dE/dx dependence on Φ for productions 2011AuAu200, 2014AuAu15, 2014AuAu200, 2015pp200, and 2016AuAu200 (StiCA).

It is presented side by side comparison of measured π peak position with respect to expected one versus Φ of the last track point for 0.5 < p_T < 3 GeV/c.

• Φ of the last track point is given in range [0,360^o]. For east part of TPC (η < 0) 360 is subtracted from Φ.
• Fig.1 presents the profile histogram for the positive and negative tracks.
• Fig.2 presents the 2D-plot for positive tracks, and
• Fig.3 presents the 2D-plot for negative tracks.

The observations are the following:

• The Φ structure is observed for all productions and associated with sectors (30^o period). The most of the deviations are within ±2%. The most drastic (±6-8%) deviations are observed for (West) sectors 9 (180^o), 8 (210^o), 6 (270^o), and 5 (300^o).
• This confirms observation by Florian Seck presented on LFS-UPS meeting, December 5, 2016.
• The comparison between data for 2011 and 2014AuAu15 (low luminosity) and 2014AuAu200 and 2016 (normal luminosity) shows that the amplitude of the abnormal deviations is increase by a factor of ~2.
• The variation within
  • a sector (with period (30^o) and
  • dependence on luminosty
  gives a possible explanation that this is due to Gatting Grid Leak
  • because density of ions is varying with radius ~ 1/(D/cos(Φ))², and
  • will be essential for Leak between the first anode wire and IFC.
  • Jumps for sectors 9, 8, 6, 5 could be explained (A.N.Lebedev) by a shift of the first (field) wire by ~0.5 mm.