Ilya Selyuzhenkov May 21, 2008

EEMC SMD data-driven library: some eta-meson QA plots

Data sample:

• Subset of 441 eta-meson candidates from Will's analysis.

• additional QA info (detector eta, pre1, pre2, etc)
  has been added to pi0-tree reader script:
  /star/institutions/iucf/wwjacobs/newEtas_fromPi0finder/ReadEtaTree.C

• pi0 trees from this RCF directory has been used to regenerate etas NTuple:
  /star/institutions/iucf/wwjacobs/newEtas_fromPi0finder/out_23/

Some observations:

• eta-meson purity within the invariant mass region [0.5, 0.65] is about 72%

• Most of the eta-candidates has detector pseudorapidity less or about 1.4,
  what may limits applicability of data-driven shower shapes
  derived from these candidates for higher pseudo-rapidity region,
  where we have most of the background for the gamma-jet
  analysis due to lack of TPC tracking

• z-vertex distribution is very asymmetric, and peaked around -50cm.
  Only a few candidates has a positive z-vertex values.

Figure 1: Eta-meson invariant mass with signal and background fits and ratio (upper left).
Pseudorapidity [detector and wrt vertex] distributions (right top and bottom plots),
vertex z distributions (bottom left)

Figure 2:2D plots for the eta-meson invariant mass vs
azimuthal angle (upper left), pseudorapidity (upper right),
z-vertex (bottom right), and detector pseudorapidity (bottom right)