[Halld-tagger] question about multiple hits in Nathan's analysis

[Nathan Sparks]

Hi Dan,

I will start working on a more detailed study of the multiple hits on Monday.
Richard, Alex, and I discussed alternative explanations (other than scattering in the plastic tubes) yesterday after the meeting.

I agree that looking for coincidences between counters in the same plane is a good place to start.
After that I will look at some low rate runs from the spring to check if the fraction of multiple hits (after accidental subtraction) has a rate dependence.

-Nathan

> On Oct 7, 2016, at 5:11 PM, Daniel Sober <sober at cua.edu> wrote:
> 
> After a long vacation break I am getting back to my tagger Monte Carlo calculations.  I have no new results yet, but would like to point out something significant about the multiple TAGH hits in the data which Nathan presented today:
>   
> Nathan sees an enhancement over randoms in double hits for counter number differences as large as 15,  while my simulations, including beam distribution, bremsstrahlung angular distribution, and multiple scattering in the exit window and the counters, show NO coincidences between TAGH counters whose numbers differ by more than 1.  I doubt that multiple scattering in the plastic tubes can cause such a large effect -- it will be very interesting to see whether their removal will make a big difference.
> 
> In particular, in Nathan's Slide 8,  differences d=2 and d=3 include coincidences between counters in the SAME PLANE.  If this is due to scattering in a counter (or plastic tube), the angles involved must be huge, of order 20 degrees.
> 
> Nathan:  could you break out the data for multiple hits to look for coincidences between counters in the same plane?  If these are appreciable, then we need to think hard about where these events come from.
> 
> Dan
> 
> 
> 
> 
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