pitch rotating modulator 8 m boom length Spectrometer/polarimeter with 0.5mm spatial resolution Detector provides time, energy, location and a polarization signature of each photon with low background

  11. Two Perspectives on GRIPS Imaging Time sequence of counts beneath each mask location/orientation measures one visibility • Each photon identifies a set of ‘probability stripes’ on Sun from which it could have originated • Observations of many photons  image uv plane 1 3 10 Continuous set of gid pitches measures solid annulus in uv plane Radial profile of PSF 30 100 1000

  12. Adaptation to HXR Energies • Could combine MPRM approach with pixelated CZT detectors to achieve subarcsecond, high-dynamic range imaging spectroscopy in a ~3m long package

  13. Detector and Grid Technology Implications • High resolution X-ray imaging spectroscopy can be done with small insturments • ~10^2 of resources of RHESSI • Feasible to put such instruments on heliocentric orbits •  Directivity •  Occultation of limb sources Can simultaneously follow the spectral and temporal evolution of coronal and footpoint sources from 3-200 keV with no dynamic range limitations

  14. Examples of Compact HXR Instrumentation

  15. Thank you

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