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SPD Vertex in LHC09a4 (MB pp 10 TeV). 2009. Simple (manual) exercise. (complementary to CAF and Grid/alienPlugin tools). AliESDanalysis_aj.C macro to look at SPD vertex (X, Y, Z, NContributors)
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SPD Vertex in LHC09a4 (MB pp 10 TeV) 2009 Adam Jacholkowski
Simple (manual) exercise (complementary to CAF and Grid/alienPlugin tools) • AliESDanalysis_aj.C macro to look at SPD vertex (X, Y, Z, NContributors) • Run directly on 10 alien chunks (662,679,710,725,733,738,777,783,870,971) of the very last run 81342 (available yesterday) • Output histograms merged using hadd ROOT facility • Extracting few basic characteristics of the SPD vertex (GetStatus() = kTRUE events) Adam Jacholkowski
(Average X,Y-vertex when Vertexer3D fails) VertexerZ Adam Jacholkowski NOTE – tracklets selection/cuts different in Vertexer3D and Z
σ(Xvertex) vs NContributors (From CAF ) IN case VertexerZ is used XRes set to 50 mic While σ(x-diamond) = 60 mic [cm] Adam Jacholkowski
Few relevant numbers • Total number of analyzed events - 2000 • Vertexer “failed” (no valid hits/tracklets) in 276 cases (~14%) • In the remaining events Vertexer3D (more than 1 tracklet) succeeded in 71.7% of cases • So 28.3% of events have got only Z vertex from VertexerZ, while X and Y vertex taken from the average (0,0) vertex position • Consistent with high statistics CAF results Adam Jacholkowski
3 classes of SPD vertex events Most of them not triggering ! Adam Jacholkowski
New boolean functions in Vertexer (Francesco Prino, commited by Jouri – revision 31911) • To make easier retrieval of the information on the actual Vertexer used: • IsFromVertexer3D() • IsFromVertexerZ() • While previously vtxESDGetTitle() needed • TString vtitle = vtxSPDGetTitle() • If( vtitle.Contains(“vertexer: 3D”)) { ….. • Where vtxSPD = fESDGetPrimaryVertexSPD() Adam Jacholkowski
ALICE coordinates Adam Jacholkowski