[d2n-analysis-talk] Positron background simulation

[Zein-Eddine Meziani]

Hi Vahe,

Sorry but I totally forgot what details I mentioned until I saw your email.
 
I thought it is important to understand  the difference we observe in the ratio of positron over electron when using Bigbite with the two different polarities  versus when we derive the ratio from the same polarity, in this case negative polarity of Bigbite, but using the bend-down  over the bend-down events.  This second method, if it works, is powerful and allows to make the correction within the same set of data and for each spin state of the given data (we do not have positive polarity Bigbite data at 5 pass and we do not have them for each target spin state). I am hoping to be able to make corrections for the dilution and asymmetry of  electrons coming from e-e+ pairs in one shot.

>From Matts study of the e+/e- ratios in the two cases described above we see differences as the momentum gets lower.
I have been wondering whether it is acceptance issues or calibration issues. Thus I thought this could be studied with a good Monte-Carlo.
I am sure Matt can point you to his studies to see these differences and the question is whether we can understand why these two methods give different results. Then be able to correct our production data using the bend-down/bend-up technique.

Zein-Eddine

On Jan 13, 2012, at 2:20 PM, Vahe Mamyan wrote:

> Hi Zein-Eddine,
> 
> During  January 05 meeting you told me you would like to study positron contamination using bigbite simulation and 
> promised to send me some details. 
> 
> Vahe