[Frost] Tagger correction analysis

[Eugene Pasyuk]

Hi Brian,

Interesting results. I thing it gives us some clues. Particularly those 
depletions in phi distributions. The dip for CH2 at ~1.6 radians (close 
to 90 degrees) is probably coming from the fact that when particle is 
emitted perpendicualrly to the beam it passes through the significant 
amount of material. On average equal to the radius of the target which 
is 7.5 mm. The is seen only for pions because protons just dont go at 
these large angles. Now we need to look in the geometry and find what 
corresponds to 0.6 radian from the center of butanol and 0.4 radians 
from the CH2. It must be some thick material along this direction or 
some corner of volume.

Brian M. and Mike: could you take a look at this? You figured out all 
the geometry. It also may be related to the start counter. We need to 
check if the ST offset is correct.

-Eugene






On 10/12/10 3:28 PM, Brian Vernarsky wrote:
> Greetings FROST list,
>
> I have been continuing to work on the discrepancy between the targets
> in the tagger correction and to that end have looked into the proton
> momentum and the energy loss calculations.  I have put together a
> document presenting all that I've looked into which is linked below.
> I present a few questions or discrepancies I wouldn't expect, but
> there may be valid reasons for them to exist, so please let me know if
> you see anything that has an obvious answer or reason.  Please let me
> know if you have any questions.  The document can be found at:
>
> http://www.andrew.cmu.edu/user/bvernars/FROST_tagger_update_10_12_2010.pdf
>
> Brian
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