First look at EP resolution in 27 GeV Au+Au
A first look at the event-plane resolution for Au+Au collisions at 27 GeV, compared to the same quantities from the Isobar collisions at 200 GeV.
Executive summary
Below find the EP resolution for both the isobars and the Au+Au. Note that panel 6 in each figure is the refMult distribution, with rough centrality classes defined according to:
For the isobars, I used trigger word 600031 and 2 (both vpdmb). For the Au+Au, I used 610011 (mb).
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Figures 1-3: Resolutions of the n=1,2,3 order Event Plane as a function of "centrality" (based on RefMult) for 200 GeV isobar collisions. The EPs have been shift-corrected. As can be seen, the n=2 and 3 order planes don't need much flattening, but the raw n=1 plane distribution is quite non-flat. There are six panels in each figure. Panel 1: the nth EP resolution (after shift correcting); panel 2: for midcentral collisions (10%-40%), East versus West EP angle; panel 3: East EPD EP distribution raw (red) and shift-corrected (blue); panel 4: same thing, but for West EPD; Panel 5: <cos(n*DeltaPhi)>; Panel 6 is the same in each figure, and is just the refMult distribution, with the centrality cuts used in the analysis.
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Figures 4-6: The same quantities as in figures 1-3, but for the 27 GeV Au+Au collisions. Resolutions of the n=1,2,3 order Event Plane as a function of "centrality" (based on RefMult) for 27 GeV Au+Au collisions. The EPs have been shift-corrected. As can be seen, the n=2 and 3 order planes don't need much flattening, but the raw n=1 plane distribution is quite non-flat. There are six panels in each figure. Panel 1: the nth EP resolution (after shift correcting); panel 2: for midcentral collisions (10%-40%), East versus West EP angle; panel 3: East EPD EP distribution raw (red) and shift-corrected (blue); panel 4: same thing, but for West EPD; Panel 5: <cos(n*DeltaPhi)>; Panel 6 is the same in each figure, and is just the refMult distribution, with the centrality cuts used in the analysis.
Executive summary
- interestingly and conveniently, the refMult for these systems is quite similar, so we can use the same cuts to define centrality classes, if we only want to do a rough job on centrality
- the EP resolution for the Au+Au is much worse than for the isobars. Something is clearly not right. This is even worse than with the BBC in run 11.
Below find the EP resolution for both the isobars and the Au+Au. Note that panel 6 in each figure is the refMult distribution, with rough centrality classes defined according to:
The % of events satisfying the cuts is shown by colored text in the plot. Clearly these cuts are approximate. What is also clear, however, is that the same cuts can be applied to the AuAu as to the Isobars! Nice.if(Multiplicity <= 19) CentId = -1; // > 80%
else if (Multiplicity > 19 && Multiplicity <= 31) CentId = 0; // 70-80%
else if (Multiplicity > 31 && Multiplicity <= 46) CentId = 1; // 60-70%
else if (Multiplicity > 46 && Multiplicity <= 67) CentId = 2; // 50-60%
else if (Multiplicity > 67 && Multiplicity <= 93) CentId = 3; // 40-50%
else if (Multiplicity > 93 && Multiplicity <= 128) CentId = 4; // 30-40%
else if (Multiplicity > 128 && Multiplicity <= 172) CentId = 5; // 20-30%
else if (Multiplicity > 172 && Multiplicity <= 230) CentId = 6; // 10-20%
else if (Multiplicity > 230 && Multiplicity <= 267) CentId = 7; // 5-10%
else if (Multiplicity > 267) CentId = 8; // 0-5%
For the isobars, I used trigger word 600031 and 2 (both vpdmb). For the Au+Au, I used 610011 (mb).
Figures 1-3: Resolutions of the n=1,2,3 order Event Plane as a function of "centrality" (based on RefMult) for 200 GeV isobar collisions. The EPs have been shift-corrected. As can be seen, the n=2 and 3 order planes don't need much flattening, but the raw n=1 plane distribution is quite non-flat. There are six panels in each figure. Panel 1: the nth EP resolution (after shift correcting); panel 2: for midcentral collisions (10%-40%), East versus West EP angle; panel 3: East EPD EP distribution raw (red) and shift-corrected (blue); panel 4: same thing, but for West EPD; Panel 5: <cos(n*DeltaPhi)>; Panel 6 is the same in each figure, and is just the refMult distribution, with the centrality cuts used in the analysis.
Figures 4-6: The same quantities as in figures 1-3, but for the 27 GeV Au+Au collisions. Resolutions of the n=1,2,3 order Event Plane as a function of "centrality" (based on RefMult) for 27 GeV Au+Au collisions. The EPs have been shift-corrected. As can be seen, the n=2 and 3 order planes don't need much flattening, but the raw n=1 plane distribution is quite non-flat. There are six panels in each figure. Panel 1: the nth EP resolution (after shift correcting); panel 2: for midcentral collisions (10%-40%), East versus West EP angle; panel 3: East EPD EP distribution raw (red) and shift-corrected (blue); panel 4: same thing, but for West EPD; Panel 5: <cos(n*DeltaPhi)>; Panel 6 is the same in each figure, and is just the refMult distribution, with the centrality cuts used in the analysis.
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