[Halld-physics] Primakov eta hadronic background

[Alexander Somov]

Hello Richard,

I broke down hadronic background into 2 categories:
  1. With eta(s)  ( eta angle < 1.6 deg) in the final state
  2. The rest

In the very begining I observed that background from 1) dominates,
so that I focused on 1). I could process through geant this subsample
much faster.

I am looking at 2) right now.

---

For both backgrounds, I reconstruct 2 photons and require them to
be within eta mass.


Cheers,
        Alex



On Wed, 2 Dec 2009, Richard Jones wrote:

> Alex,
>
> Thank you for the quick study you did.  However I am puzzled by the suggested 
> conclusion.  By combinatorial background, one means etas that are 
> reconstructed out of photons that did not come from an eta.  Maybe this is 
> small, but it is going to take considerable work to show it.
>
> Alexander Somov wrote:
>> ( The inclusive eta background should dominate combinatorial bg)
>> 
> ... in light of ...
>> (I selected events containing at least one eta in the final
>> state  with an angle < 1.6 deg, and processed these events
>> through Geant).
>> 
> To study the combinatoric background you need to look at the inclusive 
> sample.  Why should you require an eta if you are looking for 2gamma 
> combinatorial background under the eta?  I believe this restriction can lead 
> to a severe underestimate of the combinatorial background under the eta.
>
> -Richard Jones
>
>