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RHESSI gamma-ray analysis

RHESSI gamma-ray analysis. New DRM. Photon bins now go up to 150 MeV No front/rear anticoincidence Partial response elements cannot be removed. Example. segs =[ bytarr (9),1,0,bytarr(7)+1] hsi_rd_ct_edges,20,es ps =[es,11000.+1000.* findgen (90)]

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RHESSI gamma-ray analysis

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  1. RHESSI gamma-ray analysis

  2. New DRM • Photon bins now go up to 150 MeV • No front/rear anticoincidence • Partial response elements cannot be removed

  3. Example segs=[bytarr(9),1,0,bytarr(7)+1]hsi_rd_ct_edges,20,esps=[es,11000.+1000.*findgen(90)] hessi_build_srm,es,segs,srm,geo,/direct,ph_edges=ps,$ time_wanted='2005-Jan-20‘ Update: currently the default, but does not currently work for the front segments

  4. Artifacts • Full-scale artifact • Excess plateau around ~3 MeV • Depleted regions (especially detector 8) • Half-scale artifact • Primarily in detectors 5 and 8 • Excess plateau around ~1.6 MeV • Dropouts in the rear segments • …

  5. Artifact correction • Artifact regions are excised where appropriate from each detector • Given gain differences, there will still be data at all energies if enough detectors are used • Response matrix is modified in the same manner • Artifact-corrected spectra can be fit in OSPEX

  6. Example Need an spectrum object so either: • sp=hsi_spectrum() • hessi_data,sp=sp sp->filewrite,/build,/use_artifact_mask Update: selectable in the GUI

  7. Example

  8. Cosmetic correction • Artifact correction produces “dips” in count spectra that are aesthetically displeasing • Can scale the regions of the “dips” to correct for the now energy-dependent effective area • Due to off-diagonal response, the scaling is model-dependent • Cosmetic correction possible, but only after a valid best fit is first obtained

  9. Example

  10. Accessing Fermi/GBM data http://hesperia.gsfc.nasa.gov/fermi_solar/ Click on “Analyzing GBM Data in OSPEX” for more information

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