Photon Counting Update - Remove clones by applying a cut on track VP hits and add quadratic background model

I also tried to remove clones by applying a cut on track VP hits - see page 6 here

After applying this track VP hits cut, the RICH1 track entering position looks good - see below

The yield is now more stable in RICH2, but RICH1 still shows some differences between runs, and I couldn't make it consistent. At least, playing with track qualities and background models, it seems that in certain runs there is less background, resulting in a higher yield. However, I still need to understand why.