[Frost] Systematic uncertainty estimate

[Steffen Strauch]

Dear Michael,

The 4He data was supposed to simulate the effect of the butanol in our present analysis.  So in all cases I assumed for the reaction quasi-free production and gamma p in the initial state.

All the best,
Steffen


On Aug 23, 2012, at 11:46 AM, Michael Dugger wrote:

> 
> Hi,
> 
> I briefly looked at the proposal and did not see how the missing mass reaction was defined for the g3 data.
> 
> We need to know if the assumed reaction for the missing mass using g3 data was
> gamma p -> pi+ X
> Or
> gamma He -> pi+ X
> Or
> something else.
> 
> for the pi0 reaction is the reaction
> gamma p -> p X
> gamma He -> p X
> gamma He -> He X
> ?
> 
> -Michael
> 
> On Wed, 22 Aug 2012, Steffen Strauch wrote:
> 
>> Dear Michael,
>> 
>> Your study of the bound-nucleon contributions from He4, O16, and C12 reminded me that I looked at the quasi-free single-pion production off 4He (g3a data) when we prepared the proposal PR03-105.  Figure 15 in the proposal shows the missing-mass distributions.  The shape of these distributions are comparable to what I get for the pi+n channel using the C12-region data of g9a.  The one exception is a narrow
>> peak in the g9a distribution at the mass of the neutron.  The g3a data do not show any sign of such a peak.  Looking into this in more detail I am starting to believe that the FROST C12 data is contaminated with hydrogen on the downstream side of the C12 target.  You can find some plots to illustrate my points at:
>> 
>> http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Steffen%27s_analysis_page#Carbon_Target
>> 
>> For my analysis this is a big issue as it directly affects the dilution.  In my analysis I use the scaled carbon distribution for background subtraction.  The problem likely affects other analyses of the FROST data also.  We can discuss this in more detail at tomorrow's meeting.
>> 
>> All the best,
>> Steffen
>> 
>> 
>> 
>> On Aug 17, 2012, at 6:17 PM, Michael Dugger wrote:
>> 
>>> 
>>> Hi,
>>> 
>>> We have an estimate for the systematic uncertainty due to He4 and O16 not
>>> being the same as C12.
>>> 
>>> A presentation regarding the estimate can be found at
>>> http://www.jlab.org/Hall-B/secure/g9/ASU/recoil2b.pdf
>>> 
>>> Please feel free to give comments and suggestions. The most important
>>> thing is to determine if there is a consensus as to the general method
>>> used for obtaining the estimate. If the FROST group thinks the method is
>>> OK, then we can figure out where the model needs to be made more
>>> realistic. If the method is not OK, I need some suggestions on how to
>>> proceed.
>>> 
>>> Thanks for your time.
>>> 
>>> Sincerely,
>>> Michael
>>> _______________________________________________
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>>> Frost at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/frost
>> 
>>