[Frost] Systematic uncertainty estimate

[Michael Dugger]

Thanks.

That is what I thought.

The figures you show have me worried and I just want to make sure I 
understand them.

-Michael

On Thu, 23 Aug 2012, Steffen Strauch wrote:

> 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
>>>
>>>
>
>