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Ulysses HISCALE Data Analysis Handbook


Appendix 9  Geometric Factor Study for the Deflected and Unscattered Electrons of HISCALE (Buckley MS Thesis)



The fact that HISCALE has other detectors that also count electrons provides a means of checking the calculated G-factors.  One way of doing this is to simply compare the fluxes of the deflected electrons with the other electron energy channels.  In particular, HISCALE also has the two foil detectors mentioned previously that detect electrons at low energies for specified passbands.  These channels and their passbands are presented in Table A9-4.


Table A9-4  LEFS electron passbands


Table A9.4


In order to compare one channel with another, it is necessary to first adjust the passband of one of the two channels to fit the passband of the other.  This can only be done if channels adjacent to the ones of interest exist, which they do in this case.  The approximation is also most valid for passbands that overlap fairly well to begin with.  The specific details of this passband adjustment procedure are presented in Section A9.10.  Once this passband adjustment of the raw count rates is made, and the results divided by the corresponding GDE, then the resulting ratios are electron fluxes from the different detectors.  If one is dealing with an isotropic event, the resulting electron fluxes should all be the same. 


Figure A9-15a shows such a comparison for the IDF.DAT version of the G-factors for an electron event occurring on day 301 of 1991.  The agreement between the channels is good, as indicated by the close overlap of each line with the other.  Figure A9-15b shows the same plot, except now the calculated values of G from Trial 10 are used.  The agreement is not as good, as can be seen from the poor overlap of the spectra.  In fact, it appears that for passband DE1, the geometric factor has been underestimated, and for DE4 it has been overestimated.  Figure A9-15c shows the spectra for the same event using the average G-factors of all eight trials.  The overlap is worse than before.  



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Updated 8/8/19, Cameron Crane


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Mission End Date: June 30, 2009

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