2nd peak in DCAz distribution in RUN14 AuAu 200 HFT NPE analysis
- I used DCAz definded by (z value of 2-dim DCA point) - (z value of primary vertex). The difference between DCAz3d and DCAz2d is only mean value of 2nd peak. the DCAz3d has smaller value of mean of 2nd peak. The trend is same.  
- There are strong correlation with pT (linear as function of pT), Vz (>3cm), ZDC rate (<60k) and particle pieces (hadrons only, no electron!).
- and there are weak correlation with RUN/day number and centrality.
- and charge, PID method, kaon-pion-proton are independent of 2nd peak in DCAz distribution.
- Zhenyu: small statistics test with pion (~1% of total pion) to compare similar level of statistic with electrons. and ZDC rate also. What happen before day 107? Show this to HFT list. 
- Yaping:  agree with Yifei’s suggestions and include the DCAz checks into HF meeting slides for more comments.