QA - Stability of Multiplicity vs. Vz

These results follow up the heavy flavor hypernews discussion about centrality selection for Au+Au Run 7: http://www.star.bnl.gov/HyperNews-star/protected/get/heavy/2050/1/1/1/1.html

• Data set: 42.4 M events of AuAu 200GeV run 7, "2007ProductionMinBias" (P08ic)
• Trigger ID: 200013 (ZDC coincidence+VPD cut at 5 cm. Killer bits off.)
• Event cuts: only events with bad vertex removed
• Global track cuts: similar to cuts for Reference Multiplicity
  • No. Fit Pts > 10
  • |η| < 0.5
  • Vertex 3D-Dca < 3cm

General conclusion: Refenrence Mult. and No. of global tracks with cuts similar to Refenrence Mult. have similar behavior.

Fig 1: Mean of Reference Multiplicity and No. of. global tracks (with cuts like for RefMult) vs Vertex-Z position

Fig 2: Reference Multiplicity for different classes of Vz

Fig 3: No. of global tracks (with cuts like for RefMult) for different classes of Vz

Fig. 4: Reference Multiplicity vs Vz

Fig. 5:  No. of global tracks with cuts like for RefMult vs Vz

Fig. 6: Vz of primary (highest ranked) vertex

Fig. 7: No. of primary vertices per event.