[Crater-team] Another six months of D5/D6 LET spectrum tracking

[Jody Wilson]

Getting actual *spectra* from triples is impressive!   Thanks, Mark!

-Jody



On 10/4/2021 9:48 PM, Mark D Looper wrote:
>
> Hello—
>
>                 With FY21 over, and with it the scramble to finish 
> projects whose funding turned into a pumpkin at midnight last 
> Thursday, I can start returning my focus to CRaTER.  The first thing I 
> wanted to do is add another six-month extension to the GCR LET 
> spectrum time history that we published in Space Weather last year; I 
> attach one image with the full D5/D6 spectra, another with the spectra 
> blown up in the H/He region to show the (subtle) changes more readily, 
> and a third extending the plot of dose rate that we showed in the 
> paper’s appendix.  As a reminder, the last period in the full 
> peer-reviewed paper was 2019248-2020066, which showed intensity about 
> 4% above the already record-setting intensity (per Mewaldt et al.) in 
> 2009259-2010066, which is the red curve in the spectra plots. For the 
> cover image on the Space Weather issue, we added 2020066-2020248, 
> shown in blue on the plots; this was 6% above the start of the mission 
> and (as seen in the dose plot) was the peak during the past solar 
> minimum.  Since then the intensity has been declining, but the new 
> black curve for 2021066-2021248 is still slightly above the red one 
> from the start of the mission.  (The green curve for 2014066-2014248 
> is the lowest intensity measured, from the last solar maximum.)
>
>                 For quite some time I have been meaning to pull out a 
> clean triples proton measurement from the quiet-time GCR “swoosh” with 
> three-detector consistency checks; unfortunately, there is only a very 
> narrow energy window between the tip of the swoosh and where it runs 
> into the scruff near the origin of a two-detector crossplot. However, 
> there’s a decent span of energies along the helium swoosh before it 
> runs into the proton track, so I had also begun to define cuts to 
> select that out; and, looking at the D135 high-Z crossplots, there are 
> clear swooshes for many elements, albeit with more or less poor 
> statistics.  Still, using Geant4 simulations to calculate effective 
> geometry factors (i.e., accounting for particles lost to fragmentation 
> in the stack), I think we can pull out clean time series for quite a 
> few elements over an entire solar cycle with minimal background 
> (during quiet times – I still haven’t done much to figure out the SEP 
> problems).  These will cover energies for each species that are near 
> or below the GCR peak, i.e., that both have significant intensity and 
> are strongly modulated by solar activity.  My main focus still needs 
> to be on pulling together that long-delayed paper on the effects of 
> H/H2O on albedo; however, this may be of value in the “mission 
> support” part of our ESM5 proposal, as (in particular) I think we go 
> to higher energies than ACE CRIS/SIS for the lighter elements, albeit 
> with less sensitivity.
>
> Talk to you Wednesday—
>
> --Mark Looper
>
> Mark D. Looper
> Space Sciences Department
> The Aerospace Corporation
> M/S M2-260
> P.O. Box 92957
> Los Angeles, CA 90009-2957
> Mobile: 310-529-3406
> Voicemail: 310-336-6302
>
> Publications: https://www.loopers.org/curvitae.html 
> <https://www.loopers.org/curvitae.html>
>
>
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