[Crater-team] CRaTER LET spectra - Compton edges?

[Jody Wilson]

Hey Andrew,

Yes, that may be the powers-of-two (8, 16, 32) channel pattern that 
shows up in LET spectra.  The previous plot had 5-pixel smoothing. Here 
it is with 17-pixel smoothing, which would cancel out the 16-channel 
pattern.  The low-energy features aren't there any more.



On 3/13/2019 10:50 AM, Andrew Jordan wrote:
> Out of curiosity, is there a periodicity in the plot that's ~0.3 MeV 
> "long"? It's most obvious at 4-5 MeV, but I can see it from 1 MeV to 
> almost 6 MeV.
>
>
>
> On 3/13/19 10:41 AM, Jody Wilson wrote:
>> Hi CRaTER folks,
>>
>> A "work in progress" panel that I'll include in my LPSC poster next 
>> week is a ratio of the whole-mission *mare* LET spectrum to the 
>> *highlands* LET spectrum.  The idea is that mare-rich elements should 
>> make positive spectral features in this ratio, while highlands-rich 
>> elements should produce dips in the ratio.
>>
>>
>>
>>
>> New since I last addressed this:
>>
>> 1) Wouter pointed out that gamma ray Compton edges should be more 
>> prominent in our data than the primary spectral lines, since CRaTER 
>> is not at all optimized to collect all of the energy from a given 
>> gamma ray photon.  So I'm only labeling the energies of the Compton 
>> edges now.
>>
>> 2) Andrew and Wouter have been searching for new methods of 
>> normalizing CRaTER data for making maps using combinations of singles 
>> rates and the "linger time" of LRO over the Moon.  Along the way 
>> Andrew discovered that the lunar map of the raw D4 singles rate looks 
>> kind of similar to the SEPI map (ditto the raw D6 singles rate map), 
>> which means that whatever is lighting up the highlands in the SEPI 
>> map is registering in D4 as well as D6.  Therefore in the above plot 
>> I've used the mare/highlands ratio from both D4 and D6 to improve the 
>> signal.
>>
>> Notes:
>>
>> Silicon and oxygen should make the brightest features due to their 
>> high overall abundance, but they're almost as abundant in the mare as 
>> the highlands, so they should basically cancel out in this ratio, and 
>> therefore I'm not labeling them.
>>
>>
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>

-- 
Jody Wilson
Space Science Center
University of New Hampshire
---
Did you buy $ilver today?

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