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

Ilya Selyuzhenkov November 21, 2008

### 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

### Results

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):

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

### 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.

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