2008.11.21 Energy fraction from 2x1 vs. 2x2 vs. 3x3 or 0.7 radius: rapidity dependence

Ilya Selyuzhenkov November 21, 2008

Data sets:

2x1, 2x2, and 3x3 clusters definition:

  • 3x3 cluster: tower energy sum for 3x3 patch around highest tower
  • 2x2 cluster: tower energy sum for 2x2 patch
    which are closest to 3x3 tower patch centroid.
    3x3 tower patch centroid is defined based
    on tower energies weighted wrt tower centers:
    centroid = sum{E_tow * r_tow} / sum{E_tow}.
    Here r_tow=(x_tow, y_tow) denotes tower center.
  • 2x1 cluster: tower energy sum for high tower plus second highest tower in 3x3 patch
  • r=0.7 energy is calculated based on towers
    within a radius of 0.7 (in delta phi and eta) from high tower

Cuts applied

all gamma-jet candidate selection cuts except 3x3/r=0.7 energy isolation cut


There are two sets of figures in links below:

  • Number of counts for a given energy fraction
  • Yield above given energy fraction
    [figures with right integral in the caption]

    Yield is defined as the integral above given energy fraction
    up to the maximum value of 1

Gamma candidate detector eta < 1.5
(eta region where we do have most of the TPC tracking):

  1. Cluster energy fraction in 0.7 radius
  2. 2x1 and 2x2 cluster energy fraction in 3x3 patch

Gamma candidate detector eta > 1.5:
(smaller tower size)

  1. Cluster energy fraction in 0.7 radius
  2. 2x1 and 2x2 cluster energy fraction in 3x3 patch

Some observation

  • For pre1>0 condition (contains most of events)
    yield in Monte-Carlo for eta > 1.5 case
    is about factor of two different than that from pp2006 data,
    while for eta < 1.5 Monte-Carlo yield agrees with data within 10-15%.
    This could be due to trigger effect?
  • For pre1=0 case yiled for both eta > 1.5 and eta < 1.5 are different in data and MC
    This could be due to migration of counts from pre1=0 to pre1>0
    in pp2006 data due to more material budget than it is Monte-Carlo
  • For pre1=0 condition pp2006 data shapes are not reproduced by gamma-jet Monte-Carlo.
    With a larger cluster size (2x1 -> 3x3) the pp2006 and MC gamma-jet shapes
    are getting closer to each other.
  • For pre1>0 condition (with statistics available),
    pp2006 data shapes are consistent with QCD Monte-Carlo.